Mesoscale Discussion 704

Issued

May 9, 2011, 4:23 PM CDT (21:23 UTC)

Expired

May 9, 2011, 6:30 PM CDT

In force

2 hr

Issued by

the Storm Prediction Center

The Dyess AFB radar (KDYX), 58 km from the middle of the area, began a volume at 21:27 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.

760 
ACUS11 KWNS 092124
SWOMCD
SPC MCD 092123
OKZ000-TXZ000-092330-

MESOSCALE DISCUSSION 0704
NWS STORM PREDICTION CENTER NORMAN OK
0423 PM CDT MON MAY 09 2011

AREAS AFFECTED...PORTIONS OF CNTRL TX INTO SWRN OK

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 092123Z - 092330Z

AN ISOLATED SVR STORM OR TWO COULD DEVELOP ACROSS PORTIONS OF CNTRL
TX INTO SWRN OK LATER THIS AFTERNOON. GIVEN THE ANTICIPATED SPARSE
COVERAGE OF ANY SVR STORMS...THE ISSUANCE OF A WW IS UNLIKELY.

MID-AFTERNOON SFC ANALYSIS DEPICTS A DRYLINE EXTENDING FROM 20 NNE
CSM TO THE RED RIVER 20 SSW LTS TO 45 NNW ABI AND FARTHER SSW TO 55
WSW SJT. STRONG INSOLATION OVER THE ERN PERIPHERY OF A THERMAL AXIS
/LOCATED WEST OF THE DRYLINE/ HAS RESULTED IN TEMPERATURES WARMING
INTO THE UPPER 90S TO 103 DEGREES. MODIFIED 12Z OBSERVED SOUNDINGS
AND RAPID REFRESH FORECAST SOUNDINGS SUGGEST THAT THE STRONG
DIABATIC HEATING HAS SUBSTANTIALLY REDUCED SURFACE-BASED CINH WITHIN
A NARROW CORRIDOR ALONG AND JUST EAST OF THE DRYLINE. THE REDUCTION
IN CINH...ALONG WITH LOW-LEVEL CONVERGENCE ASSOCIATED WITH THE
DRYLINE...HAS LED TO THE INITIATION OF A FEW HIGHER-BASED CU WEST OF
THE DRYLINE. THIS INITIAL ATTEMPT AT CONVECTION MAY ALSO BE
SUPPORTED BY A SUBTLE MID-LEVEL WAVE EMERGING FROM THE HIGHER
TERRAIN OF NRN MEXICO INTO TX...ALSO RESPONSIBLE FOR HIGH-LEVEL
CLOUDINESS OVER THE MOIST SECTOR.

RECENT RUNS OF THE EXPERIMENTAL HRRR SUGGEST SOME POTENTIAL FOR ONE
OR TWO DEEPER CONVECTIVE PLUMES TO EMANATE FROM THE CU FIELD AS
HEATING CONTINUES AND THE BOUNDARY LAYER DEEPENS. ANY INCIPIENT
CONVECTION WILL BE HIGH BASED...WITH THE POTENTIAL FOR SUPERCELLULAR
STRUCTURES TO EVOLVE GIVEN EFFECTIVE BULK SHEAR MAGNITUDES OF 35-45
KT. THE THREAT FOR LARGE HAIL WILL EXIST PROVIDED VERY STEEP
MID-LEVEL LAPSE RATES /IN EXCESS OF 8.5 C PER KM/ ASSOCIATED WITH A
STRONG ELEVATED MIXED LAYER. STEEP LOW-LEVEL LAPSE RATES...IN PART
YIELDING DCAPE VALUES AOA 1300 J PER KG...SUGGESTS A POTENTIAL FOR
DMGG WINDS...AS WELL. THE THREAT FOR VERY LARGE HAIL /ALBEIT A LOW
THREAT/ MAY OCCUR IF CONVECTION CAN SUSTAIN ITSELF EAST OF THE
DRYLINE AND TRAVERSE RICHER LOW-LEVEL MOISTURE AND A VERY UNSTABLE
AIR MASS -- I.E. SFC DEWPOINTS AOA THE MIDDLE 60S SUPPORTING MLCAPE
VALUES OVER 3500 J/KG. HIGH LCL HEIGHTS AND RELATIVELY WEAK
LOW-LEVEL FLOW WILL MITIGATE THE THREAT FOR ANY TORNADOES. WITH THE
ONLY SUBSTANTIAL FORCING FOR CONVECTION EXPECTED TO BE MAINLY TIED
TO THE DRYLINE...AND GIVEN THE STRONG CINH AWAY FROM THE
DRYLINE...ANY SEVERE CONVECTIVE COVERAGE IS EXPECTED TO BE SPARSE.

..COHEN.. 05/09/2011

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

ATTN...WFO...FWD...OUN...EWX...SJT...LUB...MAF...

LAT...LON   35299809 35269863 34429895 33809935 33169985 32350060
            31830081 30980046 30569972 30529905 31019828 31779778
            32459746 33759750 34949751 35299809

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.