Euro coming in now, will update once we see what it is smoking tonight.

So . . . If Municipal Authorities have advance notice of the probable possibility of potential icing causing unanticipated stress on already noticeably leaning power poles, perpendicular to the normal flow of traffic, on a significantly traveled roadway, do they have a responsibility to prevent possible bad stuff happening by either shutting down the road or reinforcing the power poles?

All that sounds like BS, but it ain't.
(122nd from The Parkway to May)

Mmmk. Let's do the Euro walk through...

Precip starts in the metro around 3PM Friday. Air temp in the mid 30s from Norman and north. Dewpoint will be below freezing at this point - so we need to watch that.

Through Midnight rain will be light with a few moderate showers mixed in. Main focus will be near I-44 (either side)...at least outside the heavy precip down in SE OK. Surface air temps forecast to be above freezing through this, but evaporational cooling is going to be in play.

From Midnight through 3PM - freezing line is going to be near/in the metro area. We are looking at it setting up roughly west of I-35 and north of I-40. As Damonsmuz pointed out, Euro snowfall throws ice accumulation all in together. Main area for accumulation looks to be from El Reno to Guthrie to Stillwater and then up around Bartlesville. Area of 1-4" over that general area in this time frame...if it were all snow. It won't be...so think closer to a quarter to half inch of liquid.

By 6PM Saturday, freezing line pushed through most of the metro and we are in a wrap around band of precip. I would assume this is mostly snow/sleet - so could see a general 1-3" area from Chickasha to Norman to Shawnee and north of there. Precip should start to end pretty fast from south to north by 9PM. Euro then keeps up below freezing so any water on the road - which there isn't salt - could definitely freeze up.

With this...I would not be shocked to see winter wx advisories put on the two rows of counties south of the current watch area.

The Euro is coming in colder and further south!!! Wow..definately gonna be some folks caught off guard tomorrow. Many office Christmas parties tomorrow night in downtown Tulsa, including myself. Maybe tomorrow the storm models will correct themselves and go back north and west! I have shopping to do this weekend!

06Z NAM is rolling in now.

Precip starting late this afternoon. By 6PM around 015" of precip for most of the metro. Looks like temps will be very close to freezing at this time and air profile supports sleet or at least supercooled droplets.

6PM to 9PM - Precip continues. Looks like mostly rain during this segment and around 0.15 to 0.25". Air temp is forecast to be a degree or two above freezing, but evaporational cooling could throw a wrench in that.

9PM to Midnight - Same are earlier...another 0.15" of precip and temps very close to freezing. Still looks like mostly liquid.

Midnight to 3AM Sat - Main surge of moisture pushing up. Temps steady, mostly rain. Precip 0.15" NW Metro to 0.25" SE metro - much heavier rain just south of Norman.

3AM to 6AM - Precip continues...0.15" on average. Temps still hugging the freezing mark.

6AM to 9AM - Precip slows down a bunch, light drizzle or freezing drizzle.

9AM to Noon - Dryslot over Central OK. Heavy rain SE OK...and additional precip SW OK.

Noon to 3PM - New precip area forms over SW OK between 44 and 35. This will start to move up...about 0.10" in Norman and 0.05" up in Edmond at this time. Temps again...hugging the freezing line in some areas.

3PM to 6PM - Precip gets heavier around Norman, Midwest City, and Shawnee. Around 0.35" there, 0.15" in NW Metro.

6PM to 9PM - Precip finally moving out, trace west to 0.15" east.

For this review I used the forecast sounding for Norman. The freezing line appears to be hanging right on the OKC metro area...and we can't nail positioning this far out. As Anon said, this is likely going to be a nowcasting situation. If temps stay at 33 to 34 we dodge a bullet. If temps fall to 30 or 31...it gets really sketchy. Below that...have a generator.

Total precip we are talking 1.00 to 1.50" in NW Metro to 1.5 to 2.0" in SE Metro. NAM essentially killed off the snow over much of KS and NW OK. So this big shift is something we need to figure out if it is bogus or if it is the last minute change I've been warning about.

Do not be shocked to see Norman take a couple different routes with this. So the advisories we can see...

Freezing Rain Advisory - ice up to but not more than 0.25". If we stay below freezing more, we'll be well over this.

Winter Weather Advisory - Blanket advisory to cover below warning criteria. Pretty much the classic CYA advisory.

Ice Storm Warning - Ice accumulations over 0.25". If we stay below freezing quite a bit we will hit this.

Winter Storm Warning - Hazard tomorrow could be freezing rain and sleet combined, so that might have them do a WSWarn to cover. Mostly likely though this can be handled under one of the other advisories.

Don't be shocked either if they wait to issue any of these until it looks like it'll verify. Now I will say this...Mesonet has the freezing line well through much of NW OK already. It is almost at Watonga. NAM and RUC are in agreement with this time. GFS is about 3-4 hours behind so far on the movement of the freezing line. HRRR is in agreement with NAM and RUC as well. Now HRRR brings the freezing line to the metro by daybreak and then starts to retreat it through the morning...which NAM has as well, but then starts cooling things off through the afternoon.

Still a lot of questions, but my main advice right now - just stay weather aware today. We are going to be on the edge for the majority of this event and it can go really bad quick or just be cold and wet.

CH 9 this morning said this would be significant.

Venture -- I've gone through a significant amount of data this morning and am really interested in how nearly every model (including the HRRR) has underestimated the strength of this cold air. I was kind of hinting at this last night but now seeing how poorly they've all verified makes the forecast even more difficult.

The freezing line is pretty far to the south and east. Do we foresee any northward movement due to daytime heating?

So what do the ice accumulations on the roads and power lines look like?
Hopefully the galloping power line factor doesn’t become to strong?

Venture -- I've gone through a significant amount of data this morning and am really interested in how nearly every model (including the HRRR) has underestimated the strength of this cold air. I was kind of hinting at this last night but now seeing how poorly they've all verified makes the forecast even more difficult.

Completely agree. Freezing line is about 40 miles further south then the models picked and we are about 3-5 degrees colder than forecast. They just did not handle this correctly at all.

If you take a look at SPC's SREF plumes you will see the majority are well warmer than current obs by 3-5 degrees:

5522

The freezing line is pretty far to the south and east. Do we foresee any northward movement due to daytime heating?

There should be some, yes...but then it'll move back south later. Looking at RAP (short term model) it pull sit back to about the North Metro and then pushes it back south through Norman this evening.

66 and light rain here in Arlington.

12Z GFS has finally come in line with current obs and has decreased temps from previous runs in some places by nearly 10* from yesterday's 18Z run.

Ice Storm warning coming out for Tulsa counties...Norman will follow soon more than likely.

12Z GFS has finally come in line with current obs and has decreased temps from previous runs in some places by nearly 10* from yesterday's 18Z run.

That last minute 180...go figure.

I'm in the chat room now FYI if people are lurking. www.weatherspotlight.com/chat.html (http://www.weatherspotlight.com/chat.html)

If you take a look at SPC's SREF plumes you will see the majority are well warmer than current obs by 3-5 degrees:

5522

Translation? And thanks to all of you that post this great info.

New NAM is doomsday. Freezing rain with temps in upper 20s. Followed by wrap around snow.

RIght now it looks like the trend to eject further east is actually happening, and exactly what is happening is the storm will eject in a more west to east fashion (at least over OK) rather than a sharp angle from SW to NE.

This will increase precipitation time period over SW, C, and NE OK. Then the wrap around comes through directly over C OK.

Again this is just the NAM, but per OKCTalk standards, this is bread and milk warning.


If it actually verifies that this shallow air stays in the upper 20s, ice accumulation could be immense.

So what do the ice accumulations on the roads and power lines look like?
Hopefully the galloping power line factor doesn’t become to strong?

The areas that are in the mid 20s and lower are probably going to get really tough when it comes to the roads. Ideally the road crews are already out salting and putting brine down.

It gets really trick here in the Metro because parts may warm back up above freezing when 15-20 miles away they'll be below freezing still.

http://www.mesonet.org/images/global/pixel.gifThis isn't great to look at though when being concerned about ice accumulations...

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

Whelp so much for a mild winter :(

New NAM is doomsday. Freezing rain with temps in upper 20s. Followed by wrap around snow.

RIght now it looks like the trend to eject further east is actually happening, and exactly what is happening is the storm will eject in a more west to east fashion (at least over OK) rather than a sharp angle from SW to NE.

This will increase precipitation time period over SW, C, and NE OK. Then the wrap around comes through directly over C OK.

Again this is just the NAM, but per OKCTalk standards, this is bread and milk warning.


If it actually verifies that this shallow air stays in the upper 20s, ice accumulation could be immense.

With the hype in full force, bread and milk warning definitely.

Whelp so much for a mild winter :(

The way things have been going, the thoughts of a mild winter should have been dashed 2-3 weeks ago. ;)

No idea??? I think it's fairly clear there will not be a major winter storm in okc.

I just feel like quoting this. This was posted less than 24 hours ago. This is how volatile this storm is and can still be.

New NAM is doomsday. Freezing rain with temps in upper 20s. Followed by wrap around snow.

RIght now it looks like the trend to eject further east is actually happening, and exactly what is happening is the storm will eject in a more west to east fashion (at least over OK) rather than a sharp angle from SW to NE.

This will increase precipitation time period over SW, C, and NE OK. Then the wrap around comes through directly over C OK.

Again this is just the NAM, but per OKCTalk standards, this is bread and milk warning.


If it actually verifies that this shallow air stays in the upper 20s, ice accumulation could be immense.


With the hype in full force, bread and milk warning definitely.

You asked for it...


http://youtu.be/i6zaVYWLTkU

I want to say thank you to Venture and Anonymous and others who work so hard to keep us updated here. Even though I don't post often, I always come here when there is bad weather on the horizon. You all do a great job and I've come to depend on your forecasts much more than the television weather reports!

Here is the wet bulb map Anon refers to a lot. This is the potential temp the air can drop to once precip starts falling...

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

Based on that map^ to me it looks like their could be a lot of ice accumulations on the power lines and some on the roads.....I don't want serious galloping power lines.

Warnings incoming...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
1043 AM CST FRI DEC 20 2013


.UPDATE...
WE WILL LIKELY BE UPGRADING TO A WARNING THIS MORNING. SYNOPTIC
MODELS LOOK TO BE TOO AGGRESSIVE IN WARMING LOW-LEVEL TEMPERATURES
THIS AFTERNOON GIVEN THE MOSTLY CLOUDY SKIES AND CONTINUED COLD
AIR ADVECTION. NOW THAT THE FRONT HAS MOVED THROUGH AND WE SEE
HOW MUCH COOL AIR HAS ENTERED THE AREA... WE CAN MORE CONFIDENTLY
SEE THE AREA OF CONCERN FOR POTENTIAL ICE ACCUMULATIONS...
ESPECIALLY NEAR AND JUST WEST AND NORTH OF THE OKLAHOMA CITY
METRO. LATEST MODELS ALSO SUGGEST THAT 4 INCH SNOW ACCUMULATIONS
WILL BE POSSIBLE ACROSS NORTHWEST OKLAHOMA AS WELL. WE ARE
COORDINATING THE DETAILS WITH WPC AND OTHERS RIGHT NOW TO
DETERMINE THE SPECIFIC AREAS TO UPGRADE.

GFS...

http://grib2.com/gfs/WINTER_GFS0P5_SFC_ACCUM-FZRN_36HR.gif

Venture/Anon when is all this going to start? Overnight, this afternoon, tomorrow AM?

First light precip in the Metro area 5-7PM this evening.

http://i.imgur.com/p76JXq6.jpg%5B/IMG%5D

TUTTLE is saying maybe 1.5 inches of ice accumulations.
https://www.facebook.com/ATsFans

with his alarmist predictions, he should type in ALLCAPS.

http://wxcaster4.com/gfs/CONUS2_GFS0P5_SFC_ACCUM-FZRN_48HR.gif

That purple is alround .75" of ice.

SO lay that map over the one V posted just above this post. And you have widespread ice accumulation over heavily populated areas (I-44)

Ice Storm Warning will be issued for the OKC metro shortly. Stay tuned.

Urgent - winter weather message
national weather service norman ok
1118 am cst fri dec 20 2013

okz007-008-011>013-015>020-022>026-210130-
/o.upg.koun.ws.a.0004.131221t0000z-131222t1200z/
/o.new.koun.is.w.0002.131221t0000z-131222t1200z/
grant-kay-major-garfield-noble-dewey-custer-blaine-kingfisher-
logan-payne-wa****a-caddo-canadian-oklahoma-lincoln-
including the cities of...medford...ponca city...fairview...
Enid...perry...taloga...weatherford...clinton...wa tonga...
Kingfisher...guthrie...stillwater...cordell...anad arko...yukon...
El reno...mustang...oklahoma city...chandler
1118 am cst fri dec 20 2013

...ice storm warning in effect from 6 pm this evening to 6 am cst
sunday...

The national weather service in norman has issued an ice storm
warning...which is in effect from 6 pm this evening to 6 am cst
sunday. The winter storm watch is no longer in effect.

* main impact: Freezing rain will develop friday night and
continue saturday. Ice accumulations of around one-half inch
will be possible across portions of western... Central and north
central oklahoma friday night and saturday. This ice will
accumulate on trees and powerlines and result in the development
of slick bridges...overpasses and walkways. Isolated power
outages will be possible.

* other impacts: Freezing rain and rain will change to snow late
saturday afternoon or evening. Accumulation of 2 to 4 inches
will be possible across north central oklahoma with lighter
amounts farther south.

Precautionary/preparedness actions...

Do not travel in icy conditions. Be sure you can take care of
yourself and your family if you lose electrical power. Watch out
for falling trees...limbs and power lines.

Ice Storm Warning:

http://www.mesonet.org/data/public/noaa/wwa/maps/realtime/latest.oklahoma.snowice.gif

http://www.mesonet.org/data/public/noaa/wwa/maps/realtime/latest.oklahoma.winter.gif

Ice Storm Warning will be issued for the OKC metro shortly. Stay tuned.

Did I hear storm of the Century?

http://www.mesonet.org/data/public/noaa/wwa/maps/realtime/latest.oklahoma.winter.gif


Crap. Looks like this will miss Norman altogether.

Crap. Looks like this will miss Norman altogether.

I'm expecting advisories to eventually be issued for the counties south of the warned areas. Keep in mind one map has the ice warnings the other the basic winter warnings.

I'm expecting advisories to eventually be issued for the counties south of the warned areas. Keep in mind one map has the ice warnings the other the basic winter warnings.

It seems the cold air arrived a bit earlier than first thought. I almost froze while out tinkering with the car this morning.

It seems the cold air arrived a bit earlier than first thought. I almost froze while out tinkering with the car this morning.

The models haven't been handling the cold air well at all...it is a bit early and colder than what models were predicting. This is something we've been talking about so not completely unexpected.

First light precip in the Metro area 5-7PM this evening.

Great, thanx Ven. Just wanting to get my family home. :)

Damon posted this on twitter earlier and it was also in our chat this morning.

https://pbs.twimg.com/media/Bb8HZStIgAA0QxI.png:large

I say OG&E should scrap their new headquarter plans and start burying the utility lines!

What are the winds projected to be?

Following flights into OKC tonight are canceled - so there will be many originating flights canceled tomorrow out of OKC.

So far Southwest 2535 (Dallas), 4227 (Phoenix), and 1276 (Denver); AirTran 490 (Chicago); Delta 1259 (Atlanta), 3621 (Minneapolis), and 4969 (Detroit)...are all canceled.

What are the winds projected to be?

15 mph give or take.

So this doesn't sound like a doomsday set up

So this doesn't sound like a doomsday set up

The funny thing is, DoomNGloom KFOR was calling for .25" of ice in the metro on their noon forecast but News9 which usually seems conservative to me was forecasting .5-.75" of ice...no bueno.

https://twitter.com/NWSNorman
NWS Norman ‏@NWSNorman 1h
Brand new ice accumulation map

The 18Z NAM is a complete joke -- pulling the freezing line all the way north of Wichita by 3pm.

http://climate.cod.edu/data/forecast/NAM/18/SGP/namSGP_sfc_temp_003.gif


Models at this point are pretty much useless in terms of temperature forecast -- better to stick with current sfc observation trends.

Here's the HRRR at 2am....the entire OKC metro (including Norman) is encompassed in heavy freezing rain:

http://rapidrefresh.noaa.gov/HRRR/for_web/hrrr_jet/2013122017/t5/ptyp_t5sfc_f15.png

The weather service has so severely under forecasted what the temps would be this afternoon that I hope that means at least several inches of snow with little or no ice. White Christmas here we come, if it doesn't get warm enough to melt much off.

5523

The weather service has so severely under forecasted what the temps would be this afternoon that I hope that means at least several inches of snow with little or no ice. White Christmas here we come, if it doesn't get warm enough to melt much off.

Pretty much a 0% chance of snow occurring with this first main wave. This cold airmass is so shallow that temps just above the surface are well above freezing. You can pretty much bank on liquid precip being the main form -- with a spattering of sleet or even small hail.

Pretty much a 0% chance of snow occurring with this first main wave. This cold airmass is so shallow that temps just above the surface are well above freezing. You can pretty much bank on liquid precip being the main form -- with a spattering of sleet or even small hail.

I was afraid someone would throw that little detail in the works.

Pretty much a 0% chance of snow occurring with this first main wave. This cold airmass is so shallow that temps just above the surface are well above freezing. You can pretty much bank on liquid precip being the main form -- with a spattering of sleet or even small hail.


So if I go to the top of Devon tower I can hang out in 70" weather? How high do I need to be?

Weather chan map shows some ice/mix out around Clinton

911
wwus44 koun 202022 aaa
wswoun

urgent - winter weather message...updated
national weather service norman ok
222 pm cst fri dec 20 2013

okz027>031-034-035-038-210430-
/o.exa.koun.is.w.0002.131221t0000z-131222t1200z/
grady-mcclain-cleveland-pottawatomie-seminole-greer-kiowa-
comanche-
including the cities of...chickasha...purcell...norman...moore...
Shawnee...seminole...mangum...hobart...lawton
222 pm cst fri dec 20 2013

...ice storm warning in effect from 6 pm this evening to 6 am cst
sunday...

The national weather service in norman has issued an ice storm
warning...which is in effect from 6 pm this evening to 6 am cst
sunday.

* main impact: Widespread freezing rain will develop early this
evening and continue saturday. Ice accumulations of around one-
half inch will be possible across portions of western...central
and north-central oklahoma. This ice will accumulate mainly on
trees and powerlines and result in the development of slick
bridges...overpasses and walkways. Scattered power outages are
expected.

* other impacts: Freezing rain and rain will change to snow late
saturday afternoon or evening. Accumulation of 2 to 4 inches
will be possible across far northern oklahoma with lighter
amounts farther south.

Precautionary/preparedness actions...

Do not travel in icy conditions. Be sure you can take care of
yourself and your family if you lose electrical power. Watch out
for falling trees...limbs and power lines.

&&

$$