SWOMCD
SPC MCD 291136
NYZ000-NJZ000-PAZ000-MDZ000-VAZ000-WVZ000-291700-
MESOSCALE DISCUSSION 2277
NWS STORM PREDICTION CENTER NORMAN OK
0636 AM CDT SAT OCT 29 2011
AREAS AFFECTED...PORTIONS NERN WV...SERN NY...NWRN MD INCLUDING
PANHANDLE...CENTRAL/ERN PA...NWRN NJ...EXTREME NRN VA.
CONCERNING...HEAVY SNOW
VALID 291136Z - 291700Z
PRIND HEAVIEST SNOW RATES THROUGH 18Z...AND MOST SUSTAINED AT 1-2
INCHES/HOUR...WILL BE OVER AND W OF BLUE RIDGE FROM NERN WV AND VA
BORDER REGION NEWD ACROSS NWRN MD TO S-CENTRAL PA...SHIFTING NEWD
ACROSS NERN PA INTO INTERIOR SERN NY BY ABOUT 18Z. RAIN SHOULD
BECOME SNOW OVER PORTIONS CENTRAL-ERN PA THROUGH 16Z. ISOLATED
CONVECTIVE BURSTS ALSO ARE POSSIBLE ALONG THAT PORTION OF RAIN/SNOW
MIX ZONE FROM NRN VA TO SERN PA AND EVENTUALLY NWRN NJ.
CONCENTRATION OF HEAVY SNOW POTENTIAL ACROSS DISCUSSION AREA WILL BE
RELATED TO SEVERAL JUXTAPOSED REGIMES OF LIFT AND INSTABILITY.
THESE INCLUDE...FROM TOP TO BOTTOM OF TROPOSPHERE...
-- STRENGTHENING/NEWD-MOVING UPPER DIVERGENCE AS STG SHORTWAVE
TROUGH...NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER PORTIONS
IL/INDIANA/WRN KY/TN...APCHS AREA WITH MORE NEGATIVE TILT.
ASSOCIATED BAROCLINIC-LEAF SIGNATURE HAS BECOME VERY WELL-DEFINED
WITH COOLING IR CLOUD TOPS ACROSS NRN WV AND WRN PA DURING PAST 2-3
HOURS.
-- MIDLEVEL DCVA PRECEDING THAT TROUGH.
-- NARROW SW-NE ALIGNED RIBBONS OF MIDLEVEL CONDITIONAL SYMMETRIC
INSTABILITY SUPPORTING SLANTWISE CAPE UP TO ABOUT 200 J/KG.
-- LOW-MIDDLE LEVEL FRONTOGENETIC FORCING...ESPECIALLY STRONG 15-18Z
OVER S-CENTRAL THROUGH NERN PA AND INTERIOR SERN NY PER SREF
GUIDANCE.
-- ZONE OF ELEVATED CONVECTIVE INSTABILITY IN LOW-MIDDLE
LEVELS...INVOF RAIN/SNOW TRANSITON ZONE...SUPPORTING 100-300 J/KG
ELEVATED MUCAPE OVER ERN FRINGES OF DISCUSSION AREA THAT IN TURN CAN
ENABLE CONVECTIVELY AIDED SNOW BURSTS WITH OCNL THUNDER.
MODIFIED 6Z RNK/DCA RAOBS AND MODEL SOUNDINGS SUGGEST
NEAR-SATURATION IN LOW LEVELS...PRECLUDING APPRECIABLE WET-BULB
COOLING. HOWEVER...COLUMNAR DYNAMIC COOLING SHOULD OFFSET WAA IN
ELEVATED CONVEYOR ENOUGH TO YIELD DOMINANT PRECIP TYPE AS SNOW OVER
APPALACHIANS.
..EDWARDS.. 10/29/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...OKX...ALY...PHI...BGM...CTP...LWX...PBZ...RLX...
LAT...LON 38997991 41957649 41897395 38947787 38997991
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment