Dec 11-13 MW/Lakes/OV Snow Event? Part III

[Hoosier]

I think 2-4" is a safe call.. Though I wouldn't be surprised at a few locations getting 5 or 6 by the end..

I'm really gonna be interested to see what happens with the lake effect. Somebody especially in the eastern part of the IND cwa could make out fairly well by local standards.

[KokomoWX]

I made a map earlier for my blog.

[A-L-E-K]

Baroclinic is making a strong case for the solution north of Illinois.

[csnavywx]

Keep watching the advancement of the cA airmass/front, as this will ultimately determine how far south she goes. Like I said yesterday, always tricky business around these suckers, and they're prone to ruining forecasts.

[dilly84]

euro looks a lot closer to the ukie now at 500. still about 100 miles north with the closed contour

hey didnt get to see the 12z ukie, is it still a blizzard for us? lol

[daddylonglegs]

Warmest day so far this month...

[Harry]

Keep watching the advancement of the cA airmass/front, as this will ultimately determine how far south she goes. Like I said yesterday, always tricky business around these suckers, and they're prone to ruining forecasts.

Kinda wish you would chime in more.

[A-L-E-K]

Debating between 1-3 and 2-4 for me. Given track uncertainty and exact positioning of deformation band, was tempted to lean lower but will go 2-4" as potential for combination of brief changeover prior to dryslot and then more snow wrapping around. The earlier thought of 10-15" up north might actually prove to be slightly conservative if trends continue.

Our calls are pretty close

[mnchaser]

MPX is expected to upgrade to a blizzard warning for much of the area this afternoon...according to some of the mets I've heard from.

09z SREF

[Chicago Storm]

[MadTown]

anyone have any idea what madison is looking at....sorry

[A-L-E-K]

The wind fields are making the NAM look pretty good right now.

[daddylonglegs]

Madtown-

I know the feeling. I have no idea what to expect here. It looks iffy... lots of sleet?

[jbcmh81]

The wind fields are making the NAM look pretty good right now.

NAM gave me 6-8". I'd be fine with it.

[A-L-E-K]

Snow pack erosion on the western fringe

[The_Global_Warmer]

The 18z RUC has the SLP in the same position as the 15z RUC.

but is sharper and digging more with the UL in the plains..also faster with the cold air at the surface and 850mb

[daddylonglegs]

MSP

SYNOPSIS...STRONG 160 KT UPPER LEVEL JET WILL MOVE INTO WESTERN

WY BY LATE THIS MORNING. THIS IS THE DRIVING FORCE FOR BUCKLING

OUR FAST-PACED FLOW OVER THE AREA INTO A DEEP LONGWAVE TROUGH

ACROSS THE EAST AND FRIGID AIR INTO THE FIRST HALF OF NEXT WEEK.

THE MAIN SHORT WAVE/MID-LEVEL LOW PRESSURE WILL DROP SOUTHEAST

INTO SOUTHWEST MN BY SATURDAY MORNING AND DEEPEN AS IT DOES.

SURFACE CYCLOGENESIS WILL OCCUR IN THE CENTRAL PLAINS AND EVOLVE

EASTWARD. AS THE JET STRENGTH INCREASES AND SOME INTERACTION

OCCURS WITH A SOUTHERN STREAM WEAKER LOW...THE SYSTEM REALLY

BECOMES AN OVERALL VERY WELL-DEFINED CYCLONE NEAR SOUTHEAST MN BY

LATE SATURDAY MORNING. THE CLASSIFICATION OF SUCH A PATH AND

MAGNITUDE MAKE IT MAINLY A COLORADO TYPE LOW WITH SOME ELEMENTS OF

A CLIPPER LOW.

NUMERICAL GUIDANCE PREFERENCE...CONFERENCE CALL THIS MORNING WITH

HPC AND SURROUNDING WFOS PREFERRED THE EC AND SREF. THE SREF MAINLY

BECAUSE THERE STILL IS LARGE SPREAD IN MESOSCALE FORCING

PARAMETERS...AND AN ENSEMBLE HELPS TO CAPTURE SOME OF THAT. THE

NAM AND GFS HAVE DIFFERED GREATLY IN SPEED AND A SLOWER NAM

SOLUTION IS ALSO PREFERRED...WHICH IS NOT TOO FAR FROM THE 00Z EC.

HPC SNOWFALL AMOUNTS WERE ALSO UTILIZED FOR INITIAL LARGE SCALE

BLEND INTO GOING FORECAST. CIPS ANALOG GUIDANCE REVEALS A WINTER

EVENT CASE ON FEB 27TH 2009 THAT SEEMS TO MATCH IN MANY OF THE

MASS FIELDS WELL...AND HAVE INCORPORATED THIS INTO FORECAST

REASONING.

TONIGHT...HAVE SPED UP THE BEGINNING TIME OF HIGHEST POPS WITHIN

THIS PERIOD AND BOOSTED SNOW AMOUNTS. THE PV ANOMALY ASSOCIATED

WITH THE UPPER LEVEL WAVE WILL ADVECT INTO THE AREA THROUGH THE

EVENING AND REALLY WIND UP LATE IN THE NIGHT. WARM AIR ADVECTION

AHEAD OF THIS INCREASES WITH LARGE SCALE OMEGA ACROSS MUCH OF MN

BY 03-06Z THIS EVENING AND THE ENTIRE AREA OVERNIGHT. CONVERGENCE

ALONG THE LEADING EDGE OF THE WARM ADVECTION LINES UP WELL WITH

THE MID-LEVEL TEMPERATURE GRADIENT...AND SHOULD BE A PARTICULAR

FOCUS FOR MODERATE SNOWFALL ACROSS MUCH OF CENTRAL MN AND INTO

WESTERN WI. MIXING RATIOS ADVECTING IN ON THE 285-295K LAYER ARE

3-4 G/KG FROM 03Z TO 12Z. SO SNOWFALL AMOUNTS OF 3 TO 6 INCHES ARE

LIKELY BY MORNING ACROSS A LARGE PORTION OF THE FORECAST AREA. THE

EXCEPTION IS SOUTH CENTRAL MN WHERE THE THERMAL PROFILE ON BUFR

SOUNDINGS REVEALS A WARM LAYER OF -2C TO +2C DEEP ENOUGH TO

SUPPORT FULL MELTING. SURFACE TEMPERATURES MAY TOP FREEZING NEAR

ALBERT LEA LATE TONIGHT WITHIN THE BOUNDARY LAYER WARM ADVECTION

AHEAD OF THE LOW. BUT EVEN WITH THAT SAID...FREEZING

RAIN...POSSIBLY ICE PELLETS TO THE NORTH OF THAT...LOOK LIKELY AT

TIMES. IT IS POSSIBLE FOR SNOW AT FIRST TO CHANGE TO PELLETS OR

EVEN FREEZING RAIN OVERNIGHT GIVEN THE STRENGTH OF THE ADVECTION.

UP TO A TENTH OF AN INCH...MAYBE SLIGHTLY MORE OF ICE ACCUMULATION

IS EXPECTED. SREF DOMINANT PRECIP TYPES AND THE CIPS ANALOG CASE

MENTIONED ABOVE BOTH FAVOR SOME TYPE OF TRANSITIONAL PRECIPITATION

NEAR INTERSTATE 90...AND POSSIBLY A COUPLE TIERS OF COUNTIES TO

THE NORTH.

SATURDAY...IMPRESSIVE DEEPENING OF THE SYSTEM OCCURS DURING THIS

TIME WITH STRONG COLD AIR ADVECTION IN THE LOW LEVELS AND

DEFORMATION ALOFT. DENDRITIC GROWTH IS REALLY FAVORED IN THIS

DEFORMATION ACROSS WESTERN WI AND EASTERN MN DURING SATURDAY

MORNING AND EARLY AFTERNOON. BANDED POTENTIAL WILL EXIST IN THIS

AREA AND THERE IS LIKELY TO BE A FEW HEAVIER BANDS. TOUGH TO

PINPOINT FOR SURE AT THIS TIME. BUT GENERAL SNOWFALL AMOUNTS OF 4

TO 6 INCHES ALONE ON SATURDAY MORNING ARE LIKELY IN THAT AREA

INCLUDING THE TWIN CITIES. TRANSITIONING FROM WEST TO EAST WILL

BE THE COLD AIR ADVECTION CAUSING SURFACE TEMPERATURE DROPS OF 15

DEGREES IN 2-3 HOUR SPANS. WINDS AT THE TOP OF THE BOUNDARY LAYER

ARE FORECAST BETWEEN 35 AND 45 KTS ACROSS SOUTHWEST AND SOUTH

CENTRAL MN. THIS WILL RESULT IN GUSTS UP TO THIS STRENGTH...WHICH

WILL CERTAINLY CAUSE BLOWING SNOW ISSUES. WHILE THE SURFACE LOW

STRENGTH IS A LITTLE HIGH FOR BLIZZARD CONDITIONS SEEN IN THIS

REGION...THE COLD AIR ADVECTION...WINDS...AND HEIGHT FALLS AT 850

MB ALL ARE IN BETTER AGREEMENT. THE CONCERN THOUGH IS JUST HOW

MUCH NEW SNOW WILL FALL IN THIS AREA GIVEN THE WARM AIR ALOFT

TONIGHT AND HOW FAR BACK AROUND THE SYSTEM THAT THE TROWAL AND

DEFORMATION WILL REACH FOR NEW SNOW. SO AT THIS TIME HAVE

COORDINATED TO GO AHEAD WITH WINTER STORM WARNING GIVEN SOME ICE

TONIGHT AND FOR SURE BLOWING SNOW...AND FUTURE SHIFTS WILL MONITOR

IF BLIZZARD WARNING IS NEEDED. WILL MENTION NEAR-BLIZZARD

CONDITIONS IN WARNING. TEMPERATURES WILL DROP QUICKLY BELOW ZERO

ACROSS THE WEST BY EVENING AND FURTHER EAST OVERNIGHT WITH WIND

CHILLS OF 20 TO 35 BELOW ALMOST A DEFINITE NOW. SO TRANSITION TO

WIND CHILL HEADLINES LATER IN THIS EVENT WOULD SEEM

LIKELY...DEPENDING ON HOW LONG BLOWING SNOW LASTS.

SNOWFALL CONFIDENCE...TOTAL SNOWFALL AMOUNTS BETWEEN 8 AND 13

INCHES ARE FORECAST FOR WESTERN WI...7 TO 11 FOR EASTERN MN...AND

TAPERING BACK WEST AND SOUTH OF THERE TO 4 TO 7. CONFIDENCE IN

GETTING TO THESE AMOUNTS IN EASTERN MN AND WESTERN WI HAS REALLY

INCREASED. THE LOWEST CONFIDENCE IN SOUTHWEST AND SOUTH CENTRAL

MN. AMOUNTS OF ONLY A COUPLE INCHES ARE POSSIBLE...YET AS HIGH AS

6 TO 8 INCHES IF BANDS CAN WRAP THAT FAR AROUND THE SYSTEM ON

SATURDAY. HPC AND NAM COBB DATA ARE BOTH FAIRLY CLOSE TO GOING

FORECAST ON A LARGE SCALE.

[A-L-E-K]

Battle zone taking shape

[prinsburg_wx]

FWIW...15Z sref mean still taking track across n ia at 24 to extreme se wi at 36

[A-L-E-K]

FWIW...15Z sref mean still taking track across n ia at 24 to extreme se wi at 36

sounds like my guess for low track towards Kenosha

[OceanStWx]

This is really starting to look like an impressive wind producer here for DVN. This kind of rapid cyclogenesis going on, the isallobaric component, all points towards some impressive sustained speeds/gusts. Any amount of snowfall coupled with that is going to create near white out conditions.

[WxMidwest]

This is really starting to look like an impressive wind producer here for DVN. This kind of rapid cyclogenesis going on, the isallobaric component, all points towards some impressive sustained speeds/gusts. Any amount of snowfall coupled with that is going to create near white out conditions.

Blizzard Watches? What do you think for LSE?

[OceanStWx]

Blizzard Watches? What do you think for LSE?

I can't say right now, we're in the midst of discussions right now.

[jbcmh81]

I can't say right now, we're in the midst of discussions right now.

You can tell me, I'm a doctor.

[A-L-E-K]

18z NAM slightly weaker

[Chicago WX]

You can tell me, I'm a doctor.

No. I mean I'm not sure.

Sorry bad Airplane lingo. Back to work.

[The_Global_Warmer]

18z nam is going to dig further south

[michsnowfreak]

looking at the hourly precip-type on the GEM, looks like by the time the precip gets here to SE MI, rain will be VERY brief, before becoming all snow. Yet areas to my west will stay rain a little longer (though most of lower MI still gets decent snow per this model). Very weird, but I guess with this storm who knows.

http://collaboration.cmc.ec.gc.ca/cmc/cmdn/pcpn_type/pcpn_type_gem_reg.html

[Chicago Storm]

18z nam is going to dig further south

FWIW...SLP is a bit further south.

[Chinook]

Here is what I sent to my family in Toledo

Sunday, a low pressure area will track through Michigan, and there will be a period of rain, and then 3-6" of snow for Toledo (possibly on the low side), with windy conditions and temperatures dropping into the teens. As the low pressure moves east, the winds will pick up and be 30 to 40mph, making wind chills -5 to 0 degrees, assuming 16 degrees and a 27 mph wind. The wind chills will be somewhat worse than the previous few days for you guys.