Mesoscale Discussion 1908

Issued

Aug 8, 2011, 7:34 PM CDT (00:34 UTC)

Expired

Aug 8, 2011, 9:30 PM CDT

In force

116 min

Issued by

the Storm Prediction Center

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• Severe Thunderstorm Watch 751Aug 8, 7:55 PM CDT
• Severe Thunderstorm Watch 752Aug 8, 8:40 PM CDT

762 
ACUS11 KWNS 090034
SWOMCD
SPC MCD 090034 
ARZ000-MOZ000-OKZ000-KSZ000-090230-

MESOSCALE DISCUSSION 1908
NWS STORM PREDICTION CENTER NORMAN OK
0734 PM CDT MON AUG 08 2011

AREAS AFFECTED...PORTIONS OK...SERN KS...SWRN MO...AR.

CONCERNING...SEVERE THUNDERSTORM WATCH 748...

VALID 090034Z - 090230Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 748
CONTINUES.

SVR TSTMS WITH HISTORY OF DAMAGING WIND WILL PROCEED SEWD ACROSS NRN
OK...WITH POTENTIAL TO EVOLVE INTO EXTENDED MCS OVER ERN OK AND
PORTIONS AR.  ANOTHER WW IS LIKELY.

NRN OK CONVECTION HAS PRODUCED MEASURED SVR GUSTS 61 KT AT END AND
69 KT AT SWO SINCE 23Z...WITH INCREASINGLY WELL-DEVELOPED COLD POOL
AND FORCED ASCENT IMPINGING UPON AIR MASS CONTAINING GREATER
MOISTURE WITH EWD EXTENT.  INSTABILITY/THERMAL GRADIENT ACCOMPANYING
OUTFLOW BOUNDARY...EXTENDING FROM CENTRAL AR CONVECTION WNWWD ACROSS
FSM/TUL AREAS...SHOULD SERVE AS PRIMARY FOCUS FOR LIFT AHEAD OF NRN
OK MCS AND FOR FORWARD PROPAGATION.  AIR MASS TO ITS S WILL REMAIN
CHARACTERIZED BY CHANNEL OF RELATIVELY MINIMIZED MLCINH...AND DRY
SUBCLOUD AIR THAT SHOULD MAINTAIN DCAPE ENOUGH TO ALLOW SVR
DOWNDRAFT PENETRATION OF DIABATICALLY COOLING SKIN LAYER.  MEAN WIND
IS ALIGNED NEARLY ORTHOGONAL TO THIS CONVECTION AS WELL...AND ALMOST
PARALLEL TO FOCUSING BOUNDARY...FURTHER SUPPORTING POTENTIAL FOR
WELL-ORGANIZED TSTM WIND EVENT TO CONTINUE INTO AR.  LONGEVITY OF
SECONDARY CONVECTIVE SEGMENT OVER SWRN OK IS UNCERTAIN GIVEN WEAKER
MLCAPE IN PROSPECTIVE INFLOW REGION...PER MODIFIED OUN
RAOB...HOWEVER THIS ACTIVITY IS MOVING INTO HOT/DEEPLY-MIXED
BOUNDARY LAYER IN SUPPORT OF DAMAGING GUST THREAT FOR ANOTHER COUPLE
HOURS. 

CONVECTION FARTHER N ACROSS SERN KS AND MO/AR BORDER REGION IS
OCCURRING IN REGIME OF FAVORABLE ELEVATED BUOYANCY -- I.E. MUCAPE
1500-3000 J/KG -- AND 40-45 KT EFFECTIVE SHEAR.  THIS BUOYANCY WILL
DIMINISH SOMEWHAT WITH SEWD EXTENT...DEEPER OVER OUTFLOW AIR FROM
EARLIER CONVECTION FARTHER S...HOWEVER WAA AND ISENTROPIC ASCENT TO
LFC ALSO ARE POSSIBLE AS LLJ INCREASES ATOP THAT AIR MASS.  LARGE
HAIL IS POSSIBLE...ALONG WITH OCNL STG-SVR GUSTS WHERE MOST INTENSE
DOWNDRAFTS ACCELERATING THROUGH RELATIVELY DRY SUBCLOUD LAYER THEN
CAN PENETRATE SHALLOW LAYER OF HIGH CINH NEAR SFC.  CONVECTION OVER
CENTRAL AR ALSO MAY PRODUCE ISOLATED DAMAGING GUSTS AS ITS COLD POOL
IMPINGES UPON FAVORABLE MOIST AIR MASS OVER DELTA REGION...ALTHOUGH
DEEP-LAYER SHEAR IS RELATIVELY WEAK IN THAT AREA.

..EDWARDS.. 08/09/2011

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

ATTN...WFO...MEG...LZK...SGF...SHV...TSA...ICT...OUN...

LAT...LON   35119983 36199802 36649670 37649583 37639465 36449243
            34539065 33959376 34779574 34409758 34509881 35119983

Mesoscale Discussions in Oklahoma, 2011Mesoscale Discussions in Arkansas, 2011Mesoscale Discussions in Kansas, 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.