[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 221241
SWOMCD
SPC MCD 221241 
NJZ000-NYZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-WVZ000-OHZ000-MIZ000-INZ000-221845-

MESOSCALE DISCUSSION 0116
NWS STORM PREDICTION CENTER NORMAN OK
0641 AM CST SAT JAN 22 2005

AREAS AFFECTED...LOWER MI/NRN IND/PA/WRN NY/MD/NJ/DE/NRN VA/WV

CONCERNING...HEAVY SNOW 

VALID 221241Z - 221845Z

HEAVY SNOW WILL CONTINUE/SPREAD FROM THE LOWER PENINSULA OF MI
ACROSS THE OH VALLEY AND MID ATLANTIC THIS MORNING...WITH HOURLY
RATES 1-2"/HR WITH LOCALLY 3"/HR POSSIBLE. IN ADDITION TO THE HEAVY
SNOW...A MIX OF FREEZING RAIN/SLEET WILL OCCUR ROUGHLY SOUTH OF
PITTSBURGH TO COLUMBUS TO DAYTON.

WATER VAPOR IMAGERY LOOPS SHOW TWO DISTINCT UPPER CIRCULATION
CENTERS...WITH THE MAIN FORCING FOR LOW LEVEL CYCLOGENESIS FOCUSED
OVER THE OH VALLEY. SATELLITE IMAGERY SUGGESTS THAT THE NRN CYCLONIC
CENTER NOW ENTERING CNTRL IL WILL BECOME DOMINANT...WITH A
"DUMBBELLING" EFFECT EXPECTED TO OCCUR AS THE SRN CIRCULATION OVER
NRN IND ROTATES CYCLONICALLY AROUND IT. 

SEVERAL FACTORS WILL COMBINE TODAY TO PRODUCE HEAVY SNOW OVER THE
MID ATLANTIC INCLUDING THE ENHANCED UPPER DIVERGENCE ASSOCIATED WITH
THE EXIT REGION OF THE IL JETSTREAK...WARM AIR ADVECTION/ISENTROPIC
LIFT ON THE NOSE OF A 60 KT LOW LEVEL JET...AND STRONG PVA
ASSOCIATED WITH STRONG HEIGHT FALLS / 240 METER FALLS / BY 00Z.

IN THE SHORTER TERM...HEAVY SNOW WILL BE FOCUSED ACROSS SRN LOWER MI
AND NRN OH. LONGER RADAR LOOPS SUGGEST DEFORMATION ZONE WILL LIKELY
PIVOT TO A MORE WSW/ENE ORIENTATION IN RESPONSE TO DIGGING UPSTREAM
WAVE. THIS WILL KEEP AREAS LIKE DETROIT...ANN ARBOR AND LANSING IN
AN AXIS OF HEAVY SNOW FOR AN EXTENDED TIME. 

FARTHER SOUTH IN WAA ZONE...FZRA WILL BE DEVELOPING ESPECIALLY SOUTH
OF A DAYTON OH WHEELING WV TO PIT LINE. FZRA/FZDZ ARE BEING REPORTED
FROM CVG/LHQ/CKB...AND WITH CONTINUING WAA AND SUBFREEZING SFC
TEMPS...POTENTIAL FOR FZRA EXISTS.

FINALLY...WAA PRECIPITATION HAS ALREADY OVERSPREAD PA/MD WITH
PRECIPITATION OCCURRING MAINLY ALOFT. POINT FORECAST SOUNDINGS
SUGGEST SNOW BEGINNING BETWEEN 12-14Z ACROSS MD/ERN PA...AND ONCE
SNOW STARTS...AN EXTENDED PERIOD OF 8-12 HOURS OF MOD/HEAVY SNOW IS
LIKELY GIVEN STRONG DYNAMICS AND FAVORABLE DENDRITIC GROWTH ZONE.
ENOUGH CONVECTIVE INSTABILITY EXISTS...GIVEN RECENT LIGHTNING
OBSERVED OVER OH...THAT SNOWFALL RATES MAY APPROACH THE 2-3"/HR
RANGE BY MID MORNING INTO AFTERNOON.

..TAYLOR.. 01/22/2005

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A 
SCHEDULED BASIS...FOUR TIMES A DAY...BETWEEN 00-01 UTC...
06-07 UTC...12-13 UTC...AND 18-19 UTC AS SIGNIFICANT SHORT
RANGE WINTER WEATHER EVENTS UNFOLD.  THIS SCHEDULE WILL BE
USED FROM DECEMBER 1 THROUGH FEBRUARY 28.

ATTN...WFO...OKX...ALY...PHI...BGM...AKQ...BUF...CTP...LWX...PBZ...RLX...CLE...ILN...DTX...IWX...GRR...IND...LOT...

43278694 43848568 43477903 42317462 40117399 38127522
38007912 38888006 39148116 39258187 39248354 40398562
41178673 42428733 

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