Dec 11-13 MW/Lakes/OV snow event part 4

[cyclone77]

Suddenly getting quite foggy here, as the warmer air moves in over this snow cover. We've bumped up a few degrees over the last hour or two, and now at 35.

I'm hoping we can get a quick changeover to wet snow before it shuts off later today. Still don't think we'll see any appreciable accumulations though until the deform swings in after midnight.

[hawkeye_wx]

Just raining here with temp in the mid 30s. The inch of snow from the last storm is gone.

[janetjanet998]

Just raining here with temp in the mid 30s. The inch of snow from the last storm is gone.

I think you may chnage over to snow as the heavier band moves over you soon

[Organizing Low]

You used to be able to get them off the PSU site, but the RGEM doesn't update there anymore. I was describing what the RGEM showed in terms of p-type from this instead:

http://collaboration...pe_gem_reg.html

^^^I'm pretty sure you already know about it.

yeah ok, thanks for the info

it annoying we cant get that, but ther hourly ptype map is cool

[janetjanet998]

Ottumwa IA has gone over to moderate snow

KOTM 111617Z AUTO 28016G24KT 1/2SM SN

[goknights]

La crosse going with 14 to 18 here now

[hawkeye_wx]

While the surface low is not tracking along or north of the IA/MN border like the NAM had been showing, it's also not following the hw30 track through central Iowa like some other models were predicting.

[csnavywx]

While the surface low is not tracking along or north of the IA/MN border like the NAM had been showing, it's also not following the hw30 track through central Iowa like some other models were predicting.

Bright banding showing up very near you. Let us know when you flip to snow. Seems to be about 8-15 mins after the wind shift for most stations.

[MadTown]

weenie post.. what do you all think for madison area. supposed to be having people over before a hockey game and then head to the hockey game this evening. seems like nws is saying 6-7 here, but local mets saying 8-12".

[Moneyman]

Madison should do well I think. I would say probably between 6-10 for you guys. Probably around 7-8 inches would be a good estimate.

36 degrees here, high was only supposed to be 33. Not good.

[oldlogin]

Northwest Iowa

NWUS53 KFSD 111557

LSRFSD

PRELIMINARY LOCAL STORM REPORT

NATIONAL WEATHER SERVICE SIOUX FALLS SD

957 AM CST SAT DEC 11 2010

..REMARKS..

0950 AM BLIZZARD ORANGE CITY 43.00N 96.06W

12/11/2010 SIOUX IA EMERGENCY MNGR

WIDESPREAD LOW VISIBILITIES LESS THAN 1/4 MILE. NEW

SNOWFALL 4 INCHES.

[cyclone77]

I'm kind of wondering what the ratios will be like in that wraparound deform band later tonight and Sunday. Very cold air in the mid-levels should equate to some pretty high ratios. However, with so much wind granulating the flakes into smaller ones, I wonder if the net result will be negligible.

[cyclone77]

The St. Louis high-res WRF really cranks the lake enhanced snow over the heart of Chicago tomorrow afternoon. This is right around kickoff time as well at the Bears game. This is going to be fascinating to watch.

[MadTown]

milwaukee upgraded far southeast to WSW updated AFD

[ILSNOW]

For what is worth 12Z Bufkit for ORD is 1.689 total (.73 rain, .95 frozen)

[beavis1729]

For what is worth 12Z Bufkit for ORD is 1.689 total (.73 rain, .95 frozen)

Thanks...which model?

[ILSNOW]

Thanks...which model?

GFS

[hawkeye_wx]

New Rochester, MN nws forecast says 13-20 inches. It's amazing how easily it seems to be for a lot of areas across this region to get more than a foot of snow while Cedar Rapids has NEVER officially had a foot from any storm.

[beavis1729]

GFS

Thank you

[tornadotony]

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL

429 AM CST SAT DEC 11 2010

DISCUSSION

345 AM...

THE TIME OF THE CALM BEFORE THE STORM IS DECREASING RAPIDLY.

FOR HEADLINES...WILL MAINTAIN THE WINTER STORM WATCH FOR SEVERAL

REASONS. THROUGH MUCH OF THE DAY TODAY...THE BULK OF THE

PRECIPITATION WILL BE RAIN. RAIN SHOULD CHANGE OVER TO A RAIN/SNOW

MIX AND THEN SNOW FOR THE ROCKFORD AREA THIS EVENING WITH THE SNOW

SPREADING EAST OVERNIGHT TONIGHT. THE HEAVIEST SNOW WILL BE WELL

NORTH OF THE CWA TONIGHT AND ONLY 2 TO 4 INCHES OF SNOW IS

EXPECTED TONIGHT...FOR THE NORTHERN TIER COUNTIES. FREEZING

DRIZZLE WILL BE THE CONCERN OVERNIGHT TONIGHT...PARTICULARLY FOR

THE CENTRAL AND SOUTHERN PORTIONS OF THE CWA...BUT THE EXACT

IMPACT OF THE FREEZING DRIZZLE AND THE AMOUNT OF GLAZING IS STILL

UNCLEAR...ESPECIALLY GIVEN THE WARMING TREND TODAY. THE EXACT

TRACK OF THE LOW CENTER WILL BE CRITICAL TO THE AMOUNT OF GLAZING.

AND THEN THERE IS THE STRONG WINDS THAT WILL DEVELOP AS THE

DEFORMATION SNOW BAND MOVES ACROSS THE AREA SUNDAY. BLOWING AND

DRIFTING SNOW WILL BE A SIGNIFICANT CONCERN AS WINDS APPROACH OR

EXCEED 40 MPH. THEN BY SUNDAY NIGHT AND MONDAY...ARCTIC COLD WILL

HIT THE ILLINOIS PORTION OF THE CWA AND LAKE EFFECT SNOW WILL HIT

THE NWRN INDIANA COUNTIES. WIND CHILL READING SHOULD REACH

ADVISORY CRITERIA AND MAY EVEN HIT WARNING CRITERIA IN SOME

LOCATIONS. LAKE EFFECT SNOW AMOUNTS MAY ALSO REACH WARNING

CRITERIA LEVELS FOR PORTER COUNTY AND POSSIBLY EVEN LAKE COUNTIES

IN INDIANA. SO...GIVEN THE DIVERSITY OF HEADLINE CRITERIA

PHENOMENA EXPECTED OVER THE NEXT FEW DAYS...WE FEEL THAT IT WOULD

BE BEST TO MAINTAIN THE WINTER STORM WATCH FOR A WHILE LONGER

UNTIL THE EXACT WARNING SITUATION BECOMES MORE CLEAR.

THE WEATHER PICTURE ASSOCIATED WITH THE LOW DEEPENING OVER THE

CNTRL PLAINS IS COMING INTO BETTER FOCUS THE CLOSER WE GET TO THE

EVENT. THE VARIOUS MODELS ARE COMING INTO A BETTER CONSENSUS...AT

LEAST FOR THE NEXT 24 HOURS...WITH THE TRACK AND MOTION OF THE LOW

CENTER. THE TREND OVER RECENT RUNS HAS BEEN FOR THE LOW CENTER TO

TRACK SLIGHTLY SOUTH AND A LITTLE SLOWER WITH EACH RUN. THE LATEST

00Z MODEL RUNS CONTINUE THIS TREND...WITH THE LOW CENTER MOVING

THROUGH NRN IL...RATHER THAN SRN WI AS WAS SEEN LAST NIGHT.

ALSO...THE TIMING OF THE PROGRESSION IS SLOWING DOWN AS WELL. THIS

SLOWING TREND IS QUITE IS MATCHED BY THE LATEST SATELLITE

OBSERVATIONS WITH INDICATED THE UPPER LOW CENTER DEEPENING AND

SWINGING A LITTLE MORE SOUTHERLY INTO ERN NEBRASKA. THE OBSERVED

SATELLITE TRENDS OVER THE LAST SEVERAL HOURS NICELY MATCH THE

EARLY PERIOD MODEL TRENDS...PARTICULARLY THE NAM12. SO...SINCE THE

MODELS ARE IN DECENT AGREEMENT FOR THE EARLY PORTIONS OF THE SHORT

TERM...HAVE GENERALLY FOLLOWED THE TRACK AND TIMING OF THE NAM.

WHAT THIS MEANS AS FAR AS THE MORNING FORECAST UPDATE IS

CONCERNED IS THAT THE PROGRESSION OF THE SYSTEM WILL BE A LITTLE

SLOWER...WITH PCPN NOT HITTING THE I-39 CORRIDOR UNTIL LATER THIS

MORNING AND THEN STEADILY OVERSPREADING THE REGION THROUGH THE

MORNING AND INTO THE EARLY AFTERNOON. THE BULK OF THE PCPN WILL

MOSTLY BE RAIN THROUGH THE DAY TODAY...WITH THE EXCEPTION OF THE

FAR WESTERN LOCATIONS WHICH WILL SEE SOMETHING OF A WINTRY MIX OF

RAIN AND FREEZING RAIN THIS MORNING...CHANGING OVER TO RAIN AND

SNOW THIS AFTERNOON AND THEN CHANGING OVER TO ALL SNOW THIS

EVENING. THE SNOW WILL BEGIN TO MOVE THROUGH THE FOX VALLEY AND

INTO THE CHICAGO METRO AREA DURING THE EARLY EVENING

HOURS...THOUGH THE NWRN INDIANA COUNTIES SHOULD STILL SEE RAIN

WELL INTO THE EVENING. FINALLY BY AROUND MIDNIGHT...THE RAIN WILL

MOVE EAST OF THE CWA...AND THE WINTRY PCPN WILL COVER THE WHOLE

CWA. ONE COMPLICATING FACTOR WITH THE PCPN TYPE FORECAST IS THE

AFFECT OF A PRONOUNCED MID LEVEL DRY SLOT ASSOCIATED WITH THE

SYSTEM. THE DRY SLOT IS ALREADY OBSERVED IN THE LATEST WATER VAPOR

IMAGERY...AND FOLLOWING THE TIMING OF THE NAM12 SOLUTION...THE DRY

SLOT WILL PUSH INTO THE WRN PORTIONS OF THE CWA BY MIDNIGHT. THE

EXACT LOCATION OF THE LOW CENTER IS CRITICAL TO THE PCPN FORECAST.

THE CURRENT EXPECTATION IS THAT A PERIOD OF FREEZING

DRIZZLE...PERHAPS MIXED WITH A LITTLE LIGHT SNOW...WILL CROSS THE

AREA LATE TONIGHT THROUGH SUNDAY MORNING. THE NRN TIER COUNTIES

ALONG THE WISCONSIN BORDER MAY REMAIN NORTH OF THE IMPACT OF THE

DRY SLOT...SEEING JUST THE CHANGE FROM RAIN TO SNOW AND MISS THE

FREEZING DRIZZLE. THE AREA SEEING THE MOST IMPACT OF THE FREEZING

DRIZZLE SHOULD BE ALONG AND SOUTH OF I-80...THOUGH LOCATIONS

BETWEEN I-80 AND I-88 WILL LIKELY SEE MORE OF A MIX OF LIGHT SNOW

AND FREEZING DRIZZLE.

FOLLOWING THE PASSAGE OF THE DRY SLOT...THE WRAP AROUND SNOW AND

PORTIONS OF A DEFORMATION ZONE SNOW BAND WILL SPREAD ACROSS THE

AREA. THIS IMPACT OF THE SNOW WILL BE COMPOUNDED BY STRONG

NORTHWEST WINDS AS SFC LOW CONTINUES A SLOW DEEPENING TREND AND

STRONG ARCTIC HIGH PRESSURE BUILDS INTO THE NRN PLAINS.

INITIALLY...SNOW-LIQUID RATIOS SHOULD BE IN A FAIRLY TYPICAL 10-12

TO 1 RANGE...BUT AS THE COLD AIR ASSOCIATED WITH THE ARCTIC AIR

MASS IS DRAWN OVER NRN IL...SNOW RATIOS WILL INCREASE TO 20 TO 1

OR GREATER...LEADING TO A LIGHT...DRY SNOW. WITH WINDS INCREASING

TO 40MPH OR HIGHER... BLOWING AND DRIFTING SNOW WILL BE A

SIGNIFICANT CONCERN AS WELL AS SERIOUS REDUCTIONS OF VISIBILITY.

DEPENDING ON THE EXACT STRENGTH OF THE WINDS AND LEVEL OF

VISIBILITY REDUCTION IN THE BLOWING SNOW...SOME AREAS MAY SEE

BLIZZARD CONDITIONS SUNDAY AFTERNOON AND EVENING.

ALSO BY SUNDAY EVENING...LAKE EFFECT SNOW WILL BECOME A SERIOUS

CONCERN FOR NWRN INDIANA. AN EXTENDED NWLY FETCH OF COLD AIR OVER

THE RELATIVELY WARM LAKE MICHIGAN WATERS WILL BE PRIMED FOR LAKE

EFFECT SNOWS. LAKE EFFECT SNOW AMOUNTS WILL VARY DEPENDING ON HOW

LAKE EFFECT SNOW BANDS SET UP...BUT GIVEN THE DURATION OF THE

FAVORED FETCH...PORTIONS OF PORTER COUNTY COULD SEE AMOUNTS IN

EXCESS OF 20 INCHES.

FINALLY...TEMPERATURES WILL BE A CONCERN. AS THE ARCTIC HIGH

PRESSURE BUILDS EWD...AIR TEMPERATURES SHOULD DROP BELOW ZERO FOR

LOCATIONS AWAY FROM LAKE MICHIGAN AND THE LAKE EFFECT SNOW REGION.

TEMPERATURES SHOULD REMAIN BITTERLY COLD WELL INTO MID WEEK. WHILE

THE STRONG WINDS ARE STILL IN PLACE MONDAY AND TUESDAY...THERE

WILL LIKELY BE PERIODS WHERE THE WIND CHILL READING WILL DROP

BELOW -20F.

KREIN

The NAM absolutely destroys us...D-E-S-T-R-O-Y-S us...

[cyclone77]

New Rochester, MN nws forecast says 13-20 inches. It's amazing how easily it seems to be for a lot of areas across this region to get more than a foot of snow while Cedar Rapids has NEVER officially had a foot from any storm.

You're not gonna want to look at this. Dry slot of death FTL. This model says up to 12hrs in the dry slot, and then a brief period of snow tomorrow morning....

http://www.emc.ncep.noaa.gov/mmb/mpyle/cent4km/conus/12/

[snowstormcanuck]

New Rochester, MN nws forecast says 13-20 inches. It's amazing how easily it seems to be for a lot of areas across this region to get more than a foot of snow while Cedar Rapids has NEVER officially had a foot from any storm.

Is that a foot in a calendar day, or a storm total of a foot? If it's the latter, that's truly remarkable. How far do the records there go back?

[csnavywx]

You're not gonna want to look at this. Dry slot of death FTL. This model says up to 12hrs in the dry slot, and then a brief period of snow tomorrow morning....

http://www.emc.ncep....nt4km/conus/12/

Yeah, saw that, big pockets of dry air rotating around the north side of the low that cut into the deformation snows too. In fact, it suggests it may take a while to re-saturate the column enough to even get some light snows going again. I can say one thing since living up here, dry slots almost always over-perform. Am beginning to think I'm gonna be lucky to get more than an inch off this system, especially with the rather anemic precip signature over the northern half of the state so far.

[hawkeye_wx]

You're not gonna want to look at this. Dry slot of death FTL. This model says up to 12hrs in the dry slot, and then a brief period of snow tomorrow morning....

http://www.emc.ncep....nt4km/conus/12/

Yeah, that's why I think the nws is way overdoing our snow forecast. It's very possible we just get an inch or two as a weakening deformation band swings through overnight. It's just not much of a December for central and southern Iowa.

[hawkeye_wx]

Is that a foot in a calendar day, or a storm total of a foot? If it's the latter, that's truly remarkable. How far do the records there go back?

I think that is storm total. Records probably go back 100+ years.

Edit: I just found a site online that says Cedar Rapids got almost 20 inches over a three-day period in 1951, but I don't know if that was multiple storms or just one long one.

[cyclone77]

Yeah, saw that, big pockets of dry air rotating around the north side of the low that cut into the deformation snows too. In fact, it suggests it may take a while to re-saturate the column enough to even get some light snows going again. I can say one thing since living up here, dry slots almost always over-perform. Am beginning to think I'm gonna be lucky to get more than an inch off this system, especially with the rather anemic precip signature over the northern half of the state so far.

Yeah these dry slot intrusions can be very frustrating sometimes. The sad thing is the H7 low is tracking far enough south you'd think we'd be almost perfectly inline for some good snows. This storm just wraps up so much that, like you said, slings dry air around the north side of it.

I still think the blizzard criteria will be met over eastern Iowa and northern Illinois, even with the anemic snowfall amounts. One or two inches of snow doesn't sound like much, but with the slick glacier surface underneath from the previous snow it will become airborne very easily.

[turtlehurricane]

Up to 35.6 °F on top of the wx building, but temps is leveling off now. Plenty of melting on the ground, but snowpack is nowhere near about to go away. GFS and NAM both say the storm really starts around 7-10 pm.

So we got ourselves another night winter storm afterall, seems like the biggest wx events always happen at night.

[janetjanet998]

MSP metro getting hammered

8-12 inches down already

calling for 12-15 may have to up

[The_Global_Warmer]

You're not gonna want to look at this. Dry slot of death FTL. This model says up to 12hrs in the dry slot, and then a brief period of snow tomorrow morning....

http://www.emc.ncep....nt4km/conus/12/

That model gives me 3-4 inches tomorrow.

model consensus is for 2-3 inches now, some 3-4.

also ratios will be great, I guess the local offices think it will be much drier here.

[baroclinic_instability]

The values of frontogenesis are rather outlandish, to say the least. I have never seen anything like these.