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

[Robert Dewey]

It's interesting how the 18Z NAM is fairly similar to the 12Z NMM WRF. The finer resolution of the NMM run appears to be hinting at banding - http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/hiresw/12/images/hiresw_p03_027l.gif

If the 18Z GFS boosts QPF, I'll be more inclined to believe the +1 inch solutions.

 

[jshields]

wow things have really changed here in eastern nebraska! at noon they updated the ww advisory over all of eastern ne to a winter storm warning. models are now showing up to 8" of snow could occur somewhere near or north of a lincoln to omaha line. it looks like thunder and convective precip is very likely tonight too. i'm hoping we miss the ice as it is only 21 here in omaha(earlier forecasts were saying a hi of 27), so it looks like the colder air has held on tough. also it has finally clouded over when through noon the sun was out. precip is supposed to blossom over the area between 6pm -8pm. it's been a LONG time since i have seen thundersnow. here's hoping tonights the night!

 

[Dustin Wilcox]

so it looks like the colder air has held on tough.

We are right on the edge man, I'd say a line from York to Fremont and South and East from there still has a shot at some mix bag precip. It's fun watching the mesoanalysis page on days like this, it still has the lower levels *just* warm enough to maybe turn things to liquid before hitting the ground in OMA, still looks like it might try to surge just a little more, though not much. You can see how its struggling now by looping the 850mb temp advection.

Considering its not going to snow all that long, despite it being well overdone thats still pretty nuts...
http://www.grib2.com/wrf/CENTRAL_WRF_SFC_ACCUM-SNOWFALL_36HR.gifhttp://www.grib2.com/wrf/CENTRAL_WRF_SFC_ACCUM-SNOWFALL_48HR.gif

 

[Robert Dewey]

18Z GFS is a little wetter over IL, and a tad stronger. This seems to be the trend, though no major changes.

Loaded the 18Z NAM PTK profile into BUFKIT... it's looking a little extreme with 19 inches of snow on 1.23 inches of QPF. A ratio of 11:1 drops it to 13 inches.

What's really impressive is the insane omega (-30u to -35u) planted directly in the DGZ. Saturated theta-e shows very low stability... briefly going unstable for a couple of hours.

If all of that is true, I can see where the QPF values are coming from.

I'm still going 6-12 inches for now, at least for southern WI into southern MI.

 

[rdale]

I did end up putting double-digits on my maps and web update...

 

[David Draun]

http://www.spc.noaa.gov/exper/mesoanalysis/s4/epvm.html

http://w1.spc.woc.noaa.gov/exper/mesoanalysis/s4/epvl.html

Just some questions:

1. How do I read those maps
2. Can one forecast the possibility of thundersnow from them?

 

[Dustin Wilcox]

Wow that looks fun... 19-20 degrees in that area, already lots of lightning with this convection, as this lifts North and changes to snow there are going to be some SWEET hourly snowfall rates...

 

[Robert Dewey]

15-min lightning plots getting pretty active over the developing precip area.

Latest TAMDAR RUC shows that area as the point of origin for the 0.5in to 0.75in 3-hour QPF rates across northern IL / IN @ 12Z FRI. Incidentally, that model is now showing +12 inches of snow across lower MI.

 

[AlDanks]

Local TV station is forecasting 14.7 total for Grand Rapids, MI area before the storm winds down. Crazy rates per hour. Starts with 0 at 4 am, 1.7 at 5 am, and then jumping about 2-3 inches each hour. Something like 12 - 13 " by noon.

We'll see.

 

[rdale]

That's what the forecaster said, or that's what the model said? Anyone giving 0.1" accurate amounts is not fit for public viewing

 

[Chad Cowan]

At home in KC for the holidays with 3 inches of snow on the ground, just saw some lightning with this elevated freezing rainer!

EDIT: Looking at the National Mosaic and the GFS and WRF fcst precip, I would expect these storms over KC to grow in coverage and intensity as they move northward over the next few hours and the LLJ ramps up the WAA and the potent shortwave ejects from the panhandles. Normally I would wish I were up by the IA/MO border, but with the holidays upcoming and a lot of errands to run I will be happy with just a glazing.

EDIT 2: Just looked at the GR3 images from about 20 minutes ago... there was a 62.5 dbz return just southeast of here! Gotta love these dynamic systems.

 

[Josh Richardson]

Just wanted to point out something with the ice storm for Southern IA through tonight, we still have our next system coming through Sat/Sun as well which will bring much gustier winds(gusts above 30 mph) to the same areas that should receive decent ice accums., could be a real mess in this area.

On another note, looks like a real shot for 8-10 inches of snow in my area if we get any of this thundersnow....we'll see how it pans out.

 

[jshields]

that was absolutely impressive. no echoes on the radar at 4pm over eastern NE, and then by 6 pm everything was filled in. on my way home at 4pm, the sky was pretty much completely clouded over with mid and high level clouds, but there was low level clouds streaming in from the east and southeast. off to the northeast i could actually see some "towering" cumulus!! they were fairly small in height, but they were definitely cumulus clouds. it was like it was a summer sky! i wish i had a camera with so i could post some pics. by 530, the freezing rain had started, and around 6 we had a burst of moderate sleet. its still sleeting with a few larger flakes of snow mixed in. it just showed on the news there are some lightning strikes moving up from the south into the omaha metro! this should be an interesting night

 

[cstrunk]

Here in extreme SW IA, we've had some freezing rain that has now begun mixing more with sleet. It's a double edged sword for me, as far as wanting to see more freezing rain. If we get more freezing rain, power will likely go out and conditions outside will be a disaster. If we get more sleet, things won't be as interesting.

The first wave of the precipitation field looks to be north of here now, but I think we'll see the radar fill in with more convective precipitation from the south. Here's to seeing a major winter storm, but keeping power in the process!

 

[jshields]

First reports of thundersnow here in the omaha metro!!

Millard Airport

19:10 SE 5 1.50 Thunderstorm Light Snow in Vicinity
18:50 E 3 2.50 Thunderstorm Snow in Vicinity