Saturday, October 6, 2007

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 062000
SWODY1
SPC AC 061958

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT SAT OCT 06 2007

VALID 062000Z - 071200Z

..THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT FROM
PARTS OF THE UPPER MS VALLEY SWWD INTO CNTRL HIGH PLAINS...

..UPPER MS VALLEY INTO CNTRL HIGH PLAINS...

EARLY AFTERNOON MESOANALYSIS SHOWED SURFACE LOW NEAR HON ALONG COLD
FRONT STRETCHING FROM CNTRL ND SWWD INTO THE NEB PNHDL. A WARM
FRONT OR DIFFERENTIAL HEATING BOUNDARY WAS ALSO ANALYZED FROM
INTERSECTION WITH COLD FRONT OVER NERN SD ENEWD INTO NRN PARTS OF
MN/WI. 12Z REGIONAL SOUNDINGS SAMPLED A RELATIVELY STRONG CAP OVER
THE NRN AND CNTRL PLAINS WHICH IS EXPECTED TO LIMIT SURFACE-BASED
DEVELOPMENT ACROSS NRN PORTIONS OF SLIGHT RISK AREA THROUGH MUCH OF
THE AFTERNOON.

FARTHER SW...TEMPERATURES HAVE WARMED INTO THE UPPER 80S TO
LOWER/MID 90S OVER WRN NEB INTO S-CNTRL SD WHERE RECENT VISIBLE
SATELLITE IMAGERY SHOWS GROWING CUMULUS CONVECTION ALONG COLD FRONT
FROM AIA TO VTN TO 9V9. AMBIENT BOUNDARY LAYER IS CONSIDERABLY
DRIER THAN POINTS TO THE NE WITH DEWPOINTS COMMONLY IN THE 50S.
HOWEVER...THIS STRONG HEATING AND THE PRESENCE OF STEEP LAPSE RATES
ARE CONTRIBUTING TO MODERATE INSTABILITY WITH SBCAPES OF 1000-2000
J/KG. 40-45 KT OF DEEP LAYER SHEAR COUPLED WITH THE STEEP LAPSE
RATES AND DEEP BOUNDARY LAYER MIXING SUGGEST THE POTENTIAL FOR A
ISOLATED/SCATTERED SEVERE STORMS CAPABLE OF DAMAGING WINDS AND
PERHAPS SOME HAIL.

ADDITIONAL STORMS ARE LIKELY TO DEVELOP NEWD ALONG OR PERHAPS IN
IMMEDIATE POST-FRONTAL AIR MASS FROM CNTRL/NERN SD INTO ERN ND AND
WRN MN LATE THIS AFTERNOON INTO THIS EVENING. THE PRIMARY
UNCERTAINTY IS WHETHER STORMS WILL BE ABLE TO DEVELOP ALONG FRONT
WITHIN MODERATELY UNSTABLE /MLCAPES OF 2000-2500 J PER KG/ AND
MODERATELY SHEARED ENVIRONMENT. SHOULD THIS OCCUR...POTENTIAL WILL
EXIST FOR SUPERCELLS IN ADDITION TO LINEAR STRUCTURES WITH A THREAT
OF DAMAGING WINDS...LARGE HAIL AND POSSIBLY A TORNADO OR TWO. THE
MORE LIKELY SCENARIO APPEARS TO BE STORMS DEVELOPING IN ANAFRONTAL
FLOW REGIME W OF SURFACE FRONT WITH HAIL BEING THE PRIMARY SEVERE
WEATHER HAZARD.

..SRN HIGH PLAINS...

STRONG DIABATIC HEATING IS OCCURRING TODAY IN ADVANCE OF LEE
TROUGH/PACIFIC COLD FRONT FROM ERN NM INTO WRN TX WHERE TEMPERATURES
HAVE WARMED THROUGH THE 80S TO AROUND 90 F AS OF 19Z...CONTRIBUTING
TO SBCAPES OF 1000-1500 J/KG. CURRENT TUCUMCARI NM PROFILER IS
OBSERVING DEEP SWLY TROPOSPHERIC FLOW WITH 25-30 KT OF DEEP LAYER
VERTICAL SHEAR. GIVEN THE MODERATE INSTABILITY AND MODEST
SHEAR...POTENTIAL WILL EXIST FOR ISOLATED STRONG TO MARGINALLY
SEVERE MULTICELL STORMS CAPABLE OF LOCALLY STRONG WIND GUSTS AND
PERHAPS SOME HAIL.

..UPSTATE NY INTO WRN NEW ENGLAND...

CLUSTERS OF TSTMS ARE INCREASING IN COVERAGE THIS AFTERNOON TO THE S
OF BACKDOOR COLD FRONT WITHIN THERMODYNAMIC ENVIRONMENT
CHARACTERIZED BY STEEP LOW-LEVEL LAPSE RATES AND SBCAPES OF
1000-1500 J/KG. WHILE DEEP LAYER VERTICAL SHEAR IS NOT PARTICULARLY
STRONG /I.E. EFFECTIVE BULK SHEARS OF 25-30 KT/...LARGELY
UNIDIRECTIONAL WLY/NWLY TROPOSPHERIC FLOW MAY PROMOTE DOWNSHEAR COLD
POOL ORGANIZATION/ELONGATION WITH A THREAT OF LOCALLY DAMAGING
WINDS. SOME HAIL IS ALSO POSSIBLE WITH THE STRONGER CELLS. THIS
MARGINAL SEVERE THREAT IS EXPECTED TO CONTINUE INTO THE EARLY/MID
EVENING...PRIOR TO COOLING/STABILIZATION OF BOUNDARY LAYER.

FOR ADDITIONAL SHORT TERM GUIDANCE...PLEASE SEE MCD 2060.

.MEAD.. 10/06/2007

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