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Bo- I did read this link and it helped explain why wind helps us...to a certain degree.     http://www.ces.ncsu.edu/depts/hort/hil/hil-705.html

Zone 10a at best after 2007 AND 2013, on SW facing hill, 1 1/2 miles from coast in Oceanside, CA. 30-98 degrees, and 45-80deg. about 95% of the time.

"The great workman of nature is time."   ,  "Genius is nothing but a great aptitude for patience."

-George-Louis Leclerc de Buffon-

I do some experiments and learning in my garden with palms so you don't have to experience the pain! Look at my old threads to find various observations and tips!

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Bill,

Thanks! Way too involved for me! I'll just stay out of this... :P

Bo-Göran

Leilani Estates, 25 mls/40 km south of Hilo, Big Island of Hawai'i. Elevation 880 ft/270 m. Average rainfall 140 inches/3550 mm

 

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happ,

I'm in the foothills of the San Gabriel Mountains.  According to the topo map, it's a 160 foot decline from my garden south to Foothill Blvd. and cold air drains right down the slope.  A gardener friend who lives at the end of a canyon not a mile away but 160 feet below me gets freezing temperatures several times every winter.  Before last weekend, I'd never had a freeze in the thirteen years I've lived at this house.

Fred Zone 10A

La Cañada, California at 1,600 ft. elevation in the foothills of the San Gabriel Mountains just north of Los Angeles

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(Dypsisdean @ Jan. 17 2007,01:37)

QUOTE
Scott,

I have stayed out of all of these frost/freeze radiational/advective discussions before because of all the complicated concepts involved, and the difficulty of communicating them accurately in a venue such as this.

Perhaps I should have stayed that course.  :) .

Dean,

Maybe I should have followed your lead, and not gotten involved in this discussion! :;):

You are right it is technical, and hard to explain exactly what you mean in this format.  And once you get started ,you feel you have to rebut every argument,that confonts you! :D

At the risk of getting deeper into this,I will answer your question regarding frost as precise as I can.

The frost I am referring to is HOAR frost (the white ice crystals you can see). And  YES I am talking about it on PALM fronds, leaves, NOT on the ground, grass. NOT on objects that loose heat much faster than plant tissue, like metal cars,windshields,patio chairs,lawn oraments, however when it forms on the plants,at least here it is on those things also!It can kinda look like it snowed to anyone who has never seen snow before,but it is not snow it's FROST!

And as I said before it will do a serious number on certain palm foliage if it forms on them, even if the ambient temp in the air isn't  below freezing! That was my reason for the  question in regard to this data base,  asking if the palms saw frost.

Scott

Titusville, FL

1/2 mile from the Indian River

USDA Zone COLD

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(gsn @ Jan. 17 2007,00:59)

QUOTE
There is a ridge that runs down the  western center of central florida,the LAKE WALES RIDGE,which I guess does help som people with micro climates.I think it is like a 150 feet high! A mountain of elevation in Florida :;):

Mike In Kurtisstown,

Just wondering if you read my post?(quote from it above)

Your comment is well taken though, as there will be some advatage to elevation  even here in Florida. That ridge is exactly the area you/I refered to. However I think as much as the elevation that area is surrounded by lakes which provide  a micro climate also.Get very far from those lakes and you will see the vegitation change!

And to be factually correct,there are some actual HILLS in north  Florida and the panhandle,but these are cancelled out by lattitude. It gets to cold up there to grown many crown shafted palms!

And yes in each yard, there will differences in temp,backyard might be warmer or colder than the front yard, south side might be warmer,even here in Florida. If you have a ditch the cold air will run to the ditch because cold air wants to find the lowest spot,to a point!

What really blew me away durning this California freeze event,was the amazing(to me anyway) difference  between temps sometimes  very short distances apart.

The topography out there is such that as best I can glean, makes hill tops warmer,and if you live at the bottom of a canyon,well your toast. It seems like it can be a 15 to 20 degree difference.We have nothing even remotely comparable with regard to elevation micro climates!

Scott

Titusville, FL

1/2 mile from the Indian River

USDA Zone COLD

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The issue of wind chill puzzled me when it was referred to by Florida gardeners as a negative factor.

The term, "wind chill" is rarely mentioned except in high elevations of the mountains.  And, I believe, I understand one reason why wind is considered lifesavers for California gardeners.  And it goes back to the fact that mountains play a major role in the climate of California.

For example, the citrus growers farms are basically located in the upper elevations of the San Joaquin valley above the lowest part of the valley floor.  The simple principle of colder air is heavier that warm air.

In & around Los Angeles are many foothills/mountain ranges.  When the cold air races down the mountainside is warms by being compressed/forced downward.  For example, Monday morning many readings in the low valleys were some 20 degrees warmer than the day before when the wind picked up yet in wind-protected area very closely it was freezing.

Hope this makes sense, as a way to explain by wind is beneficial to California gardens versus the wind accompanying a frost event in Florida,

Los Angeles/Pasadena

34° 10' N   118° 18' W

Elevation: 910'/278m

January Average Hi/Lo: 69F/50F

July Average Hi/Lo: 88F/66F

Average Rainfall: 19"/48cm

USDA 11/Sunset 23

http://cdec.water.ca.gov/cgi-progs/queryF?MTW

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(gsn @ Jan. 17 2007,06:42)

QUOTE
The frost I am referring to is HOAR frost (the white ice crystals you can see). And  YES I am talking about it on PALM fronds, leaves, NOT on the ground, grass. NOT on objects that loose heat much faster than plant tissue, like metal cars,windshields,patio chairs,lawn oraments, however when it forms on the plants,at least here it is on those things also!It can kinda look like it snowed to anyone who has never seen snow before,but it is not snow it's FROST!

And as I said before it will do a serious number on certain palm foliage if it forms on them, even if the ambient temp in the air isn't  below freezing! That was my reason for the  question in regard to this data base,  asking if the palms saw frost.

Scott,

I think I can see now where this "failure to communicate" is coming from. Now if I can only communicate it.  :)

Now keep in mind that I am speaking of my experiences in coastal San Diego County, but I believe this holds true for 99% of the "agricultural" areas of SoCal (i.e. south of Santa Barbara, excluding mountains and deserts).

We do not experience advective freezes here. If the wind is blowing, we don't freeze. We only experience bad freeze damage when the nights become very clear and very calm, and these conditions occur almost exclusively when it is also very very dry. The reason being these clear cold air masses arrive from the deserts to our east, and therefore are very dry.

Let me quote happ, our weatherman:

"The arctic air mass in California, unlike what Texas is currently observing, was extremely dry.  There was little if any clouds and with dew points/relative humidity well below 20% the night time temps plunged.  Low humidity is common during winter & certainly during offshore winds."

Do you ever get relative humidity well below 20% in Florida? In California there is never frost during the most severe freezes. That is why I breath a sigh of relief when I see frost forming (on the ground).

So to overly simplify this thinking --- when the air is moving and/or there is some moisture in the air (visible frost on the ground) we will not suffer a hard freeze.

If you will notice. Unless I missed one or two, everyone that mentioned frost in SoCal in the data section indicated "no frost." So for me, when I see frost (moisture), I know the air mass arrived from the north or west, and therefore has some maritime influence from the ocean, as opposed to the bitter dry Canadian cold arriving out of the east. These "maritime events" may get to 28,29,30 degrees on rare occasions in certain locations, but will never get colder than that unless it is dry, clear, and calm.

This leads in to my next point on why I believe you guys are so concerned about frost on your palm leaves and we are not. First, as I mentioned in another post, in most cases (at least in coastal areas here) we never experience frost on leaves. It is never cold and wet enough at the same time for this to occur. Again, when a Californian says frost, he means frost on the ground or other objects, not on foliage well above the ground.

This is what you said that explained to me why we view this topic differently: "FROST can be devastating here in Florida even when temps don't go below freezing. There are certain palms that will not tolerate FROST here at all veitchia,kings,foxtails, and royals are a few."

Yes, frost on the leaves of a tender palm will be damaging, because if a palm is damaged at 32 and there is ice on it, there will be damage, regardless of what the thermometer says. However, in California, if there is frost on the ground, that does not mean the air temp at 6 feet is 32. In fact it could be 35 resulting in no palm damage to the same tender palm. You say there was frost and my Vetchia was damaged, and we say we had frost and no damage. But again, no frost here indicates it could get much colder than that.

Another reason for your heightened concern with visible frost may be the following. I am guessing that as a rule you guys are growing more of the marginal palms than we are. That is, the palms that will damage at 30-32, and therefore frost formation on their leaves causes considerable damage. We just don't grow a lot of those palms here, the Veitchias, the Arecas, the Ptychospermas. I have none of those in my garden of a few hundred palms. IMO, we grow more of the palms that even if we saw frost formation on their leaves, it would not cause damage. So to us it is of little or no concern.

So, to summerize:

Frost to us is frost on the ground, and indicates a mild freeze which will not really damage the majority of the palms we are growing. No frost indicates a possible bitter dry cold event with temp readings in the mid to low 20 and severe damage to most palms.

Frost to you is frost on the leaves, and indicates damage to your marginal palms regardless of what the temp readings may actually indicate.

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Kona, on The Big Island
Hawaii - Land of Volcanoes

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Another point about this freeze that seems connected to the lack of moisture.  Feedback from the citrus growers was that orange/lemon/grapefruit/etc trees actually split as if hit by lightning when the moisture inside the tree structure froze! :o  Some farmers wrapped the tree trunks in burlap and soaked them in water as a way to keep water moving within the tree, if that makes sense.  But at 18F it was hopeless & they will need to buldoze the trees down and replant new trees.

Los Angeles/Pasadena

34° 10' N   118° 18' W

Elevation: 910'/278m

January Average Hi/Lo: 69F/50F

July Average Hi/Lo: 88F/66F

Average Rainfall: 19"/48cm

USDA 11/Sunset 23

http://cdec.water.ca.gov/cgi-progs/queryF?MTW

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(happ @ Jan. 17 2007,12:12)

QUOTE
Another point about this freeze that seems connected to the lack of moisture.  Feedback from the citrus growers was that orange/lemon/grapefruit/etc trees actually split as if hit by lightning when the moisture inside the tree structure froze! :o  Some farmers wrapped the tree trunks in burlap and soaked them in water as a way to keep water moving within the tree, if that makes sense.  But at 18F it was hopeless & they will need to buldoze the trees down and replant new trees.

Happ,

Another point I observed I know you will find of interest.

In the severe 1990 event (I remember it clearly) there was absolutely no moisture associated with the front whatsoever. Not even clouds. In this recent event there were brief episodes of initial rain and/or brief snow as witnessed in Riverside.

This may or may not have been why in this event the immediate coastal areas (my place) were spared this time and not in 1990. In 1990, I got almost as cold as areas 20 miles inland. In this event, there was some of the normal differential between coast and inland we usually see. That is, in '90 the ocean was totally taken out of the equation, and this time the very immediate coast was still partially influenced by the Pacific waters.

animated-volcano-image-0010.gif.71ccc48bfc1ec622a0adca187eabaaa4.gif

Kona, on The Big Island
Hawaii - Land of Volcanoes

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(happ @ Jan. 17 2007,15:38)

QUOTE
The issue of wind chill puzzled me when it was referred to by Florida gardeners as a negative factor.

The term, "wind chill" is rarely mentioned except in high elevations of the mountains.  And, I believe, I understand one reason why wind is considered lifesavers for California gardeners.  And it goes back to the fact that mountains play a major role in the climate of California.

For example, the citrus growers farms are basically located in the upper elevations of the San Joaquin valley above the lowest part of the valley floor.  The simple principle of colder air is heavier that warm air.

In & around Los Angeles are many foothills/mountain ranges.  When the cold air races down the mountainside is warms by being compressed/forced downward.  For example, Monday morning many readings in the low valleys were some 20 degrees warmer than the day before when the wind picked up yet in wind-protected area very closely it was freezing.

Hope this makes sense, as a way to explain by wind is beneficial to California gardens versus the wind accompanying a frost event in Florida,

Happ,

I don't know who brought up wind chill, but as far as I know WIND CHILL doesn't have any effect on plants!

People, yes our skin perceives the lower temp (wind chill) relative to how cold the ambient temp is, wind speed,and humidity combined. It is a peception rather than an actual fact! As far as I know plants don't perceive!

Wind doesn't accompany FROST here in Florida, if there is WIND we have no frost! Frost usually happens only on radiational nights with little or no wind! Wind here usually indicates an ADVECTIVE freeze,rather than a  radiational freeze.With the accompaning wind, temps usually drop,and worse there are no useful ways to protect plants,crops, ie overhead irrigation,wind machines,even heaters or smudge pots are pretty ineffective in and ADVECTIVE freeze, where the wind is above 10-15 MPH!

And looking at it from an outsiders point of view, from what I have observered on these threads.The wind you are talking about raises the temps,but only in certain areas! It doesn't raise the temp by compressing air,it raises the temp because all the cold air ,as you say is heavier,and is being pushed down hill by the WIND! Leaving warmer air in it's place.

This seems to buffer the temps in hill top or higher elevations,at the expense of your neighbor at the bottom of the hill, or bottom of the valley! What you don't want to be  in California,is the last house at the bottom of the hill!

Maybe that observation is incorrect, but that's the conclusion I have come too reading material here.  Because the freeze didn't quit  even when elevation microclimates warmed  even more. People as of today, Wednesday were still posting freezing temps.  

In a radiational freeze the air is stratifed cold air close to the surface,warmer air as you go farther aloft! This why in a radiational event farmers will try to mix this air using wind machines to mix the warmer air aloft,with the cold air near the surface,thus raising the surface air temp.  Helicopters have even been used to do this.This seems to be what the wind did for hilltop or elevated

microclimates out in California!

Scott

Titusville, FL

1/2 mile from the Indian River

USDA Zone COLD

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Dean,

Thanks for the reply and explainantion.

I think I will follow BO's lead and say this  is getting way to involved for me! :D

Suffice it to say things are different in California than Florida RE: frosts and freezes!

You guys are there on the ground, you know the terrain,it was your event unfortunately. So I will leave it to you Californians to discuss the details!

Good luck out there with the weather! :)

Scott

Titusville, FL

1/2 mile from the Indian River

USDA Zone COLD

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Thanks Scott  :D

You are right.  It is still chilly here especially today since a weak low pressure system moved down the coast over still cold low layers & some areas experienced brief snowfall down as low as 1500' Tonight will be cold but partly cloudy w/ higher dewpoints until the wind begins after midnight.  By then is should be warmer as the air mixes but humidity will lower again.

The groves here have wind machines since smudge pots aren't allowed in California [air quality regulations].  Also, thanks for the clarity on wind chill factors having nothing to do with plant life.  In summer we occasionally have heat indexes during hot/humid days [like last July].  Because of the humidity I think very little or any plants were damaged even with a maximum one day of 118F near Los Angeles  :o  Over 100 people died during the worse of the summer heat when air conditioning wasn't available but no crops were affected.  Dry heat can hurt palms & require lots of irrigation w/overhead sprinklers to combat.

Another comment about wind.  This freeze in Texas is wet & I believe windy yet the temps are at or below freezing even during the day in central Texas.  Wind blowing frozen air doesn't seem to warm the air, right ???

Los Angeles/Pasadena

34° 10' N   118° 18' W

Elevation: 910'/278m

January Average Hi/Lo: 69F/50F

July Average Hi/Lo: 88F/66F

Average Rainfall: 19"/48cm

USDA 11/Sunset 23

http://cdec.water.ca.gov/cgi-progs/queryF?MTW

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(spockvr6 @ Jan. 15 2007,22:20)

QUOTE
If you guys can.....please try and make a note if the palm being discussed was subjected to frost.

None of my damaged palms experienced any frost.

d

a

v

e

Let's keep our forum fun and friendly.

Any data in this post is provided 'as is' and in no event shall I be liable for any damages, including, without limitation, damages resulting from accuracy or lack thereof, insult, or lost profits or revenue, claims by third parties or for other similar costs, or any special, incidental, or consequential damages arising out of my opinion or the use of this data. The accuracy or reliability of the data is not guaranteed or warranted in any way and I disclaim liability of any kind whatsoever, including, without limitation, liability for quality, performance, merchantability and fitness for a particular purpose arising out of the use, or inability to use my data. Other terms may apply.

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Hmm.

Wind chill seems to apply to people not plants.

People have to keep their body temps up; if they don't they die.  Period.  The wind takes that body heat.  

Which is why you get VERY VERY uncomfy when it's cold out and it's windy.

Plants don't have that problem.  As long as they stay above whatever temp they're adapted to, they're okay.  The wind keeps the air moving, and, for whatever reason it doesn't freeze.  EDIT ==>  SEE JACK'S EXPLANATION BELOW #67

As long as the breeze blew on our terrible nights, it stayed about 40 F.  As soon as the wind died, the temps plummetted, down to about 30 and below, very fast, in an hour or less.

Brrr.  Wearing my flannel jammies . . . .

dave

Let's keep our forum fun and friendly.

Any data in this post is provided 'as is' and in no event shall I be liable for any damages, including, without limitation, damages resulting from accuracy or lack thereof, insult, or lost profits or revenue, claims by third parties or for other similar costs, or any special, incidental, or consequential damages arising out of my opinion or the use of this data. The accuracy or reliability of the data is not guaranteed or warranted in any way and I disclaim liability of any kind whatsoever, including, without limitation, liability for quality, performance, merchantability and fitness for a particular purpose arising out of the use, or inability to use my data. Other terms may apply.

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(Dypsisdean @ Jan. 17 2007,14:31)

QUOTE

(happ @ Jan. 17 2007,12:12)

QUOTE
Another point about this freeze that seems connected to the lack of moisture.  Feedback from the citrus growers was that orange/lemon/grapefruit/etc trees actually split as if hit by lightning when the moisture inside the tree structure froze! :o  Some farmers wrapped the tree trunks in burlap and soaked them in water as a way to keep water moving within the tree, if that makes sense.  But at 18F it was hopeless & they will need to buldoze the trees down and replant new trees.

Happ,

Another point I observed I know you will find of interest.

In the severe 1990 event (I remember it clearly) there was absolutely no moisture associated with the front whatsoever. Not even clouds. In this recent event there were brief episodes of initial rain and/or brief snow as witnessed in Riverside.

This may or may not have been why in this event the immediate coastal areas (my place) were spared this time and not in 1990. In 1990, I got almost as cold as areas 20 miles inland. In this event, there was some of the normal differential between coast and inland we usually see. That is, in '90 the ocean was totally taken out of the equation, and this time the very immediate coast was still partially influenced by the Pacific waters.

Dean- I know you are taking this all in from Hawaii, but from what I've heard and observed, this freeze was probably closer to the 1990 event than you think. I've talked to several coastal guys that were only 1 or 2 degrees warmer than the inland guys. It seems elevation/cold drainage was more important than coastal influence.

Zone 10a at best after 2007 AND 2013, on SW facing hill, 1 1/2 miles from coast in Oceanside, CA. 30-98 degrees, and 45-80deg. about 95% of the time.

"The great workman of nature is time."   ,  "Genius is nothing but a great aptitude for patience."

-George-Louis Leclerc de Buffon-

I do some experiments and learning in my garden with palms so you don't have to experience the pain! Look at my old threads to find various observations and tips!

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Bill,

Same thermometer, same exact location in Leucadia:

1990 --- 28 degrees

2007 --- 33.5 degrees

Quote from Jeff in Modesto:

"I am not so sure that we were even close to 1990's freeze. My coldest in 1990 was 22.9f... this year 26.9f."

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Kona, on The Big Island
Hawaii - Land of Volcanoes

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(Dypsisdean @ Jan. 17 2007,22:50)

QUOTE
Bill,

Same thermometer, same exact location in Leucadia:

1990 --- 28 degrees

2007 --- 33.5 degrees

Quote from Jeff in Modesto:

"I am not so sure that we were even close to 1990's freeze. My coldest in 1990 was 22.9f... this year 26.9f."

Didn't you mention you probably had a lot more canopy now?

As for Jeff, isn't he close to the center of the state?  ???

I was refering to Southern Cal.

Zone 10a at best after 2007 AND 2013, on SW facing hill, 1 1/2 miles from coast in Oceanside, CA. 30-98 degrees, and 45-80deg. about 95% of the time.

"The great workman of nature is time."   ,  "Genius is nothing but a great aptitude for patience."

-George-Louis Leclerc de Buffon-

I do some experiments and learning in my garden with palms so you don't have to experience the pain! Look at my old threads to find various observations and tips!

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I saw one weather report on TV that said it was as cold in some inland valley areas as it was in Julian(one of our local mountain communities) If this is true, was elevation a factor? Also, my Dendrocalumus Gigantea(bamboo) was torched to the top, about 30' tall.

Microclimates were the saviour for some...I spoke with Jeff Breusseau yesterday, and his hilltop Vista garden was spared..hardly any damage, and he has lots of the New Calidonia stuff. BTW, he agreed to share his data with the board, so he should be chiming in soon.

If global warming means I can grow Cocos Nucifera, then bring it on....

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Bill makes some real good points and my too my palm friendly pal Jack. That guy should sure be President of the US of A.

Good wishes to all down Altadena way.

I sure hope them forecasts we got over here were real wrong.

Regardez

(Jack Im sure willing to do a wife swap at any time - shucks we might even get a couple of half decent palms for them two!)

Regardez

Juan

Juan

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Yeah, from what I've heard the actual lows weren't as low as in 1990.

It's the duration that's so nasty this time.

One other lesson is that topography is all that will save you in So-Cal's lowlands in a freeze like this.  Proximity to the ocean will not.  You need to be on a high knob of land that the cold sinks completely away from.  

dave

Let's keep our forum fun and friendly.

Any data in this post is provided 'as is' and in no event shall I be liable for any damages, including, without limitation, damages resulting from accuracy or lack thereof, insult, or lost profits or revenue, claims by third parties or for other similar costs, or any special, incidental, or consequential damages arising out of my opinion or the use of this data. The accuracy or reliability of the data is not guaranteed or warranted in any way and I disclaim liability of any kind whatsoever, including, without limitation, liability for quality, performance, merchantability and fitness for a particular purpose arising out of the use, or inability to use my data. Other terms may apply.

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Dean,

I don't think you can take a single point (or even a couple points) to generalize about this freeze vs. 1990.  Lindbergh field got down to 35F this time and was 34F in 1990, so at least for coastal San Diego, it's pretty close.  I think that the 1990 freeze had a more general and widespread effect with very few places being spared, whereas this freeze seemed to have more locally restricted disasters.  I would bet that some areas had it worse this time than 1990 and vise versa.  It looks to me like LA was definitely better off this time than 1990, while San Diego was pretty comparable.

Matt

San Diego

0.6 Acres of a south facing, gently sloped dirt pile, soon to be impenetrable jungle

East of Mount Soledad, in the biggest cold sink in San Diego County.

Zone 10a (I hope), Sunset 24

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I'm learning a lot from these posts, so I thought I'd share a few things I know about wind....

First, almost all of the daily warming/nightly cooling of the atmosphere happens because it interacts with the surface of the earth.  So, if there is no advection and no wind then the temperature at altitudes of ~500m or more above the surface of the earth will not change much over the day.  The closer you get to the surface the larger the daily fluctuation in temperature, with the largest fluctuations just above the surface.  This means the temperature higher in the atmosphere will be colder than the surface temperature during the day and warmer than the surface temperature at night.  This is why, on calm nights, wind machines are so beneficial.  They mix the atmosphere to even out the temperature, which means the air near the surface gets warmer and the air higher up gets colder.

Obviously, during a windy advective freeze wind machines won't do anything.  The atmosphere is already being mixed by the wind.  This means the temperature at the surface will be warmer at night than it would have been without the wind, but it doesn't guarantee that the temperature will be above freezing!  This also means that the temperature during the day won't be very warm, like what we're seeing now in Texas.

Why don't we have advective freezes in SoCal?  Winds from the north can only reach us by 1) going over the ocean or 2) going over the mountains.  In the first case the cold airmass is moderated by the ocean, in the second case we benefit from compressional heating.  This is because descending air warms up according to the adiabatic lapse rate in the atmosphere.  In Florida the cold can come in over flat ground, which is why advective freezes happen there.

Scott - I agree with a lot of what you've said, I wasn't trying to pick a fight!  I hope it didn't come accross that way...

Jack Sayers

East Los Angeles

growing cold tolerant palms halfway between the equator and the arctic circle...

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Ineresting points Jack,

Since you seem  to have a good grasp of this stuff I have a question that has bugged me since I've lived here.

I'm from Oregon, and growing up I was always told (and observed it to be true) that the higher you go the colder it gets.  When it was near freezing, you woudl see that the frost formed at the tops of the hills and not at the bottoms.  This was true nearly all the time, and when it wasn't, we called it a "temperature inversion" and tended to get freezing rain.  

Down here in SoCal, it seems that "temperature inversions" are the norm, and people seem comfortable with the logical explanation that cold air sinks so the low spots are colder.  

So why is it that in Oregon (and Hawaii too) the standard temperature progression is a decrease of temperature (I think 2 degrees per 1000 ft or so) with altitude, while in SoCal, at least for the first couple thousand feet, there is very commonly an opposite relationship.  

I'm guessing from your previous post that it's probably because in Oregon and Hawaii there tends to be wind, and generally complete mixing of the air from the upper layers down.  But it's still funny that that most people seem comfortable that both scenarios "make sense".

Matt

San Diego

0.6 Acres of a south facing, gently sloped dirt pile, soon to be impenetrable jungle

East of Mount Soledad, in the biggest cold sink in San Diego County.

Zone 10a (I hope), Sunset 24

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(BS, Man about Palms @ Jan. 18 2007,03:12)

QUOTE

(Dypsisdean @ Jan. 17 2007,22:50)

QUOTE
Bill,

Same thermometer, same exact location in Leucadia:

1990 --- 28 degrees

2007 --- 33.5 degrees

Quote from Jeff in Modesto:

"I am not so sure that we were even close to 1990's freeze. My coldest in 1990 was 22.9f... this year 26.9f."

Didn't you mention you probably had a lot more canopy now?

As for Jeff, isn't he close to the center of the state?  ???

I was refering to Southern Cal.

Bill,

Yes, I have more surrounding canopy now, but the thermometer is still open to the sky.

But I still think that the same thermometer, in the exact same location, open to the same sky, is data worth respecting. And a 5 degree difference is considerable.

We are not in disagreement. This was a bad freeze, no doubt about it. However, from what I have seen and heard (and I am in Hawaii, so am not "on the ground"), it was not any worse than 1990. I am fairly certain the immediate coastal areas were not worse.

In 1990 there were constant references to that event being a "50 year event." Have there been references to that effect this time? In 1990 I suffered major loses. This time, as far as my son has reported, nothing.

And as Matt said, generalizing over an area as large as SoCal is just that, a generalization. Some areas may very well have been worse.

At any rate, I think it's safe to say that unfortunately, SoCal has suffered worse freezes than this one. And IMO, 1990 may have been one of them.

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Kona, on The Big Island
Hawaii - Land of Volcanoes

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(Matt in SD @ Jan. 18 2007,07:44)

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Dean,

I don't think you can take a single point (or even a couple points) to generalize about this freeze vs. 1990.  Lindbergh field got down to 35F this time and was 34F in 1990, so at least for coastal San Diego, it's pretty close.  I think that the 1990 freeze had a more general and widespread effect with very few places being spared, whereas this freeze seemed to have more locally restricted disasters.  I would bet that some areas had it worse this time than 1990 and vise versa.  It looks to me like LA was definitely better off this time than 1990, while San Diego was pretty comparable.

Matt

Matt,

That's pretty much my opinion. I think if you had to answer the question, "Was this freeze worse than 1990?" I think you would have to answer, "No."

That's all I'm saying.

And BTW, maybe you could check......I seem to remember for a couple of days during the '90 event the daily high barely got to 50 if at all.

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Kona, on The Big Island
Hawaii - Land of Volcanoes

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(Matt in SD @ Jan. 18 2007,10:23)

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Ineresting points Jack,

Since you seem  to have a good grasp of this stuff I have a question that has bugged me since I've lived here.

I'm from Oregon, and growing up I was always told (and observed it to be true) that the higher you go the colder it gets.  When it was near freezing, you woudl see that the frost formed at the tops of the hills and not at the bottoms.  This was true nearly all the time, and when it wasn't, we called it a "temperature inversion" and tended to get freezing rain.  

Down here in SoCal, it seems that "temperature inversions" are the norm, and people seem comfortable with the logical explanation that cold air sinks so the low spots are colder.  

So why is it that in Oregon (and Hawaii too) the standard temperature progression is a decrease of temperature (I think 2 degrees per 1000 ft or so) with altitude, while in SoCal, at least for the first couple thousand feet, there is very commonly an opposite relationship.  

I'm guessing from your previous post that it's probably because in Oregon and Hawaii there tends to be wind, and generally complete mixing of the air from the upper layers down.  But it's still funny that that most people seem comfortable that both scenarios "make sense".

Matt

Matt,

I wouldn't say I have a good grasp on most of this stuff.  But, I've always been interested in weather/climate and I've studied it quite a bit.  Anyway, your question has been on my mind for a while, and I've come up with a what seems like a reasonable explanation.

 

In coastal Oregon (and Hawaii) the air tends to very humid and the skies are cloudy.  Also, the ground tends to be wet.  All of these things mean there isn't a lot of temperature difference between day and night.  I can explain why if anyone is interested.  Anyway, if there isn't much change in temperature from day to night, there isn't much of a temperature gradiant to promote the flow of cold air to "low spots", and the air that is flowing isn't that cold.  Also, water vapor in the atmosphere and cloud cover tend to help the atmospheric temperature equilibrate, similar to wind.  

The adiabatic lapse rate (usually between 0.6 and 1.0 degrees C per 100 m) works the same way in Oregon as in SoCal.  So does the fact that cold air currents pool the cold air in low spots.  It's just a matter of which effect is stronger.  In SoCal, on dry clear nights, the cold air currents have much more of an effect than the lapse rate.  But, in Oregon and Hawaii, the lapse rate tends to be much more important than the cold air currents.

Even in SoCal, the lapse rate is the stronger effect sometimes.  Think of when a storm comes through with lots of clouds and moisture.  There is always a "snow level" quoted at some elevation.  

You're also correct about the wind.  With wind there's no temperature gradiants and no cold air flows...

Jack Sayers

East Los Angeles

growing cold tolerant palms halfway between the equator and the arctic circle...

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Before the great 1980s freezes in central Florida, it was noticeable that citrus didn't extend all the way down the hills to the sinkhole lakes.  Frost pockets from sinking air.  There were some spectacular ones near the Penn State campus in central Pennsylvania, too--very short growing seasons.  Not to mention that some Wyoming towns at the bottoms of valleys are in giant frost pockets.  Very nice on a -20 morning to drive up the hill and ski.

Even Vero Beach (well south of Cape Canaveral) gets light frosts fairly regularly.  Not too big of a deal.  But temperatures can vary wildly around the county for reasons that I can't exactly figure out.  

The severe freezes are from masses of cold air that have moved very rapidly south from Alberta.  This air is extremely dry, which is a prime reason why we rarely get snow.  When it's cold enough for snow, the air is nearly always far too dry.

Fla. climate center: 100-119 days>85 F
USDA 1990 hardiness zone 9B
Current USDA hardiness zone 10a
4 km inland from Indian River; 27º N (equivalent to Brisbane)

Central Orlando's urban heat island may be warmer than us

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Dave-Vero

Your comments explain that a continental/upper level pool of arctic air is DRY. There is moisture only if oceans are nearby [i.e. thunderstorm/hail/snow].  Recent snowfall stunned/thrilled Angelenos  :P  

Warm/moist Florida likely generates frost   ???

Here's the data for LA that suggests 1990 was colder but 2007 is longer :

NWS-LA

SATURDAY 57/39

SUNDAY 56/36 record

MONDAY 61/36

TUESDAY 65/37

WEDNESDAY 59/44

TODAY 70/38

1990 [My station]

55/44

51/38

52/30

53/30

65/37

Anyone know what downtown/LAX reported?

Los Angeles/Pasadena

34° 10' N   118° 18' W

Elevation: 910'/278m

January Average Hi/Lo: 69F/50F

July Average Hi/Lo: 88F/66F

Average Rainfall: 19"/48cm

USDA 11/Sunset 23

http://cdec.water.ca.gov/cgi-progs/queryF?MTW

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Hey, I have to say a perfect example of the observation differences of Californians regarding "frost".  Since this annoyance started, everytime I pick up my sheets in the morning, its been a bit like taking them out of the dryer (just a lot colder! )  BUT, this morning, even though it was 6F warmer than my two coldest nights, the sheets were nice and stiff and holding their shape, "spread out" all because we had at least double the humidity here.  I did see frost on a few "things", but not on the palms. (Like explained earlier)

And yes, 1990 or 2007, cold weather sucks!!!!!!

Zone 10a at best after 2007 AND 2013, on SW facing hill, 1 1/2 miles from coast in Oceanside, CA. 30-98 degrees, and 45-80deg. about 95% of the time.

"The great workman of nature is time."   ,  "Genius is nothing but a great aptitude for patience."

-George-Louis Leclerc de Buffon-

I do some experiments and learning in my garden with palms so you don't have to experience the pain! Look at my old threads to find various observations and tips!

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I don't know where to look (online) to see how dry the freezes of the past were here in Florida. I have lived here for 10 years now and I have noticed that when it gets "cold" here the skin on my hands gets dry, cracks etc. This did not happen when I grew up in Indiana and I have to guess it got pretty dry there at times (-25 F sucks). I think I have just got accostomed to high humidity here. Maybe I am over estimating how dry it gets in FL during some of the colder radaitional freezes. I have no education in meteorology at all. period. All that I have learned has come from this IPS forum. I am guessing that similar temperatures occur at similar humidity levels no matter where it happens in CA or FL (in a canadian air mass during a radiational event). So if I ever had a radiational freeze that made it down to 24F or lower, then it probably was in a very dry atmosphere just like in CA. I think that radiational freezes don't make it that low here in FL most of the time (as in within 10 or 15 miles of either ocean, I know more inland FL can have wicked radiational freezes that make it to the low 20's out of nowhere, probably gets drier inland.......there is Walt from south central FL that posts on CFPACS that has seen bad, dry radiational freezes). However, the advective freezes are the ones that set the record lows into the low 20's and even lower near the coasts. The winds blow in too fast to be moderated by the seas. I think it is cool how you all explained how the air compresses and heats while descending topography during windy events. That makes sense. Unfortunately , that does not happen here as there is a derth of topography in most of FL. Anyway, I don't know where I am going with this post except to say that I have learned alot from all of you and I am glad you are all sharing your experiences with this latest cold (CA, AZ, NM, TX, GA, VA etc.) All of the data is relevant to me to make informed decisions about what I will plant in the future knowing that this warm year in FL is very, very abnormal.

Parrish, FL

Zone 9B

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(ruskinPalms @ Jan. 18 2007,19:32)

QUOTE
I am guessing that similar temperatures occur at similar humidity levels no matter where it happens in CA or FL (in a canadian air mass during a radiational event).

Bill,

I think this mindset is why Florida guys have trouble understanding why So.California freezes are so different.

California has a desert on one side and 50-60 degree ocean on the other. Florida has neither, and is essentially surrounded by 70-80 degree water. These are major differences, and I would have to believe, create different end results.

When arctic air reaches SoCal it has travelled over completely different sets of terrain (either thousands of miles of ocean or desert) than when it reaches Florida. So, IMO, it has a completely different "personality" once it arrives. And in the instances when arctic air may reach Florida that is as dry and cold as SoCal experiences at times, the super warm ocean surrounding Florida pumps moisture right back into it. In Cal, the moisture levels take days to rise, and if the winds stay even slightly offshore the humidity becomes as dry as anywhere in the world.

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Kona, on The Big Island
Hawaii - Land of Volcanoes

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I realize that the waters of the Gulf of Mexico and the Atlantic moderate the humidity/dewpoint here in FL, but it seems that cold fronts blast through down the peninsula unobstructed from the north and bring very dry air that is not moderated by water until much later. Yeh, we may only have one maybe two nasty radiational nights back to back before the seas on both sides have a say, but the humidity levels can be very low for a short while. I DON'T KNOW HOW LOW, but I have seen this winter, ZONE 11 so far for most, humidity levels on my weather station in the low 30's% on cooler nights that have made it into the 40's F and even upper 30's F - ooops did I say zone 11 I mean 10B. Ha ha, my zone is 9B 'nuff said. It can get cold here, colder than all the other stations in my area - oh wait, my sensors are in the open yard at 5' and not within 5 or 10 feet of the house or 20-30' elevation meaning mounted on the top of the house. They have a passive solar shield, not as good as a fan aspirated shield , but better than a raw sensor any day. Sorry, some of the stations are suspect in my area, it is cold here compared to more coastal areas (st. pete, clearwater, tarpon springs, saratota and bradenton) and the other stations (on weather underground in my area) are very generous in inland Hillsorough county, FL to say the least. It  gets cold and DRY here! Maybe I am nuts and it does not get that dry here and I am just accostomed to high humidity levels. But the skin on my hands does crack (from the dry air) in this environment time to time with the cold fronts. anyway, what I really wanted is an integrated cold database that does not descriminate between locations in this nation or any other nation. That's why I am fighting to show the similarities. Thanks all! It really is nice that you are documenting your experiences and sharing. Even though here in FL we will likely will not expereince 7 nights of radaitional freeze back to back, it is nice to see what makes it. Frost be damned, these must be tough palms to live through such an extended period of freezes whatever the nature. I like Dean's idea of ranking 'hardiness' or 'toughness' of palms.

Parrish, FL

Zone 9B

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Bill

What's incredible is that Florida is at it's most vulnerable right now.  Thanks to several weeks of Arctic air and a considerable snow pack all the way down to Oklahoma/Texas panhandle.  This factor would import very cold air into Florida  :o

Cosgrove refers to the persistent "Sea of Sargasso" subtropical high protecting Florida this winter  :D

If dew points/humidity had been higher last week then I believe frost would have been more widespread but minimums would have been higher.  Temps in the 20's for coastal valleys is considered unnatural cold for California. But the atmosphere was oxygen-deprived  [well, almost] cold thin night air.  

Anyone have the data on Burbank/Pasadena/Santa Ana/Woodland Hills/etc for both 2007 & 1990?  ???

Los Angeles/Pasadena

34° 10' N   118° 18' W

Elevation: 910'/278m

January Average Hi/Lo: 69F/50F

July Average Hi/Lo: 88F/66F

Average Rainfall: 19"/48cm

USDA 11/Sunset 23

http://cdec.water.ca.gov/cgi-progs/queryF?MTW

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According to the Pierce College weather station, the all time low record for Woodland Hills is 18d recorded on Feb. 6/89.  The low recorded last week was 19.8d.

San Fernando Valley, California

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  • 3 years later...

There are lots of disconnects between the california and florida folks. I used to live in phoenix arizona, admittedly not socal, but I have plenty of experience with radiative cold events including the 20.4F 2 nights in a row in 2007. In Florida I was caught off guard with what appeared to be cold but not disastrous temps 30F, 28.5, 2 nights in december. I covered the more fragile palms left the "tough ones" uncovered. Frost formed on palm leaflets and serious damage was done to some supposedly cold hardy palms. Beccariophoenix alfredii is a wimp, @28.5 apparently more than 70% burned and the damage isnt fully realized yet seems to be expanding, every pinnate frond hit hard. All royals and toxtails every frond leaflet burnt and some spears burnt even though I wrapped them the second, colder night. There was lots of frost on palms. the supposedly cold hardy Dypsis pembana, covered both nights, roasted to a stump. Kentiopsis oliviformis covered and scortched. Sheets didnt work as well as I would have thought. Foxy ladies, double covered and totally burned including spears, another wimp. Caryota mitis under sheets plus shadecloth, badly burned(70%). Phoenix sylvestris showed no damage and bismarckias showed a small amount of leaflet burn(10-15%). My takeaway is that a florida frost event is colder to the palm that you think based on the ambient temperatures. If my poalms have to see 28F I want it dry anytime! Seeing burn spots on bismarckias @ 28.5F just didnt happen with radiational cold events in the desert.

And one more thing, I wish florida was "surrounded by 70 degree water", the gulf was 54F when the frost hit this past december. The gulf is shallow and cools off much more than the atlantic in winter. When the cold wind comes down from the center of the country however, the east coast of Florida wont have the wind coming off their warmer water, it will be coming across the cold inland landmass to the west and north west. I dont think many californians understand florida climate any better than floridians understand california climate.

Formerly in Gilbert AZ, zone 9a/9b. Now in Palmetto, Florida Zone 9b/10a??

 

Tom Blank

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