2007 California Freeze repeat in the long term forecast

[Mauna Kea Cloudforest]

Before you freak out, read the post, right now it's not likely we're gonna get another 2007, but it's worth being vigilant and checking on the long term forecasts.

The weather has me concerned this year. The drought hasn't broken, and there's no signs of any decent strong onshore jet stream over the West coast. Instead we have a meandering jet stream with a lot of amplified patterns with cut-off lows dancing with a stubborn East Pacific high. This is a bad, bad sign for the West Coast, such a pattern can easily spew out the right conditions for a Yukon express. We all need to pray for a strong pineapple express.

The 9 day 850mb GFS is showing a pretty strong Yucon express reaching all the way into Southern California. It's got a strongly Northerly component, meaning just like in 2007, a lot of cold air running due North-South, so it can easily spill West of the rockies, and which is worse for Southern California with less over-water trajectory. So far, at least the forecast has a lot of over-water trajectory, which is good for California. Let's hope it's not a repeat of 2007.

It's too early yet, the GFS had not been very reliable this year, but it's worth noting the large intensity of the cold air accumulating over the Northern latitudes with a weak jet stream which appears unable to confine any of the cold so a lot of it is already dumping to much lower latitudes much earlier than usual.

GFS 9 day 850mb, this GIF will always reflect +9days as this post age, so you will need to go to http://weather.unisys.com/gfs/gfs.php?inv=0&plot=850&region=us&t=9d to get the latest "less days ahead" forecasts as we get closer.

The ECMF 6-day 500mb surface is showing a West Coast high that stays in place, but there's no 9 day forecast. The ECMF is usually the better model, and when the ECMF and the GFS are in synch, it's usually a much more reliable forecast.

It's worthy to note that the 8-14 day official long term outlook suggests colder temps along the West coast with a probability above 40% for Socal and above 50% North of Los Angeles.

[Palmy]

9 day GFS temp forecasts are usually a joke and the ECMWF and GEM models are a bit warmer anyways. GFS trends colder than what actually happens in later periods. Looking at overall synoptic pattern 9 days out there may be a trough. Just looking at the dprog/dt on the GFS that far out shows extreme spread. For example looking at the GFS ENSEMBLE models, there is already significant spread on the 138 hour forecast however one can tell where the 500 mb troughs and ridges are. When looking at the 216 hour forecast at the time you are mentioning, there is little to no skill forecasting a freeze at this point. Ensemble models are everywhere with the timing of the synoptic trough. Perhaps there will be an overall 500 mb trough over the southwest, but even then, things can change. Lets hope there wont be a freeze.

Plot 1 - 138 Hour forecast - 1200 UTC 12/1

Plot 2 - 216 hour forecast - 1800 UTC 12/4

Edited November 26, 2013 by Palmy

[Mauna Kea Cloudforest]

Hey thanks, good to hear from a professional. I've never liked the long term GFS.

[Palmy]

GFS 8 days or so out all the way to 17 days is always interesting and fun to look at but oftentimes it shouldn't be taken too seriously. Every now and then the GFS from 7-10 days does well, but its consistency is lacking.

http://mag.ncep.noaa.gov/model-guidance-model-parameter.php?group=Model%20Guidance&model=gefs-spag&area=namer&cycle=20131126%2006%20UTC&param=500_534_576_ht&fourpan=no&imageSize=

This shows the same plots above and one can see how consistent the ensemble models of the GFS are. They are very consistent the first five days or so but they quickly diverge. Shows how quickly models fall apart however there are still some synoptic (large scale) features that can be deduced in the long range. This is at 500 mb.

[Mauna Kea Cloudforest]

GFS 8 days or so out all the way to 17 days is always interesting and fun to look at but oftentimes it shouldn't be taken too seriously. Every now and then the GFS from 7-10 days does well, but its consistency is lacking.

http://mag.ncep.noaa.gov/model-guidance-model-parameter.php?group=Model%20Guidance&model=gefs-spag&area=namer&cycle=20131126%2006%20UTC&param=500_534_576_ht&fourpan=no&imageSize=

This shows the same plots above and one can see how consistent the ensemble models of the GFS are. They are very consistent the first five days or so but they quickly diverge. Shows how quickly models fall apart however there are still some synoptic (large scale) features that can be deduced in the long range. This is at 500 mb.

Looks like the NWS Monterey office has picked up on this today:

FOR EARLY NEXT WEEK...WILL HAVE TO CONTINUE TO LOOK FOR

CONSISTENCY IN THE MODELS WITH RESPECT TO THE NEXT MID/UPPER LEVEL

LOW THAT IS CURRENTLY EXPECTED TO DROP SOUTHWARD OUT OF BRITISH

COLUMBIA. THIS SYSTEM WOULD PUSH A COLD FRONT THROUGH CENTRAL

CALIFORNIA MONDAY OR TUESDAY. THE FRONTAL BOUNDARY WOULD BE

FOLLOWED BY CHANCES FOR PRECIPITATION AND MUCH COOLER

TEMPERATURES. TO NOTE...THE GFS AND ECMWF BOTH SHOW SNOW LEVELS

DROPPING BELOW 3-4KFT BY TUESDAY AND WEDNESDAY OF NEXT WEEK.

Doesn't sound like it's lining up to be record cold, but we will probably get frost, and this seems much earlier than usual. Sounds like more of an inside slider with very cold air and not much moisture to support good precipitation. These are usually followed by frosty conditions if the atmosphere stabilizes quickly after the passage of the front.

[Palmy]

Whew, check out the GEM model on surface temps. That would be bad if that were to happen. Note that the high pressure is a big higher on GEM than GFS on this model run.

Same day and time for GFS

There are big differences way out. That's nine days out (dec 6) and there is still quite a bit of model spread on the event on Tuesday and Wednesday that NWS Monterey however you are right, it looks like it will cool off significantly. I don't think it will be record breaking but it may be a frost. Too far out to determine exact temps but as we get closer models will continue to have less spread.

[Mauna Kea Cloudforest]

Whew, check out the GEM model on surface temps. That would be bad if that were to happen. Note that the high pressure is a big higher on GEM than GFS on this model run.

Same day and time for GFS

There are big differences way out. That's nine days out (dec 6) and there is still quite a bit of model spread on the event on Tuesday and Wednesday that NWS Monterey however you are right, it looks like it will cool off significantly. I don't think it will be record breaking but it may be a frost. Too far out to determine exact temps but as we get closer models will continue to have less spread.

I am beginning to like the GFS better. Right now 27-29F is what's being forecast for most Norcal stations for Wednesday Morning. This sucks. I hope this doesn't come to pass. I guess we just have to be prepared.

[Perito]

Upper 20's; really? I just checked long range forecasts for my area and don't see any predictions under 39F for weeks! I'm glad I live a couple hundred miles south of you Axel. Long range forecasts are what they are- pretty unreliable, but I'm seeing (and hoping for) mild overnight lows this Winter.

[Mauna Kea Cloudforest]

Upper 20's; really? I just checked long range forecasts for my area and don't see any predictions under 39F for weeks! I'm glad I live a couple hundred miles south of you Axel. Long range forecasts are what they are- pretty unreliable, but I'm seeing (and hoping for) mild overnight lows this Winter.

Perry, it depends on which forecast you look at. Accuweather has 29F as a low for both Santa Cruz and Grover Beach next Wednesday so those 200 miles aren't going to help you if Accuweather is correct. But Accuweather is famously inaccurate and is always too cold. The good news is that the more accurate NWS forecast as seen on Wunderground indicates 39F for Santa Cruz and 41F for Grover Beach.

Stay tuned, these long term forecast change on a dime given how chaotic the models are with the current conditions as initial boundaries.

Edit: here is a link to the "evil" forecast: http://www.accuweather.com/en/us/grover-beach-ca/93433/daily-weather-forecast/2154427?day=8

[Perito]

Thanks Axel, I was looking at the Wunderground forecast, and sure am hoping their model is accurate. Last year was too cold for my liking and I need a normal mild California Winter!

[Perito]

Even the Accuweather forecast is just a 3 or 4 day event with overnight lows moderating after that. Bad enough, but not the two weeks of freezing night temps we saw in January 2007. Still would start driving soil temps down early so I hope it doesn't happen.

[Silas_Sancona]

Axel,
Just looked over forecasts for several W.U. weather stations around the valley and up your way.. Looks like ( as of this point ) a dip into the upper 20's may be in store for always cold, when it is cold spots around Gilroy.. and, possibly down to a real nasty 19!! being forecasted by a couple stations around Scott's Valley. (Deer Run/Whispering Pines/ Scott's Valley Heights) Wondering if those stations are reading too cold for the forecast period since other stations nearby aren't nearly as cold. NWS forecast stated that the pattern setting up for next week seems to mirror what happened here last January. Hopefully this is the one and only cold blast for the winter.

-Nathan-

[Mauna Kea Cloudforest]

Axel,

Just looked over forecasts for several W.U. weather stations around the valley and up your way.. Looks like ( as of this point ) a dip into the upper 20's may be in store for always cold, when it is cold spots around Gilroy.. and, possibly down to a real nasty 19!! being forecasted by a couple stations around Scott's Valley. (Deer Run/Whispering Pines/ Scott's Valley Heights) Wondering if those stations are reading too cold for the forecast period since other stations nearby aren't nearly as cold. NWS forecast stated that the pattern setting up for next week seems to mirror what happened here last January. Hopefully this is the one and only cold blast for the winter.

-Nathan-

Models are continuing to back off on rain, this means clear skies. Any wind sheltered spot is going to see very cold temperatures. Unless there is an overall change in the large scale pattern, we may be in for more than just this cold wave this Winter.

Keep watching those forecasts.

[Jim in Los Altos]

Upper 20's; really? I just checked long range forecasts for my area and don't see any predictions under 39F for weeks! I'm glad I live a couple hundred miles south of you Axel. Long range forecasts are what they are- pretty unreliable, but I'm seeing (and hoping for) mild overnight lows this Winter.

Perry, it depends on which forecast you look at. Accuweather has 29F as a low for both Santa Cruz and Grover Beach next Wednesday so those 200 miles aren't going to help you if Accuweather is correct. But Accuweather is famously inaccurate and is always too cold. The good news is that the more accurate NWS forecast as seen on Wunderground indicates 39F for Santa Cruz and 41F for Grover Beach.

Stay tuned, these long term forecast change on a dime given how chaotic the models are with the current conditions as initial boundaries.

Edit: here is a link to the "evil" forecast: http://www.accuweather.com/en/us/grover-beach-ca/93433/daily-weather-forecast/2154427?day=8

Axel, unfortunately, Weather underground is totally screwy for me and makes absolutely no sense. They have Los Altos and Mt. View at 21F Thursday night and Gilroy, which is MUCH colder than us, at 28F. I can never rely on them for accurate winter lows. My best bet is local TV station online weather outlooks from their meteorologists.

[Perito]

I just checked the Accuweather forecast and the scenario has gotten worse with two full weeks of lows in the upper and lower 30's (Starting around the 7th of December) . Not good news.

[Mauna Kea Cloudforest]

NWS Hanford issued this warning this Morning:

THE BIGGEST THREAT FROM THIS INCOMING SYSTEM WILL BE THE VERY COLD

AIR. BY THURSDAY AND FRIDAY OF NEXT WEEK, SEVERAL FORECAST MODELS

ARE PROJECTING WIDESPREAD 20S OVER THE SAN JOAQUIN VALLEY. THE

COLDEST SOLUTIONS SUGGEST EVEN SOME LOWER 20S, THUS AGRICULTURAL

INTERESTS NEED TO PREPARE. IF THE PROJECTED PATTERN HOLDS, FREEZE

OUTLOOKS MAY NEED ISSUANCE. GET READY.

[Perito]

The Wunderground forecast is beginning to fall more in line with Accuweather now. Axel, you were on top of this early and unfortunately looks like a good call. We have a few days to do prepare. Thanks for the vigilance!

[Silas_Sancona]

Been checking over all the forecast updates anytime id take breaks between getting the house and yard packed up. Saw the update Axel noted, and see the nearby W. Underground stations have lowered the nighttime lows around the area for later next week. The stations id noted earlier were forecasting bottoming out around 18F when I checked this morning. They're back up to a balmy 21F atm.

-Nathan-

[Mauna Kea Cloudforest]

This is getting more serious and is beginning to line up more with a major freeze event. I see a lot of similarities with 2007 and 1998. More cold advection is supposed to take place later in the week, so the coldest could be the end of the week. The Sacramento office is now calling for a 5-10 year freeze event. See below:

Of more interest is the strong negative COLD anomalies setting up

for the middle to end of next week in our CWA...and what may

turn-out to be a one in every 5-10 year event. The RMOP would also

suggest a likely" probability that a deep/cold trof would be

carved out over the region by the middle of next week. JHM

[Mauna Kea Cloudforest]

Update: going to post a new thread so that folks in Southern California don't think this is a repeat of 2007 since this Morning's models are showing a nice active pattern over Baja that's going to help to confine the crap North, and an East Pacific High nudging Eastward. Fortunately for folks down south It's not looking like 2007 at all, but unfortunately for folks in the Central Valley of California, the bulk of the energy is heading inland over Central California.

[enigma99]

We hit 22F in 2007... Here comes 2007 again... Wish I could share with SoCal haha

[John Case]

I expect a low of 29F in Brentwood/Oakley/Antioch....on Thursday....low 30s on Tue and Wed....made some moves for some of the potted plants but expecting defoliation of bananas and aroids.....which will grow back next spring.

Doing rain dances to try for some precipitation, though.

[Mauna Kea Cloudforest]

I expect a low of 29F in Brentwood/Oakley/Antioch....on Thursday....low 30s on Tue and Wed....made some moves for some of the potted plants but expecting defoliation of bananas and aroids.....which will grow back next spring.

Doing rain dances to try for some precipitation, though.

I am hoping for more wind to keep things moving. But as of right now, the forecast for Santa Cruz says 64/32 for Wed, 63/30 for Thursday and 64/32 on Friday, and after that we're out of the woods. What puzzles me is that when i looked up Brentwood, it says 28F for the following Sunday and Monday nights as if more cold was on its way.

No matter what, I am preparing for a worse case scenario. Did a test run on heaters today. The propane air blowers are awesome, those will get turned on if we drop below 30F. I also have some infrared heaters that might get used. Other than that, I am using passive protection with mulch and straw on small seedlings in the ground just for the week.

[ghar41]

This is why I have so many cold hardy palms in my yard! Yuck!

[Mauna Kea Cloudforest]

This is why I have so many cold hardy palms in my yard! Yuck!

You're right. Usually I am more lax about this and I just let nature weed stuff out. I didn't bother to do any protection in 2007, and nothing actually happened here except 30F. Even some of my ensete bananas stayed green. but this forecast scares me, the conditions are too favorable to line up with a 30 year event.