12/8/08-12/10/08 FCST KS/NE/IA/SD/MO/MN/WI/IL/IN/MI/OH

[Joel Wright]

Well the models have certainly backed off on the heavy snow potential for the Lakes region. GFS/UKMET/EURO/GEM/ and even the NAM pretty much agree on a fairly progressive storm system. This should keep snowfall amounts from getting too out of hand. Some areas from NE into the NW half of IA/southern MN, and into WI should still get some decent accumulations though. Most accumulations now appear to be more in the 3-7" range.

Last night and even this morning the GFS suggested the possibility of a stronger surface low evolving out of the mid-Mississippi valley region Tuesday, but that scenario is looking less likely now. Certainly seems like a waste of excellent baroclinicy and gulf moisture.

This may eventually get it's act together and form a major east coast storm by later in the week.

 

[Robert Dewey]

Well the models have certainly backed off on the heavy snow potential for the Lakes region. GFS/UKMET/EURO/GEM/ and even the NAM pretty much agree on a fairly progressive storm system.

WI and northern MI still look really good. NAM is actually a bit less progressive on the 00Z run... GFS, NAM, and RGEM still outputting tons of QPF on the cold side too. I definitely wouldn't write it off as a bust just yet.

 

[Bill Schintler]

Monday through Wednesday winter storm

A major winter storm will affect much of the Mississippi valley into the Upper Midwest, bringing with it a mixture of snow, freezing rain, and rain. Locations in Eastern Iowa north of US-30 will see a brief period of freezing rain, which quickly transitions to (liquid) rain when precipitation starts late Monday morning. Rain will change over to snow early Tuesday morning, with significant accumulations likely along with winds gusting to nearly 40 mph. Snowfall will wind down by daybreak Wednesday.

Cedar Rapids:
Rain or freezing rain will start at 11 AM Monday, and quickly change to rain. Rain will change to snow at 7 AM Tuesday morning and accumulate to 4 inches.

Iowa City:
Rain showers will start at 10 AM Monday and change to light rain by early afternoon. Rain will change to snow at 8 AM Tuesday morning and accumulate to 2.5 inches.

Marengo:
Rain will start at 11:30 AM Monday. Rain will change to snow at 7 AM Tuesday morning and accumulate to 3.5 inches.

North Linn Co. (Paris and Coggon):
Freezing rain will start at 10:30 AM Monday and change to rain by 1 PM. Rain will change to snow at 6:30 AM Tuesday morning and accumulate to 5.5 inches.

Twin Cities:
Snow will start at 10 AM Monday, and accumulate to 3 inches on the south side of the metro, while tapering down to 2 inches in the northern suburbs.

Discussion:
UA analysis shows a 130kt H3 streak approaching the PAC NW, while further S an ULVL low spins away over SRN CA. Light radar returns and IR satellite enhancements are showing up along the NE/KS border through WCNTRL NE, although no SFC stations are reporting precipitation as of 05Z. This is associated with frontogensis and isentropic uplift centered at the H8 layer and will continue strengthen overnight while shifting EWD. Overnight and early on Monday, a brief period of ZR will be likely before a change over to R. Recent FCST trends continue to reduce the ZR duration with an overall warming trend, and it now appears as though icing will not be a significant problem. The longer RNFL duration may also keep SNWFL totals at bay.

A complicated FCST indeed as the location of strongest mesoscale forcing depends on details in the phasing of two branches of the H3 jet. Furthermore, the degree of warm sector precipitation is uncertain; and may serve to limit NWD moisture transport. Models continue to be all over the place with regard to WAA, and tend to exhibit a NWD bias in this type of regime while underestimating the degree of WAA. Models differ on the degree of phasing of the NRN and SRN jet branches over the upper Midwest. The GFS is strongest, the WRF weakest (although recent two runs bring it more into line with the consensus), and the ECMWF has been the most consistent overall. The HPC model ensemble prefers a solution taking the SFC low from near CDS (00Z, 12/09), COU (12Z, 12/09) and then 80 miles S of LAN (00Z, 12/10).

Overnight, WAA really kicks in, and some ZL will be possible with moisture ADVCTN over the cold snow pack. The precipitation now over the NE/KS border shifts E and will reach SERN IA Monday morning. During the day Monday, SFC low-pressure organizes over OK; and reaches NRN MO late on Monday. The latest WRF has come into line with other guidance with a stronger SFC/H85 solution and with more WAA. The overall storm QPF will likely be in excess of an inch, given overrunning combined with strong dynamics of the FCST ULVL system. The all-important question is the type and timing of precipitation. Bufkit FCST soundings indicate all R until the passage of the CF between 10Z-14Z on Tuesday. Given the snow pack along and N of US-34, the cold SFC AMS should hang on longer then models suggest. The SFC low will strengthen and move NE Monday night into Tuesday with an attendant 50-60kt LLJ which will result in NWD transport of moisture. Finally, A TROWAL feature develops between 12Z Tuesday and 00Z Wednesday with attendant SNWFL enhancement from CNTRL KS through ERN IA and NRN IL. N/S FCST cross sections indicate strong lift in the dendritic growth region between US-20 and US-30. A zone of slantwise assent/descent and negative EPV is also likely in this area, favoring banding of snow.
- bill

KD0DJG
10:25 PM CST, 12/07/08

 

[Joel Wright]

Looks like the big winner for the heaviest snow will be somewhere in northern lower MI. Someone up in that area could easily see more than 10". Looks like all the heaviest snow will stay north of the major cities such as Lansing, Detroit, etc. Saginaw might be close though, but I think the heaviest will be north of them even.

Back in Wisconsin it looks like the heaviest snow will fall just north and west of Milwaukee and maybe even Madison. Although both of those areas could still get some respectable snowfall. Should be a nice 5-10" band setting up from near Richland Center to the Fond du Lac/Sheboygan area. Amounts may be a little bit lower right next to Lake Michigan though due to relatively warm air from the Lake.

It looks like as you head southwest the snowfall amounts will slowly drop off. Still could see a nice 3-7" band through IA though. Probably from the Webster City area northeast towards Prairie du Chien.

For much of southeast Iowa towards the Chicagoland area it's now looking like mainly a soaking rain event. Some areas could pick up 0.75"+ of rain though before transitioning over to a brief period of wet snow. Most of these areas will probably see less than an inch of slush, but the snow falling on wet roads will make for a very icy scenario for the evening rush hour. The changeover to snow in Chicago may be just late enough that the worst of the road conditions develop shortly after the main rush hour time period. Certainly looks to be more of a problem as you head west from the city.

 

[Dean Baron]

Winter weather advisories issued for the southern two-thirds of Minnesota, 3-6" for the Twin Cities, snowfall likely to increase to near 10" as you go south towards La Crosse, WI. Looks like from southeast Minnesota northeast in to Wisconsin towards Lake Michigan could easily see 10"+ of snow, the models have been pretty consistent in putting a big swath over this area.

 

[L.B. LaForce]

Freezing Rain Advisory in effect here in Battle Creek, from 4:00PM today, till 10:00AM tomorrow. This could get interesting.

 

[Jim Saueressig]

We have only had just a few flakes of snow up to this point but today we currently have light freezing rain and a forecast of a few inches of snow when it switches over.

 

[Scott Weberpal]

A narrow swath across central Wisconsin has received 8"+ to this point with snow continuing to fall.

 

[Matthew Harding]

Officially there is about an inch of snow at Mid-Continent airport with numerous accidents across the Wichita area. There has been a persistent band of moderate-heavy snow across the Flint Hills that is associated with some 800-700mb frontogenesis so there may be some slightly higher amounts in that area. Snow should wrap up here within the next few hours.