1/11 - 1/12 Southern Midwest Snowstorm

[Grizzcoat]

Area Forecast Discussion

National Weather Service Des Moines IA

321 AM CST Thu Jan 10 2019

 

.DISCUSSION.../Today through Wednesday/

Issued at 321 AM CST Thu Jan 10 2019

 

The seven day forecast is quiet with the exception of a potential

winter storm affecting much of Iowa from Friday through Saturday.

As a broad and somewhat discombobulated 500 mb trough moves slowly

eastward across the central U.S. at the end of this week, it will

gradually come into phase with several shortwave impulses rounding

into the trough. As this occurs a reflective surface cyclone will

develop near the Texas panhandle and subsequently move eastward

near the Missouri/Arkansas border. The broad lift along the

leading flank of the 500 mb trough will overlay a broad inverted

surface trough in the northern hemisphere of the surface low,

resulting in a large shield of precipitation affecting much of

Kansas, Missouri, southern Iowa, and Illinois along with smaller

portions of Nebraska and Wisconsin. The signal for this overall

scenario has been present for days now and confidence is high in

precipitation across southern and southeastern Iowa from Friday

night into Saturday. As a result, POPs have been increased to 100

percent in these areas during the most likely precipitation time,

from midnight to noon Saturday morning. However, the devil is in

the details in terms of recent forecast trends.

 

There has been fairly solid agreement in the various prognostic

models over the last 36 hours or so in better/more quickly phasing

the trough structure as the system moves over Iowa, resulting in a

somewhat more organized precipitation shield structure and higher

QPF. The improved phasing has also pushed the

northern/northwestern edge of the precipitation further northwest

within our forecast area. Whereas a couple days ago it appeared

the cutoff would fall somewhere down around Ottumwa and Albia,

trends now favor the cutoff falling more toward Atlantic, Ames and

Tama, and have trended the outgoing forecast this way

accordingly, with accumulating snowfall now extending roughly up

to around Highway 30. There has also been a corresponding increase

in forecast snowfall amounts in our southeastern counties, with

accumulations in the 4 to 6 inch range looking quite possible. In

addition, forecast soundings also indicate the possibility of

freezing drizzle/light freezing rain on the northwestern/back edge

of the precipitation, likely across northern and northwestern

portions of the forecast area, and have maintained that in the

forecast as well.

 

Despite the potential for moderate snowfall accumulations, mainly

in our southeast, and very light icing, mainly in our northwest,

the hazards will be somewhat mitigated by two factors. First,

there is a lack of any meaningful surface winds associated with

the system in our area, thus no real blowing snow is anticipated.

Second, the bulk of the precipitation will fall on Friday night

and Saturday, especially during the overnight and morning hours,

when traffic flow is much lower, which will also lower the overall

travel impacts. It seems clear that a winter weather advisory will

be needed at some point, and there is the possibility that if

recent model trends continue forecast snow amounts could edge up

toward 6 inches in the southeast and necessitate a winter storm

warning. However, given this uncertainty and the still unclear

details of amounts and location of the edge of the precipitation

shield, no headlines have been issued on this shift.

[Grizzcoat]

06Z GFS-

[Grizzcoat]

When you love snow storms (and rarely get any anymore) ; following computer guidance is like  the relationships I had with women 25 years ago. Ups and downs and gone so quick you never even got to  her HRRR or RAP - until you find that "one". 

[Grizzcoat]

06Z CMC seems better for most...

[Grizzcoat]

[Grizzcoat]

06Z CMC North and wetter compared to 00Z---

[Clinton]

NAM and Euro almost in agreement I expect a WSW to come out today.

[Tom]

The energy is still out in the PAC and there is a lack of upper air data in this region and I wouldn't be surprised to see some adjustments.  STL NWS has a nice graphic showing this energy and the graphic below shows where the ECMWF has weather stations and ship observations that input data into the model.

 

 

 

 

 

Clearly, there is a lack of data and usually as systems approach the desert SW we see some subtle shifts....

 

[Clinton]

NWS Kansas City going a little conservative but still showing 4-6 for me.

[Tom]

12z EPS did shift the snow shield a bit south compared to the previous couple runs across N IL/IN/MI but still looks good for S IA and back W towards SE NE into KC/MO.

[Tom]

06z Euro...

 

 

[Grizzcoat]

Liking the overall trend of the SREF--- and so should those in Windy City-- getting so close!!

[Tom]

Liking the overall trend of the SREF--- and so should those in Windy City-- getting so close!!sref_namer_081_snow_total_mean.gif

Extended out it even looks better over here....

 

http://mag.ncep.noaa.gov/data/sref/09/sref_namer_087_snow_total_sprd.gif

[Niko]

Confluence is killing this storm for MI peeps.

 

For those that do get it, enjoy it!

 

Edit: My niece who is in Vanderbilt, University in Tennessee told me this morning that a couple of inches are likely there. Trucks are preparing w salt.

[Tom]

12z NAM looks a bit north across NE and IA thru HR48

[Tony]

Nam pushes snow line past the border on 12z

[Grizzcoat]

Sweetness on Nam!!

[Tony]

Nam pushes snow line past the border on 12z

Matches up nicely with the SREF maps above.

[Clinton]

_{12z NAM a nice hit for many.}

[gabel23]

Ok if the Nam wins out we are gonna have a lot of surprised people around my area. Nobody is even talking about this storm! @Tom, crazy how the LRC is working to a T my man. Expect another major storm sometime next week as my area got blasted by a storm the week after the Blizzard in Kansas back in November! 

[Tom]

_{12z NAM a nice hit for many.}

Are we seeing the 1st “Share the Wealth”? Hope so!

[Clinton]

Are we seeing the 1st “Share the Wealth”? Hope so!

Seems like somebody predicted that a while back LOL!

[Grizzcoat]

3km Nam also much better!

[Minny_Weather]

I guess all I have to do is punt on a system for it to trend well here.

 

Oh well. I'm punting on this one

[Tom]

I guess all I have to do is punt on a system for it to trend well here.

 

Oh well. I'm punting on this one

That goes for both you and GDR!

[jcwxguy]

3k nam is much less for eastern Nebraska

[Tom]

12z NAM gives 1-3" in general across N IL...I'll take a couple inches in a sec...

[Stormhunter87]

Ok if the Nam wins out we are gonna have a lot of surprised people around my area. Nobody is even talking about this storm! @Tom, crazy how the LRC is working to a T my man. Expect another major storm sometime next week as my area got blasted by a storm the week after the Blizzard in Kansas back in November!

 

Local guys are still going trace to one inch. If this pains out I'll get in a good laugh.

[Tom]

Locally speaking, there will be a solid easterly flow off LM and temps look to be cold enough to support some Lehs.  The higher rez models could start picking up on that tomorrow.  Something to watch.

[CentralNebWeather]

Ok if the Nam wins out we are gonna have a lot of surprised people around my area. Nobody is even talking about this storm! @Tom, crazy how the LRC is working to a T my man. Expect another major storm sometime next week as my area got blasted by a storm the week after the Blizzard in Kansas back in November! 

You are right, no one is talking about anything but a little light snow.  Still may be very little here as we are on the northern edge unless it sneaks a little farther north

[james1976]

Nice NAM run. I'll take 2-3 inches any day.

[Grizzcoat]

GFS through 42 seems further N in IA-- slightly more QPF than 06Z

[Stormhunter87]

GFS definitely developed the northern section very interesting.

[Stormhunter87]

Icon is as well but nothing like the nam.

[Grizzcoat]

[Minny_Weather]

3k nam is much less for eastern Nebraska

I feel like this is also more realistic in terms of max amounts. Temps near freezing won't exactly be combined with great amounts. I think there will also be a layer of dry air for this thing to fight off so that will kick down amounts. Obviously some people will see higher amounts, but this is a good guide for people who don't have CentNeb levels of luck.

[Minny_Weather]

RGEM is stronger but also farther South. Still snowing at the end of the run.

[Hawkeye]

I'm certainly liking the trend this morning.  The models that kept all the snow south of CR have now jumped north and show >0.20".  The 12k NAM is up to 0.40-0.50".  Just as good, the models have slowed the system so now I'll actually get to watch it snow at least through the morning if not all day.  

[Clinton]

CMC staying strong.

[Stormhunter87]

Either way looks like the I-70 corridor is the sweet spot. Looks like my parents just north of Columbia will end up with 10 inches. They have had better luck this year than us, and we have been luckier than most.