Southern Plains winter wx thread (2008-2009)

[BlueIce]

It looks like a reinforcing shot of cool, dry air has moved into the OK panhandle this evening, and I am really surprised at how fast they cooled down! Those areas reached nearly 50F earlier today, but are already falling back into the upper teens as of 10pm!



...The Amarillo NWS certainly wasn't expecting this to happen. Most of the low temperature forecasts up in that area have already busted by a few degrees. Guymon, OK, for example, was only forecast to drop to 23F but are currently at 18F (5 degrees cooler than forecast).

Is it just me or has the weather service been busting forecasts for almost 4 days now? This weather system is really throwing them a curve ball every day!!

[Texas Snowman]

It's not you - the NWS has really had trouble with this air mass. This far south, they often do have trouble with winter weather events and/or arctic air intrusions.

Case in point is today where the point and click says 46 in Sherman/Denison. Right now it is cloudy, a little misty, and 36.

Live by the models, die by the models.

Tx Snowman

[jasons2k]

It's not you - the NWS has really had trouble with this air mass. This far south, they often do have trouble with winter weather events and/or arctic air intrusions.

Case in point is today where the point and click says 46 in Sherman/Denison. Right now it is cloudy, a little misty, and 36.

Live by the models, die by the models.

Tx Snowman

Just keep in mind that 46 has until midnight to verify, and it has a good chance of doing so.

[jinftl]

Forecasts are so tricky and can change very quickly...esp for areas that are at the 'crossroads' of airmasses...for some time now the outlook has been that for the relatively small geographic area between say, Wichita and Dallas to go from below normal temps to normal to even above normal temps. CPC 8-14 day Outlook maintains this level of temp variance through the end of the year practically. Small shifts...even 100 or 200 miles could mean a huge diffrence for any one area in this airmass 'crossroads'. Doesn't look like the complex and interesting weather in that region will let up any time soon.

It looks like a reinforcing shot of cool, dry air has moved into the OK panhandle this evening, and I am really surprised at how fast they cooled down! Those areas reached nearly 50F earlier today, but are already falling back into the upper teens as of 10pm!



...The Amarillo NWS certainly wasn't expecting this to happen. Most of the low temperature forecasts up in that area have already busted by a few degrees. Guymon, OK, for example, was only forecast to drop to 23F but are currently at 18F (5 degrees cooler than forecast).

Is it just me or has the weather service been busting forecasts for almost 4 days now? This weather system is really throwing them a curve ball every day!!

[Texas Snowman]

Good point Jasons.

The only thing that I would add is that the 46 is the high that they (FW NWS) have slated for this afternoon, a temperature which would then hold steady overnight. And actually, now the point/click high for this afternoon is bumped up to 47 degrees.

Seriously, seriously doubt that will happen at this point with cloudy, cold, damp conditions and a temp of 36 at Grayson County Airport. Perhaps the actual high will verify before midnight, but their forecast for the daylight hours so far is a bust.

Tx Snowman

[somethingfunny]

NWS did an excellent job of predicting 2 solid days of widely scattered freezing drizzle a few days in advance. I knew what was coming....and there weren't any changes in coverage, temperature, timing, or intensity to surprise me this time.

I know that is the exception to the rule when forecasting winter weather in north Texas. Case in point, last week's tornado.

[jinftl]

Just to show that a lot can change even in less than a week….this was last Thursday’s forecast (12/11) for OKC for the week we are currently in….compared to the actual temps (or the ones in tonight’s and tomorrow’s forecasts issued today) with the variance from last Thursday’s forecast…

Sunday Night: A chance of rain showers before midnight, then a chance of freezing rain. Cloudy, with a low around 21.
ACTUAL LOW = 18 (-3)

Monday: A slight chance of freezing drizzle. Cloudy, with a high near 28.
ACTUAL HIGH = 18 (-10)

Monday Night: A slight chance of freezing drizzle. Cloudy, with a low around 22.
ACTUAL LOW = 15 (-7)

Tuesday: A chance of freezing rain. Mostly cloudy, with a high near 28.
ACTUAL HIGH = 27 (-1)

Tuesday Night: A slight chance of freezing drizzle. Mostly cloudy, with a low around 23.
ACTUAL LOW = 16 (-7)

Wednesday: A slight chance of freezing rain. Cloudy, with a high near 27.
ACTUAL HIGH (UNOFFICIAL) = 40 (+13)

Wednesday Night: A slight chance of freezing rain. Cloudy, with a low around 22.
CURRENT FORECAST LOW = 33 (+11)

Thursday: A slight chance of freezing rain. Cloudy, with a high near 28.
CURRENT FORECAST HIGH = 52 (+24)

[Brent]

Monday looks brutally cold for most of the country.

[Extremeweatherguy]

The fog we are getting in OKC today is some of the thickest I have ever seen!

Oklahoma City, Will Rogers World Airport
Lat: 35.41 Lon: -97.6 Elev: 1280
Last Update on Dec 18, 2:52 pm CST

Fog

49°F
(9°C)
Humidity: 97 %
Wind Speed: SE 13 MPH
Barometer: 29.90" (1012.8 mb)
Dewpoint: 48°F (9°C)
Wind Chill: 44°F (7°C)
Visibility: 0.00 mi.
More Local Wx: 3 Day History:

[amawea]

I'm reading that there may be a little bit of a pattern change starting the middle to end of next week. The met out of Springfield is hinting at some possible phasing of the sub-tropical and polar jet. This could mean snow for the mid south and southern plains! Lets hope!

[Portastorm]

I'm reading that there may be a little bit of a pattern change starting the middle to end of next week. The met out of Springfield is hinting at some possible phasing of the sub-tropical and polar jet. This could mean snow for the mid south and southern plains! Lets hope!

Hmmm ... I'm no pro met nor did I sleep at a Holiday Inn Express last night ... but I don't see it. Just checked the 500mb flow for middle to late next week for the 0z GFS and Euro and all I can see is a medium-sized trough crossing the Plains west to east. Nothing spectacular and it looks like it'll probably be moving too far north to have much impact on the Southern Plains.

[Extremeweatherguy]

Check out the huge expansion of the US snowpack in the last week or so...

http://www.natice.noaa.gov/ims/loop/usa-1mo-loop.html

[amawea]

Well, I don't see it either Portastorm, but that's what he said on the 5 a.m. discussion.
Here ya go.

MONDAY THROUGH WEDNESDAY...MEDIUM RANGE MODELS DRASTICALLY DIVERGE
DURING THE PERIOD. WEAK UPPER LEVEL RIDGING WILL TRANSITION TO A
SOUTHWESTERLY FLOW ALOFT EARLY IN THE PERIOD. SURFACE PRESSURE
FALLS ACROSS THE HIGH PLAINS WILL LEAD TO INCREASING SOUTHERLY
LOW LEVEL FLOW AND WARMER TEMPERATURES. THE BIGGEST QUESTION OF
THE PERIOD WILL BE THE EVOLUTION OF AN UPPER LEVEL TROUGH OVER THE
WESTERN UNITED STATES. MEDIUM RANGE MODELS SEEM TO BE STRUGGLING
WITH THE PHASING OF TWO DISTINCT SHORT WAVE TROUGHS. THE ECMWF
USUALLY HAS A MUCH BETTER TRACK RECORD WHEN IT COMES TO THE
PHASING OF ENERGY IN REGARDS TO THE POLAR AND SUB TROPICAL JETS...
SO WILL FOLLOW IT FOR THE MOST PART. WE SHOULD
THEREFORE SEE INCREASED PRECIPITATION CHANCES AROUND THE TUESDAY
AND WEDNESDAY TIME FRAME AS THAT UPPER LEVEL ENERGY CROSSES THE
CENTRAL UNITED STATES. WE WILL NEED TO WATCH TEMPERATURE PROFILES
CLOSELY WITH THIS ONE AS THE AMOUNT OF WARM ADVECTION AHEAD OF
THIS FEATURE IS IN QUESTION. IN OTHER WORDS...FROZEN PRECIPITATION
CANNOT BE RULED OUT.

SCHAUMANN

[amawea]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
532 PM CST FRI DEC 19 2008



Update
LONG TERM (MONDAY THROUGH FRIDAY)...

THE EXTEND PERIOD WILL START OFF BELOW NORMAL AS THE ARCTIC AIRMASS
AND UPPER LEVEL LOW REMAIN ACROSS THE CENTRAL US. THERE WILL BE A
WARMING TREND MONDAY INTO WEDNESDAY AS UPPER LEVEL RIDGING BUILDS
ACROSS THE REGION. TEMPERATURES WILL STILL BE AT OR BELOW NORMAL
ON TUESDAY AND WEDNESDAY...BUT WARMER THAN THOSE EXPECTED SATURDAY
NIGHT THROUGH MONDAY.

ANOTHER UPPER LEVEL TROUGH WILL MOVE ACROSS THE REGION TUESDAY
INTO WEDNESDAY. THERE ARE SIGNIFICANT DIFFERENCES BETWEEN THE
ECMWF AND THE GFS MODELS FOR THIS TIME PERIOD. HAVE GENERALLY
FOLLOWED MORE IN LINE WITH HPC GUIDANCE AND THE ECMWF MODEL
SOLUTION WITH THIS SYSTEM. WARM AIR ADVECTION SHOULD KICK INTO
GEAR ON TUESDAY WARMING THE ENTIRE AREA ABOVE FREEZING. SCATTERED
RAINS SHOWERS WILL BE POSSIBLE IN THIS WARM AIR REGIME AND HAVE
BUMPED UP POPS ON THE TUESDAY. TUESDAY NIGHT THE UPPER LEVEL
TROUGH IS EXPECTED TO SWING THROUGH THE AREA AND WILL PUSH AN
ASSOCIATED COLD FRONT THROUGH THE AREA. AT THIS TIME EXPECTING
MOST OF THE PRECIPITATION TO BE PRE FRONTAL AND IN THE FORM OF
RAIN. AS THE COLD FRONT PUSHES THROUGH THE AREA TEMPERATURES WILL
FALL INTO THE LOWER 30S TO UPPER 20S...CHANGING ANY RAIN OVER TO
SNOW. AT THIS TIME ONLY LIGHT SNOW IS EXPECTED ACROSS THE
AREA...WITH LIGHT ACCUMULATIONS POSSIBLE ACROSS THE NORTHWESTERN
PORTION OF THE FORECAST AREA. THERE COULD BE A FEW LINGERING
FLURRIES ACROSS THE AREA ON WEDNESDAY AS THE SYSTEM LIFTS OUT OF
THE AREA.

AT THIS TIME ANY SNOW THAT FALLS IS EXPECTED TO BE LIGHT. HOWEVER...WE
WILL HAVE TO CONTINUE TO MONITOR THIS SYSTEM CLOSELY. IF THE COLDER
AIR FILTERS INTO THE AREA MORE QUICKLY OR THE SYSTEM DROPS A
LITTLE FURTHER SOUTH...MORE SNOW WOULD BE POSSIBLE.

WISE

[jinftl]

What a difference a week or 2 can make....the locations below are just a few examples of areas that were running below....in some cases well below...normal in avg temps for the month a week or 2 ago. These locations are now above normal for the month to date...or on the verge of being so. Even with some colder temps early in the week, the upcoming week overall could average above normal in most of these places.


As of 12/19, month to date departures from normal temps:

Daytona Beach +2.1 deg
Orlando -0.2 deg
Tampa +0.8 deg
Miami -0.1 deg
New Orleans +1.2 deg
Dallas +0.9 deg
Houston -0.8 deg

[Portastorm]

What a difference a week or 2 can make....the locations below are just a few examples of areas that were running below....in some cases well below...normal in avg temps for the month a week or 2 ago. These locations are now above normal for the month to date...or on the verge of being so. Even with some colder temps early in the week, the upcoming week overall could average above normal in most of these places.


As of 12/19, month to date departures from normal temps:

Daytona Beach +2.1 deg
Orlando -0.2 deg
Tampa +0.8 deg
Miami -0.1 deg
New Orleans +1.2 deg
Dallas +0.9 deg
Houston -0.8 deg

That is really interesting stuff ... wow. Great post, jinftl!

I never would have imagined the Texas locations to be nearly a degree above normal given what we have seen this month.

[jinftl]

Especially in Texas, the swings in temps have been amazing....either it has been 10 or 20 deg below normal, or 10 or 20 deg above....and when you put it all together, they pretty much end up 'average'.

Add in the 20 or 25 degrees above normal some locations are today, the monthly averages will be pushed up a bit more than even shown below. Last night's low in Houston was 69 deg....27 deg above normal!!

What a difference a week or 2 can make....the locations below are just a few examples of areas that were running below....in some cases well below...normal in avg temps for the month a week or 2 ago. These locations are now above normal for the month to date...or on the verge of being so. Even with some colder temps early in the week, the upcoming week overall could average above normal in most of these places.


As of 12/19, month to date departures from normal temps:

Daytona Beach +2.1 deg
Orlando -0.2 deg
Tampa +0.8 deg
Miami -0.1 deg
New Orleans +1.2 deg
Dallas +0.9 deg
Houston -0.8 deg

That is really interesting stuff ... wow. Great post, jinftl!

I never would have imagined the Texas locations to be nearly a degree above normal given what we have seen this month.

[iorange55]

So the cold front has come through, it's been through for awhile now but the temps aren't dropping near as fast as the last one. Is it because this is not as shallow? and the cold is taken a little awhile to filter in or what?

[Portastorm]

So the cold front has come through, it's been through for awhile now but the temps aren't dropping near as fast as the last one. Is it because this is not as shallow? and the cold is taken a little awhile to filter in or what?

I think the real CAA (cold air advection) is lagging several hours behind the actual front which you can determine by dewpoint temps in the state almost as much as surface temps. We should all "feel it" by tomorrow morning I'm sure.

At 7 pm here are the temps, followed by another graphic with the dew pt temps which I believe you can see the CAA a little more dramatically.

Surface Temperature



Dew point temperature

[PTPatrick]

I think the airmass just moderated or something. Denver had highs forecast in the mid teens and we reached 32. Low last night supposed to be 7, woke up to 19. Will be interesting to see if tonights forecast holds. But either way, I wouldnt be surprised if temp forecast down the plains dont bust as well.