SPC AC 040533
DAY 1 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
1233 AM CDT SAT JUL 04 2009
VALID 041200Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE LWR OH/MID-MS VLY
WWD INTO THE SRN PLNS...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE CNTRL/NRN HIGH
PLAINS...
CORRECTED FOR DAY OF WEEK
...SYNOPSIS...
QSTNRY UPR LOW OVER ONT/QUE WILL PERSIST INTO SATURDAY AS AN ASSOCD
UPR TROUGH WEAKENS ALONG THE ERN SEABOARD. IN ITS WAKE...WNWLY UPR
FLOW REGIME WILL EXIST FROM THE NRN GRT BASIN TO THE MID-ATLC
CST...ALONG THE PERIPHERY OF A SUBTROPICAL HIGH. AT THE SFC...A LOW
WILL MOVE FROM ERN KS INTO THE LWR OH VLY BY SATURDAY NIGHT. A
TRAILING CDFNT WILL SETTLE SWD INTO THE MID-SOUTH AND PARTS OF THE
SRN PLNS WHILE A WRMFNT DEVELOPS NEWD THROUGH THE UPR OH VLY.
...MO/AR OZARKS EWD INTO THE LWR OH VLY...
SVRL TSTM CLUSTERS...MOSTLY ELEVATED AND SUB-SVR...WILL BE ONGOING
AT 12Z SATURDAY FROM PARTS OF ERN KS INTO CNTRL IL. STORMS WILL BE
ENHANCED BY CONSIDERABLE LOW/MID-LVL THETA-E ADVECTION ALONG/N OF
THE SFC LOW/WRMFNT. ACTIVITY WILL CONTINUE EWD INTO THE MIDWEST
THROUGH THE DAY.
PRIMARY SVR THREATS SHOULD EVOLVE SATURDAY AFTN FROM THE LWR OH VLY
WWD INTO THE MO/AR OZARKS. MODELS ARE IN EXCELLENT AGREEMENT
TRACKING THE CNTRL ROCKIES MID-LVL SHORTWAVE TROUGH TO THE MID-MS
VLY BY LATE AFTN. INFLUENCE OF THIS WAVE/ASCENT AND STRONG HEATING
ALONG/S OF OUTFLOW BOUNDARIES/CDFNT WILL CONTRIBUTE TO STRENGTHENING
STORMS. DEEP LAYER SHEAR OF 45-50 KTS WILL AID IN STORM
ORGANIZATION/SUPERCELLS WITH LARGE HAIL AND DMGG WIND GUSTS. ISOLD
TORNADOES MAY ALSO OCCUR...PRIMARILY FROM SERN MO INTO SRN IL NEAR
THE TRACK OF THE SFC LOW. ACTIVITY SHOULD EVOLVE INTO SMALL SCALE
BOWS AND WEAKEN AS THEY TRACK INTO CNTRL KY/MIDDLE TN AFTER ABOUT
03Z SUNDAY.
...SRN PLNS...
STRONG HEATING IS EXPECTED ALONG/S OF ADVANCING CDFNT AND OUTFLOW
BOUNDARIES SATURDAY AFTN. SFC DEW POINTS UPR 60S/LWR 70S COMBINED
WITH VERY HOT TEMPERATURES WILL PRODUCE MLCAPES 2000 J/KG FROM THE
TX S PLNS EWD INTO OK. SUSTAINED LLVL CONVERGENCE INVOF THE
BOUNDARIES WILL YIELD WDLY SCT ROBUST TSTM DEVELOPMENT...INITIALLY
ALONG OUTFLOW BOUNDARIES IN CNTRL/ERN OK...THEN ALONG THE CDFNT FROM
WRN OK/TX S PLNS LATER. THOUGH DEEP LAYER SHEAR WILL BE
COMPARATIVELY LESS ACROSS THE REGION THAN AT POINTS FARTHER
NE...INVERTED-V SUB-CLOUD THERMODYNAMIC PROFILES AND MID-LVL DRY AIR
WILL AUGMENT DOWNDRAFTS RESULTING IN DMGG WIND GUSTS. THE STRONGEST
OF STORMS MAY ALSO PRODUCE LARGE HAIL...THOUGH TROPOSPHERIC
TEMPERATURES WILL BE RATHER WARM. SVR THREATS WILL CONTINUE SWD
INVOF BOUNDARIES DURING THE EVENING.
...ERN CO/WY...
AFTER EARLY DAY LOW CLOUDS...DIURNAL UPSLOPE WILL COMMENCE SATURDAY
AFTN AMIDST INCREASING HEATING/MAINTENANCE OF LLVL MOISTURE. WEAK
PV-ANAMOLY OVER NRN CA IS EXPECTED TO AID IN HIGHER TERRAIN STORMS
BY LATE SATURDAY AFTN FROM ERN CO NWD INTO WY. REGION WILL REMAIN
WITHIN A MODEST BELT OF WLYS WITH DEEP LAYER SHEAR SUFFICIENT FOR
SUPERCELLS WITH LARGE HAIL. STORM MOTION IS EXPECTED TO BE SLOW
SSEWD WITH THE ADJACENT HIGH PLNS SVR THREATS /SVR HAIL-WIND GUSTS/
INCREASING DURING THE EVENING.
..RACY.. 07/04/2009
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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