Mesoscale Discussion 678

Issued

May 1, 2011, 3:19 AM CDT (08:19 UTC)

Expired

May 1, 2011, 4:45 AM CDT

In force

86 min

Issued by

the Storm Prediction Center

The Dallas/Ft Worth radar (KFWS), 101 km from the middle of the area, began a volume at 08:21 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.

• Tornado Watch 260May 1, 4:45 AM CDT

819 
ACUS11 KWNS 010819
SWOMCD
SPC MCD 010819 
TXZ000-OKZ000-010945-

MESOSCALE DISCUSSION 0678
NWS STORM PREDICTION CENTER NORMAN OK
0319 AM CDT SUN MAY 01 2011

AREAS AFFECTED...PORTIONS N-CENTRAL/NW TX...SRN-CENTRAL OK.

CONCERNING...SEVERE THUNDERSTORM WATCH 259...

VALID 010819Z - 010945Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 259
CONTINUES.

CONTINUE WW.  MAIN THREAT OVER REGION SHOULD CONTINUE TO BE LARGE
HAIL AND ISOLATED SVR GUSTS OVER WW AREA FROM RIGHT-MOVING
SUPERCELLS...INITIALLY ROOTED IN LAYER OF ELEVATED WAA/ASCENT NEAR
850 MB.

08Z SFC MESOANALYSIS SHOWS COLD/QUASISTATIONARY FRONT FROM MCCURTAIN
COUNTY OK WSWWD ACROSS KAUFMAN/BOSQUE/SCHLEICHER COUNTIES TX. 
LITTLE MOTION OTHER THAN LOCALIZED SWD DRIFT IS EXPECTED WITH THAT
BOUNDARY DURING NEXT FEW HOURS.  ISOLATED...INITIALLY ELEVATED
SUPERCELL THAT FORMED NEAR DYS IS MOVING EWD 30-35 KT TOWARD SRN
PORTIONS METROPLEX.  THIS TSTM HAS PRODUCED HAIL ESTIMATED TO 2.75
INCH DIAMETER OVER SRN PALO PINTO COUNTY ALONG WITH MEASURED GUSTS
UP TO 62 KT BENEATH ITS REAR-FLANK DOWNDRAFT.  RELATIVELY DRY
POSTFRONTAL AIR MASS IN BOUNDARY LAYER APPEARS TO OFFSET ITS
COOLER/MORE STATICALLY STABLE CHARACTER IN ALLOWING SVR DOWNDRAFT
PENETRATION TO SFC.  IF THIS CONVECTION SURVIVES IN SUPERCELLULAR
FORM WITHOUT GETTING TOO OUTFLOW-DOMINANT FIRST...IT MAY POSE SOME
TORNADO RISK UPON CROSSING SFC FRONTAL ZONE AND INTO WARM SECTOR. 
CONVECTIVE TRENDS WILL BE MONITORED FOR POSSIBILITY OF ADDITIONAL WW
E OF WW 259 AS WELL.  ANOTHER SUPERCELL ENTERING YOUNG COUNTY AS OF
815Z EVENTUALLY MAY AFFECT NRN PORTIONS METROPLEX WITH LARGE HAIL AS
WELL.

850-MB STREAMLINES DERIVED FROM VWP/PROFILER DATA AND PLANAR RUC
ANALYSES INDICATE STG CONFLUENCE ALONG AND N OF ESTIMATED 850-MB
FRONT FROM DUA WSWWD ACROSS AREA BETWEEN ABI-LBB...IN ZONE OF STG
ISENTROPIC ASCENT AND INCREASING WAA/MOISTURE TRANSPORT ABOVE
BOUNDARY LAYER ASSOCIATED WITH WRN BRANCH OF LLJ.  THIS REGIME MAY
SPREAD NWD ACROSS RED RIVER...INCREASING MUCAPE IN ENVIRONMENT OF
FAVORABLE DEEP-LAYER/EFFECTIVE SHEAR FOR ORGANIZED TSTMS OF AT LEAST
OCNL SUPERCELL CHARACTER.  AS SUCH...ADDITIONAL PORTIONS NW TX/SRN
OK WILL BE MONITORED FOR POSSIBLE WW DURING REMAINDER PRE-DAWN
HOURS...FOR HAIL POTENTIAL WITH CONVECTION MOVING NEWD FROM NW TX
AND/OR DEVELOPING OVER SWRN OK.

..EDWARDS.. 05/01/2011

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

ATTN...WFO...SHV...FWD...OUN...SJT...LUB...

LAT...LON   32169656 31769881 32260000 33220050 33880060 34699999
            35289877 35049736 33829624 32729541 32169537 32169656

Mesoscale Discussions in Texas, 2011Mesoscale Discussions in Oklahoma, 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.