SPC AC 020540
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1240 AM CDT SAT MAY 02 2009
VALID 021200Z - 031200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN PLAINS EWD ACROSS
THE TN VLY INTO THE CAROLINAS/SRN VA...
...SYNOPSIS...
SPLIT UPR FLOW REGIME WILL CONTINUE INTO SATURDAY AND FEATURE A DEEP
TROUGH OVER ERN CANADA AND NERN STATES AND ACROSS THE N PACIFIC
BASIN. ACTIVE SRN BRANCH WILL CONTINUE FROM THE SRN ROCKIES ACROSS
THE SRN PLNS AND INTO THE CAROLINAS. EMBEDDED CONVECTIVELY ENHANCED
DISTURBANCES WILL BE CARRIED ALONG WITHIN THIS JET. A SYNOPTIC
SCALE WAVE...NOW OVER THE SRN GRT BASIN...IS PROGGED TO MOVE INTO
OK/TX SATURDAY NIGHT.
IN THE LWR LEVELS...A CDFNT WILL SLOWLY SETTLE SEWD INTO VA...TN...
ARKLATEX AND THE SRN HIGH PLNS BY SATURDAY NIGHT. PRE-FRONTAL
MYRIAD OF OUTFLOW BOUNDARIES WILL EXIST FROM THE CAROLINAS INTO THE
TN VLY...AND ACROSS NRN MS...SRN AR AND NCNTRL TX. MEANWHILE...A
DRYLINE WILL MIX EWD TO THE CNTRL/ERN EDWARDS PLATEAU.
...SRN PLNS TO THE MID-SOUTH...
TRAILING PORTION OF THE MCS WILL BE ONGOING AT 12Z ACROSS ERN/CNTRL
AR WITH ADDITIONAL WIDESPREAD ELEVATED STORMS UPSTREAM ACROSS
CNTRL/ERN OK ALONG NOSE OF A WEAK VEERING LLJ. FORWARD FLANK OF THE
MCS MAY INCREASE IN INTENSITY AS IT MOVES TOWARD NRN/CNTRL MS DURING
THE AFTN WITH DMGG WINDS/HAIL THREATS.
HIGHER SVR POTENTIAL WILL LIKELY EVOLVE SATURDAY AFTN/EVE UPSTREAM
ACROSS THE ARKLATEX...NCNTRL TX SWWD TO THE TX HILL COUNTRY. TSTMS
WILL READILY FORM ALONG THE TRAILING OUTFLOW BOUNDARY AND CDFNT OVER
CNTRL/SRN AR AND SERN OK BY EARLY AFTN...THEN GRADUALLY BACKBUILD
SWWD THROUGH NCNTRL/NERN TX AND PORTIONS OF THE HILL COUNTRY BY LATE
AFTN AS SBCINH ERODES AND THE SYNOPTIC SCALE WAVE ARRIVES.
COMBINATION OF MID-LVL LAPSE RATES OF 7-7.5 C/KM AND RICH LLVL
MOISTURE WILL RESULT IN MLCAPES RANGING FROM 2000 J/KG IN SRN AR TO
OVER 3500 J/KG OVER THE HILL COUNTRY. ARRIVAL OF A 60-65 KT WLY
MID-LVL JET ASSOCD WITH THE INCOMING WAVE WILL BOOST VERTICAL SHEAR
MORE THAN SUFFICIENT FOR SUPERCELLS. CONVECTIVE MODE WILL PROBABLY
TREND TOWARD A MIXED MODE OF ROTATING STRUCTURES AND LINEAR
MODES/BOWS ACROSS THE ARKLATEX REGION WHERE DMGG WINDS/LARGE HAIL
AND A COUPLE OF TORNADOES WILL BE LIKELY. FARTHER S...DISCRETE
MODES WILL BE FAVORED THE LONGEST AS THE NUMBER OF STORMS IS
MODULATED BY STRENGTH OF THE EML. THESE STORMS WILL BE CAPABLE OF
VERY LARGE HAIL AND DMGG WINDS. EARLY LIFE CYCLE TORNADOES WILL BE
POSSIBLE WITH THESE STORMS LATE AFTN/EARLY EVE.
FINALLY...TSTMS THAT INITIATE ACROSS THE MOUNTAINS OF NERN MEXICO
WILL ATTEMPT TO MAINTAIN CHARACTER AS THEY APCH THE RIO GRANDE VLY
IN SCNTRL TX BY NIGHTFALL. STRONGER CAP IN THE LWR ELEVATIONS MAY
RESULT IN A DEMISE OF THE STORMS BEFORE REACHING THE U.S.
BUT...FAVORED WLY FLOW AND WEAK HEIGHT FALLS MAY MAINTAIN STORMS
LONGER THAN USUAL AND LOW SVR PROBABILITIES HAVE BEEN MAINTAINED
ACROSS THIS REGION. DMGG WINDS/HAIL WOULD BE THE PRIMARY THREATS.
...TN VLY TO VA/CAROLINAS...
MCV WAS ORGANIZING OVER ERN AR AT 06Z AND WILL TRANSLATE ACROSS THE
TN VLY TO THE SRN APLCNS BY SATURDAY NIGHT. THIS FEATURE WILL
ENHANCE DIURNAL TSTM DEVELOPMENT BOTH ALONG THE CDFNT AND INVOF
RESIDUAL OUTFLOW BOUNDARIES ACROSS MIDDLE/ERN TN...SRN VA...PARTS OF
THE CAROLINAS...AND NRN SECTIONS OF AL/GA. ENHANCED FLOW ALONG SRN
PERIPHERY OF THE MCV AND CLOSE PROXIMITY OF STRONGER WLYS LOCATED
OVER THE MID-ATLANTIC STATES WILL CONTRIBUTE TO SOME STORM
ORGANIZATION...MAINLY IN THE FORM OF FORWARD PROPAGATING BOWS WITH
DMGG WINDS AND LARGE HAIL. AT THIS POINT...IT IS VERY DIFFICULT TO
DELINEATE ANY POSSIBLE ENHANCED CORRIDORS/HIGHER SVR PROBABILITIES
WITHIN THE OTHERWISE BROAD CATEGORICAL SLGT RISK.
..RACY/HURLBUT.. 05/02/2009
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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