Winter 2010-11 for the Southern Plains

[Extremeweatherguy]

00z NAM skew-T output for tomorrow evening/night in Oklahoma City...

http://www.twisterdata.com/data/tmp/scr ... .5000W.png
http://www.twisterdata.com/data/tmp/scr ... .5000W.png
http://www.twisterdata.com/data/tmp/scr ... .5000W.png <-- *best sounding*
http://www.twisterdata.com/data/tmp/scr ... .5000W.png
http://www.twisterdata.com/data/tmp/scr ... .5000W.png

Composite reflectivity for the same timeframe...

http://www.twisterdata.com/data/models/ ... URFACE.png
http://www.twisterdata.com/data/models/ ... URFACE.png
http://www.twisterdata.com/data/models/ ... URFACE.png
http://www.twisterdata.com/data/models/ ... URFACE.png
http://www.twisterdata.com/data/models/ ... URFACE.png

Looks good for a mixing with or changeover to snow on this run, especially towards the end of the "event" when the dry surface layer might be overcome. The actual QPF output for Oklahoma City is 0.10" on this run. The NAM predicted ground-level temperatures look a tad too warm for any kind of noteworthy snow accumulations if the changeover occurs, but if the surface temperatures are slightly cooler than shown, then a light dusting would be possible in a few locations.

[Ntxw]

0z GFS. Dry atmosphere sigh. I hope this ends up more robust than what it shows. Maybe we can get some Pacific moisture entrenched into it since the gulf isn't much help.

[Extremeweatherguy]

00z GFS soundings for OKC...

3pm Tues: http://www.twisterdata.com/data/tmp/scr ... .5000W.png
6pm Tues: http://www.twisterdata.com/data/tmp/scr ... .5000W.png
9pm Tues: http://www.twisterdata.com/data/tmp/scr ... .5000W.png
12am Wed: http://www.twisterdata.com/data/tmp/scr ... .5000W.png
3am Wed: http://www.twisterdata.com/data/tmp/scr ... .5000W.png

Very dry surface layer, but precipitation definitely being produced overhead. There would probably be a nice virga storm going on for a period tomorrow afternoon/evening if this plays out, but mainly just a few scattered flurries at ground level. If the surface layer can moisten up a bit more than shown though, which is very possible, then things would become a little more interesting. That is the scenario the GFS is showing happening over towards eastern Oklahoma, with some light accumulations indicated (http://www.twisterdata.com/data/models/ ... URFACE.png).

[Extremeweatherguy]

From the OUN NWS...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
920 PM CST MON DEC 6 2010

.DISCUSSION...
LOWERED TEMPERATURES FOR TONIGHT ACROSS NORTH-CENTRAL AND
SOUTHEAST PORTIONS OF OKLAHOMA BASED ON CURRENT OBSERVATION
TRENDS. OTHERWISE...LIGHT SOUTHERLY WIND AND INCREASING HIGH
CLOUDS WILL ALLOW MOST OF TONIGHTS LOWS TO BE 5 TO 10 DEGREES
WARMER THAN THIS MORNING.

COMPACT AND FAST MOVING UPPER WAVE STILL PROGD TO IMPACT CWA
TOMORROW AFTERNOON AND EVENING. MIXTURE OF RAIN AND SNOW WILL
LIKELY CHANGE TO ALL SNOW IN ANY HEAVIER/CONCENTRATED BANDS OF
PRECIPITATION...BUT INTENSITY AND DURATION NOT EXPECTED TO RESULT
IN MUCH ACCUMULATION. PERHAPS ENOUGH TO TURN SOME GRASSY/ELEVATED
SURFACES WHITE FOR A SHORT TIME. HIGHEST CHANCE FOR THIS TO OCCUR
WILL BE NEAR/NORTH OF OKC.

[orangeblood]

Never thought I would say this but you have to give it up for the GFS model. It has been dominating the other models over the past month. In particular, this storm coming out of the rockies now - It did a superb job depicting this event over a week ago while the other models were showing a much stronger storm.

[Ntxw]

Never thought I would say this but you have to give it up for the GFS model. It has been dominating the other models over the past month. In particular, this storm coming out of the rockies now - It did a superb job depicting this event over a week ago while the other models were showing a much stronger storm.

Many, including professionals in the field criticized the GFS for under performing compared to the Euro. Recent changes and fixes has made the GFS quite reliable not just the past month, but was noticed relatively in the tropical season. Though there has been a few, but phantom storms have not been as rampant this year as previous on the GFS long term. Perhaps it's a better future for forecasters in that regards.

[TwisterFanatic]

GFS still likes the idea of some snow in about 5-6 days in eastern Oklahoma.

[Extremeweatherguy]

The NWS has raised our precip. chances from 20% to 30% for tonight.

From the morning OUN discussion:

DISCUSSION...
A FAST MOVING SHORT WAVE TROUGH...AT MID LEVELS CURRENTLY CENTERED
OVER NORTH CENTRAL CO...HAS TURNED SOUTHEAST TO DROP DOWN THE EAST
SIDE OF THE WESTERN STATES RIDGE. PRECIPITATION CHANCES ASSOCIATED
WITH THIS TROUGH SPREAD INTO NORTHWEST OK THIS AFTERNOON...WITH
THE BULK OF ANY PRECIP NEAR AND EAST OF INTERSTATE 35 EXPECTED TO
OCCUR AFTER DARK. THERE IS SOME INTENSE LIFT EVIDENCED BY RADAR
ECHOES IN EASTERN CO/NORTHWEST KS...BUT THE FAST MOVEMENT OF THE
LOW AS IT PASSES OVER OK/NORTH TX LATER TODAY COMBINED WITH THE
VERY DRY NEAR SURFACE AIR THAT WILL TAKE A WHILE TO BE MOISTENED
SHOULD KEEP PRECIPITATION AMOUNTS LIGHT. THAT SAME DRY AIR MAY BE
COOLED BELOW FREEZING EVEN DURING THE DAY TODAY IN SOME
LOCATIONS...BUT ESPECIALLY TONIGHT. WITH THE ENTIRE ATMOSPHERIC
COLUMN ABOVE THE LOWEST LEVELS BELOW FREEZING...THIS MAY ALLOW FOR
A FEW FLAKES OF SNOW.

[Portastorm]

Never thought I would say this but you have to give it up for the GFS model. It has been dominating the other models over the past month. In particular, this storm coming out of the rockies now - It did a superb job depicting this event over a week ago while the other models were showing a much stronger storm.

Many, including professionals in the field criticized the GFS for under performing compared to the Euro. Recent changes and fixes has made the GFS quite reliable not just the past month, but was noticed relatively in the tropical season. Though there has been a few, but phantom storms have not been as rampant this year as previous on the GFS long term. Perhaps it's a better future for forecasters in that regards.

I understand how one might think anecdotally that the GFS is more reliable. It seems that way to me as well and I have seen the Euro blow a few forecasts lately. However, the statistics show that the Euro is still beating the GFS on a regular/daily basis. Take a look at the 5-day and 6-day scores at this link or even the monthly scores.

http://www.emc.ncep.noaa.gov/gmb/STATS/STATS.html

[Extremeweatherguy]

The latest run of the HRRR is showing the best shot at precipitation reaching the ground in central Oklahoma being between 3pm and 10pm. This is still a very tricky situation though, and low-level temperatures and dry air will definitely be working against us.

Surface temperatures right now are between 45-50F with dewpoints in the upper teens to near 20F. With temperatures this warm, any initial precipitation to reach the surface would almost definitely be in liquid form. The dry air will also make getting that precipitation to the ground a challenge in the first place. Assuming it can happen though, then wetbulb cooling should help to pull the air temperature into the 30s once the precipitation begins.

If the above process plays out exactly as described, then that is when we could potentially see a mixing with or changeover to snow occur. This would probably happen late in the afternoon or during the evening. Accumulations still look very unlikely if the changeover to snow does indeed take place; but a quick dusting cannot be ruled out if things come together perfectly.

[Ntxw]

I understand how one might think anecdotally that the GFS is more reliable. It seems that way to me as well and I have seen the Euro blow a few forecasts lately. However, the statistics show that the Euro is still beating the GFS on a regular/daily basis. Take a look at the 5-day and 6-day scores at this link or even the monthly scores.

http://www.emc.ncep.noaa.gov/gmb/STATS/STATS.html

The Euro is better than the GFS on track record. By no means do I believe the GFS is better than the EC yet! I was just stating how the changes improved the GFS to more tolerable levels compared to how it was resulting vs the euro in the past. Think you may have misread me Portastorm =P.

I still see mostly a virga storm coming today . Do hope someone in the soplains see something special tonight.

Looking ahead, the next system (next week) is trending more and more like a GL cutter. Usually in this case the far northern/northeastern plains (Tulsa to Fayetteville to Springfield triangle) are best at seeing some snow. I'm guessing the Ozarks region will get plastered. I'm sure many east coasters are looking at this growling at the fact it may just be all rain. The EC today actually has the blizzard confined to the upper midwest almost a thousand miles difference than the GFS lol. In that scenario, no snow for the soplains.

[TwisterFanatic]

The RUC is actually going with a bit more QPF than the NAM or GFS. It has anywhere from a .10-.25 from OKC to the Arkansas-Oklahoma border.

[Extremeweatherguy]

The RUC is actually going with a bit more QPF than the NAM or GFS. It has anywhere from a .10-.25 from OKC to the Arkansas-Oklahoma border.

Yeah, I noticed that. It is showing some nice saturated soundings over OKC starting later this afternoon and lasting into the evening. Surface temperatures are just above freezing during this time, but the entire atmosphere overhead would be below freezing; meaning a good chance for a mix or changeover to snow. I am still in a "i'll believe it when I see it" mode though, so i'm not going to get too worked up about this RUC run just yet. Let's see what actually happens over the next few hours first, and whether or not the RUC appears to be on the right track..

[Ntxw]

Woodward, Oklahoma is reporting light snow at 34 degrees with 0.75 visibility. That's a pretty good clip.

[Extremeweatherguy]

That is a very good sign. If snow is reaching the ground in Woodward, then that definitely raises the chances for everyone else.

[Ntxw]

That is a very good sign. If snow is reaching the ground in Woodward, then that definitely raises the chances for everyone else.

With the big batch heading their way, and if it's truly snowing at that rate, an inch + is not out of realm there.

Also radar reflective returns in southern KS is pretty good, with some yellow showing up. Perhaps it is more robust than proclaimed.

[srainhoutx]

Dodge City has been in the snow for a couple of hours now. Good luck on seeing those flakes fly!

[Ntxw]

It looks like being under the low/shortwave center will be key where the heaviest precip/lower temps will be concentrated. Take a look at the bullseye in NW Oklahoma.



Ruc currently.



Ruc at 5hrs.

[Extremeweatherguy]

I wouldn't be surprised if there are a few flakes mixing in just to the northeast of OKC right now. The temperatures up there have fallen into the upper 30s recently and the radar is starting to take on that "look" you expect to see when there are big, wet snowflakes just above the surface. I don't know if these flakes are actually reaching the ground just yet, but with temperatures sub-40F in that zone right now, it is certainly possible.

http://www.mesonet.org/data/public/meso ... R.grad.png

http://www.mesonet.org/index.php/weather/radar/KTLX

[Extremeweatherguy]

Precipitation is starting to fall now at my location. Still all rain at the moment with temperatures near 40F, but that is liable to change soon as the air continues to cool. Just to my north near Oklahoma City, temperatures are in the mid 30s right now and I am pretty confident that they are probably getting a nice rain/snow mix or even a changeover in spots. It will be interesting to see how this all plays out over the next few hours..

http://www.wunderground.com/radar/radbl ... rainsnow=0

http://www.mesonet.org/data/public/meso ... R.grad.png