WINTER WEATHER ADVISORY - Includes entire OKC metro area.

Updated: Thu Nov-21-13 04:14am CST
Effective: Thu Nov-21-13 04:14am CST
Expires: Sat Nov-23-13 06:00am CST

Severity: Minor
Urgency: Expected
Certainty: Likely

Status: Actual
Type: Alert
Category: Met

Areas affected: Alfalfa; Beckham; Blaine; Caddo; Canadian; Cleveland; Comanche; Custer; Dewey; Ellis; Garfield; Grady; Grant; Greer; Harmon; Harper; Jackson; Kay; Kingfisher; Kiowa; Lincoln; Logan; Major; McClain; Noble; Oklahoma; Payne; Pottawatomie; Roger Mills; Tillman; Wash ita; Woods; Woodward

Instructions: Be careful if you have to travel. Even small amounts of ice can make roads and sidewalks slick and dangerous.

Message summary: ...winter weather advisory in effect from 6 pm this evening to 6 am cst saturday...
The national weather service in norman has issued a winter weather advisory for freezing rain...which is in effect from 6 pm this evening to 6 am cst saturday.

* timing: late thursday night through early saturday morning.
* main impact: freezing rain is expected to develop behind a strong arctic cold front late thursday night and early friday morning...with areas of light freezing drizzle possible as late as saturday morning. Ice accumulation near one tenth of an inch is expected on elevated surfaces such as trees...powerlines and bridges. Some locations could experience slightly more or less accumulation.

* other impacts: strong north winds through friday combined with the weight of the ice on powerlines and trees could result in some power outages across the advisory area. Elevated roadways such as bridges and overpasses may develop a thin layer of ice resulting in hazardous driving conditions...especially friday morning across central ok. Some snow and sleet is also expected across extreme northern oklahoma where light accumulations of less than one inch can be expected through late friday morning.

Ole Emily is saying Saturday morning might be messier than tomorrow morning...Works for me!

I guess I have to color myself a bit confused. I'm seeing forecasts of .1-.3" of ice, but mainly on bridges, tree limbs, etc. Is the lack of general accumulation on the roads (non-elevated) because of surface temps being too high?

Seems to me that if the temps are that low and you have a general precip event over a long enough period of time, the surface temps will become low enough for that general accumulation.

Only reason I'm in a bit of a tizzy on this is because I"m supposed to drive to Lawton tomorrow afternoon around 5pm, but if there's going to be ice all over the place, I'm obviously not going to make the trip....

Cold front is approaching Woodward area right now. 30s behind front, with 50s and 60s ahead.


NAM is bread and milk warning worthy right now. Will have to see next couple runs for consistency, but it produces 6+ inches of snow over a good part of W, SW, and C OK with main low eject by Sunday evening.

GFS is keeping colder air back, but is continuing the trend mentioned earlier about bringing the low track further north into OK.



One little note I want to add, the surface temperatures are decently warm, but we have not really seen any sunlight this week to really bring them up. A prolonged period of sub 30F (notice I didn't say 32F) will result in rapid cooling on surface if precipitation is falling. Wet-bulb temps will plummet and we could see significant problems.

Dave - yes. With surface temps still in the 50s, this will reduce accumulation on the roads. Now if we see a lot of sleet for a time, that will help to cool things down and allow ground accumulation. The other issue for the roads is bridges may be iced up but the rest of the roadway won't be and that might catch people off guard.

12Z NAM is a bit higher in precip amounts for Central OK again. Essentially right along I-44 and the counties north and south of it are showing up to 0.8" of liquid now. The vast majority of it falling from 6AM tomorrow through early afternoon. NAM has surface temps below freezing for the entire period. With that said, the 06Z GFS was mostly dry for tomorrow. 00Z ECMWF is pretty dry as well north of I-44.

Edit...and what Anon said. :)

Not too tough to pick out the cold front which is running a bit ahead of schedule.

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

Anyone want to bet on school/business closings for Friday?

5084

I say Gov. Fallin (if she has a kind heart) will close all State offices before 8:00 a.m. tomorrow.

I say Gov. Fallin (if she has a kind heart) will close all State offices before 8:00 a.m. tomorrow.
It's not like anyone would notice. ;-)

any guesses as to what time the precip will arrive? TV weather folks just keep saying tonight and Friday am but sure would like to know if it is around
6 pm. . . 10 pm. . .midnight??

Is this system going to create a road issue considering ground temps are still pretty warm or is it primarily going to be a danger from above storm (trees and powerlines)? I know bridges and overpasses are a concern but if I'm driving to work tomorrow morning, how long is it going to take to cautiously drive 10 miles on city streets?

Is this system going to create a road issue considering ground temps are still pretty warm or is it primarily going to be a danger from above storm (trees and powerlines)? I know bridges and overpasses are a concern but if I'm driving to work tomorrow morning, how long is it going to take to cautiously drive 10 miles on city streets?

http://www.okctalk.com/current-events-open-topic/35494-oklahoma-weather-discussion-november-december-2013-a-5.html#post709401

Post #125

any guesses as to what time the precip will arrive? TV weather folks just keep saying tonight and Friday am but sure would like to know if it is around
6 pm. . . 10 pm. . .midnight??

Going by the HRRR (which is the short term model) looks like Frontal Passage happens around 3PM today with some rain possible a storm or two. Behind it maybe some drizzle as the cold air comes in. We will start falling through the 30s by drive time this evening, but things should still be okay. NAM doesn't show much precip until early tomorrow morning when it begins to increase in intensity quite a bit.

I do have the chat room open now with the twitter updates popping in from time to time: Weather Spotlight - Live Weather Event Coverage (http://www.weatherspotlight.com/chat.html)

I'll be in an out most of the day as I sit here coding away all day. :)

This is the weekend NAM Snow storm that Anon was hinting at earlier. Snow would be late morning on Saturday through Sunday (NAM period ends during Sunday)...

http://wxcaster4.com/nam/CONUS1_ETA212_SFC_ACCUM-SNOWFALL_84HR.gif

So if you were to measure distance by putting your index finger and thumb this far apart, how close are we to a true "bread and milk" warning for tomorrow?

Or is it still too close to call?

5+".... Sounds great...

So I'm driving to OKC right now from florida. Current plan is to drive halfway and stay in Alabama tonight and arrive in OKC about 3 or 4 tomorrow afternoon. If we drive straight through we would get into OKC about 10 or 11 tonight. What am I looking at weather wise in either situation? And which would be better for traveling?

venture I get out of college at 4 pm on Fridays, will there be any winter precip and what will roads be like by then?

I think we really need to see how the precip starts developing later tonight to get a good idea of what tomorrow is going to be like. If the GFS verifies as mostly dry, this is all for nothing. If NAM verifies, some areas will probably need to be upgraded in the advisory level.

Update from Norman...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
956 AM CST THU NOV 21 2013


.UPDATE...
COLD FRONT IS MOVING QUICKLY AND IS WELL AHEAD OF SCHEDULE. NONE
OF THE SYNOPTIC SCALE MODELS HAVE DONE WELL WITH THIS TIMING AND
THE TIMING IS EVEN QUICKER THAN THE ACCELERATED TIMING THAT THE
MIDNIGHT SHIFT WORKED IN. HAVE UPDATED THE FORECAST WITH AN EVEN
FASTER ARRIVAL OF THE COLD FRONT CLOSER TO WHAT THE RAP IS
FORECASTING.

12Z GFS is still pretty much completely dry. Time to see who is right in all of this.

12Z GFS is still pretty much completely dry. Time to see who is right in all of this.

"A Tale of Two Models..."

"It was the best of models, it was the worst of models, it was the age of Venture, it was the age of Morgan, it was the epoch of confidence intervals, it was the epoch of dry slots...It was the season of GFS, it was the season of Reed Timmer..."

..just a little literary humor between model runs :)

Damon just retweeted a pic of sand trucks out already...sigh. Does anyone know if the brine trucks are already out pre-treating bridges?

Damon just retweeted a pic of sand trucks out already...sigh. Does anyone know if the brine trucks are already out pre-treating bridges?

Kinda putting the cart before the horse.

Has sand ever in the history of life given people more traction in winter weather?

I don't get the sand stuff...

Not too tough to pick out the cold front which is running a bit ahead of schedule.



Oh, wow, gotta get my dozen pansies planted that I bought at Lowe's for 75% off before the temperature starts plummeting. I never tried growing pansies before to have flowers during the winter. I know I'm a little late. I hope they're blooming nice by Christmas.

12Z GFS for Sunday/Monday storm...

Some variance here based on how precip falls. I would side with more snow than freezing rain, but that really depends on any warm air getting pulled up in the upper levels ahead of the main system. So for right now if we are looking at all snow, OKC area specifically only here, 2-4". If we get some warm air pulled in, which is what GFS is thinking right now, look at < 1" of snow plus up to 0.25" of freezing rain and 0.25" of sleet. Depending on how the next few model runs evolve, don't be shocked to see Winter Storm Watches put up for Sunday and Monday.

Has sand ever in the history of life given people more traction in winter weather?

I don't get the sand stuff...

They turn our cars red more than anything. I've always chalked it up to the city/state being too cheap with buying salt. Not that salt is all that great for a car either, but at least it melts the stuff. :)

Front is moving through the NW side of the Metro area now, almost into the inner core/downtown. Some light drizzle with this...as well as a few scattered showers just behind it. Should be through most of the populated metro area here in the next hour or two. Enjoy the 60s that are out there right now...they are gone after this. :)

http://i26.photobucket.com/albums/c142/sacolton/1460139_10101857146116187_221134521_n_zps23bcf156. jpg

This would be interesting:

http://wxcaster4.com/nam/CONUS1_ETA212_SFC_ACCUM-SNOWFALL_84HR.gif

This would be interesting:

Mmhmm. I put it on the last page. ;) Granted things are going to scroll away fast now. This thread has added like 2,000 views today so far. LOL

Wind just shifted from the north about 15 min ago in Midtown.

I am really interested into what happens Sunday into Monday. Right now GFS is way slower to eject the low and dumps heavy precip via wrap-around over main body of OK. However, right now it is in the form of rain.

NAM ejects it faster but with moderate precip. over main body of OK.


One thing I do know, by the time Sunday rolls around - ground temperatures will have had about 48 hours of freezing to sub-freezing temperatures. So any frozen precipitation will be accumulating.

So, putting one's speculating cap on, if the 18Z GFS comes out again with a dry solution, does that constitute enough consistency to say the Friday scenario isn't as big a deal as the Sunday/Monday scenario?

Or do we still have the models competing on moisture for tomorrow?

So, putting one's speculating cap on, if the 18Z GFS comes out again with a dry solution, does that constitute enough consistency to say the Friday scenario isn't as big a deal as the Sunday/Monday scenario?

Or do we still have the models competing on moisture for tomorrow?

If the NAM goes dry, then I would start writing tomorrow off. They are both stubbornly locked into their solutions - which is nothing new with winter systems.

Looking at current obs I'd say the NAM had a better handle on the cold air intrusion -- remains to be seen which model handles the precip more accurately.

Light freezing drizzle/icing being reported from a few folks in NW OK already.

Give me liquid winter precip that doesn't freeze, snow, or a dry slot and I'll be happy. No bueno for sleet, ice and freezing rain!

Man, this front is flying and way ahead of schedule. Already cleared Norman. I don't know what that means in terms of the overrunning precipitation developing, but I don't envy the forecasters right now.

When is the next NAM sounding?

18Z NAM is in...running drier for the first half and then moderate precip later Friday and overnight into Saturday.

http://wxcaster4.com/nam/CONUS1_MESO-NAM212_SFC_ACCUM-SLEET_48HR.gif

http://wxcaster4.com/nam/CONUS1_MESO-NAM212_SFC_ACCUM-FZRN_48HR.gif

Looks like there is minor icing starting to go in NW OK:

http://www.mesonet.org/data/public/mesonet/maps/realtime/current.gustarrows.gif
*
Gage, OK:
KGAG 212053Z AUTO 35014KT 4SM BR OVC007 M02/M03 A3024 RMK AO2 PK WND 35027/2033 SLP245 60000 T10171028 51023
*
Woodward, OK:
KWWR 212055Z AUTO 34014G19KT 4SM BR OVC005 00/M01 A3026 RMK AO2
*
Alva, OK:
KAVK 212050Z AUTO 36017G24KT 2SM -RA OVC006 00/M01 A3024 RMK AO2

18Z NAM is in...running drier for the first half and then moderate precip later Friday and overnight into Saturday.

http://wxcaster4.com/nam/CONUS1_MESO-NAM212_SFC_ACCUM-SLEET_48HR.gif

http://wxcaster4.com/nam/CONUS1_MESO-NAM212_SFC_ACCUM-FZRN_48HR.gif

How late Friday to start, venture?

Drizzle and fog behind the front is just icing stuff up pretty good now in places.

How late Friday to start, venture?

Freezing drizzle is already starting in places...so there might be a glaze over things from tonight regardless of when the heavier precip moves in. Right now its after noon for the heavier precip.

Also a side note to the weekend. 18Z NAM continues snow storm...

http://wxcaster4.com/nam/CONUS1_MESO-ETA212_SFC_ACCUM-SNOWFALL_84HR.gif

I don't know why but many, many times and probably over a hundred times I have seen these arctic cold fronts move in much faster than the expected.

Its almost like there is a land friction component to them. They start moving faster than expected on the flat Kansas, Oklahoma and Texas panhandle plains, sometimes more so on the high plains west of the 100th meridian?

I've been working on the new Winter Weather model comparison page for the website. Still trying to figure out how to work in the 18Z/06Z models, but will probably just have to do that on another page.

Weather Spotlight - Live Weather Event Coverage (http://www.weatherspotlight.com/winter.html)

Wet-bulb temps really starting to fall as the sun sets.

Look for rapid temperature drops as soon as drizzle and fog form behind this front. NW OK is a good example of this effect. They are in the mid to upper 20s and we aren't even dark yet.

WSWatch issued for southern TX Panhandle for the duration of the event (through Tuesday with emphasis on icing tomorrow).

WSWatch issued for W Central TX for the duration of the event (through Sunday with emphasis on minor accumulations).


Goes to show you just how different areas are in their criteria for watches/warnings in weather events.

Yeah for sure. Though if we see some consistency in the models for Sunday/Monday...I wouldn't doubt OUN pulling the trigger on a WSW by tomorrow afternoon.

Winter Wx Advisory extended to cover all of South Central OK now.

Just drove from downtown okc to north. Drizzle and fog developing.

00Z NAM has some subtle changes to it for tomorrow. It takes OKC up to near or just above freezing by Noon, but then starts to head back below after 3PM. Total precip accumulations through 3AM Saturday is around 0.2" NW Side of the Metro to 0.4" near Norman and south. Bulk of the precip at this point appears as though it will occur after we start cooling back off tomorrow afternoon. So freezing rain threat remains and will go up after a morning bout of freezing drizzle and freezing fog.

NAM's Sunday snow storm forecast remains.

Tulsa - Stillwater - Guthrie - Kingfisher and west in the line: 1-3"
I-40 Corridor: 3-6"
South of I-40 including Norman - Chickasha - SW to Altus: 6-12" with isolated 14"

Again, the Winter forecast model comparison that I put together is at: Weather Spotlight - Winter Weather Model Comparisons (http://www.weatherspotlight.com/winter.html)

NAM's Sunday snow storm forecast remains.

Tulsa - Stillwater - Guthrie - Kingfisher and west in the line: 1-3"
I-40 Corridor: 3-6"
South of I-40 including Norman - Chickasha - SW to Altus: 6-12" with isolated 14"

Again, the Winter forecast model comparison that I put together is at: Weather Spotlight - Winter Weather Model Comparisons (http://www.weatherspotlight.com/winter.html)

Good.

Grief.

Geez, we're supposed to leave Sunday morning to drive to Dallas to drop off our daughter with my mom so she can take her back to Houston. How legit is that model?

I'll be surprised if we get anything tonight.