Oklahoma Weather Discussion - February/March 2013

[venture]

MESOSCALE DISCUSSION 0175
NWS STORM PREDICTION CENTER NORMAN OK
0709 AM CST WED FEB 20 2013

AREAS AFFECTED...CENTRAL OK

CONCERNING...HEAVY SNOW

VALID 201309Z - 201715Z

SUMMARY...SNOWFALL RATES OF ONE INCH PER HOUR LOCALLY WILL AFFECT
PARTS OF THE CENTRAL OK VICINITY THIS MORNING.

DISCUSSION...DESPITE WET-BULB TEMPERATURES WHICH WERE WELL ABOVE
FREEZING EARLIER THIS MORNING ACROSS CENTRAL OK...MELTING ALOFT OF
PERSISTENTLY FALLING PRECIPITATION ACROSS THIS AREA HAS COOLED THE
LOWER-TROPOSPHERIC COLUMN WITH TIME. THIS COOLING HAS NOW REACHED
THE SURFACE...WITH TEMPERATURES PER THE OK MESONET HAVING FALLEN
SEVERAL DEGREES OVER THE PAST 1-2 HOURS DOWN TO NEAR FREEZING. THIS
MELTING-INDUCED COOLING HAS RESULTED IN A CHANGEOVER FROM RAIN TO
SNOW IN MANY AREAS PER LATEST SURFACE OBS. WHILE THE PRECIPITATION
REMAINS FAIRLY HEAVY/STEADY...PERSISTENT MELTING-INDUCED COOLING
WILL MAINTAIN A THERMAL STRUCTURE SUPPORTIVE OF CONTINUED SNOWFALL.
WITH WIDESPREAD PRECIPITATION STILL EVIDENT ON RADAR OVER NWRN
TX/SWRN OK WHICH WILL SHIFT NEWD WITH TIME...EXPECT THIS
MELTING/COOLING PROCESS TO CONTINUE DESPITE BACKGROUND WARM
ADVECTION -- WHICH WILL THUS SUPPORT SNOWFALL FOR AT LEAST A FEW
HOURS. EVENTUALLY...AS PRECIPITATION SLACKENS LATER THIS MORNING
AND THE MELTING-INDUCED COOLING LESSENS...THE LOWER TROPOSPHERE WILL
WARM A FEW DEGREES AND SNOWFALL SHOULD REVERT BACK TO RAIN.
MEANWHILE...SEVERAL INCHES OF WET SNOW COULD ACCUMULATE IN MANY
AREAS -- AT LEAST ON GRASSY SURFACES.

[venture]

Finally they woke up or looked outside...

#OUN extends area of Winter Weather Advisory for Beckham, Caddo, Cleveland, Coal, Garvin, Grady, Hughes, McClain http://bit.ly/VvBRzT?OUN

[ZYX2]

Snowfall has picked up in Bixby. Moderate/heavy now with occasionally strong wind gusts. Already sticking to the roof above our back porch.

[venture]

Latest AFD...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
745 AM CST WED FEB 20 2013


.UPDATE...
12Z OUN SOUNDING CAME IN COOLER THAN THE MODEL FORECASTS IN THE
LOW LEVELS. WE HAVE ALSO SEEN COLUMN COOLING APPARENTLY OCCUR
ACROSS PORTIONS OF SOUTH CENTRAL AND SOUTHEAST OKLAHOMA WHERE
TEMPERATURES HAVE COOLED SUFFICIENTLY TO ALLOW PRECIPITATION TO
CHANGE TO SNOW IN THE ADA... PAULS VALLEY... NORMAN AND SHAWNEE
AREAS THIS MORNING. BECAUSE OF THESE CHANGES... THE WINTER WEATHER
ADVISORY WILL BE EXPANDED FARTHER SOUTH. WILL CONTINUE TO WATCH
TRENDS IN THE LATEST DATA AND MAKE ADJUSTMENTS AS NEEDED THROUGH
THE DAY.

[venture]

The other side of the storm...severe weather. Slight Risk for extreme SW and Southern OK today.

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0648 AM CST WED FEB 20 2013

VALID 201300Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS TONIGHT FOR PARTS OF NW/N
CENTRAL TX INTO EXTREME SW OK...

...TX/OK THROUGH TONIGHT...
THE PRIMARY FEATURE OF INTEREST THIS PERIOD WILL BE THE EWD
PROGRESSION OF A STRONG MIDLEVEL LOW FROM SRN CA THIS MORNING TO THE
SRN HIGH PLAINS BY EARLY THURSDAY. LEE CYCLOGENESIS WILL OCCUR
INVOF NE NM/SE CO IN ADVANCE OF THE STRONG MIDLEVEL LOW...THOUGH A
SOMEWHAT COOL/STABLE AIR MASS NEAR THE GROUND WILL LIMIT DEEPENING
OF THE SURFACE LOW. OTHERWISE...A MODIFYING MARINE AIR MASS WILL
SPREAD NWD/NWWD ALONG THE RIO GRANDE VALLEY AND ACROSS THE
LOWER/MIDDLE TX COASTAL PLAIN THROUGH TONIGHT...TO THE S OF A
DEVELOPING WARM FRONT AND WEAK SECONDARY LOW THAT IS EXPECTED TO
FORM AT THE TRIPLE POINT IN CENTRAL/N CENTRAL TX OVERNIGHT.

FOR MUCH OF TODAY...WEAK ELEVATED CONVECTION WILL BE LIMITED TO THE
ZONE OF ASCENT EXTENDING FROM NW TX TO CENTRAL OK AND E TX...IN
ASSOCIATION WITH STRONG LOW-LEVEL WAA AND AN EJECTING SPEED MAX
WITHIN THE SUBTROPICAL JET. THE DEVELOPING WARM SECTOR ACROSS S TX
WILL LIKELY REMAIN CAPPED THROUGH THE PERIOD. LATER
TONIGHT...ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED AS ASCENT
INCREASES WITH THE APPROACH OF THE MIDLEVEL LOW AND AN ASSOCIATED
PACIFIC COLD FRONT. THIS CONVECTION WILL LIKELY DEVELOP IN THE
03-06Z TIME FRAME OVER THE S PLAINS AREA...AND THEN SPREAD NEWD OVER
OK AND EWD INTO N CENTRAL AND CENTRAL TX. MOST OF THE CONVECTION
WILL REMAIN ROOTED ABOVE THE COOL/STABLE LAYER NEAR THE SURFACE THAT
WILL BE REINFORCED BY WET BULB COOLING TODAY. HOWEVER...CAPE BASED
NEAR 850 MB COULD REACH THE 750-1500 J/KG RANGE TONIGHT OVER NW
TX...ON THE EDGE OF THE RICHER RETURNING MOISTURE AND A PLUME OF
STEEPER MIDLEVEL LAPSE RATES. EFFECTIVE BULK SHEAR WILL ALSO BE
SUFFICIENT FOR ELEVATED SUPERCELLS...WITH AN ATTENDANT RISK FOR
LARGE HAIL.

ISOLATED STRONG/DAMAGING GUSTS WILL BE POSSIBLE ALONG THE SRN FRINGE
OF THE CONVECTION WHERE THE NEAR-SURFACE STABLE LAYER WILL BE
SHALLOWER AND ERODING WITH TIME. ANY TORNADO THREAT WILL DEPEND ON
SURFACE-BASED STORM DEVELOPMENT NEAR THE TRIPLE POINT DURING THE
EARLY MORNING HOURS...THUS WILL MAINTAIN ONLY LOW PROBABILITIES.

[venture]

HRRR shows mostly snow through 1PM before suggesting mix/change to rain. We'll see what happens as the falling winter precip will assist with cooling the air (as has been the case already). Here is the forecast snow totals through 1PM...keep in mind HRR doesn't handle melting all that well.

[ShiroiHikari]

Holy crap, more snow! - YouTube

Awful quality because I took this from behind my kitchen window, but here's what it looked like here about 15 minutes ago. A little bit of melting is already happening and as I type this, all precipitation has stopped.

[venture]

Little battle going on in Norman right now. Seeing a back and forth from moderate snow to moderate rain. Still about an inch total on the ground right now. Perfect example of riding the edge like has been talked about with this system.

[LocoAko]

Loved waking up to a coating of snow here in Norman. We do keep swinging between snow and rain, but I have to say I was pretty surprised to wake up to this. Not a thing a meteorologist wants to say in the morning, ha. Some of the totals the HRRR is pointing out is troubling. As you said, seems completely unlikely on roads and whatnot, but that'd be quite the bust considering yesterday most forecasts for the metro were rain. Don't envy the NWS today.

[venture]

Good representation when it comes to the differences in precip falling right now...



HCA Key: HA = Hail, GR = Graupel, BD = Big Drops, HR = Heavy Rain, RA = Rain, WS = Wet Snow, DS = Dry Snow, IC = Ice Crystals, GC = Ground Clutter, BI = Biological

[Anonymous.]

Snow was much heavier in N OKC, and was sticking to side streets.

As I came into work into DT OKC, it was 3 degrees warmer with rain and little bit of snow.

[Anonymous.]

This is essentially the second storm in a row that the NWS called incorrectly. [Friday's dusting not a storm].

To be fair, both storms were tinkering on a few degrees. (maybe someday they will learn to be cautious and issue advisories before precip is actually falling)

[SoonerDave]

Man, I bet its days like this that even the most tea-totaling meteorologist here in OKC at least contemplates taking up drinking

[venture]

This is essentially the second storm in a row that the NWS called incorrectly. [Friday's dusting not a storm].

To be fair, both storms were tinkering on a few degrees. (maybe someday they will learn to be cautious and issue advisories before precip is actually falling)

Not just the NWS...pretty much all local media.

I think we keep seeing the failings of relying or favoring a single model and its products. I've read many discussions on Faceplace and elsewhere how many were throwing out the GFS because its been off. When right now, it pretty much is the model that nailed this a few days out. It keep the higher precip totals and lower total snow accumulations (at least it actually showed them)...which is pretty much what we got.

[pw405]

I drove from Nichols hills to norman starting at 7:00a - road accumulation wasn't too bad, but bridges were getting slick combined with extremely large snowflakes which obstructed vision. Quite dangerous travel conditions on the highways and people had already slid off the road on SB I35 and NB I35 was a parking lot... Be careful out there!

[Anonymous.]

Not just the NWS...pretty much all local media.

I think we keep seeing the failings of relying or favoring a single model and its products. I've read many discussions on Faceplace and elsewhere how many were throwing out the GFS because its been off. When right now, it pretty much is the model that nailed this a few days out. It keep the higher precip totals and lower total snow accumulations (at least it actually showed them)...which is pretty much what we got.

I am pretty sure the local stations are puppets for the NWS. They never go against them it seems. KFOR is somewhat independent in forecasting, but even they often are scared to call something that the NWS is not.




Melting has begun as precip is slowing and temperatures are rebounding a few degrees. Now to wait for tonight...

[venture]

I am pretty sure the local stations are puppets for the NWS. They never go against them it seems. KFOR is somewhat independent in forecasting, but even they often are scared to call something that the NWS is not.

It depends on the station I think. Yesterday it seemed KOCO was definitely in copy/paste mode and just reproducing the NWS forecast. KWTV wasn't really picking a side and KFOR went with the snow trend in the models. So as much as we all like to make fun of Morgan...LOL

Melting has begun as precip is slowing and temperatures are rebounding a few degrees. Now to wait for tonight...

Depends on where you are too. Here in Norman we are moving back into a more snow mode and way from rain. There is also a pretty good band of precip going back to Lawton now that still has to move through. Oklahoma Co is slowing some as the back edge for up there is right at the Canadian Co border...unless this stuff over us moves up that way more. Temp wise we are up around a degree over the last 2 hours...at 33.1°F now up from a low at 32.1 at 7:05AM. So not a major rebound here.

[iambecoming]

So, is the rain/snow done for the day in Norman?

[venture]

So, is the rain/snow done for the day in Norman?

Nope. Stream of moisture runs all the way back to NW Texas so it'll continue for awhile. Plus the main system pulls through tonight which will bring the chance of heavier rain and storms along the front overnight and early tomorrow.

[JayhawkTransplant]

I'm going to be driving from OKC to Stillwater for the KU/OSU game tonight, and will be driving back after the game around 11pm. I will be relying on the updates you guys post here!

[venture]

Next push of precip coming in from the south. This will be just for a few hours before drying out again. Right now appears to be mostly a rain/sleet mix (at least going by what it is in Norman right now). Could still see some snow mix in, but I think we are out of that mode for now.

[Bunty]

I'm going to be driving from OKC to Stillwater for the KU/OSU game tonight, and will be driving back after the game around 11pm. I will be relying on the updates you guys post here!

This as of 3:02PM:

Stillwater Weather Forecast - Outlook This Afternoon & Tonight:

This
Afternoon
Snow Likely. Chance for Measurable Precipitation 60% Hi 37 °F
NWS forecast: Snow likely. Cloudy, with a high near 37. East southeast wind around 14 mph, with gusts as high as 20 mph. Chance of precipitation is 60%. Total daytime snow accumulation of 2 to 4 inches possible.

Tonight
Wintry Mix. Chance for Measurable Precipitation 100% Lo 32 °F
NWS forecast: Rain, possibly mixed with freezing rain and sleet before midnight, then rain, snow, and freezing rain. Low around 32. East wind 6 to 15 mph, with gusts as high as 21 mph. Chance of precipitation is 100%. Little or no ice accumulation expected. New snow and sleet accumulation of 2 to 4 inches possible.

[ZYX2]

At one time I would guess that we had 3+ inches of snow here in Bixby, but the snow stopped and then changed to rain for an hour or so, then mixed, and is now back to moderately falling all snow. Probably about 1-2 inches at my house.

[ZYX2]

This is a picture out my back window taken at 4:05 pm.

[ZYX2]

Any predictions for tonight?