Mesoscale Discussion 2146

Issued

Sep 6, 2011, 7:33 PM EDT (23:33 UTC)

Expired

Sep 6, 2011, 9:30 PM EDT

In force

117 min

Issued by

the Storm Prediction Center

The Wilmington radar (KLTX), 84 km from the middle of the area, began a volume at 23:36 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

995 
ACUS11 KWNS 062334
SWOMCD
SPC MCD 062333
NCZ000-VAZ000-SCZ000-070130-

MESOSCALE DISCUSSION 2146
NWS STORM PREDICTION CENTER NORMAN OK
0633 PM CDT TUE SEP 06 2011

AREAS AFFECTED...PORTIONS CENTRAL/ERN NC...SERN VA...ERN SC.

CONCERNING...TORNADO WATCH 848...

VALID 062333Z - 070130Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 848 CONTINUES.

WW MAY CLEARED FROM W-E IN STEP WITH POSITION/SHIFT OF UNFAVORABLE
BOUNDARY-LAYER AIR W AND NW OF BOUNDARIES DESCRIBED BELOW.
OTHERWISE...PRIND WW MAY BE ALLOWED TO EXPIRE AS SCHEDULED AT 01Z.
SVR THREAT...WHILE NOT ENTIRELY ABSENT...WILL DIMINISH SLOWLY WITH
TIME THROUGH EVENING.

23Z SFC MESOANALYSIS SHOWS PRIMARY SFC LOW INVOF TRI...OCCLUDED
FRONT ESEWD TO TRIPLE POINT BETWEEN CLT-VUJ.  FROM THERE COLD FRONT
WAS ANALYZED SWD BETWEEN SSC-FLOW AND APCHG CHS.  QUASISTATIONARY
FRONT EXTENDED NEWD NEAR RDU...EMV...WAL.  WITH CONTINUED NELY FLOW
TO ITS N AND REINFORCEMENT OF SFC-BASED STATIC STABILITY BY
PRECIP...ONLY MINOR LOCALIZED DRIFTING IS EXPECTED WITH LATTER
BOUNDARY DURING NEXT 2-3 HOURS...THOUGH SOME NWWD RETREAT IS
POSSIBLE OVER SRN CHESAPEAKE BAY REGION LATER THIS EVENING AS PARENT
CYCLONE MOVES SLOWLY NNEWD.  COLD FRONT...WHICH SO FAR HAS BEEN
CHARACTERIZED MORE STRONGLY BY DRYING THAN SENSIBLE COOLING GIVEN
DIABATIC HEATING OF POSTFRONTAL BOUNDARY LAYER...SHOULD CONTINUE TO
MOVE EWD ACROSS ERN SC AND SRN/ERN NC...ENDING SVR THREAT FROM W-E.

MEANWHILE...AIR MASS BETWEEN FRONTS WILL BE CHARACTERIZED BY RICH
LOW-LEVEL MOISTURE/THETAE...WITH SFC DEW POINTS 70S F...HELPING TO
OFFSET WEAK LAPSE RATES ALOFT IN MAINTAINING AT LEAST MRGL BUOYANCY.
 MLCAPE WILL DIMINISH GRADUALLY WITH ONSET OF NOCTURNAL SFC
COOLING...BUT REMAIN SFC-BASED WITH MLCAPE VALUES 500-1500 J/KG
THROUGH ABOUT 03Z.  STRONGEST DEEP-LAYER SHEAR NOW IS ALONG AND W OF
COLD FRONT AND SHOULD REMAIN SO...THOUGH LOW-LEVEL SRH WILL REMAIN
MAXIMIZED INVOF QUASISTATIONARY BOUNDARY FARTHER N AND NE.  CORRIDOR
OF 150-250 J/KG EFFECTIVE SRH ALSO MAY PERSIST SWD ACROSS SERN NC.
ANY RELATIVELY SUSTAINED/DISCRETE CELLS INTERACTING WITH THAT
BOUNDARY AND CROSSING NEAR SERN NC SRH AXIS STILL MAY POSE TORNADO
RISK.  HOWEVER...AMBIENT WIND PROFILE WILL CONTINUE TO FEATURE
BACKING WITH HEIGHT IN VARIOUS MID-UPPER TROPOSPHERIC
LAYERS...SUPPORTING DOMINANCE OF SEGMENTED/QUASI-LINEAR MODES.

..EDWARDS.. 09/06/2011

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

ATTN...WFO...AKQ...MHX...RAH...ILM...RNK...

LAT...LON   33197926 33977988 35627922 36547882 37167672 36817603
            35547622 34477648 34667662 34607720 34277774 34027789
            33697796 33897805 33687883 33477906 33197926

Mesoscale Discussions in North Carolina, 2011Mesoscale Discussions in Virginia, 2011Mesoscale Discussions in South Carolina, 2011Every mesoscale discussion in 2011

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.