Mesoscale Discussion 2138

Issued

Sep 5, 2011, 6:37 PM CDT (23:37 UTC)

Expired

Sep 5, 2011, 8:30 PM CDT

In force

113 min

Issued by

the Storm Prediction Center

The Greer radar (KGSP), 38 km from the middle of the area, began a volume at 23:38 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.

002 
ACUS11 KWNS 052337
SWOMCD
SPC MCD 052337 
VAZ000-NCZ000-WVZ000-SCZ000-GAZ000-ALZ000-060130-

MESOSCALE DISCUSSION 2138
NWS STORM PREDICTION CENTER NORMAN OK
0637 PM CDT MON SEP 05 2011

AREAS AFFECTED...PORTIONS CENTRAL/ERN AL...CENTRAL/NRN
GA...W-CENTRAL/NWRN SC...WRN NC...S-CENTRAL/W-CENTRAL VA.

CONCERNING...TORNADO WATCH 840...842...844...

VALID 052337Z - 060130Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH
840...842...844...CONTINUES.

CONTINUE WWS 840 AND 844.  WW 842 IS BEING CLEARED FROM W-E PER
COORD W/WFO BMX...AND MAY BE CANCELED ENTIRELY BEFORE SCHEDULED 02Z
EXPIRATION AS POTENTIAL FOR DEEP CONVECTION SHIFTS NEWD.  THIS TREND
ALSO WILL BEGIN TO AFFECT WRN PORTIONS WW 840 FROM SW-NE IN STEP
WITH NEWD TRANSLATION OF DRY SLOT INTRUDING SRN SEMICIRCLE OF
REMAINS OF T.D. LEE...ALONG AND E OF BAROCLINIC CORRIDOR.  THREAT
WILL CONTINUE TO SHIFT NEWD OVER WW AREAS.

23Z SFC ANALYSIS SHOWS CYCLONE CENTER OVER CENTRAL AL BETWEEN
TCL-MGM...MOVING NEWD ALONG QUASISTATIONARY FRONT ANALYZED NEAR
ANB-GVL-HKY LINE.  COLD FRONT WAS DRAWN GENERALLY SSEWD-SWD ACROSS
S-CENTRAL AL BETWEEN GZH-TOI TEN SWD OVER CEW AREA...AND WILL MOVE
ENEWD OVER REMAINDER SRN AL AND WRN FL PANHANDLE THROUGH ABOUT 04Z. 
SHARP DECLINE IN BUOYANCY AND INCREASE IN MLCINH OCCURS WITH WWD
EXTENT THROUGH BOTH COLD AND QUASISTATIONARY FRONTAL ZONES...A
TENDENCY WITH SHOULD CONTINUE GIVEN EXTENSIVE/PERSISTENT PRECIP
SHIELD OVER APPALACHIANS AND LIKELIHOOD OF CONTINUED NEGATIVE THETAE
ADVECTION S-SW OF LOW.  ALTHOUGH LAPSE RATES ALOFT ARE WEAK...AT
LEAST MRGLLY SUFFICIENT BUOYANCY SHOULD CONTINUE E OF FRONT -- I.E.
MLCAPE INCREASING FROM AROUND 250 J/KG ALONG FRONT TO 1000 J/KG
INVOF FALL LINE.  LOW-LEVEL SRH WILL REMAIN MAXIMIZED IN AND JUST E
OF QUASISTATIONARY BRANCH OF FRONTAL ZONE...WITH VWP DATA AND FCST
SOUNDINGS INDICATING VERY FAVORABLE EFFECTIVE SRH 200-500 J/KG. 
AMBIENT SWLYS ALOFT AUGMENT DEEP-LAYER SHEAR SUCH THAT BROAD PLUME
OF 45-55 KT EFFECTIVE SHEAR MAGNITUDES EXTEND FROM E-CENTRAL AL NEWD
ACROSS NRN GA...NWRN SC AND WRN NC.  ANY SUSTAINED/PERSISTENT CELLS
IN ENVIRONMENT E OF FRONT AND W OF ATLC COASTAL PLAIN MAY POSE
TORNADO RISK.

..EDWARDS.. 09/05/2011

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

ATTN...WFO...AKQ...LWX...RAH...RNK...CAE...GSP...FFC...TAE...
BMX...MOB...

LAT...LON   31658601 32608653 33868585 34868369 35468243 36548069
            38048010 37697888 37657807 35887916 35507962 35398041
            32828258 31888371 31938503 31658601

Mesoscale Discussions in Georgia, 2011Mesoscale Discussions in North Carolina, 2011Mesoscale Discussions in Virginia, 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.