FORECASTS: 1/28/10 - Southern/Central Plains Winter Storm

[Michael O'Keeffe]

New 18z NAM has continued the northward trend with 6-8" of the white stuff here in Olathe, KS (SW of Kansas City). The heaviest band of snow continues to look like it will setup in the TX/OK Panhandles, NW Oklahoma, all of S Kansas, and extending into SW Missouri.

 

[John Farley]

Well, we're getting the first wave of snow, associated with warm air advection out ahead of the main system, here in the STL area now. Coming down quite hard in Edwardsville, but it won't last long enough to get much accumulation. A couple reports of 1/2 inch in various parts of the STL area have come in, but that's about it.

It will be interesting to see if the northward trend in the models continues any further - the main storm would still have to get farther north than projected to have much impact here.

 

[Mike Hollingshead]

Sleet could really cut into the ice accumulations in Oklahoma...that's why an inch is the current max amount forecast.

Sleet, the most annoying form of weather for storm lovers! I remember trying to get into Springdale AR last year this time and driving on several inches of that crap compacted into extremely bumping mounds. That was amazing, as much sleet as they had and they still had over an inch of ice.

Just looking at 900mb prog's off the 12z NAM it seems some zone/stripe is still going to get blasted with heavy freezing rain. Just using the +4c line at that level it essentially doesn't move on the 24, 30, or 36hr progs. Not till the 42hr prog does it drop south a fair bit. Of course that move would be before heavy precip ends. Seems with that degree and depth of a low level pump going on, some area will get seriously hosed with ice. Of course the more I look at surface temps right now, the more I wonder about any sub-freezing surfce air in the liquid zones.

Sure glad I don't have to forecast for anyone. Don't envy that task at all.

 

[Mike Umscheid]

In Dumas, TX

I arrived in Dumas awaiting the snow which should begin around daybreak tomorrow morning. Still looks like a healthy 12-15" axis very near here (hopefully over me!!). There will be a time tomorrow when sustained winds will reach 20 to 25mph with frequent gusts in the 30-40mph range perhaps. This would approach blizzard territory. Anxiously awaiting this storm! In the meantime, I think the hot tub is calling my name...

http://www.underthemeso.com/blog

 

[Mike Johnson]

I arrived in Dumas awaiting the snow which should begin around daybreak tomorrow morning. Still looks like a healthy 12-15" axis very near here (hopefully over me!!). There will be a time tomorrow when sustained winds will reach 20 to 25mph with frequent gusts in the 30-40mph range perhaps. This would approach blizzard territory. Anxiously awaiting this storm! In the meantime, I think the hot tub is calling my name...

http://www.underthemeso.com/blog

That is my concern, Mike. Seeing the guidance winds continue to climb with each new run has me concerned about blizzard criteria being reached. coupled with the initial icing, this storm has trouble written all over it.

 

[Greg McLaughlin]

I have been watching the latest surface obs in the central/southern Plains and comparing surface temps to what the models have been forecasting for the same time. The cold air is surging south much faster than what the models are showing. It is my experience that this is typical with the ice storms we have had in OK. I think the models are too warm at the surface tomorrow.

 

[Andrew Francis]

I have been watching the latest surface obs in the central/southern Plains and comparing surface temps to what the models have been forecasting for the same time. The cold air is surging south much faster than what the models are showing. It is my experience that this is typical with the ice storms we have had in OK. I think the models are too warm at the surface tomorrow.

This.

The winds are already shifted from the North here in Central OK, I think the front is moving much faster than thought after this morning's runs. Could this mean the beginning of the shift back south towards original forecasts from a day or 2 ago?

Local stations backing off their storm totals since last night. Leaning more towards ice in OKC.

I am hoping the model runs tonight will take into account the quicker moving front - and adjust storm track accordingly :]

 

[Brendon Lindsey]

This.

The winds are already shifted from the North here in Central OK, I think the front is moving much faster than thought after this morning's runs. Could this mean the beginning of the shift back south towards original forecasts from a day or 2 ago?

Local stations backing off their storm totals since last night. Leaning more towards ice in OKC.

I am hoping the model runs tonight will take into account the quicker moving front - and adjust storm track accordingly :]

I am going to believe you guys and do my happy dance lol jk jk well kinda. I am looking at the news now and see schools in NE OK are already closing for Thursday, haha If we were going off the 12z and 18z they would be canceling school for rain...

 

[Andrew Francis]

Yea I do not see how schools tomorrow would be closing, unless they have not listened to the latest forecasts, and are going off of the forecasts from a couple days ago.

The system has slowed, moving the show to more of Thursday late afternoon into evening. I can see the southern plains being a standstill on Friday, though.

 

[John Massura]

I asked my wife (Moore Public Schools), and she said they do not close early, it's either all or nothing. Granted, they (and most of the major metro school districts) have not made a decision to close yet. Of course, they usually wait for the OKC schools to make their decision. In any event, I have never seen them cancel before the 10pm newscast (on new events anyway, Day 2 of an event is a different story).

However, with the cold air apparently moving in quicker (I have not looked at anything since the 12Z runs), who knows how early the freezing rain might start.

 

[Greg Blumberg]

Wow! That cold air is haulin'! I remember looking earlier (about 0z) at the cold air in NE and being worried that it may not make it down here in time. The front looked incredibly weak at that time. Now it's in southern KS!

The Oklahoma Mesonet has a 3 hour temperature change from the SW to the NE part of the state ranging from -4 to -12 degrees F with most in the higher end of that distribution. That's pretty impressive! The Mesonet is also reporting 10-20 kt winds from the north and northeast with some gusts in the 25-30 kt range.

http://www.mesonet.org/

 

[Tim Vasquez]

As regards the OKC area:

I just looked through the 00Z cycle NAM and RUC/MAPS and looked at the building blocks. Unless anything is fishy with the handling of the cold air mass, the depth and temperature of the cold air layer, even in the pre-dawn hours, advertises 100% sleet and is not shallow enough to support FZRA. This seems to jive with what some of you have said about the CAA being stronger than expected. On average I'm seeing a depth of 2000-2500 ft and temperature of -2 to -5C, which is more than sufficient for IP.

I guess this is good news as far as having our accustomed electricity and conveniences, as we'd be toast with a shallower cold layer. I don't see freezing rain problems unless we have some kind of erosion of the polar air mass by the strengthening southerly flow at 850-700 mb and/or if we fail to get sufficient wet-bulbing with the onset of precip.

With 2.00" QPFs in the form of sleet, it is interesting to think what that will work out to in terms of sleet depth. It should be interesting. There's still good forcing for ascent depicted through midnight CST, then we're on the back side and wraparound becomes the question (which I guess will be mostly just light snow and add frosting to the sleetcake).

Glad I went on the Internet and bought chains for my Toyota a few weeks ago! I'll probably go in the garage and put those things on tomorrow.

Is anyone seeing FZRA in the OKC/TUL area given the 0000Z products, or does it look like sleet to you too? Any comments about how the models have handled thermal fields in previous situations?

Tim

 

[Karen Politte]

Well the 0zs are coming in and the differences between the NAM and the GFS still remain almost irreconcilable......which is probably why in our local LZK's fcst discussion as of 2:30PM today they stated they were completely discarding the NAM's solution and going with a GFS/ECMWF blend. If that holds true - then I am once again curious about our chances for something significant IF the cold air gets here in time. I don't care what it is - just give me something to remember this winter by.

KP

 

[Greg Blumberg]

Tim,

I don't know much about the difference between the sleet and freezing rain forecasting. I don't have that much experience in that realm. But to see what BUFKIT would say about the current situation, I plugged the 0z NAM into it. I'll have to wait till the 0z GFS is out to compare. This is for the OUN area.

BUFKIT has the precip type changing between freezing rain and ice pellets before settling on snow Friday morning. How accurate this is or what algorithm they are using...I don't know. But it is something to consider.

Here's a general overview for the NAM output:

Precip begins at 6z with rain on Thurs, sleet till ~18z Thurs where it changes into heavy freezing rain till 6z Fri back into sleet, then snow at 12z Fri. It does not look like a real heavy snow.

 

[Tim Vasquez]

This is the synoptic setup for 00Z Friday according to the NAM. It's essentially a LLJ feeding intense isentropic lift over the frontal surface. This is just an 850 mb chart and is not 3-D but gives the general idea:

Karen, good point about the NAM/GFS discrepancy. I found an 18Z GFS forecast sounding and (for us) it seems to paint out the same basic idea as the 00Z NAM (sleet) so perhaps they've converged somewhat.

One thing is for sure... if we end up with RA, FZRA, or SN, we'll have quite a spectacular case study, as there's no way I can reconcile those thermal fields as being anything but sleet.

Tim