Mesoscale Discussion 2118

Issued

Nov 11, 2012, 2:47 PM CST (20:47 UTC)

Expired

Nov 11, 2012, 4:15 PM CST

In force

88 min

Issued by

the Storm Prediction Center

The Shreveport radar (KSHV), 77 km from the middle of the area, began a volume at 20:49 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.

709 
ACUS11 KWNS 112048
SWOMCD
SPC MCD 112047
ARZ000-LAZ000-TXZ000-112215-

MESOSCALE DISCUSSION 2118
NWS STORM PREDICTION CENTER NORMAN OK
0247 PM CST SUN NOV 11 2012

AREAS AFFECTED...NERN TX...CNTRL/SRN AR...NWRN LA

CONCERNING...TORNADO WATCH 676...

VALID 112047Z - 112215Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 676 CONTINUES.

SUMMARY...AS THE COLD FRONT OVERTAKES A PERSISTENT PRE-FRONTAL BAND
OF TSTMS...AN INCREASE IN ISOLATED DAMAGING WIND/BRIEF TORNADO
POTENTIAL SHOULD OCCUR. THE SEVERE THREAT WILL LIKELY PEAK THROUGH
ABOUT 00Z AS THE FRONT INTERCEPTS THE THERMAL/MOIST AXES EMANATING
N/NEWD FROM THE WRN GULF COAST.

DISCUSSION...PRE-FRONTAL LINE OF TSTMS EXTENDED FROM NEAR HOT TO 25
S TYR AS OF 2030Z. SEVERAL TRANSIENT LOW-LEVEL CIRCULATIONS HAVE
BEEN NOTED ALONG THE LINE WITH ONE REPORT OF DAMAGING WIND THUS FAR.
CONVECTIVE INTENSITY SHOULD INCREASE SOON AS THE SYNOPTIC COLD FRONT
MERGES WITH THE LINE...INTERCEPTING THE SURFACE THERMAL/MOIST AXES
THAT ARE EMANATING N/NEWD FROM SERN TX.

ALTHOUGH LOW-LEVEL FLOW S/SWLYS HAVE SUBSIDED SOMEWHAT AND A
WEAKNESS IN THE 2-4 KM HODOGRAPH PERSISTS IN SHV VWP DATA...THE
STRENGTH OF THE FLOW REMAINS FAVORABLE FOR LEWP/BOWING STRUCTURES
PRIMARILY PRODUCING DAMAGING WINDS AND POSSIBLY A TORNADO OR TWO.

THE SUSTAINABILITY OF THE SEVERE THREAT DOWNSTREAM OF THE WATCH INTO
PARTS OF CNTRL/SERN AR IS UNCERTAIN AS MODIFIED 18Z LZK RAOB
SUGGESTS THAT THE AIR MASS IS ONLY MEAGERLY UNSTABLE. BUT WITH
IMPRESSIVELY LARGE HODOGRAPHS SAMPLED IN THE LZK RAOB AND VWP
DATA...A LOCAL AREAL EXTENSION OF WW 676 MAY NEED BE CONSIDERED.

..GRAMS.. 11/11/2012

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

ATTN...WFO...LZK...SHV...

LAT...LON   32369517 33409423 34379333 34809264 34869193 34699163
            34389159 34009187 33359270 32499372 31849422 31679457
            31679485 31799508 31829514 32369517

Mesoscale Discussions in Arkansas, 2012Mesoscale Discussions in Texas, 2012Mesoscale Discussions in Louisiana, 2012Every mesoscale discussion in 2012

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.