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February 25-27 Winter Storm Part 2


Chicago Storm

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Cool, wanted to gauge your thoughts right now. I assume more north and west of you?

 

Hopefully it overachieves for you. Good luck Mike. 

 

 

Yeah, I don't think I'll be in the bullseye. More to the NW. Only if somehow I manage to get completely below 32 at the surface for the entire event will some of those bigger numbers verify here. Not likely but not impossible.

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The afd just came out and it kinda contradicts what's in the zones.

 

lol, kind of a confusing forecast.

 

Tuesday: Breezy. Freezing rain and sleet...possibly mixed with rain until midday...then rain...possibly mixed with snow and sleet in the afternoon. No snow and sleet accumulation. Ice accumulation of one tenth to two tenths of an inch. Of one tenth to one quarter of an inch. Nearly steady temperatures in the mid 30s. East winds 15 to 20 mph with gusts to around 30 mph. Chance of precipitation near 100 percent.

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I hate buying into ice events when the days leading up are well above freezing and the temps during prime hours are at best right around freezing

 

anyways, rush hour crippler

 

The visibility alone with wind, will be enough to be a crippler.

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I agree, only because LOT is very difficult to change in their opinions. They may be right, but model runs suggest for the possibility of reaching warning criteria. Idk, it's an extremely difficult forecast to make.

 

 

warning criteria amounts still look to be the exception...go WWA and upgrade if radar trends look good.

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URGENT - WINTER WEATHER MESSAGE

NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI

353 PM EST MON FEB 25 2013

...A WINTER STORM TO AFFECT SOUTHEAST MICHIGAN TUESDAY AFTERNOON

THROUGH TUESDAY NIGHT...

.A LOW PRESSURE SYSTEM IS FORECAST TO DEEPEN OVER THE SOUTHERN

MISSISSIPPI VALLEY TONIGHT AND LIFT INTO THE OHIO VALLEY BY

TUESDAY NIGHT. AS THE SYSTEM APPROACHES...A PLUME OF DEEP MOISTURE

WILL STREAM ACROSS SOUTHERN MICHIGAN LATE TUESDAY AFTERNOON

THROUGH TUESDAY NIGHT. THE ATMOSPHERE IS EXPECTED TO BE COLD

ENOUGH TO SUSTAIN A BAND OF HEAVY SNOW WITHIN THIS MOISTURE PLUME.

CONSEQUENTLY...THE SNOW IS EXPECTED TO BE WET AND HEAVY IN NATURE.

HEAVY SNOW IS EXPECTED TO LIFT FROM SOUTH TO NORTH ACROSS THE AREA

DURING THE LATE AFTERNOON TUESDAY AND CONTINUE INTO TUESDAY NIGHT.

THERE IS THE POTENTIAL FOR 6 OR MORE INCHES OF HEAVY WET SNOW TO

ACCUMULATE ACROSS EASTERN PORTIONS OF SOUTHEAST MICHIGAN...WITH

LIGHTER AMOUNTS FARTHER WEST. SOME UNCERTAINTY REMAINS AS TO THE

OVERALL TRACK OF THIS STORM SYSTEM AND THE LOCATIONS WHICH WILL

RECEIVE THE MORE PROLONGED PERIOD OF HEAVY SNOW.

...WINTER STORM WATCH NOW IN EFFECT FROM TUESDAY AFTERNOON

THROUGH WEDNESDAY MORNING...

THE WINTER STORM WATCH IS NOW IN EFFECT FROM TUESDAY AFTERNOON

THROUGH WEDNESDAY MORNING.

HAZARDOUS WEATHER...

* THERE IS THE POTENTIAL FOR 6 OR MORE INCHES OF SNOW.

* SNOWFALL RATES MAY EXCEED AN INCH AN HOUR TUESDAY EVENING.

IMPACTS...

* RAPID SNOW ACCUMULATIONS AND POOR VISIBILITIES MAY LEAD TO

HAZARDOUS TRAVEL CONDITIONS.

* THE HEAVY WET SNOW MAY PUT STRESS ON TREES AND POWER LINES...

CAUSING SOME POWER OUTAGES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

* A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR

SIGNIFICANT SNOW THAT MAY IMPACT TRAVEL. CONTINUE TO MONITOR

THE LATEST FORECASTS.

* PREPARE...PLAN...AND STAY INFORMED. VISIT

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Bet the overnight crew cancels that...as stated is possible in their AFD. But better to be cautious I guess...

Gonna be close no matter what. 43 right now, you can thank late Feb sun for that but it still means that we have farther to drop to get AOB freezing. A couple positives are the early morning onset and E/NE flow in the lowest 100 mb or so which is not conducive to rapid warming.

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Even so, those are 6+ amounts in northwest Indiana that weren't there before. The axis of the heaviest snows in Chicagoland has shifted slightly southeast to now encompass those two Indiana counties (Porter and Lake I think?).

You are guys are gonna do super up there though. Take pictures please!!

 

I'll make sure to post pics of my mud tomorrow.

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MKX

 

TUESDAY NIGHT AND WEDNESDAY  FORECAST CONFIDENCE IS MEDIUM.     THE HEAVIEST BAND OF QPF/SNOW WILL ROLL THROUGH TUESDAY EVENING AS  THE MAIN DEEP FORCING WITH THE UPPER LOW MOVES IN. THE MODELS ARE  STILL SHOWING QUITE A BIT OF VARIABILITY ON QPF NUMBERS. THE  NAM/ECMWF KICK OUT ABOUT .7 TO .8 INCH LIQUID ACROSS KENOSHA COUNTY  BETWEEN 6PM TUE-NOON WED. ABOUT 1/10 INCH LESS IN MILWAUKEE...EVEN  LESS TOWARD SHEBOYGAN. THE GFS IS MORE ON THE ORDER OF    25-.35  QUITE A BIT LESS.    THE TRACK OF THE LOW HASN/T CHANGED SIGNIFICANTLY. THE MODELS ARE  JUST STRUGGLING WITH HOW MUCH MOISTURE WILL BE WRAPPING AROUND  THIS SYSTEM AS IT ARRIVES. ALSO...THE NAM STILL LOOKS LIKE  IT/S OVERDOING THE IMPACT OF THE LOW LEVEL OMEGA CAUSED BY THE  MECHANICAL FRICTIONAL CONVERGENCE ON THE WEST SHORE OF THE LAKE.  THE EXTRA QPF ACROSS THE SE IS NOT FROM TYPICAL LAKE EFFECT DUE TO  A BIG TEMP DIFFERENTIAL ACROSS THE WATER. WE DON/T HAVE THOSE  DELTA T/S IN THIS CASE. WE SHOULD SEE SOME ADDITIONAL QPF/SNOW  FROM THE EXTRA UPWARD VERTICAL MOTION...BUT NOT LIKELY WHAT THE  NAM DEPICTS.    CIPS ANALOGS CONTINUE TO LOOK UNIMPRESSIVE. THIS HAS BEEN THE CASE  FOR THE LAST FEW DAYS...THEY CONTINUE TO SHOW A SOLID 3 TO MAYBE 5  INCH EVENT.      BACK TO THE QPF. THOSE VALUES ARE IMPRESSIVE...BUT...THE ATMOSPHERE  WILL BE RATHER MILD WITH SNOW TO LIQUID RATIOS FOR THE INITIAL  HEAVIEST SNOW IN THE 7 OR 8 TO 1 RATIOS /MAYBE LOWER IF WE GET  MORE WARM AIR UP HERE LIKE TODAY/. AS THE COLUMN COOLS...THOSE  RATIOS WILL INCREASE...BUT THE PRECIP WILL BE DIMINISHING BY THAT  TIME.    SO...WILL CONTINUE THE WINTER WEATHER ADVISORY FOR THE FAR  SOUTHEAST. THERE/S A CHANCE IT MIGHT HAVE TO BE EXPANDED IF THE  QPF CONTINUES TO INCREASE. THE SNOW WILL CONTINUE INTO  WEDNESDAY...BUT BE RATHER LIGHT AND WITH TEMPS AT OR ABOVE  FREEZING...ROAD CONDITIONS SHOULD BE IN DECENT SHAPE. 
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fwiw I set the over/under at 2.3" (for no particular reason actually) and when I left the weather center it was roughly 2:1 over:under.

 

This looks like the kind of event where we either get an inch of slush, or hammered with 6-8", but in-between is almost impossible.  Obviously I'm leaning towards the former right now.

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afternoon package from LOT keeps watches in place for another forecast cycle.  Gino really deflating everyone's weenies by saying that convection will be required for snow to stick (not that I'm disagreeing with that, but it's still depressing to hear)

 

.DISCUSSION...
SHORT TERM (TONIGHT THROUGH THURSDAY)...
254 PM CST

HAVE OPTED TO LET THE WINTER STORM WATCH RIDE FOR ANOTHER
FORECAST CYCLE FOR TUESDAY AFTERNOON AND EVENING.

EXTRAORDINARILY CHALLENGING FORECAST TODAY ONLY COMPOUNDED BY MAJOR
DATA OUTAGES THIS MORNING IN AWIPS. VIGOROUS CYCLONE CONTINUES
TO MOVE EASTWARD ACROSS TEXAS THIS AFTERNOON WITH STRONG 3HR
PRESSURE FALLS (NEAR 5MB) IN ADVANCE OF THE LOW FROM AR/LA EAST-
NORTHEAST INTO THE OHIO VALLEY LIKELY INDICATING THE NEAR FUTURE
TRACK/MOVEMENT OF THE SURFACE LOW. EXPLOSIVE CONVECTIVE
DEVELOPMENT IS TAKING PLACE FROM EASTERN KS SOUTH TO WESTERN LA
WITH A WELL DEVELOPED TROWAL FROM KANSAS SW TO WEST TEXAS.

UPPER LOW IS PROGGED TO TRACK NORTHEAST TOWARD THE MID MISSISSIPPI
VALLEY TONIGHT WITH ASSOCIATED TROWAL LIKELY TO PROPAGATE NORTHEAST
INTO MISSOURI AND DOWNSTATE ILLINOIS...BEFORE LIFTING NORTH INTO OUR
CWA EARLY TUESDAY MORNING GRADUALLY SPREADING NORTH TO THE WISCONSIN
BORDER BY EARLY AFTERNOON. SYSTEM IS PROGGED TO OCCLUDE AND BEGIN
WEAKENING TUESDAY WITH ASSOCIATED TROWAL ALSO EXPECTED TO BEGIN TO
WEAKEN TUESDAY...BUT THERE IS SPREAD IN MODEL SOLUTIONS IN HOW
QUICKLY THE WEAKENING WILL TAKE PLACE AND HOW INTENSE THE VERTICAL
MOTION AND ASSOCIATED DYNAMIC COOLING WILL BE OVER OUR CWA TUESDAY.
THE DYNAMIC COOLING WILL NEED TO BE SUFFICIENT TO OVER COME THE VERY
STRONG WARM AIR ADVECTION THAT WILL BE TAKING PLACE AS RESULT OF
50KT+ LLJ. GUIDANCE SUGGESTS THAT THE COOLING ALOFT WILL BE
SUFFICIENT FOR A CHANGE OVER TO SNOW...BUT MY CONFIDENCE IN THEIR
HANDLING OF THIS IS NOT OVERLY HIGH AND SREF P-TYPE PROBABILITIES
HAVE BEEN SHOWING A DISTINCT AND NOTICEABLE NORTHWESTWARD TREND WITH
RAIN/SNOW TUESDAY. STEEP MID LEVEL LAPSE RATES RESULTING FROM MID
LEVEL COLD POOL (NEARLY -30C AT 500MB) DOES RAISE CONCERNS ABOUT THE
POTENTIAL FOR CONVECTIVE PRECIPITATION TUESDAY...WHICH SHOULD THIS
OCCUR WOULD INCREASE THE CHANCES FOR SUBSTANTIAL DYNAMIC COOLING AND
LOCALLY HEAVY SNOW.

ONE OF THE BIGGEST POTENTIAL COMPLICATIONS WITH RESPECT TO SNOWFALL
ACCUMULATION LIES WITH LOW LEVEL THERMAL PROFILE. AS ALLUDED TO IN
PREVIOUS DISCUSSIONS THE MODELS DO AN ABSOLUTELY HORRENDOUS JOB
HANDLING BOUNDARY LAYER TEMPERATURES WHEN THERE IS SNOW COVER...OR
WORSE YET WHEN THE MODEL THINKS THERE IS SNOW COVER THAT IS NOT
THERE. AFTER BACK TO BACK DAYS BLOWING AWAY GUIDANCE TEMPS A HUGE
DENT HAS BEEN MADE ON THE SNOW PACK WITH VIRTUALLY NO SNOW COVER
LEFT IN INDIANA AND VERY LITTLE (OTHER THAN PILES) FROM CHICAGO TO
PERU SOUTHEASTWARD. MODELS ARE STILL INDICATING SNOW COVER IN THIS
AREA AND ARE RESPONDING BY PRODUCING AN UNREALISTIC THERMAL GRADIENT
AT THE EDGE OF THE MODEL PERCEIVED SNOW COVER OVER SOUTHERN ILLINOIS
AND INDIANA TUESDAY. STRONGLY SUSPECT THAT TEMPERATURES WILL GET
MUCH WARMER THAN RAW 2M TEMPS IN THE MODELS SUGGEST...AND HAVE
RAISED HIGHS CLOSER TO MOS VALUES WHICH MAY STILL BE A BIT TOO COOL.

ONCE PRECIP BEGINS EXPECT SFC TEMPS TO DROP SOME...BUT WITH WET
BULBS PROGGED TO BE NEAR IF NOT JUST A BIT OVER FREEZING THINKING
THAT MANY AREAS COULD SEE THE BULK OF THE PRECIPITATION FALL WITH
SFC TEMPS AOA FREEZING. THIS WOULD DRAMATICALLY REDUCE SNOW
ACCUMULATIONS...ESPECIALLY ON ROADWAYS...AND RAISES SUBSTANTIAL
DOUBTS ABOUT GOING SNOWFALL FORECASTS AND ANY POTENTIAL TO REACH
WARNING CRITERIA. GIVEN THE PRECIP WILL BE LARGELY OCCURRING DURING
THE DAYTIME BATTLING ABOVE FREEZING TEMPS AND THE INCREASINGLY HIGH
LATE FEB SUN ANGLE...THE POTENTIAL EXISTS FOR A TREMENDOUS AMOUNT OF
MELTING TO OCCUR GREATLY LIMITING SNOW ACCUMULATION POTENTIAL. IN
ORDER FOR SNOW ACCUMULATIONS TO REACH THE GOING FORECAST FOR THE
WATCH AREA (3-6") IT WOULD ALMOST CERTAINLY REQUIRE CONVECTIVE IF
NOT THUNDERSNOW. GIVEN THAT THERE IS SOME POTENTIAL FOR THIS TO
OCCUR FELT THE COURSE OF LEAST REGRET WAS TO LET THE WATCH AND GOING
SNOWFALL FORECAST RIDE...HOWEVER THE MOST LIKELY SCENARIO IS
INCREASINGLY LOOKING LIKE A BORDERLINE ADVISORY SNOWFALL AT WORST.
IN CONVECTIVE SNOWFALL DOESN`T OCCUR THEN IT WOULD NOT BE DIFFICULT
TO ENVISION A SCENARIO WITH SNOW ACCUMULATIONS LESS THAN 3" OVER
MOST OF THE WATCH AREA WITH VERY LOW SNOW:LIQUID RATIOS AND A LOT OF
MELTING.

CLEARLY THIS IS AN EXCEEDINGLY LOW CONFIDENCE FORECAST...WHICH IS
ALMOST ALWAYS THE CASE WITH SPRING SNOW STORMS AND IN ALL LIKELIHOOD
THIS IS GOING TO TURN INTO A SCENARIO WHERE WE WONT HAVE A TRULY
GOOD HANDLE ON THE FORECAST UNTIL WE GET INTO THE "NOWCAST" TIME
RANGE TOMORROW MORNING.

NO BIG CHANGES TO THE REMAINDER OF THE SHORT TERM PERIOD WITH UPPER
LOW PROGGED TO WEAKEN AND ESTABLISH RESIDENCY OVER THE EAST GREAT
LAKES. SMALL...DIFFICULT TO FORECAST...WEAK DISTURBANCES WILL LIKELY
PIVOT AROUND THE UPPER LOW BRINGING AT LEAST OCCASIONAL BOUTS OF
LIGHT SNOW/FLURRIES WITH OTHERWISE CLOUDY AND DISMAL WEATHER TO
CLOSE OUT WHAT HAS OTHERWISE BEEN A TOLERABLE CHICAGO METEOROLOGICAL
WINTER.

IZZI/MTF
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Gonna be close no matter what. 43 right now, you can thank late Feb sun for that but it still means that we have farther to drop to get AOB freezing. A couple positives are the early morning onset and E/NE flow in the lowest 100 mb or so which is not conducive to rapid warming.

 

Looks like one of those weird advisory set ups with a WWA here and nothing to the west in ILX's CWA (east of I-55) all the way up to LOT's SE CWA.

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