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Feb. 19th-22nd Winter Storm Part 2


wisconsinwx

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LOT

THIS WEEKEND...DIGGING TROF EVIDENT ON WATER VAPOR IMAGERY OFF THE

CALIFORNIA COAST WILL QUICKLY LIFT NORTHEAST REACHING THE CENTRAL

PLAINS BY SATURDAY NIGHT WHILE SURFACE LOW UNDERGOES CYCLOGENESIS.

ISENTROPIC UPGLIDE GRADUALLY SATURATES ATMOSPHERE OVERNIGHT SATURDAY

WITH PRECIP BEGINNING ACROSS THE FORECAST AREA AFTER MIDNIGHT.

AGAIN...IMPORTANT DISCREPANCIES IN THE LOW TRACK CONTINUE BUT MODELS

DID SHIFT BACK SOUTH FROM YESTERDAYS TRACK. GFS/NAM/ECWMF COMING

INTO SOMEWHAT BETTER AGREEMENT WITH LOW TRACKING ACROSS THE NORTHERN

THIRD OF ILLINOIS WHILE SREF TAKES A WORST CASE TRACK ACROSS CENTRAL

ILLINOIS. BASED ON CURRENT NAM/GFS BUFR SOUNDINGS AND ANTICIPATED

POSITION OF WARM FRONT...LOOKS LIKE PRECIP WILL MOSTLY BE IN THE

FORM OF RAIN. THE EXCEPTION/MAIN CONCERN RIGHT NOW WILL BE THE

NORTHERN COUPLE TIERS OF COUNTIES SUNDAY MORNING. SOUNDINGS SHOW A

SUFFICIENTLY DEEP COLD LAYER BELOW ELEVATED WARM LAYER THAT WILL

REFREEZE FALLING PRECIP. PER THIS SOLUTION...SLEET WOULD BE EXPECTED

SUNDAY MORNING THROUGH EARLY SUNDAY AFTERNOON BEFORE BECOMING ALL

RAIN. SHOULD SREF SOLUTION PAN OUT...MAIN THREAT WOULD BE FREEZING

RAIN WHICH WOULD FALL ACROSS FAR NORTHERN ILLINOIS. RIGHT NOW...SREF

SOLUTION IS AN OUTLIER.

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What do you think as of now? Along and north of 96 in west michigan and 59 in the east could be all snow?

FWIW....GRR AFD....

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 419 PM EST FRI FEB 18 2011 LATEST UPDATE...LONG TERM... .SYNOPSIS...(330 PM EST FRI FEB 18 2011) ANOTHER WINTER STORM IS TAKING SHAPE AND COULD AFFECT SOUTHWEST LOWER MICHIGAN SUNDAY INTO MONDAY. THIS STORM HAS THE POTENTIAL TO PRODUCE SIGNIFICANT ACCUMULATING SNOW NORTH OF I-96 AND MIXED SNOW AND FREEZING RAIN SOUTH OF I-96. THE POTENTIAL EXISTS FOR SIGNIFICANT ICE ACCUMULATION ALONG AND SOUTH OF I-94. THE EXACT TRACK OF THE STORM HASN/T BEEN NAILED DOWN YET AND SOME UNCERTAINTY STILL EXISTS. && .SHORT TERM...(330 PM EST FRI FEB 18 2011) (TONIGHT THROUGH SUNDAY NIGHT) FORECAST CONCERNS DEAL WITH HEADLINES. SFC OBS SHOW WINDS HAVE BEEN GUSTING TO 35 TO 40KTS ACROSS THE CWA AS GOOD MIXING VIA ABUNDANT SUNSHINE HAS BROUGHT DOWN 80 PERCENT OR SO OF THE 50KTS SEEN AT 2K FT. WINDS SHOULD BEGIN TO DIMINSH THIS EVENING AS MIXING DECREASES AND THE ADVISORY WILL LIKELY NOT BE CONTINUED PAST 05Z. AFTER A MOSTLY SUNNY DAY SATURDAY...CLOUDS WILL BE ON THE INCREASE SATURDAY NIGHT AHEAD OF THE NEXT STORM. THE ECMWF/GFS/NAM HAVE ALL CONVERGED ON A TRACK OF THE LOW FROM OMAHA TO CHICAGO AND ACROSS NRN INDIANA. STRONG ISENTROPIC LIFT IS PROGD TO BEGIN LATE SATURDAY NIGHT AND QUICKLY SATURATE THE PROFILE BY SUNDAY MORNING LEADING TO SNOW DEVELOPING BY 12Z OR SO. A 50KT LLJ WILL SUPPLY PLENTY OF GULF MOISTURE. IN FACT THE WARMER AIR ALOFT WILL POTENTIALLY LEAD TO AN ICE STORM OVER THE SRN CWA. FCST SOUNDINGS ON THE NAM AND GFS SHOW A LARGE WEDGE OF ABOVE FREEZING AIR BETWEEN 750-900MB AND SUBFREEZING AIR AT THE SFC. IT LOOKS AT THIS TIME THAT THE NRN TWO ROWS OF COUNTIES WILL SEE ALL SNOW WITH OVER 6 INCHES POSSIBLE. ACROSS THE SRN CWA THERE WILL LIKELY BE A PERIOD OF SNOW BEFORE THE FREEZING RAIN MIXES IN AS THE STORM GETS CLOSER. BUT SEVERAL INCHES OF SNOW AND THEN SOME FREEZING RAIN WILL LEAD TO QUITE A FEW IMPACTS. ACROSS THE SRN CWA THIS LOOKS LIKE MAINLY A FREEZING RAIN EVENT...ALTHOUGH THERE TOO SOME SNOW WILL BEGIN SUNDAY MORNING. IT/S ALSO POSSIBLE THAT THE FREEZING RAIN WILL MIX WITH AND PERHAPS CHANGE TO RAIN SUNDAY EVENING...DEPENDING ON JUST HOW MUCH WARM AIR MAKES IT IN HERE. AS A RESULT OF ALL THIS A WINTER STORM WATCH WILL BE ISSUED FOR SUNDAY AND SUNDAY NIGHT ACROSS THE ENTIRE CWA.

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another nice discussion from DVN

...SIGNIFICANT PRECIPITATION EVENT SUNDAY WITH QUESTIONS REGARDING

RAIN AND POSSIBLY SNOW/SLEET AND FREEZING RAIN THE MAIN CHALLENGE...

OVERVIEW...MODEL INITIALIZATION SIMILAR TO YESTERDAY. FAIR ON THE

LARGER SCALE ISSUES AND POOR ON LOW LEVEL MOISTURE. ADD COMPLEX

ENERGY WRAPPED WITH UPPER LOW OFF CALIFORNIA TO MAKE FOR

EXCEPTIONALLY LOW CONFIDENCE ON TYPES OF PRECIPITATION...LOCATION

AND AMOUNTS SUNDAY. INITIALIZATION AND VERIFICATION AT 18Z SUPPORTS A

BLEND OF 50/50 OF UKMET/HI-RES ECMWF FOR SFC LOW TRACK NEAR I-80

CORRIDOR WITH THERMAL FIELDS AND FORCING FROM 80KM NAM-WRF.

SIGNIFICANT EVAPORATIVE COOLING FEEDBACK IS SUGGESTED WHICH WILL

IMPACT ON HOW SYSTEM EVOLVES AND WHERE HEAVIEST AMOUNTS AND TYPES OF

PRECIPITATION WILL OCCUR. THESE QUESTIONS WILL LIKELY LINGER TO A

DEGREE DUE TO ENERGY OFFSHORE AND LOW LEVEL RH FEEDBACK ISSUES UNTIL

SATURDAY PM FORECAST PACKAGE.

SATURDAY NIGHT AND SUNDAY...HAVE ADJUSTED POPS FOR WARM ADVECTION

RAIN TO ARRIVE IN AREA...CIRCA 04-06Z AND EVOLVE AND MOVE OVER MOST

OF THE FORECAST AREA BY 12Z. BEST ESTIMATE AT THIS TIME IS RAIN WILL

MIX WITH SLEET BY 09Z AS THESE BAND MOVE EAST-NORTHEAST ALONG AND

ESPECIALLY NORTH OF I-80 CORRIDOR. SIGNIFICANT SLEET AND POSSIBLY

SOME ACCUMULATING SNOW AND SLEET ARE SUGGESTED ALONG HIGHWAY 20

CORRIDOR BY 12Z. THIS RISK AT THIS TIME IS NOT ENOUGH TO WARRANT A

WATCH BUT PASS THIS AS THE MAJOR CONCERN TO LATER SHIFTS AS

FORCING TOOLS INDICATE HIGHLY DEPENDENT ON SFC LOW TRACK. IF LOW

TRACKS 30 TO 40 MILES SOUTH OF I-80 CORRIDOR...DYNAMICS AND

THERMODYNAMICS DOES SUPPORT PUTTING A WATCH OUT FOR NORTHERN ROW OF

COUNTIES. SURFACE TEMPERATURES ALONG/NORTH OF I-80 SHOULD STAY NEAR

TO JUST ABOVE 32F SATURDAY NIGHT LIMITING ANY ICING RISK EXCEPT NEAR

30-31F POSSIBLE ALONG HIGHWAY 20 CORRIDOR AROUND SUNRISE SUNDAY.

THE COMPLEX FORCING ASSOCIATED WITH THIS SFC LOW SUGGESTS SOME

ISOLATED THUNDER IS POSSIBLE...BUT THIS WILL BE STRONGLY INFLUENCED

BY EVAPORATIVE COOLING AND PRECIPITATION TYPE. LOCAL TOOLS STILL

SUGGEST MAINLY MODERATE AMOUNTS OF PRECIPITATION WITH SWATHS OF .25

TO .75 INCHES OF PRECIPITATION WITH VERY LOCALIZED AMOUNTS NEAR 1

INCH POSSIBLE DEPENDING ON FORCING AND PHASING ISSUE. THIS MAY BE A

BIT FURTHER CLARIFIED NEXT 12 HOURS. THIS AMOUNT OF PRECIPITATION

WILL HAVE ONLY MINOR TO LOCALLY MODEST AFFECTS ON AREA RIVERS...

MAINLY KEEPING RIVER LEVELS HIGH OR SLOWING THE RATE OF FALL. HIGH

TEMPERATURES SUNDAY MAY VARY UP TO 25 DEGREES ACROSS THE AREA WITH

50S TO NEAR 60F POSSIBLE FAR SOUTH AND 30S FAR NORTH. STRONGEST

GRADIENT SUGGESTED +/-20 MILES EITHER SIDE OF HIGHWAY 30 CORRIDOR. A

10 UP TO 15 PLUS DEGREE DIFFERENCE IS POSSIBLE OVER THESE DISTANCES.

SUNDAY NIGHT AND MONDAY...COLDER WITH PRECIPITATION TO CHANGE TO SNOW

WITH FLURRIES AND AREAS OF LIGHT SNOW INTO MONDAY NIGHT WITH UPPER

TROUGH PASSAGE. ADDITIONAL NEW SNOW AMOUNTS SUGGESTED TO BE MINOR OF

AN INCH OR LESS MOST LOCATIONS. GUSTY NORTH WINDS AND LATE CLEARING

MAY HAVE MAJOR IMPACT ON LOWS MONDAY MORNING FOR LATER SHIFTS TO

REASSESS.

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FWIW DTX AFD....

A COLD AND DRY AIRMASS WILL BE IN PLACE ACROSS THE CENTRAL GREAT LAKES PRECEDING THIS SYSTEM WITH LOWS IN THE UPPER TEENS/LOW 20S ON SATURDAY NIGHT. MOISTURE WILL SURGE NORTH OVER THE AREA ON SUNDAY WITH STRONG ISENTROPIC ASCENT CAUSING PRECIPITATION TO FILL IN ON SUNDAY AFTERNOON. A WARM LAYER OF AIR ALOFT SURGES NORTH AHEAD OF THE LOW PRESSURE SYSTEM WITH A VERY COMPACT BAROCLINIC ZONE IN THE 925-850MB SETTING UP ACROSS SOUTHERN LOWER MICHIGAN BY SUNDAY EVENING. PRECIPITATION WILL LIKELY START AS SNOW IN ALL AREAS BEFORE QUICKLY CHANGING OVER TO A WINTRY MIX ACROSS THE SOUTH. SURFACE TEMPERATURES WILL BE ONE OF THE CHALLENGING ASPECTS OF THIS STORM AS WE DEAL WITH EVAPORATIONAL COOLING...A VERY TIGHT TEMPERATURE GRADIENT AND A SURFACE WARM FRONT THAT LIFTS UP VERY CLOSE TO THE MICHIGAN BORDER. TEMPERATURES BELOW FREEZING ARE A CONCERN ALL THE WAY SOUTH TO THE OHIO BORDER...ALTHOUGH LENAWEE AND MONROE COUNTY STAND THE BEST CHANCE OF SNEAKING INTO THE WARMER AIR. CURRENT MODEL PROJECTIONS PULL THE FREEZING RAIN ALL THE WAY UP TO NEAR THE I-69 CORRIDOR BY SUNDAY NIGHT WITH ICING POSSIBLE. IF THIS SYSTEM SHIFTS FURTHER TO THE SOUTH...THE SNOW WILL EXPAND FURTHER SOUTH...AND IF THIS SYSTEM SHIFTS TO THE NORTH...THE FREEZING RAIN CORRIDOR WILL SHIFT FURTHER NORTH WITH JUST RAIN IN THE SOUTHERN COUNTIES. THE SYSTEM DOES OCCLUDE AS IT PASSES TO OUR SOUTH ON SUNDAY NIGHT AND WOULD EXPECT TO SEE TEMPERATURES SLOWLY START TO FALL AFTER MIDNIGHT. AT THIS TIME MOST LIKELY PROJECTIONS ARE FOR A SWATCH OF SNOW ACROSS THE SAGINAW VALLEY/NORTHERN THUMB(POSSIBLY EXCEEDING 5 INCHES)...AN AREA OF MINOR SNOW ACCUMULATIONS WITH ICING ON TOP ACROSS THE M-59 AND I-69 CORRIDOR...WITH FREEZING RAIN/RAIN FOR THE ANN ARBOR/DETROIT AREA AND SOUTH. A SIGNIFICANT ICING EVENT IS POSSIBLE FOR PORTIONS OF THE AREA BUT PLENTY OF THINGS COULD CHANGE OVER THE NEXT 48

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GIVEN THIS...HAVE TRENDED WEATHER TYPE GRIDS

ALONG/NORTH OF I-90 TO MOSTLY SNOW WITH SOME SLEET MIXED IN. OVER

NORTHEAST IA/SOUTHWEST WI...WHERE WARMER AIR /ABOVE 0C/ COMES IN

ALOFT...PRECIP EXPECTED TO START OUT AS SNOW THEN TRANSITION TO

SLEET/FZRA AND EVENTUALLY RAIN BY SUN AFTERNOON. BY SUN AFTERNOON A

VERY SHARP GRADIENT OF SNOW TO RAIN EXPECTED ACROSS THE CENTRAL PART

OF THE FCST AREA.

6-12 here... Wondering if being in the river valley will help/hurt any? Bluffs could pile it up good while i get glazed like a donut

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AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN

356 PM CST FRI FEB 18 2011

12Z MODEL RUNS ARE NOW KEEPING TEMPERATURE PROFILES A BIT COLDER

THAN EARLIER RUNS WHICH WOULD LIMIT ANY FRZG PRECIPITATION TO

PERHAPS THE SOUTHERN TIER OF ONE OR TWO COUNTIES. MODELS APPEAR TO

BE SETTLING ON A STORM TRACK ACROSS S IA...PROBABLY NEAR DSM BY

SUNDAY EVENING AND THEN PUSHING TOWARD CHICAGO. QPF OUTPUT VERY

IMPRESSIVE AS PWATS INCREASE TO AROUND .75 INCH...AND 295K

ISENTROPIC SURFACE BRING AROUND 4G/KG INTO SE MN. SREF 24 HOUR QPF

PROBABILITY OF 1 INCH OR MORE ACROSS SW MN. THERE SHOULD BE A BAND

OF PERHAPS 10 INCHES OF SNOW FROM NEAR RWF THROUGH THE TC METRO

AND INTO WESTERN WI. SREF SNOW PLUMES ACROSS THIS AREA DO SHOW

CONSIDERABLE RANGE AMONG THE MEMBERS...BUT THE MAJORITY ARE ABOVE

10 INCHES. WOULDN`T RULE OUT THE POTENTIAL OF CONVECTION ACROSS N

IA OR INTO SC MN ON SUNDAY WITH ELEVATED INSTABILITY PRESENT...K

INDEX IN THE MID TO UPPER 20S.

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FWIW....

Wow if this did verify....NAM Bufkit shows with the onset of the snow accum rates (using a 10:1) of 1.3 and 3.0 per hour with 4.4 at DTX before ZR begins.... then 0.57 ice....DTW....6 inches snow then 0.48 ice....MOP stays all snow total 8.6....LAN....6.9 snow then 0.55 ice....GRR....7.6 snow then 0.52 ice....for AZO....4.3 snow then 0.66 ice....SBN....5.4 snow then 0.10 ice then 0.05 rain with 1/0 sfc but compared to other sites looks underdone/bad data set....ORD 5.4 snow then .25 ice but it then shows .31 rain with a 1/0 SFC so could still be ice....for MKX 4.9 snow then 0.44 ice....GRB....7.2 all snow.....also of note was from I-94 south to I-80/90 ZR rates are initially at .25 per hour.

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FWIW....

Wow if this did verify....NAM Bufkit shows with the onset of the snow accum rates (using a 10:1) of 1.3 and 3.0 per hour with 4.4 at DTX before ZR begins....

I believe it, and it's certainly plausible.

Impressive to extreme Omega values are centered directly in the DGZ. It's going to be a aggregated type of snow too, which accumulates rather efficiently.

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I wouldnt mind snow to ice to snow...as long as we get the white back so we can resume the snowcover days that had been piling up in earnest this winter. DTX keeps talking rain/freezing rain south of Detroit, and thats NOT to my liking, though if the latest model trends are correct, that wont be the case. Actually if it all works out just right, lay down a blanket of snow, then glaze crystal icicles on all the trees before ending as snow, it would be a literal fairyland of beauty. Of course, Id still take ALL snow in a heartbeat, even if its a nonflocking snow!

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