FCST: 12/18/08-12/19/08 Central Plains / Upper Midwest Winter Storm

[cstrunk]

Surprised that there isn't a discussion going specifically for this potentially significant winter storm. It looks like the Gulf of Mexico is going to be wide open as moisture surges northward. A layer of warm air is expected to surge northward also, creating a scenario for a potentially significant icing event setting up across central and southern Iowa (and adjacent areas also). An inch of QPF is possible with this storm. It looks like 0.25-0.5" of ice is likely close to where the surface temperatures stay at/below freezing, with higher accumulations possible. Farther north, heavy snow will be falling.

What are everyone's thoughts on this storm? Also looks to be active through next week as well.

 

[Robert Dewey]

This is definitely looking like a wet system. Once again, I'm right on the SN/ZR/IP line. GFS has been trending a bit further south with the system.

 

[rdale]

GFS has been HORRIBLE with this one, Euro has been very consistent. I don't see too much "wet stuff" around Michigan though. Looks like at the least a nice snower, with some ice in the south and east parts of the state.

Then maybe another on Sunday that (again) the Euro has had, and now GFS is picking up...

 

[Matthew Harding]

I am extremely green when it comes to forecasting, but it seems that the models discounted today's snow event in the midwest and want to dislodge the cold air too quick. It will be interesting to see if they all trend colder and take the low pressure further south in future runs, which could spell more icing and snow for the same areas that are getting hit today.

 

[Adam Penney]

As I right this, I now have 3 inches of fresh snow on the ground here in south KC. Both the NAM and especially the GFS advertise extreme WAA over the area beginning Wednesday night. In fact, the GFS would advertise highs in the 50's here on Thursday! Wow...

At last check, temps in SC TX are still holding in the mid 30's with 18 degrees at my location in KC. DFW is also still in the mid to upper 20's at this hour. I am very curious with the snowpack now in place all the way down near ICT and SGF, exactly how far the front will retreat north, and whether or not this low actually tracks further south than currently projected.

EAX as well as SGF seem to be downplaying the potential. I am not so sure yet..

 

[Jeff Snyder]

I'm considerably interested in this event since my wife and I will be driving from OKC to MSP Thursday, barring severe or impossible travel conditions (in which case we'll stay overnight in DSM or somewhere near there). The interesting thing that I see is the massive difference bewteen the 12z GFS and the 12z NAM... The 12z NAM has upwards of a foot of snow falling over southern MN and adjacent areas of northern IA and sw WI thursday evening into the overnight. The 12z GFS, however, only shows a couple inches of snow over southern-central MN Thursday evening. FRZA and IP seem likely along and S of I80 (and N of I70) Thursday afternoon. I hope we can make it north fast enough to avoid the heaviest freezing precip (mainly FRZA, which makes travel almost impossible many times, particularly when asphalt road temps are much below freezing). I can take some moderate snowfall, particularly along a major interstate such as I35, and I think we'll be okay if we're to or through DSM by mid-late afternoon.

 

[Robert Dewey]

Official NCEP QPF forecast puts a 2 inch maxima over southern MI... I was mistaken with the southward trend. Looping the latest NAM to the old one shows a bump in the 850MB temps.

If it's ice, there will certainly be a lot of it.

 

[Michael O'Keeffe]

Based on what I am seeing like a few have mentioned earlier we may see some ice accumulations across the C Plains and Midwest. Here in KC we could see up to a quarter of a inch at the moment with a rise above freezing which will just change to heavy rain, but based on current surface obs and snow cover across the region it appears possible that we will not get above 32F which could lead to a potentially devastating ice storm in E KS/MO/IA/IL. Right now we are projected to get .75 - 1 inch of rain/freezing rain with only about a quarter of an inch or less being ice (at this time), but the 18z NAM and based on what I am seeing we won't see 32F on Thursday leading to possibly 1" of ice accumulation for mainly areas near (just south of I70) from Topeka to St. Louis north to Omaha and Des Moines. If not then we could see some heavy rain none the less and very slick roads Thursday mornings when I have mid terms. Oh boy!!

 

[Greg Blumberg]

I'm noticing there's quite a bit of discussion going on about KC. I'm flying out of MCI back home around on Wed at 7 PM and am slightly wondering if there's a potential for my flight being delayed. The NWS is predicting a 20% chance of freezing rain Wed night, and transitioning to 70% Thursday, but I'm not seeing any cause for that on the models. Any ideas where they're getting this from? I know this might be slightly off topic, but I'm assuming that there is a connection between this forecast and dates of this thread.

 

[Chris Allington]

I'm noticing there's quite a bit of discussion going on about KC. I'm flying out of MCI back home around on Wed at 7 PM and am slightly wondering if there's a potential for my flight being delayed. The NWS is predicting a 20% chance of freezing rain Wed night, and transitioning to 70% Thursday, but I'm not seeing any cause for that on the models. Any ideas where they're getting this from? I know this might be slightly off topic, but I'm assuming that there is a connection between this forecast and dates of this thread.

I would guess they inserted freezing drizzle for tomorrow because of the moist airmass screaming north out of the Gulf ahead of this system. While there isn't really a forcing mechanizm or any kind of lift to produce snow... the saturated low level air mass tends to produce some fog and patchy freezing drizzle.

Also, interested in this storm in the Omaha area... though at the current time the precip type for us depends on which model you want to believe. Like Michael, I'm doubting we can get above freezing, especially with -10 reported at Norfolk right now... but with the overrunning I bet we could still get some freezing rain and sleet... followed by a couple inches of snow. Will be interesting to see how this plays out... I definately have to give it a bit more detailed look here in a bit.

 

[Joel Wright]

This looks to have the potential to be a very damaging icestorm for someone in the midwest. Today's snowfall did nothing to help prevent that from happening as a nice 3-6" snowfield was layed down from Iowa to Michigan. This should push the storm further south per what the Euro says. I agree with Rob about the GFS handling of this storm so far. It will be making an adjustment southward for sure over the next 12-24hrs. Looks to me like a major to potentially devastating icestorm could set up along and north of I-80 from Iowa into northern Illinois, and perhaps southern lower MI. Just north of this there'll likely be some heavy wet snows from northern IA into southern WI and parts of lower MI.

This storm will have a considerable amount more gulf moisture to take advantage of compared to the little wave we saw today.

 

[Robert Dewey]

Still looking pretty impressive. The 00Z NAM shows widespread 12-18 inches... with GFS showing widespread 18-20 inches from SE WI to NY (on the wxcaster site).

Joel was right with the slight southward adjustments on the GFS.

Regardless of the model snow values, a pretty large area should get hammered with up to a foot.

 

[jshields]

the models keep slowing down the speed of the system too, so that will allow more warm air and moisture to stream northward. what looked like an arrival early thursday across the western and central plains is now looking more like late thursday afternoon before the show really starts. i think with the large area of the snowpack, the temps could still remain below freezing right at the surface over a large area which means alot of freezing rain with the strong waa. i'm hoping for some snow on the back side here in omaha thursday nt, friday am. the models are hinting at 3-6" possible in the deformation band on the back side in nw iowa and eastern nebraska. we'll see how much ice occurs on thursday afternoon though they're saying it could be alot of sleet instead.

 

[Chris Allington]

Checking out the models the WRF generates a pretty classic deformation zone over Ern NE and W IA after the icing event so someone should see some nice banded snows out of this storm. It also shows about .7 inches of total liquid with the start of this being ice in the form of freezing rain with surface temps hovering around 30. The GFS being a bit further south, but also slower... gives roughly the same amount of precip falling as mostly snow with temps in the mid 20s. UKMET wants to eject the low father north across the KS/NE border region and into Western Iowa and the NGM has this same bias... but with the cold air entrenched I just don't see it happening. Either way, it appears that the most significant icing potential is across Central Iowa... moisture and WAA in this area will be maximized with the cold bubble at the surface and models are outputting some pretty incredible precip totals... mostly as freezing rain or sleet. I would think the greatest icing would occur just south of the I-80 corridor with an area of significant snows just north of that.

 

[Robert Dewey]

GFS took a pretty big jog to the south.

I took a look at the Cobb algorithm... NAM spitting out almost 15 inches over LAN.