OUN must be pretty confident in their forecast.

Still no advisory other than the initial WSWatch.

I would not be so confident with wet bulb temps still below freezing and clear skies above heading into this evening.

Yeah, they are showing a bias towards the air not getting cold enough, fast enough for too much snow. My concern is that this could go wrong for them very quickly and then they are playing catch up with headlines tomorrow. Maybe i'm more cautious than anything, but I would have done a Winter Storm Watch for everywhere north of a Altus - Lawton - Pauls Valley - Ada line. Just too much uncertainty. As much as I dislike the 18Z runs with models...GFS did move the bulk of the heavy snow right over Central OK.

Venture I was saying the exact same about an hour ago....that they could be reversing course rather rapidly should the GFS verify. What's the harm in issuing a watch just to be on the safe side?

What conditions determine a 'winter storm'? I fail to see that 2-4" of snow is a 'storm'. Snow advisory perhaps. Storm? No.

Moisture streaming up from TX very rapidly ahead of the storm. I wish the clouds would hold off for several more hours and let temps fall more...


This is so complex... I totally understand why the local media and OUN is going with rain in OKC instead of snow. But at the same time they are going to get burned if we go to snow earlier than anticipated.

Either way nearly an inch of precip is going to be great.

Local offices modify these a bit based on various conditions. For instance a Winter Weather Advisory issued by NWS North Webster, IN will cover 2-4" of snow, by NWS Cleveland they require 3-5" of snow.

College of DuPage/NEXLAB Watch, Warning and Advisory Criteria Page (http://weather.cod.edu/notes/criteria.html)

SNOW ADVISORY -- A Snow Advisory will be issued when 3-5 inches is expected to fall.

*Check with your NWS office for local snowfall requirements.

BLOWING SNOW ADVISORY -- A Blowing Snow advisory will be posted for events in which visibility is intermittently 1/4 mile or less.

FREEZING RAIN / FREEZING DRIZZLE ADVISORY -- This requires that hazardous driving conditions be taking place and/or up to 1/4 inch of freezing rain on tree branches and/or if power lines break.

WINTER WEATHER ADVISORY -- A Winter Weather Advisory will be issued if conditions warranting two separate winter advisories are met.

WINTER STORM WATCH -- A Winter Storm Watch may be issued when conditions are forecast to meet the criteria for more than one warning with in the next 36 hours. A watch for a single winter weather event does not exist, for example a Wind Chill Watch or a Heavy Snow Watch. Just the same, if a forecaster thinks there will be significant snow and ice tomorrow, he/she will issue a Winter Storm Watch.

WINTER STORM WARNING -- A Winter Storm Warning will be issued if conditions are forecast to meet the criteria for two separate warnings in the next 12-24 hours. Example: If you have Heavy Snow Warning conditions along with Wind Chill Warning conditions, a Winter Storm Warning will be issued.

BLIZZARD WARNING -- A Blizzard Warning will be issued when the following conditions are forecast to last at least 3 hours. Falling and/or blowing snow frequently reducing visibility to < 1/4 mile AND sustained winds or frequent gusts > 35 mph.

ICE STORM WARNING -- An Ice Storm Warning will be issued if freezing rain/drizzle is occurring with a significant accumulation of ice (more than 1/4 inch) or accumlation of 1/2 inch of sleet.

HEAVY SNOW WARNING -- A Heavy Snow Warning will be issued if 6 or more inches of snow is expected in a 12 hour period.

The thick clouds are holding steady in N TX, OKC has already dropped to 47 with the sun setting right now. [which btw, looks awesomely red, atm]

My thermometer already says it is 42F.

Just looked outside, skies are basically clear, a few high clouds streaming in from southwest and that is it.


Wet bulb temp is 34 atm.

OUN has drastically changed their snowfall forecast map -- thinking nearly all precip in the metro will be rain:

http://www.srh.noaa.gov/images/fxc/oun/graphicast/image5.jpg

FWIW, based on an exchange I saw on FB involving one of the NWS forecasters, that is specifically an accumulation map. I think they still expect snow in the metro but that little, if any, will actually stick.

New NAM has cut off heavy snow in Western OK a ton. Heaviest area (around 3"+) From OKC area up to Ponca.

Soundings also show it much colder than before, and the NAM had previously been the warmest solution (that I'm aware of). It would be snow from mid-morning on in the metro... Yikes. I don't envy the workers at the Norman WFO this evening.

Noon in Norman:

http://www.twisterdata.com/data/tmp/scratch/models/processing/NAM_218_2013021200_F18_35.0000N_97.5000W.png

40 degrees now and still clear skies... So are we going to see a WSWatch for metro or are they going to let this be a disaster?

http://img443.imageshack.us/img443/7650/feb11.jpg



So the models think it is going to be warmer longer and thus bringing down all the snow totals, yet the temperatures are already approaching the zone?

Unfortunately we are still quite a ways from 32* and the main concern (for those wanting the temp to drop further) has to be the warmer air in S OK and the winds that are now shifting in that area advecting that warmer air into central OK. Here are the temp and wind maps:

http://www.mesonet.org/data/public/mesonet/maps/realtime/current.TAIR.grad.png

http://www.mesonet.org/data/public/mesonet/maps/realtime/current.WIND.grad.png

I have to say it again....OUN is walking a fine line in my opinion with this storm considering the 00z NAM's output. I still have to say I'd issue a watch just to have my bases covered even on the 20% chance this were to verify:

http://wxcaster4.com/nam/CONUS1_ETA212_SFC_ACCUMSNOWFALL_36HR.gif

Interesting discussion. Makes me want to geek out and read it all night.

Western OK is finally getting some precip!

venture, those wind speeds are basically stationary and more out of the northeast than any southern changes.

The dewpoint over C OK right now is in the low to mid twenties and wet-bulb is ranging around 34-36. Both of these combined = OKC will be cold enough for snow from the get go of precip, or very shortly thereafter. I keep checking outside to see cloud cover, and I see stars. I am worried that this could be a total bust in terms of forecast [in which tomorrow is all white].

Anonymous,
You have to remember that the orientation of this storm will lend itself to fairly substantial warm air advection especially considering the amount of moisture being pulled in. Clouds are already becoming the norm overhead here in Moore and cloudcover will only become more dense as the low pressure draws closer.

venture, those wind speeds are basically stationary and more out of the northeast than any southern changes.

The dewpoint over C OK right now is in the low to mid twenties and wet-bulb is ranging around 34-36. Both of these combined = OKC will be cold enough for snow from the get go of precip, or very shortly thereafter. I keep checking outside to see cloud cover, and I see stars. I am worried that this could be a total bust in terms of forecast [in which tomorrow is all white].

I've seen snow down here with surface temps in the upper 30s before, so I'm not worried. All that is going to matter is the depth of cold air upstairs and how borderline it is. I really don't know what else to add outside of what we've been discussing for days now. We are all viewing the setup the same way and I'm just a little stumped Norman is not being a little more cautious. If this does go all snow, it'll be around an inch an hour. Any heavy snowfall at that rate is going to overcome ground melting fairly quickly. I just worry about people complaining about being caught off guard and unprepared if this does go all snow.

Winter Storm Watch just issued (for Cleveland County at least). Still waiting on the text.

Yes, no doubt warm air will be a problem, this is the downfall of very wet systems that you want to produce snow.

The clouds you see out now are very spotty and pocketed low level clouds, these will not hold our temps up as the night progresses. In my opinion, this combination will allow for lower temps from the start, once precip begins and we have rapid evaporation cooling taking place - things will go downhill quick.



And now the back pedaling begins...




URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE NORMAN OK
942 PM CST MON FEB 11 2013

OKZ008-013-019-020-023>029-035-036-038-TXZ083-121145-
/O.EXB.KOUN.WS.A.0001.130212T1300Z-130213T0200Z/
KAY-NOBLE-LOGAN-PAYNE-CADDO-CANADIAN-OKLAHOMA-LINCOLN-GRADY-
MCCLAIN-CLEVELAND-KIOWA-JACKSON-COMANCHE-HARDEMAN-
INCLUDING THE CITIES OF...PONCA CITY...PERRY...GUTHRIE...
STILLWATER...ANADARKO...YUKON...EL RENO...MUSTANG...
OKLAHOMA CITY...CHANDLER...CHICKASHA...PURCELL...NORMAN...M OORE...
HOBART...ALTUS...LAWTON...QUANAH...CHILLICOTHE
942 PM CST MON FEB 11 2013

...WINTER STORM WATCH IN EFFECT FROM 7 AM CST TUESDAY THROUGH
TUESDAY EVENING...

THE NATIONAL WEATHER SERVICE IN NORMAN HAS ISSUED A WINTER STORM
WATCH...WHICH IS IN EFFECT FROM 7 AM CST TUESDAY THROUGH TUESDAY
EVENING.

* MAIN IMPACT: RAIN IS EXPECTED TO BEGIN IN CENTRAL OKLAHOMA
BEFORE SUNRISE TUESDAY MORNING. RAIN IS EXPECTED TO MIX WITH AND
CHANGE TO SNOW BEFORE NOON. SNOW ACCUMULATION OF 3 TO 6 INCHES
IS POSSIBLE ACROSS CENTRAL OKLAHOMA.

* OTHER IMPACTS:SNOW ACCUMULATIONS MAY RESULT IN SLICK AND
HAZARDOUS ROADWAYS TUESDAY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

KEEP UP WITH THE LATEST WEATHER INFORMATION...ESPECIALLY IF YOU
PLAN TO TRAVEL.

Winter Storm Watch just issued (for Cleveland County at least). Still waiting on the text.

IMO this had to be done after looking at the 00z data....if at worst just as a CYA move.

Anonymous,
You have to remember that the orientation of this storm will lend itself to fairly substantial warm air advection especially considering the amount of moisture being pulled in. Clouds are already becoming the norm overhead here in Moore and cloudcover will only become more dense as the low pressure draws closer.

Looking at the quality of the air south of us, there isn't really a lot of warm air to push in...except right at the surface.

http://climate.cod.edu/data/upper/US/925/US925raw.20130212.00.gif

They listened!

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE NORMAN OK
942 PM CST MON FEB 11 2013


OKZ008-013-019-020-023>029-035-036-038-TXZ083-121145-
/O.EXB.KOUN.WS.A.0001.130212T1300Z-130213T0200Z/
KAY-NOBLE-LOGAN-PAYNE-CADDO-CANADIAN-OKLAHOMA-LINCOLN-GRADY-
MCCLAIN-CLEVELAND-KIOWA-JACKSON-COMANCHE-HARDEMAN-
INCLUDING THE CITIES OF...PONCA CITY...PERRY...GUTHRIE...
STILLWATER...ANADARKO...YUKON...EL RENO...MUSTANG...
OKLAHOMA CITY...CHANDLER...CHICKASHA...PURCELL...NORMAN...M OORE...
HOBART...ALTUS...LAWTON...QUANAH...CHILLICOTHE
942 PM CST MON FEB 11 2013


...WINTER STORM WATCH IN EFFECT FROM 7 AM CST TUESDAY THROUGH
TUESDAY EVENING...


THE NATIONAL WEATHER SERVICE IN NORMAN HAS ISSUED A WINTER STORM
WATCH...WHICH IS IN EFFECT FROM 7 AM CST TUESDAY THROUGH TUESDAY
EVENING.


* MAIN IMPACT: RAIN IS EXPECTED TO BEGIN IN CENTRAL OKLAHOMA
BEFORE SUNRISE TUESDAY MORNING. RAIN IS EXPECTED TO MIX WITH AND
CHANGE TO SNOW BEFORE NOON. SNOW ACCUMULATION OF 3 TO 6 INCHES
IS POSSIBLE ACROSS CENTRAL OKLAHOMA.


* OTHER IMPACTS:SNOW ACCUMULATIONS MAY RESULT IN SLICK AND
HAZARDOUS ROADWAYS TUESDAY.


PRECAUTIONARY/PREPAREDNESS ACTIONS...


KEEP UP WITH THE LATEST WEATHER INFORMATION...ESPECIALLY IF YOU
PLAN TO TRAVEL.

Warning Details...

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE NORMAN OK
942 PM CST MON FEB 11 2013


OKZ009>011-014>017-021-022-121145-
/O.UPG.KOUN.WS.A.0001.130212T0900Z-130213T0000Z/
/O.NEW.KOUN.WS.W.0001.130212T1300Z-130213T0200Z/
ELLIS-WOODWARD-MAJOR-ROGER MILLS-DEWEY-CUSTER-BLAINE-BECKHAM-
WA****A-
INCLUDING THE CITIES OF...ARNETT...WOODWARD...FAIRVIEW...
CHEYENNE...TALOGA...WEATHERFORD...CLINTON...WATONG A...ELK CITY...
SAYRE...CORDELL
942 PM CST MON FEB 11 2013


...WINTER STORM WARNING IN EFFECT FROM 7 AM TO 8 PM CST TUESDAY...


THE NATIONAL WEATHER SERVICE IN NORMAN HAS ISSUED A WINTER STORM
WARNING FOR SNOW...WHICH IS IN EFFECT FROM 7 AM TO 8 PM CST
TUESDAY. THE WINTER STORM WATCH IS NO LONGER IN EFFECT.


* MAIN IMPACT: SNOW IS EXPECTED TO DEVELOP IN WESTERN OKLAHOMA
BEFORE SUNRISE TUESDAY MORNING AND SPREAD EAST DURING THE DAY.
SNOW ACCUMULATION OF 5 TO 9 INCHES IS POSSIBLE ACROSS PARTS OF
WESTERN OKLAHOMA.


* OTHER IMPACTS: SNOW ACCUMULATIONS WILL RESULT IN SLICK AND
HAZARDOUS ROADWAYS TUESDAY.


PRECAUTIONARY/PREPAREDNESS ACTIONS...


AVOID TRAVEL. BE SURE YOU CAN TAKE CARE OF YOURSELF AND YOUR
FAMILY IF YOU LOSE ELECTRICAL POWER. MONITOR WEATHER FORECASTS
AND INFORMATION.

Now I hope the Tulsa office believes the same way...

Well that is certainly ramped up wording from the afternoon forecast crew and I still say they should have done this much earlier this afternoon. None of the model data throughout the day has completely ruled out heavy snowfall somewhere near central OK. However I still say there are many hurdles to overcome for a heavy snow event in the metro.

No explanation from them? Weak...

"Uhhhh yea OKC, you shouldn't really see anything except for a dusting around 5pm."


"Oh hey, OKC, I know you're going to bed right now, but it will be snowing when you wake up, gnight!"

Cursory glance at the 00Z GFS keeps it warm and wouldn't change Norman over to a wet snow until after sunset. Meanwhile the NAM which had been the warm outlier is now the colder solution. Nasty forecast situation shaping up.

Uhhhh, so reading this their view of the models hasn't changed yet they've waited until now to issue the watch? Definitely SMH on this one:



AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
945 PM CST MON FEB 11 2013

.DISCUSSION...
EARLY EVENING MODEL RUNS ARE FAIRLY CONSISTENT WITH PREVIOUS RUNS IN
POSITION OF THE SNOW ACCUMULATION FOR TUESDAY. WITH PERSISTENT
AMOUNTS, INCREASED FORECAST AMOUNTS IN WHAT LOOKS LIKE THE BELT OF
GREATEST SNOWFALL POTENTIAL FROM WEST CENTRAL OKLAHOMA TO THE EAST
OR NORTHEAST. THE WATCH WAS EXPANDED EAST TO INCLUDE CENTRAL
OKLAHOMA AND WAS CONVERTED TO A WARNING BEGINNING AROUND SUNRISE
FOR WEST CENTRAL OKLAHOMA. IF RAIN CHANGES TO SNOW EARLY ENOUGH,
SNOFALL RATES MAY BE SUFFICIENT TO INSULATE THE RELATIVELY WARM
GROUND AND ALLOW FOR MORE ACCUMULATION. NEW WSW HAS BEEN ISSUED.

The RAP pretty much kisses chances of heavy snow in OKC goodbye:

http://climate.cod.edu/data/forecast/RUC/00/SP/rucSP_2_temp_18.gif

My temp here in OKC is sitting @ 41 still.

I definitely figured I would be in the upper 30s by now. With clouds increasing in the SW part of the state, this is going to be ridiculously close for the metro.


Just turned on the local news, KFOR doesn't even have the updated WSW... Totally clueless.


Here is NWS in Norman continuing the back pedaling:



https://o.twimg.com/1/proxy.jpg?t=FQQVBBgraHR0cDovL3N0YXRpYy5vdy5seS9waG 90b3Mvbm9ybWFsLzF2QkRoLmpwZxQEFgASAA&s=KjDclAZmptErbZmCGtAVHJS_3AkB6YlNWGHU-tGzvrA

Wet-Bulb temperature continues to drop slowly. OKC is @ 34 on north side, 36 south.

My air temp is now 40, it touched 39 just a bit ago.

I think at this point Anonymous we should all just be hoping the falling precip will do the cooling.

Yup, it will come down to just a few degrees,


Melting rates will also be high due to warmer ground temperatures, not bone chilling air temperatures, AND snowfall during daylight hours... This will be a great event for the drought. Even if we stay rain in OKC [which i doubt].

Wtf is "wet-bulb"??

Wtf is "wet-bulb"??

LOL. Sounds like a porn euphemism.

Wet-bulb temperature - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Wet-bulb_temperature)

The wet-bulb temperature is the temperature (http://en.wikipedia.org/wiki/Temperature) a parcel of air would have if it were cooled to saturation (100% relative humidity (http://en.wikipedia.org/wiki/Relative_humidity)) by the evaporation (http://en.wikipedia.org/wiki/Evaporation) of water into it, with the latent heat (http://en.wikipedia.org/wiki/Latent_heat) being supplied by the parcel.[1] (http://en.wikipedia.org/wiki/Wet-bulb_temperature#cite_note-1) An actual wet-bulb thermometer (http://en.wikipedia.org/wiki/Wet-bulb_temperature#Temperature_reading_of_wet-bulb_thermometer) indicates a temperature close to the true (thermodynamic) wet-bulb temperature. The wet-bulb temperature is the lowest temperature that can be reached under current ambient conditions by the evaporation of water only; it is the temperature felt when the skin is wet and exposed to moving air. Wet-bulb temperature is largely determined by both actual air temperature (dry-bulb temperature (http://en.wikipedia.org/wiki/Dry-bulb_temperature)) and humidity, the amount of moisture in the air.
The thermodynamic wet-bulb temperature is the minimum temperature which may be achieved by purely evaporative cooling (http://en.wikipedia.org/wiki/Evaporative_cooling) of a water-wetted (or even ice-covered), ventilated surface.

Was just about to post the definition as well.

Right now ~11:35pm the wet-bulb is 34 in N OKC and 33 in S OKC.



I just looked outside once again (I am in N OKC) and the skies are CLEAR. My temperature says 39 right now.

According to the Mesonet it is 33 near my location in Bixby. Hoping for it to drop a few more degrees before clouds move in!

Closest thick cloud cover is just across the SW border of OK.

This is going to allow temperature to drop steadily as we head into the midnight hour. Since my last post my temp has dropped to 38, and the mesonets around the OKC metro have dropped 2-3 degrees. I am telling you without cloud cover, we will get very close to 32. Add in precip falling and the wet bulb effect is easily making us snow very early on.


Well I am going to get some sleep i suppose since work exists despite fun hobbies in weather.


I will probably wake up with excitement multiple times like a child on Christmas Eve. And as I do such, I will post updates about current conditions best to my ability.

I'm still at 45 degrees here in Norman. I wonder why the temp here has remained fairly steady?

I'm still at 45 degrees here in Norman. I wonder why the temp here has remained fairly steady?

Moisture content of the air is slowly increasing, so that's going to play with the temps some. Wind also picked up a good deal up until an hour ago. Also maybe a little urban heat effect happening too. Shouldn't last much longer though. Temps are falling off pretty good as wind is set coming form the NE now. Spencer is down to 36, same up in Chandler and then upper 20s just NE of there. El Reno is down to 32 now. As I'm typing this and seeing the new mesonet reports coming in, the temp in Norman has dropped 2 degrees just with the wind stopping...down to 41 now. Roughly falling about half a degree every 5 minutes at this point.

One more post before retiring for the evening.

Current radar images showing wide spread and rapidly development showers and thunderstorms to our SW. Looks like the freezing level is around 3600' over Central OK and down to 3000' over SW OK.

Latest HRRR run has precip change over for the Metro area starting around 9AM on the far west side. With change over in the city around 11AM-1PM now.

Through 2PM here are the snow totals...

http://rapidrefresh.noaa.gov/HRRR/from_jet/hrrr_jet/2013021205/t5/acsnw_t5sfc_f15.png

Sitting at 38 here ~ 3:30am.

Temps are having a very hard time making any further progress. Cloud cover over majority of state now. Wet bulb for OKC is right at freezing and 33. Bouncing back and forth. Unless the temps can drop 3-4 more degrees in the next 3 hours the sun will begin counter acting the entire event.


The precip shield is entering SW OK right now. Temps down there are about the same as in C OK so it will be interesting to see what happens. If the low can wrap up and cool itself off we may see faster changeover. Really the only parts of the state at or below freezing is the NE, far N, and panhandle.

WSWarning extended another row east. Travelors advisory for everyone around it.

Storm is really trying to wrap itself up. Heavy snow about to move into W OK.

Too bad temperatures stalled out, this would easily be 10+ inches over much of the state. At least we all know it is beneficial.

The GFS keeps this storm a snow event for much of he state, while the NAM shows the snow never making it to most parts of the OKC metro or west of I-35. We will see how this plays out.

It's pretty much all snow/sleet at NW Expressway and Portland already

Al Roker flashed a snow total map on the Today Show this morning with 9-12 inches from Elk City and over the metro. Where is he getting that?

Rain at WRWA still. A few flakes every now and then.

Turning to slush/freezing rain in S. Edmond/N. OKC.

Yeah, getting reports that far west OK County is starting to see snow.

Just got to work in downtown OKC.

Heading down Broadway Ext was 80/20 rain/snow.

35 degrees.

NWS has a Winter Weather Advisory out for 1-3 inches while the Weather Channel said up to a half foot possible in OKC. Today should be fun.

So recapping, Winter Storm warning from Enid to Yukon to Anadarko and back to the west and southwest. Winter Weather Advisory (there is no such thing as a Travelers Advisory) surrounding that for the other counties in the OKC metro area except for Pott County.

HRRR showing anywhere from 2 up to 8 inches across the OKC metro area. Still mostly rain in Norman temps at 34. Though it'll start mixing fast...

http://www.weatherspotlight.com/radar/ktlx_hca1.png

Slush is falling at WRWA.

Looks like the change over to snow is happening pretty rapidly.. Finally wet-bulb effect kicking in.

MD out for all of W. C. OK for heavy snow rates @ 1"/hour.

Time to warm up the de-ice trucks....

*Sigh*

http://www.spc.noaa.gov/products/md/mcd0155.gif

MESOSCALE DISCUSSION 0155
NWS STORM PREDICTION CENTER NORMAN OK
0758 AM CST TUE FEB 12 2013

AREAS AFFECTED...TX PANHANDLE TO WESTERN/NORTH-CENTRAL OK

CONCERNING...HEAVY SNOW

VALID 121358Z - 121800Z

SUMMARY...MODERATE/HEAVY SNOW WILL CONTINUE TO DEVELOP
EAST-NORTHEASTWARD FROM THE TX PANHANDLE INTO WESTERN/NORTH-CENTRAL
OK THROUGH 18Z. SNOWFALL RATES SHOULD CONTINUE TO REACH 1 IN/HR
THROUGH EARLY AFTERNOON...WITH LOCALLY HIGHER RATES POSSIBLE FOR
RELATIVELY SHORT DURATIONS.

DISCUSSION...IN ASSOCIATION WITH AN EAST-NORTHEAST ADVANCING UPPER
TROUGH OVER NM/APPROACHING FAR WEST TX EARLY THIS MORNING...DEEP
LAYER ASCENT VIA UPPER JET EXIT REGION/WARM ADVECTION CONTINUES TO
CONTRIBUTE TO AN EAST-NORTHEASTWARD DEVELOPMENT OF PRECIPITATION
ACROSS FAR NORTH TX/TX PANHANDLE INTO WESTERN/SOUTHERN OK. AS OF
13Z...ZERO/SUB-ZERO SURFACE WET BULB TEMPERATURES ARE EVIDENT ACROSS
THE MAJORITY OF THE TX PANHANDLE AND INTO NORTHWEST OK /AREAS NORTH
OF I-40/. THESE COLDER TEMPERATURES CONTINUE TO ROUGHLY COINCIDE
WITH AREAS THAT ARE ALONG AND NORTH-NORTHWEST OF A WEAK SURFACE
INVERTED TROUGH/ZONE OF LOW-LEVEL CONFLUENCE.

ALTHOUGH THE 12Z OBSERVED SOUNDING FROM NORMAN WAS INDICATIVE OF AN
ABOVE-FREEZING WET BULB PROFILE BELOW 850 MB...THE ONSET OF STRONGER
FORCING FOR ASCENT/HIGHER PRECIPITATION RATES AND LOW-LEVEL COLD
ADVECTION SHOULD CONTINUE TO LEAD TO A GENERAL WEST TO EAST
TRANSITION OF RAIN TO SNOW INTO WEST-CENTRAL/NORTH-CENTRAL OK
THROUGH MIDDAY. THIS ASIDE...SOME SLEET WILL BE POSSIBLE WITH
PRECIPITATION ONSET AND/OR EXISTING CONVECTIVE ELEMENTS ACROSS
SOUTH-CENTRAL OK.

DEEP FORCING/SATURATION ASIDE...MID-LEVEL FRONTOGENESIS /800-600
MB/...ALONG WITH WEAK UPRIGHT INSTABILITY AND/OR SLANTWISE
INSTABILITY...WILL LIKELY ENHANCE SNOWFALL WITH RATES OF 1+ IN/HR
POSSIBLE INTO EARLY AFTERNOON. THIS WILL ESPECIALLY BE THE CASE
ACROSS THE EASTERN TX PANHANDLE INTO WEST-CENTRAL OK AND PERHAPS
NORTH-CENTRAL OK BY EARLY AFTERNOON.

..GUYER.. 02/12/2013

Downtown OKC has switched to 80/20 snow/rain now.


Looks like a cold pocket has worked its way over the OKC Metro, sitting in 33-34 temps while areas north, east, and south are all closer to 40.


EDIT: Almost 100% snow now in downtown. ~9:15am