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ghar41

Freeze warning

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iwan

Cold here this morning!

21:00  31.5

22:00  30.0

23:00  28.8  35.5

05:00  25.6 30.4

06:00  25.0 30.1

07:00  23.9 29.3

 LOW  23.6 28.3

08:30  27.7

The second number is the temp at the crown of my A. Cunninghamiana protected by an overhead umbrella and rope lights.  The first number is the air temp about 6' away.  Another 12 hour night at/below freezing.

Last night I wanted to test what the temperature differential was in my shade house under 70% cloth.  The exposed sensor was about 3' away.  I found the thermometer under the shade cloth covered with ice at 8:30AM today.  Doesn't look like shade cloth provides much protection (although this measurement was just a couple feet inside the shade house.  It was selected as it was sitting on top of my 1 gallon Bismarkia that rooted there while I was on vacation.  I covered it with a 15g pot and blanket.  The shade house is on one of the highest parts of my property.

Exposed 21.6, protected,  22.7

About 30 minutes after sunrise the clear sky turned to freezing fog, trapping in the cold.  Water pressure was down to 15psi this morning due to semi-frozen pipes.

Should be fun tonight.

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ghar41

(happ @ Dec. 17 2006,20:17)

QUOTE
 

In SoCal the LA foothills are considered as safe as San Diego bay [over 100 miles south].  The unusual circumstance of an east/west mountain range facilitates  the import of Pacific or continental air interaction.  Nocturnal/diurnal descending off-short air flow is more pronounced in LA/Orange Co than in San Diego due to topography.

 

San Francisco : 53/43

LA : 59/45

San Diego : 58/48

Excellent point, Happ.  Much of this area covering the coveted "Sunset Zone 23"  one of the prime horticultural zones in the US.  

Northern California counters with "Sunset Zone 16."  In specific locations within the SF Bay Area, Zone 16 is not only one of the least likely to freeze, but in differing from San Francisco's Zone 17, it gets some good HEAT.  The Northern California Palm Society sponsored Lakeside Palmetum sits in prime Sunset Zone 16.

http://www.palmsnc.org/pages/palmetum.php

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Don Little

Got down to 36.5 last night in the most exposed parts of my yard and no frost, 39.7 in the warmest part of my yard.

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Brett in Mission Viejo

I am expecting 34 degrees fahrenheit tonight. At my location here in Mission Viejo,CA  I am in probably one of the worst microclimates in Orange County and I am only 3-4 miles from the Ocean. I am near the Saddleback valley floor where cold air pools and am situated between the Laguna Hills and Santa Ana mountains where there is little coastal influence. I get several frosts per year and an occasional freeze.  Compared to Capistrano Beach, which is four miles south and enjoys coastal influence, Mission Viejo is about 7-8 degress fahrenheit colder on the average during winter nights.

On a related note, I use 1.5 oz. permeable fabric to cover all my frost sensitive palms and cycads.  It works great if it is draped over the plant and allowed to hang straight down to trap maximum ground heat. And you can leave it on for several days without any harm to the plant. There comes a point where some of the palms are too big to cover with fabric. In those cases I have had mixed results using fans to try and mix the air.

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tropical1

There are plenty of fruiting coconuts in the Tampa Bay Area now to attest to the mild winters since 1989 .  That probably distinguishes the warmth of central florida better than anything else. Clearly, a good indicator of microclimate is to see what has been in the ground for a while. Perhaps, global warming is kicking in and our climate is becoming more like so fla.

However, in California you can grow some amazing palms such as: Howeas, Jubea, Rhopalostylis

even the washingtonias look better.  Both are  great places to grow palms. As I said before, I would summer in Cali and winter here if feasible.

Good luck to all in California.

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happ

WOW the intensity of this cold air mass   :o

The upper low is still overhead though the sky is clear w/ 50 mile visibility.  Due points/relative humidity down into 20%. The December sun can not compete with polar jet overhead.  Most people are freaking about the mt. snow & enjoying the change in weather.

Grieve over the low temps inland/coastal valleys & even Del Mar recorded 35F.  Urban areas in the 40's.  Tonight could very well be colder but the wind is gusting.

San Francisco : 57/40

LA : 62/44

San Diego/Sea World : 60/47

However areas of sub-freezing minimums in the upper Bay Area & near freezing across sections of SoCal.

This is a significant polar outbreak that will linger for another night before moderating.   :D

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BS Man about Palms

(syersj @ Dec. 18 2006,07:13)

QUOTE

(BS @ Man about Palms,Dec. 18 2006,09:49)

QUOTE

(syersj @ Dec. 17 2006,18:22)

QUOTE
Average Temperature Comparison (from Yahoo Weather):

                   Orlando                 LA                        San Diego

November  79.0° F 59.0°   73.0° F 53.0° F     70.0° F 54.0° F

December  73.0° F 53.0°   69.0° F 48.0° F     66.0° F 49.0° F

January      72.0° F 50.0°  68.0° F 48.0° F      66.0° F 50.0° F

February    74.0° F 51.0°  70.0° F 50.0° F      66.0° F 52.0° F

March         79.0° F 56.0°  70.0° F 52.0° F     66.0° F 54.0° F

April           83.0° F 60.0°   73.0° F 54.0° F     69.0° F 56.0° F

Bottom line is Orlando is quite a bit warmer in every month, and MUCH warmer in Feb - April time frame, as much as 10-15 degrees warmer.  If it weren't for the occasional artic fronts going through Central FL, they wouldn't even be in the same ball park.

Sorry Jim,

I know you can only go by data you can find on the internet, but I drive a lot of San Diego county year round and I know its warmer than the statistics will show.  A lot of that is the measuring point being so near the water in the bay. That keeps the lows constant but the highs don't rise much either.  I can think of several spots within a mile or at the most 3 , that would be within 1 degree on the low and yet add 3-4 degrees on the high.  

Either way both great places.

Yeah, I actually thought that 66F seemed kind of cool for SD, not being from or having lived there.  I'm sure inland locations are frequently above 70F (I assume).  Don't you guys have frequent fog or a marine layer near the coast, when you go a couple miles inland it might be sunny and warmer?  Or is that just during the May Grey, June Gloom time frame.

Yes Jim, most of the "gloom" is in May and June.  

This morning was a great example to see microclimates for me, I had to drive roughly 25 miles inland at 7:30 am. I didn't check my "out side" thermometer (now working only in place, not remote) anyway, my coldframe hit "hi" 42 this morn, but "dripping dew" etc as I left. As I headed inland over various hills and valleys, south facing, north facing, etc It was neat to see where the frost was. any south facing hill, no problem, no frost, any flat area, or valley, especially the north facing ones, had frost.  I also noted a small creek area that had frost on the ground anywhere outside the canopy of the pines.

I had a customer in Rancho Santa Fe, roughly 5 miles from the coast in a deep valley, say she had a very hard time cleaning the ice from her windshield this morning, she moved from Ill. some time back and threw out all her ice scrapers!

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Blast39

For what it's worth.... if it gets below 32 degrees... go out and throw water all over your palms. Let ice form everywhere. That way, the plant can't get colder than 32 degrees. I used to do it when I lived in San Diego and it got to 19 degrees one year. Saved a lot of plants that way.

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BS Man about Palms

Just got in from watering them, have done a few times in the past, but its always good to bring that tip, up. Thanks!

It was 38F in the cold frame at 0530 this AM!   30F out front by my mailbox (new place to try) and 33-35F in the back.  No frost yet that I saw or felt.

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STEVE IN SO CAL

0630...23 lower field... 29 top of hill, lawn area, no canopy...36 near pool w/canopy, boulders, concrete, etc.

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gsn

(Blast39 @ Dec. 19 2006,01:28)

QUOTE
For what it's worth.... if it gets below 32 degrees... go out and throw water all over your palms. Let ice form everywhere. That way, the plant can't get colder than 32 degrees. I used to do it when I lived in San Diego and it got to 19 degrees one year. Saved a lot of plants that way.

For what it is worth, I would be just a little more careful ,than going out and throwing some water on plants if it gets below 32 F!

It is my understanding that if ice forms on the plant ,then irrigation has to continue until the ice melts or you will do more damge than if you didn't irrigate.

Here is the info and then a link to frost /freeze protection.

"Irrigation; Irrigation is another method of frost/freeze protection. Heat lost from the crop to the environment is replaced by heat released as the applied water changes to ice. Specifically, as 1 gram of water freezes, 80 calories of heat energy are released. As long as ice is being formed, this latent heat of fusion will provide heat.

Irrigation for frost protection, often called sprinkler irrigation, is done with sprinklers mounted above or below the crop canopy. Under-canopy, usually under-tree, sprinkling with micro-sprinkler nozzles has been successful in California and Florida. This relatively new method of irrigation for frost protection has not as yet found widespread use in North Carolina.

Although there is some risk involved, the advantages of irrigation are significant. Operational costs are lower, because water is much cheaper than oil or gas. Irrigation systems are convenient to operate, because they are controlled at a central pump house. In addition, there are multiple uses for the same system, e.g., drought prevention, evaporative cooling, fertilizer application, and possibly pest control.

There are some disadvantages. The first and most important is that if the irrigation rate is not adequate, the damage incurred will be more severe than if no protection had been provided. Inadequate irrigation rate means that too little water is being applied to freeze at a rate which will provide enough heat to protect the crop. The situation is made complex by another property of water, evaporative cooling or the latent heat of evaporation. As 1 gram of water evaporates, 600 calories of heat energy are absorbed from the surrounding environment. When compared to the 80 calories released by freezing, it becomes apparent that more than 7 1/2 times more water must be freezing than evaporating to provide a net heating effect. Otherwise, the process of evaporation will take heat from the crop. An ice-covered plant will cool below the temperature of a comparable dry plant if freezing stops and evaporation begins. Since wind promotes evaporative cooling, wind speeds above 5 mph limit the success of irrigation for frost protection.

Secondly, with overhead irrigation, ice buildup can cause limb breakage; and thirdly, over-watering can cause waterlogged soils and nutrient leaching problems. Lastly, at present, most systems are of fixed-rate design. They can only be turned on and off, and no variability exists for the irrigation rate. Thus, most systems are designed for the worst possible case. This means excess water is applied in most frosts, further increasing the problems of too much water on the crop.

The details of designing and operating an overhead irrigation system for frost/freeze protection are contained in the NCCES bulletin Irrigation for Apple Orchards. Several very important points are repeated here. If the capacity of the irrigation system is not sufficient to provide protection under the extreme conditions expected during the night, the system should not be turned on. In general, no system will provide protection in wind speeds greater than 5 mph for tree crops, 10 mph for low growing crops. A backup power source is essential. Once started, irrigation must continue until the ice is melting and loose. This usually occurs soon after the morning sun hits the trees. A power failure can be devastating due to the evaporative cooling effect."

http://www.ces.ncsu.edu/depts/hort/hil/hil-705.html

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Cristóbal

i have low temprature of 6.2 C - 43.2 F this morning on digital thermometer.  8.15 am now and 9.0 C - 48.3 F how cold ! this is not good for plumeria and cocos nucifera, dypsis but howea is ok with this cold.

i have very good micro climate for winter cold - im close to ocen and on hill - only bad things when it rains, all tijuana is a big flood, even with less of 1 inch of rain.

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ghar41

(gsn @ Dec. 19 2006,11:04)

QUOTE

(Blast39 @ Dec. 19 2006,01:28)

QUOTE
For what it's worth.... if it gets below 32 degrees... go out and throw water all over your palms. Let ice form everywhere. That way, the plant can't get colder than 32 degrees. I used to do it when I lived in San Diego and it got to 19 degrees one year. Saved a lot of plants that way.

For what it is worth, I would be just a little more careful ,than going out and throwing some water on plants if it gets below 32 F!

http://www.ces.ncsu.edu/depts/hort/hil/hil-705.html

I have to agree on this one.  Back in my earliest palm days, I defoliated all my queen palms by spraying the crowns with water during freezing weather.  My neighbors did nothing and theirs were fine.

Didn't kill em, but we looked at trunks for an entire summer!

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elHoagie

about 1.5C (35F) with no frost in Altadena this morning...

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happ

I think the worst is over  ???

Not that tonight won't be cold.  But not as low as Tuesday's bitter temps, esp in NoCal & widespread 30's/40's in SoCal.

Moist Pacific flow will usher in minimums 10+ degrees warmer Thursday AM in NoCal & continue to rise.

SoCal will stay dry, as usual  :(  But seasonal by week's end.  Like nothing happened.   :o

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epicure3

(happ @ Dec. 20 2006,00:22)

QUOTE
I think the worst is over  ???

Not that tonight won't be cold.  But not as low as Tuesday's bitter temps, esp in NoCal & widespread 30's/40's in SoCal.

Moist Pacific flow will usher in minimums 10+ degrees warmer Thursday AM in NoCal & continue to rise.

SoCal will stay dry, as usual  :(  But seasonal by week's end.  Like nothing happened.   :o

I look forward to that.

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Don Little

It didn't get dangerously low as 35 was the lowest I saw but still to cold for comfort.  Hope it's the only one of those we get this year.

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Exotic Life

I have got last night my first freeze from this season... i recorded -0,3C / 31.4F. Oke it's not to bad ... :) The next 5 day's the don't expect any frost ... :)

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happ

Cold once again but mostly above freezing except Central Valley/high desert.  I was struck by how chilly it was today.

This polar pillage is waning  :D   But cool for a few more days.

NWS - DOWNTOWN LOS ANGELES  

THUR  /  FRI  /  SAT  /  SUN  /  MON  /  TUES / WED

42/67  48/67  47/67  45/71  46/72  48/71  50/71

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