WINTER STORM FCST 11/30/07-12/02/07: IA, NE, SD, MN, MI, WI, IL

[Joel Wright]

Wow, what an interesting storm. The warm air advection wing precip is going to be quite significant. Many areas are going to see all four forms of precip within a 12 hour period of time. Just look at that tremendous WAA at 850mb! Incredible.

The NAM shows quite a wide band of sleet from Nebraska through Iowa, and into Illinois for much of the day on Saturday. Judging by the QPF forecasts, some of these areas may receive quite a bit of sleet. For example, Des Moines and Davenport are forecasted to have sleet for over 6hrs. If that were indeed the case, it would accumulate quite significantly over that duration.

 

[Jeff Miller]

New GFS run in and pretty much everything totally on - with no significant changes then what we have here

Expect upgrades to Warnings in the morning package and suspect some of them will be of the Ice Storm variety.

 

[Brandon Sullivan]

Taking a look at the 0z NAM and GFS...

The NAM/WRF takes the low on a further south path, keeping freezing surface temps over the IL area the whole duration of the event. However, it still shows nice WAA advection northward, with 850mb hovering between 6-9 degrees Celsius. This would spell s nice ice storm setup, with surface temps forecast to be sub freezing by at least a couple degrees..

Taking a look at the GFS.. It continues to drag the low further north, this time taking the low into central and northern iowa up into central wisconsin!! The WAA did not cut back too much either, and this would mean a lot of rain for areas in Western IL into north central Illinois and eastern/southeastern IA.

Hopefully things will converge one way or the other here soon..

 

[rdale]

Remarkable how the GEM & EC had this track all week long - what do those foreigners know about long-range models that NCEP doesn't?!? Remember the GFS track from Sunday / Monday's runs that had everyone excited, as it brought the low across Tennessee :>

 

[Rhyuan Janssen]

I do not buy into the GFS taking the low from SC Iowa and then up thru wisconsin. I think it will be further to the south; unless the low bombs out and is much stronger than anticipated

Some of our local stations where I live are saying an inch of ice on top of 3-6 inches of snow; then 35mph gusty winds. They are also mentioning thunder will occur with our freezing rain. I'd like to see that!! That would cause major issues for us, in fact, maybe worse than last years Feb/March Ice storm.

I would also agree with morning update that some of these WSW will become Ice Storm warnings (cent. IA and eastward); especially if thinking edges towards NAM QPF output.

In any solution someone is going to get a major ice storm IMO, and I hope it is me!

 

[Dustin Wilcox]

Still looks as though the Sioux City NE to Storm Lake to Spencer IA area looks most at risk for a sig icing event. Models have been pretty consistent warming areas south of a Columbus NE to Harlan IA line to above freezing, though some early morning frozen precip looks likely. I think being in Lincoln I will probably be missing out on this one, I would head North towards my hometown, and maybe even farther North to enjoy the storm, but have to stick around Lincoln just in case we get any snow, as its my weekend to move snow on campus.

 

[Corey Sloan]

Temps not verifying????

I am new to the winter weather discussion, usually only involved in the spring season....does anyone put any weight into the models not verifying the temps in the Upper Midwest during the latest 00Z run today....they are anywhere from 8 to 14 degrees warmer than the actual station plots....if I am correct, could this affect the precip type across southern IA and northern MO?

 

[Jeff Miller]

What a mess.

Am Ice Storm Warning is hoisted for extreme NE KS and extreme NW MO.

Winter storm watches are now in effect for SE SD, Central and Eastern NE, Central and southern MN, all of Iowa, NW/NC KS, Northern IL, All of Wisconsin, Extreme N IN, All of MI, Extreme NW OH, West NY and Central PA.

Freezing Rain advisories are in effect for Central and portions of NE KS

Major winter storm developing and this one is giving headaches to forecasters all over this country this morning. There are many, many highly complicating issues at play and this one is going to be a storm that is going to be evolving even at and beyond crunch time, and I would expect frequent changes as the "now" becomes more real then the "forecast".

The biggest issue will be how strong the mid level warm air advection can overcome the shallow cold air at the surface for many locations. I've noticed some weather service offices this morning look at the strength of midlevel WAA and agree with models on a warmer scenario. However historically colder air is not as easy to shallow out as models like to indicate. It seems that in this case just a few degrees difference is going to spell out the difference between a paralyzing ice storm and a cold rainy day with little consequence.

At any note, this is going to be a nailbiter and a challenge to even the most experienced forecasters.

Again, what a mess.

 

[Joel Wright]

The DVN NWS calls for up to 3/4" ice accumulation by Saturday evening. They note that internal gravity waves combined with VERY strong winds just off the surface may induce some wind gusts up to 50mph. That exact thing happened in the icestorm this past February and it was a real mess.

The real question for many of us though is how much of that ice will just be sleet. That would make a huge impact on glazing accumulations.

 

[Rhyuan Janssen]

For me I am hearing very conflicting forecasts. Several NWS stations say it will NEVER get above freezing in NE Iowa and Far North NE and NW Iowa in which case, we are all in for it.
Then on the flip side of things some say rain by afternoon? IMO I still think the warmer air is being overdone and the shallow cold air will stick around longer than anticiapted. In fact this morning my local station said 1-2 inches of ice??!! I think they are overdoing that a bit.
Now DVN says possibly 50+mph winds and crippling ice storm and Des Moines is talkin about lightning and thunder with the freezing rain! If the wind and thunder truly occur I think someone in Iowa is going to have an Ice storm beyond what we had last march. Again, hoping is it as my house

 

[Brandon Sullivan]

Glancing at the 12z WRF. It has come in somewhat slower and holds precip into sunday night. It has also shown warmer trends, likely due to the more northern track.

The 9z SREF shows probabilities of Freezing Rain being higher thatn Ice Pellets/Sleet.

The GFS in all honesty hasnt changed much... It is however slightly slower this run.. Not too much to add

Edit: Emergency Manager Conference Call has been scheduled by DVN for their CWA.

 

[Darren Addy]

The NE forecasters discussion continues to be interesting:

BELIEVE THE 00Z MODEL RUNS DID NOT HAVE A GOOD HANDLE ON
THE STRENGTH OF THIS COLD AIR...WITH 1032MB SURFACE PRESSURES INTO
NORTHERN NEBRASKA. CLOUDS ALSO NOW SLIDING OVER THE CWFA. WINDS
PROGGED TO TURN NORTHEAST/EAST TODAY AS WELL. THOSE TWO FACTORS
DON/T SUPPORT MUCH WARMING...AND HAVE LOWERED TODAY/S HIGH TEMPS.
THAT ALSO MEANS THE COLD AIR WILL BE SLOWER TO DISLODGE TONIGHT.

Naturally, they are discussing only their CWA, but they seem to think that the most significant ice will be north and east of Grand Island (at this time). It does sound like somebody is going to get a repeat of what we got in south-central Nebraska last year (and that ain't pretty):

BUT THE MOISTURE TRANSPORT
ASSOCIATED WITH MASSIVE WARM ADVECTION IS ANOTHER BIG POINT.
PRECIPITABLE WATER VALUES ARE UP TO 4+ STANDARD DEVIATION ABOVE
NORMAL FOR EARLY DECEMBER...AND ABOVE 1 INCH. SUCH ANOMALOUS
INGREDIENTS CAN RESULT IN ANOMALOUS RESULTS (SEE ICE STORM
2006).

The good news is that this will be much more short-lived event with temps warming significantly rather quickly. (This is NOT altogether good news if you happen to be under a warming traffic light or business sign that decides to drop a significant block/sheet of ice off when you - or your car - is under it.) The most damage will occur where there is the most ice (weight) combined with wind which is often the straw that breaks the camel's (tree's) backs.

As someone who lived through multiple days of no power last year, I hope anyone who lives in the affected area is telling friends/relatives to stock up on food that does not require cooking, candles, etc. (Count your blessings if you have a gas stove/oven and gas water heater). If you live on a farm, you probably know the drill: The pump won't be pumping with no electricity, so fill the bathtub with cold water before going to beddie tonight. In particular, before the storm, check for branches over the lines that bring electrical power from the pole to your house. If that branch gives: you are unplugged from the grid, even if the grid is UP. That's the line that will be the lowest on the power company's priority list to fix.

 

[Bill Doms]

Really curious to see how the warm air works in tomorrow. Last GFS run puts me in the 8"-10". I'm still thinking may see a fair amount of sleet first really cutting down on the totals up here based on forecasted soundings for MPX. FWIW west metro suburbs started pre-treating the road surfaces this morning up here.

 

[Darren Addy]

Well, crap.
The ice storm warning area shifted from this:

to this:

I can't believe we are going to get it again. This will be the third significant ice storm for this area in 12 months.

 

[Brad Case]

Eastern Nebraska and Western Iowa weather updating at

http://w0tvs.net

Brad - Bellevue NE