SPC AC 231630
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT SUN MAY 23 2010
VALID 231630Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER MS VALLEY
THROUGH THE CNTRL PLAINS INTO THE SRN HIGH PLAINS...
...SYNOPSIS...
THE PRIMARY FEATURE OF INTEREST THIS PERIOD IS A STRONG MID AND
UPPER-LEVEL LOW CURRENTLY DIGGING SEWD OVER CA/NV. THIS SYSTEM WILL
BEGIN TO TURN EWD LATER TODAY PRIOR TO ACCELERATING NEWD INTO THE
FOUR CORNERS REGION TONIGHT AS MID/HIGH-LEVEL JET STREAKS ROUND THE
TROUGH BASE AND DEVELOP DOWNSTREAM OVER THE ROCKIES. THIS EVOLUTION
WILL RESULT IN A CORRIDOR OF SIGNIFICANT HEIGHT FALLS/DYNAMIC
FORCING FOR ASCENT SPREADING EWD/NEWD FROM THE LOWER CO VALLEY INTO
THE CNTRL/SRN ROCKIES.
AT THE SURFACE...CURRENT MESOANALYSIS SHOWS PRIMARY SYNOPTIC FRONT
EXTENDING FROM CNTRL MN SWWD THROUGH THE MID MO VALLEY INTO THE SRN
HIGH PLAINS AND SRN ROCKIES. THE NRN PORTION OF THIS BOUNDARY WILL
SHIFT SLOWLY EWD TODAY GRADUALLY WEAKENING WITH TIME BENEATH
BUILDING MIDLEVEL HEIGHTS. MEANWHILE...THE SWRN EXTENSION OF THIS
FRONT WILL RETREAT NWD THROUGH THE CNTRL PLAINS IN RESPONSE TO LEE
CYCLOGENESIS OVER ERN CO LATER TODAY INTO TONIGHT. AS THIS
OCCURS...A LEE TROUGH/DRY LINE WILL BE ENHANCED OVER THE HIGH
PLAINS...ALLOWING FOR THE WWD/NWWD ADVECTION OF A MOIST BOUNDARY
LAYER INTO THE HIGH PLAINS REGION.
...UPPER MS VALLEY TODAY...
12Z MODEL GUIDANCE CONTINUES TO SUGGEST THAT DIURNAL STORM
DEVELOPMENT WILL BE POSSIBLE ALONG THE WEAKENING COLD FRONT TODAY
WITHIN A MOIST AND MODERATELY UNSTABLE ENVIRONMENT BASED ON 12Z MPX
SOUNDING. FACTORS POTENTIALLY LIMITING A MORE ROBUST SEVERE WEATHER
THREAT APPEAR TO BE RISING MIDLEVEL HEIGHTS ACROSS THE REGION AND
THE PRESENCE OF WIDESPREAD LOW CLOUDS WHICH COULD LIMIT THE
DEVELOPMENT OF STRONGER AIR MASS DESTABILIZATION. NONETHELESS...THE
PRESENCE OF 30-40 KT DEEP...SWLY SHEAR AND THE MOIST BOUNDARY LAYER
MAY YIELD A FEW SEVERE STORMS/CLUSTERS CAPABLE OF MAINLY DAMAGING
WINDS AND HAIL.
...CNTRL/SRN HIGH PLAINS THIS AFTERNOON AND TONIGHT...
12Z OBSERVED SOUNDINGS INDICATE THE PRESENCE OF A STRONG CAP
ASSOCIATED WITH AN ESTABLISHED EML OVER THE REGION. STEEP MIDLEVEL
LAPSE RATES ASSOCIATED WITH THE EML...BOUNDARY LAYER DEW POINTS IN
THE 60S AND DIABATIC HEATING WILL CONTRIBUTE TO A MODERATE TO
STRONGLY UNSTABLE WARM SECTOR AIR MASS TODAY WITH MLCAPE OF
2000-3000 J/KG.
GIVEN THE TENDENCY FOR SLIGHT MIDLEVEL HEIGHT RISES/RIDGING IN
ADVANCE OF THE SWRN U.S. SYSTEM...IT APPEARS THAT THE CAP MAY
SUPPRESS SURFACE-BASED STORM INITIATION THROUGH MUCH OF THE
AFTERNOON. BY 24/00Z THE COMBINATION OF NEUTRAL TO WEAK HEIGHT
FALLS COUPLED WITH THE INITIAL DEVELOPMENT OF A 50+ KT LLJ SUGGEST
AN INCREASED LIKELIHOOD OF STORM FORMATION ALONG THE RETREATING WARM
FRONT ACROSS WRN KS/ERN CO...AND PERHAPS SWD ALONG THE LEE
TROUGH/RETREATING DRY LINE.
THE PRESENCE OF 45-55 KT SWLY FLOW ACROSS THE HIGH PLAINS WILL
RESULT IN SUFFICIENT DEEP-LAYER SHEAR FOR SUPERCELLS CAPABLE OF
LARGE HAIL THROUGH THE DIURNAL HEATING CYCLE INTO TONIGHT.
MOREOVER...INITIALLY VEERED LOW-LEVEL FLOW WILL BACK AND
STRENGTHEN...PARTICULARLY THIS EVENING...SUGGESTING AN INCREASED
THREAT FOR TORNADOES WITH ANY SURFACE-BASED SUPERCELLS THAT CAN
BECOME ESTABLISHED.
STRONG-SEVERE TSTMS ARE EXPECTED TO INCREASE IN COVERAGE TONIGHT
ALONG THE RETREATING WARM FRONT FROM NERN CO/NWRN KS THROUGH NEB/ERN
WY INTO SD. LARGE HAIL WILL BE THE PRIMARY HAZARD WITH THESE
STORMS...THOUGH A TORNADO OR TWO WILL REMAIN POSSIBLE WITH ANY
SUPERCELLS THAT CAN REMAIN MORE ISOLATED.
...CAROLINAS TODAY...
12Z UPPER-AIR ANALYSIS SHOWED A POCKET OF RELATIVELY COOL MIDLEVEL
TEMPERATURES /I.E. -11 TO -14 C AT 500 MB/ ASSOCIATED WITH A
WELL-DEFINED VORTICITY MAXIMUM SLOWLY TRANSLATING SWD INTO THE
REGION FROM WV/VA. CLOUD SHIELD ASSOCIATED WITH ONGOING TSTM
COMPLEX OVER ERN NC MAY LOCALLY INHIBIT DAYTIME HEATING AND AIR MASS
DESTABILIZATION. ELSEWHERE...STRONG DIABATIC HEATING...DEW POINTS
IN THE 60S AND MIDLEVEL COOLING WILL CONTRIBUTE TO A MODERATELY
UNSTABLE AIR MASS LATER TODAY WITH MLCAPE OF 1000-2000 J/KG.
VERTICAL SHEAR WILL REMAIN RELATIVELY WEAK...THOUGH THE DEGREE OF
INSTABILITY AND INCREASED FORCING FOR ASCENT ASSOCIATED WITH THE
UPPER SYSTEM MAY FOSTER ISOLATED SEVERE STORMS CAPABLE OF STRONG
WIND GUSTS AND PERHAPS SOME HAIL.
..MEAD/HURLBUT.. 05/23/2010
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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