SWOMCD
SPC MCD 162238
NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-WVZ000-170015-
MESOSCALE DISCUSSION 0461
NWS STORM PREDICTION CENTER NORMAN OK
0538 PM CDT SAT APR 16 2011
AREAS AFFECTED...DC...MD...NRN VA...ERN WV...DE...SWRN NJ...SRN PA
CONCERNING...TORNADO WATCH 151...152...
VALID 162238Z - 170015Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 151...152...CONTINUES.
LATEST SFC MESOANALYSIS DEPICTS LOW PRESSURE OVER NWRN VA WITH A
PREFRONTAL TROUGH TRAILING SWD FROM THE LOW ACROSS THE WRN PERIPHERY
OF WW 151. EAST OF THIS FEATURE...THE MOIST/UNSTABLE SECTOR IS SOUTH
OF A BAROCLINIC ZONE ARCING NEWD FROM THE SFC LOW TOWARD 30 S MRB
AND THEN SEWD TOWARD CHESAPEAKE BAY. SOUTH OF THIS
BOUNDARY...DEWPOINTS IN THE LOWER TO MIDDLE 60S ARE FOUND OVER CNTRL
VA SUPPORTING A WEAKLY UNSTABLE AIR MASS /MLCAPE VALUES OF 250 TO
AROUND 500 J PER KG/. NORTH OF THE BOUNDARY...INSTABILITY IS EVEN
MORE MARGINAL GIVEN SFC DEWPOINTS IN THE MIDDLE 50S.
PERSISTENT SHOWER AND TSTM ACTIVITY IS REINFORCING THE COOL AIR
NORTH OF THE BOUNDARY TO SOME EXTENT. HOWEVER...STRONG ASCENT OVER
THE MID ATLANTIC...REFLECTED BY SFC PRESSURE FALLS OF 4 TO 6 MB PER
2 HRS OVER SERN PA...WILL ALLOW THE SFC LOW TO TRANSLATE NEWD OVER
THE NEXT FEW HOURS WITH SFC WINDS GRADUALLY VEERING ACROSS CNTRL/ERN
VA INTO ERN MD AND SERN PA IN RESPONSE TO ISALLOBARIC FORCING. IN
TURN...MOISTURE TRAJECTORIES WILL BECOME MORE FAVORABLE IN THIS AREA
FOR THE SLIGHTLY HIGHER INSTABILITY /ALBEIT MARGINAL/ AND MORE
ROBUST UPDRAFT POTENTIAL TO NOSE NWD IN TIME. DESPITE THE MARGINAL
DEGREE OF INSTABILITY...STRONG DEEP-LAYER SHEAR /71 KT OF 0-6 KM
SHEAR PER STERLING VWP/ AHEAD OF THE PREFRONTAL TROUGH WILL PROVIDE
ADDITIONAL SUPPORT FOR UPDRAFTS.
THE PRIMARY CONVECTIVE MODE IS FORECAST TO CONSIST OF LINE
SEGMENTS/QLCS STRUCTURES MOVING NEWD...WITH EMBEDDED SUPERCELL
STRUCTURES POSSIBLE OVER SRN PORTIONS OF WW151 INVOF STRONGER
INSTABILITY. VERY STRONG WINDS JUST OFF THE SFC /AROUND 50 KT AT 1
KM PER STERLING VWP/ WILL SUPPORT A DMGG WIND THREAT WITH ANY OF
THIS ACTIVITY. A FEW TORNADOES WILL REMAIN POSSIBLE...AS
WELL...GIVEN THE DEGREE OF LOW-LEVEL SHEAR /EFFECTIVE SRH WELL ABOVE
400 M2 PER S2 IN MANY AREAS/...PARTICULARLY WITH ANY LEWP
STRUCTURES.
..COHEN.. 04/16/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...PHI...AKQ...CTP...LWX...RNK...
LAT...LON 38227947 39367876 40467829 40947709 40857629 40477550
39757501 39377492 39027518 38767561 38457576 38227588
38057603 37967631 38077686 38147722 38057752 37967814
37707882 37897920 38227947
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
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