Major LES Event

[TheWeatherPimp]

I figured I would get a topic started for the upcoming LES event beginning Sunday and continuing into Tuesday. With this storm system wrapping up across the NE US, extremely strong low level winds should cause some crazy LES bands to form and possibly penetrate pretty far inland. This definitely has major event written all over it.

[TheWeatherPimp]

From IWX:

REGARDLESS OF WHICH SOLUTION COMES TRUE IN THE

MODELS (NORTHERN LOW VS EAST COAST STORM) NORTH TO NORTHWEST FLOW

WILL SETUP ACROSS THE GREAT LAKES ONCE AGAIN. THIS WILL RESULT IN AN

INCREASED THREAT FOR LAKE EFFECT SNOWS FOR A PROLONGED PERIOD. WHILE

LITTLE CONFIDENCE CAN BE GAINED FROM COARSER MED RANGE

MODELS...HINTS OF ANOTHER LAKE SUPERIOR CONNECTION DO EXIST WHICH

COULD RESULT IN POTENTIAL HEADLINES FOR THE LAKE EFFECT.

[TheWeatherPimp]

[ArmyGreens]

Wow! This past week I was impressed with the snow we got from L Mich...but this could be interesting!

[Hoosier]

I think the only thing that could mitigate this to some extent would be the strength of the low level wind field. Right now, the NAM is progging 925 mb winds in excess of 40 knots in the area (at least for a while). That being said, even if band organization isn't totally optimal, almost everything else looks favorable at this point and suggestive of a potentially large event. Areas well inland that are less accustomed to significant lake effect snow accumulations look to be at risk with this type of setup.

[KeenerWx]

This is a situation where a large area will see moderate lake snow accumulations. Significant accumulations will likely be displaced from the lake about 30-50 miles. I don't think this will be a blockbuster event, though.

[IWXwx]

This is a situation where a large area will see moderate lake snow accumulations. Significant accumulations will likely be displaced from the lake about 30-50 miles. I don't think this will be a blockbuster event, though.

Maybe not blockbuster, but it could be a significant event. It would be a consolation after being in the bullseye for some good synoptic snow a few days ago that didn't pan out. If it turns out to be a good event, I might grab my camera and go for a drive.

[Chagrin Falls]

CLE:

THE FLOW IN THE COLD AIR ADVECTION LOOKS LIKE IT WILL SET UP MUCH

LIKE IT DID THIS PAST WEEK AND PRODUCE AN EXTENDED PERIOD OF

SIGNIFICANT LAKE EFFECT SNOW. THE WORST OF IT WILL LIKELY ARRIVE

LATE SUNDAY NIGHT INTO MONDAY MORNING MAKING FOR A DIFFICULT MORNING

COMMUTE. MODEL SOUNDINGS SUGGEST THE BEST SNOW GROWTH SETTLES RIGHT

DOWN INTO THE HIGHEST MEAN RELATIVE HUMIDITY AND BEST UPWARD

VERTICAL MOTION. INVERSION HANGS AROUND 10K FEET SUNDAY NIGHT INTO

TUESDAY. INSTABILITY THIS GO AROUND WILL BE MUCH GREATER THAN THIS

PAST WEEK DUE TO THE MUCH COLDER AIR OVER THE WARM WATER OF THE

LAKE. I ANTICIPATE WE COULD MATCH OR EVEN EXCEED SNOW ACCUMULATIONS

OF THIS PAST WEEK WITH THIS EVENT.

I think Burton in Geauga County had the most snowfall with this week's lake event, about 39". CLE is thinking the new event could exceed that, and I agree.

Northeast Ohio is in a cyclonic flow all of next week. The ridge axis never passes overhead as the coastal low remains quasi-stationary across

New England the Maritimes. As the low begins to weaken mid week the pressure gradient will reduce but the cold air will remain. Lake temp to 850 hPa lapse

rates could easily exceed 20°C meaning the thermal gradient over the lake will be very, very unstable.

Someone is going to get nailed and nailed good.

[TheWeatherPimp]

IWX WRF:

[Indystorm]

I am expecting to get really smacked by the LES event here in the Elkhart area even if the system snow is not that much.

[NEOH]

CLE:

THE FLOW IN THE COLD AIR ADVECTION LOOKS LIKE IT WILL SET UP MUCH

LIKE IT DID THIS PAST WEEK AND PRODUCE AN EXTENDED PERIOD OF

SIGNIFICANT LAKE EFFECT SNOW. THE WORST OF IT WILL LIKELY ARRIVE

LATE SUNDAY NIGHT INTO MONDAY MORNING MAKING FOR A DIFFICULT MORNING

COMMUTE. MODEL SOUNDINGS SUGGEST THE BEST SNOW GROWTH SETTLES RIGHT

DOWN INTO THE HIGHEST MEAN RELATIVE HUMIDITY AND BEST UPWARD

VERTICAL MOTION. INVERSION HANGS AROUND 10K FEET SUNDAY NIGHT INTO

TUESDAY. INSTABILITY THIS GO AROUND WILL BE MUCH GREATER THAN THIS

PAST WEEK DUE TO THE MUCH COLDER AIR OVER THE WARM WATER OF THE

LAKE. I ANTICIPATE WE COULD MATCH OR EVEN EXCEED SNOW ACCUMULATIONS

OF THIS PAST WEEK WITH THIS EVENT.

I think Burton in Geauga County had the most snowfall with this week's lake event, about 39". CLE is thinking the new event could exceed that, and I agree.

Northeast Ohio is in a cyclonic flow all of next week. The ridge axis never passes overhead as the coastal low remains quasi-stationary across

New England the Maritimes. As the low begins to weaken mid week the pressure gradient will reduce but the cold air will remain. Lake temp to 850 hPa lapse

rates could easily exceed 20°C meaning the thermal gradient over the lake will be very, very unstable.

Someone is going to get nailed and nailed good.

My biggest concern is the wind speed which is going to greatly reduce residence time over the lake and affect band development. Lake MI areas will probably due well as the fetch is much longer.

For those of us that don't have a long fetch, it appears an upstream connection will be necessary for significant snow. The far inland areas should do well again. But again, I think wind speed will be the limiting factor.

[ArmyGreens]

IWX WRF:

Almost identical to the setup for us north and west of columbus this past week, except colder and windier.

[Chagrin Falls]

My biggest concern is the wind speed which is going to greatly reduce residence time over the lake and affect band development. Lake MI areas will probably due well as the fetch is much longer.

For those of us that don't have a long fetch, it appears an upstream connection will be necessary for significant snow. The far inland areas should do well again. But again, I think wind speed will be the limiting factor.

I agree with you NEOH, however I think as the week progresses the deep quasi-stationary low in the Maritimes will fill in and the ridge to our west will weaken, this each day should see less and less wind. Perhaps as the week progresses conditions will become more favorable for significant lake effect snow, similar to the event this week?

Here is some ECMWF Ensemble data (0Z) from the 850 hPa level for Cleveland:

Saturday evening: Temp: 0°C Wind speed: 38 mph

Sunday evening: Temp: -8°C Wind speed: 38 mph

Monday evening: Temp -18°C Wind speed: 40 mph

Tuesday evening: Temp: -16°C Wind speed: 34 mph

Wednesday evening: Temp: -12°C Wind speed: 31 mph

Thursday evening: Temp: -5°C Wind speed: 20 mph

The heavy snow band in CLE a couple days ago occurred with a 850 hPa wind speed of about 23 mph, so yes this time winds will be stronger, but the air is just so cold. And I'm thinking day after day of onshore winds, very unstable air and cyclonic flow at some point the conditions will be ripe for a big snow.

[ValpoVike]

I agree with you NEOH, however I think as the week progresses the deep quasi-stationary low in the Maritimes will fill in and the ridge to our west will weaken, this each day should see less and less wind. Perhaps as the week progresses conditions will become more favorable for significant lake effect snow, similar to the event this week?

Here is some ECMWF Ensemble data (0Z) from the 850 hPa level for Cleveland:

Saturday evening: Temp: 0°C Wind speed: 38 mph

Sunday evening: Temp: -8°C Wind speed: 38 mph

Monday evening: Temp -18°C Wind speed: 40 mph

Tuesday evening: Temp: -16°C Wind speed: 34 mph

Wednesday evening: Temp: -12°C Wind speed: 31 mph

Thursday evening: Temp: -5°C Wind speed: 20 mph

The heavy snow band in CLE a couple days ago occurred with a 850 hPa wind speed of about 23 mph, so yes this time winds will be stronger, but the air is just so cold. And I'm thinking day after day of onshore winds, very unstable air and cyclonic flow at some point the conditions will be ripe for a big snow.

It appears NE Ohio will get some help from Lake Huron as well, which should negate some of the wind speed concerns.

I lived in Chardon for 7 years, and boy do I miss it. Folks around here just *think* they live in a snow belt

[NEOH]

I agree with you NEOH, however I think as the week progresses the deep quasi-stationary low in the Maritimes will fill in and the ridge to our west will weaken, this each day should see less and less wind. Perhaps as the week progresses conditions will become more favorable for significant lake effect snow, similar to the event this week?

Here is some ECMWF Ensemble data (0Z) from the 850 hPa level for Cleveland:

Saturday evening: Temp: 0°C Wind speed: 38 mph

Sunday evening: Temp: -8°C Wind speed: 38 mph

Monday evening: Temp -18°C Wind speed: 40 mph

Tuesday evening: Temp: -16°C Wind speed: 34 mph

Wednesday evening: Temp: -12°C Wind speed: 31 mph

Thursday evening: Temp: -5°C Wind speed: 20 mph

The heavy snow band in CLE a couple days ago occurred with a 850 hPa wind speed of about 23 mph, so yes this time winds will be stronger, but the air is just so cold. And I'm thinking day after day of onshore winds, very unstable air and cyclonic flow at some point the conditions will be ripe for a big snow.

It may be a situation similar to this week. The low track is the biggest variable at this point. Looking at BUFKIT (data from todays model runs), winds don't come around to more than 310... so lake huron is out of the mix for now. L Huron will only come into play when the winds are roughly 340 and higher. If the low tracks over lake erie the heaviest snows would likely fall immediately behind the low as we would benefit from a due north wind for awhile, with alot of lake enhacement in the wrap around snows.

Lake temps have dropped dramatically, so the colder 850's for the upcoming event will create about the same instability as what we saw this week. That said, good moisture and a cyclonic flow can offset the negatives.

[NEOH]

It appears NE Ohio will get some help from Lake Huron as well, which should negate some of the wind speed concerns.

I lived in Chardon for 7 years, and boy do I miss it. Folks around here just *think* they live in a snow belt

Chardon is a whole different world when it comes to snowfall. Nothing compares in NE OH to that area. Sorry you had to leave.

[KeenerWx]

NAM is going absolutely bonkers with the lake effect snow...

SW Michigan is going to have quite the December.

[OHSnow]

I don't see this being as big of an event as it's being hyped, these high winds are going to screw everything up. Lake effect seems to do best with a light to moderate flow.

[Chagrin Falls]

I don't think I've ever seen "100% Heavy snow" graphics in the pinpoint forecasts more than 48 hours out.

[TheWeatherPimp]

The way things are going, it isn't out of the question that ILN and IND might see advisory criteria across portions of their CWA for pure lake-effect snow. Could be interesting.

[Hoosier]

The way things are going, it isn't out of the question that ILN and IND might see advisory criteria across portions of their CWA for pure lake-effect snow. Could be interesting.

The NAM omega plume looks really impressive...it goes way inland.

[KeenerWx]

Wasn't sure where to put this, because it kind-of deals with both the system snow and the lake effect portion, but nonetheless here's the IWX AFD. It would be cool to have it in both, as it's interesting to look back at this stuff (and wrt to Lake Effect, you wouldn't have to thread through 30+ pages). So, I posted it in the other thread as well that deals with the main system.

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE NORTHERN INDIANA

447 AM EST SAT DEC 11 2010

SHORT TERM

DYNAMIC AND VRY COMPLEX WINTER STORM TO WREAK HAVOC ACROSS THE AREA

THIS WEEKEND.

OF NOTE IS ABRUPT SWD SHIFT SEEN IN ALL NCEP BASED 00Z MODEL

GUIDANCE. THIS ALIGNS MUCH BTR W/HEDGE PREFERENCE FM YDA FOLLOWING

GEM/UKMET BLEND AND LENDS GREATER CONFIDENCE GOING FORWARD ESP

W/NECESSITATED CHGS. WILL EXPAND ERN/SWRN EXTENT OF EXISTING WATCH

AND BACK START TIME TO 12Z SUN. WATER VAPOR THIS MORNING CLEARLY

CONFIRMS PRIOR GUIDANCE DISMAL HANDLING OF STG SW TROUGH DIGGING

SEWD THROUGH SRN NE THIS MORNING AND ALREADY SOUTH OF MANY 06Z MODEL

PROJECTIONS. 00Z CONSENSUS TURNED ABRUPTLY SOUTH AND HAVE CAUGHT ON

ALTHOUGH DOUBT ANY PARTICULAR PIECE OF MODEL BASED GUIDANCE OFFERS A

CONCRETE SOLUTION YET AS SWD DISPLACEMENT HAS PROBABLY NOT RUN ITS

FULL COURSE YET. THAT SAID...SWD SHIFT IN STG MID LVL DEFORMATION

ZONE XPCD AND MORE ACCURATELY PORTRAYED IN 00Z GEM FOLLOWED BY 03Z

SREF AND 00Z GEFS WHICH TAKE RAPIDLY DEEPENING SFC CYCLONE OVR NW IA

SEWD INTO WRN IN NR KLAF W/SECONDARY SFC DVLPMNT LT TONIGHT NR KJKL

THEN TURNS NWD TWD KCLE SUN AFTN. THIS WOULD PLACE MUCH OF CWA

SQUARELY WITHIN IMPRESSIVE TROWAL W/SIG SNOW ACCUMULATIONS SUN AND

SUN NIGHT. PROXIMITY OF 00Z MODEL BASED MID LVL DRY SLOT CONCERNING

BUT AGAIN GIVEN OBVIOUS ACROSS THE BOARD MODEL TREND FEEL QUITE

COMFORTABLE W/WATCH EXTENSION AND DAYSHIFT MAY NEED TO EXPAND

FURTHER TO ENCOMPASS NW OH.

CHG OVR THIS EVENING COMPLICATED W/ANOMALOUSLY STG WAA PUSH HWVR

VARIETY OF POINT SNDGS KEY IN ON SIG ADIABATIC ADJUSTMENT IN 03-06Z

TIMEFRAME COINCIDENT W/ARRIVAL OF DEEP LYRD ASCENT PLUME AND XPC A

RAPID CHANGE OVER W/ALL SNOW BY 06Z. AFT THAT...FCST BOILS DOWN TO

PLACEMENT OF STG MID LVL DEFORMATION ZONE AND HOW CLOSED MID LVL

TROUGH PIVOTS NORTH OUT OF THE OH VALLEY W/CONSENSUS BASICALLY

DUMBBELLING MID LVL TROUGH ARND CWA W/A PROLONGED PD OF MOD-HVY SNOW

ESP NORTH HALF AND RAPIDLY INCREASING GRADIENT FLW SUN AFTN BASED ON

CURRENT GUIDANCE SUITE AND THUS THE REASONING FOR WATCH EXPANSION.

MORE COMPLICATING FCTR LIES W/PLACEMENT OF LIKELY EXTREME LK

ENHANCED SNOW BAND W/BLEND OF HIGHRES GUIDANCE SLWR IN DVLPG INTENSE

SINGLE BAND SUN EVE AND THEN SLOWLY PIVOTING THIS EWD MON. EQL HGTS

NOTED NR 10 KFT AND LIKELY SEEDER-FEEDER MECHANISM ALOFT STILL IN

PLACE SUGGEST ADDNL SWD EXPANSION TO INCLUDE WHITE/CASS/AND MIAMI

COUNTIES PSBL BUT THIS IS QUITE RARE AND NOT INCLINED TO PUSH IT

THAT FAR SOUTH. OTHERWISE EWD PROGRESSION OF LK EFFECT HOLDS W/PRIOR

INITIAL WATCH YET DID EXTEND THROUGH 06Z TUE W/NEWER 06Z GUIDANCE

KEEPING THE ERN BAND W/LK SUPERIOR CONNECTION GOING WELL INTO TUE

AFTN AS INVERSION HGTS SLOW TO DROP GIVEN DOWNSTREAM BLOCKING

HOLDING FIRM AND DEEP MID LVL TROUGH STILL EXTENDING WWD THROUGH THE

LAKES. QPF GRIDS WEIGHTED TWD SYNOPTIC EVENT W/POTENTIAL LK EFFECT

CONTRIBUTION HEAVILY CONSERVED AS SOMEWHAT WAVERING PLACEMENT OF

BAND AND MORE IMPORTANTLY DURATION AS YET MOST UNCERTAIN AND TIED

DIRECTLY W/PLACEMENT OF MID LVL TROUGH AXIS AND TRACK/INTENSITY OF

SFC CYCLONE. NEVER THE LESS...SOME HIGHRES BASED GUIDANCE SUGGESTS

STORM TOTAL SNOW ACCUMULATIONS APCHG 30 INCHES OVR

LAPORTE/BERRIEN/ST JOE COUNTIES.

[KeenerWx]

Goodness, if only finals weren't this week, I would DEFINITELY make the chase. Boy, a forecast like this is to die for. INZ003>005-014-016-MIZ077-078-111900-

/O.EXT.KIWX.WS.A.0004.101212T1200Z-101214T0600Z/

LA PORTE-ST. JOSEPH IN-ELKHART-MARSHALL-KOSCIUSKO-BERRIEN-CASS MI-

INCLUDING THE CITIES OF...MICHIGAN CITY...LA PORTE...SOUTH BEND...

MISHAWAKA...NEW CARLISLE...WALKERTON...ELKHART...GOSHEN...

NAPPANEE...PLYMOUTH...BREMEN...CULVER...WARSAW...WINONA LAKE...

SYRACUSE...MENTONE...NILES...BENTON HARBOR...ST. JOSEPH...

BUCHANAN...DOWAGIAC...CASSOPOLIS...MARCELLUS

510 AM EST SAT DEC 11 2010 /410 AM CST SAT DEC 11 2010/

...WINTER STORM WATCH NOW IN EFFECT FROM SUNDAY MORNING THROUGH

LATE MONDAY NIGHT...

THE WINTER STORM WATCH IS NOW IN EFFECT FROM SUNDAY MORNING

THROUGH LATE MONDAY NIGHT.

* TIMING...PERIODS OF SNOW WILL TRANSITION TO SNOW SHOWERS BY

SUNDAY AFTERNOON ACROSS THE WATCH AREA. THE SNOW MAY BE HEAVY AT

TIMES SUNDAY THROUGH MONDAY NIGHT.

* MAIN IMPACT...TOTAL ACCUMULATIONS OF 10 TO 14 INCHES OF SNOW...

WITH LOCALLY HIGHER AMOUNTS OF 16 TO 20 INCHES CLOSER TO LAKE

MICHIGAN...ARE POSSIBLE IN SOME LOCATIONS. STRONG WINDS WILL

CAUSE WIDESPREAD BLOWING AND DRIFTING OF THE SNOW AND

SIGNIFICANTLY REDUCE VISIBILITIES.

* OTHER IMPACTS...MOTORISTS WILL LIKELY ENCOUNTER RAPIDLY

CHANGING CONDITIONS...WITH ROADS BEING SNOW COVERED...SLIPPERY

AND IN SOME AREAS IMPASSABLE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT

SNOW ACCUMULATIONS AS WELL AS BLOWING AND DRIFTING SNOW THAT MAY

IMPACT TRAVEL. CONTINUE TO MONITOR THE LATEST FORECASTS.

[janetjanet998]

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL

429 AM CST SAT DEC 11 2010

DISCUSSION

345 AM...

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.

[IWXwx]

Wasn't sure where to put this, because it kind-of deals with both the system snow and the lake effect portion, but nonetheless here's the IWX AFD. It would be cool to have it in both, as it's interesting to look back at this stuff (and wrt to Lake Effect, you wouldn't have to thread through 30+ pages). So, I posted it in the other thread as well that deals with the main system.

NEVER THE LESS...SOME HIGHRES BASED GUIDANCE SUGGESTS

STORM TOTAL SNOW ACCUMULATIONS APCHG 30 INCHES OVR

LAPORTE/BERRIEN/ST JOE COUNTIES.

Seriously considering making the drive.

[KeenerWx]

Seriously considering making the drive.

Don't get stuck...

I would do the same if it weren't for finals Monday, Tuesday, and Wednesday.

[Chagrin Falls]

BUF is almost always a good read:

OFF LAKE ERIE...MODELS SUGGEST A BRIEF PERIOD OF WSW FLOW FOR AWHILE

MONDAY AS THE COLDER AIR ARRIVES...WHICH MAY SUPPORT A PERIOD OF

LAKE ENHANCED SNOW ACROSS THE BUFFALO SOUTHTOWNS. LATER IN THE

AFTERNOON A SECONDARY TROUGH PASSAGE WILL QUICKLY SHIFT WINDS TO THE

NORTHWEST...PUSHING LAKE ENHANCEMENT INTO THE WESTERN SOUTHERN TIER

WHERE IT WILL REMAIN. UPSTREAM SUPPORT FROM LAKE HURON MAY BECOME

ESTABLISHED BY AFTERNOON ACROSS THE CHAUTAUQUA RIDGE WITH AN

INCREASING RISK OF LOCALLY HEAVY SNOWFALL THROUGH THE COURSE OF THE

DAY. BY MONDAY NIGHT NORTHWEST FLOW WILL BE WELL ESTABLISHED WITH

THE BEST HEAVY SNOW POTENTIAL APPEARING TO BE THE CHAUTAUQUA RIDGE

AND WESTERN CATTARAUGUS COUNTY GIVEN CURRENT BOUNDARY LAYER WIND

FORECAST.

[KeenerWx]

Interestingly enough, IWX stretches heavy snow accumulations all the way to Pulaski/Fulton County with 8-12" (locally higher).

[Hoosier]

Keener, you asked for my thoughts on LES. They're pretty much unchanged. The signal for extreme and rare inland penetration remains solid and I think we will see advisory type amounts all the way down to the Kokomo/Marion areas. Latest trends would even support some minor lake accumulations in LAF. Totals of 1-2 feet closer to the lake look pretty likely with isolated higher amounts possible.

[KeenerWx]

Keener, you asked for my thoughts on LES. They're pretty much unchanged. The signal for extreme and rare inland penetration remains solid and I think we will see advisory type amounts all the way down to the Kokomo/Marion areas. Latest trends would even support some minor lake accumulations in LAF. Totals of 1-2 feet closer to the lake look pretty likely with isolated higher amounts possible.

Yeah, latest trends want to keep the band in or near the extreme NW corner of Indiana (and points southward) for an extended period of time. Definitely believe Lafayette will get a little boost from this event.

The only thing keeping me from sounding the red flag is the flow strength (mentioned this in the other thread). With that said, I definitely think 1'+ across LaPorte/Berrien Counties. Everything else is a wildcard to me at this point, but the whole northern 1/3rd of Indiana looks to benefit from modest lake accumulations.