SWODY1
SPC AC 222059
DAY 1 CONVECTIVE OUTLOOK AMEND 1
NWS STORM PREDICTION CENTER NORMAN OK
0359 PM CDT SAT SEP 22 2007
VALID 222055Z - 231200Z
..THERE IS A SLGT RISK OF SVR TSTMS FOR AZ...
AMENDED FOR SLIGHT RISK UPGRADE IN AZ
..GRT BASIN/DESERT SW...
FOR SHORT TERM DISCUSSION...PLEASE SEE MESOSCALE DISCUSSION 2007 AND
SEVERE THUNDERSTORM WATCH 684.
UPR LOW WAS BEGINNING TO ACCELERATE NEWD ALONG THE SRN CA COAST THIS
AFTN. ENERGETIC WARM CONVEYOR WELL E OF THE LOW CENTER HAS BEEN
SHIFTING SLOWLY EWD ACROSS UT AND AZ AND WILL CONTINUE EWD TONIGHT
TOWARD THE ROCKIES. VWP FROM ICX/FSX INDICATE A DEEP AND STRONG SLY
FETCH WITH 45+ KT WINDS DOWN INTO THE 1-2 KM RANGE. BULK SHEAR WAS
SUFFICIENT FOR ORGANIZED STORMS...GIVEN ENOUGH BUOYANCY. PRIND THAT
STRONGER STORMS WILL FAVOR AREAS FROM EXTREME SRN UT SWD INTO AZ
WHERE UPSLOPE FLOW AND STRONGER HEATING COEXIST THIS AFTN.
OTHERWISE...STRONGER STORMS MIGHT EVOLVE LATER IN THE EVENING ALONG
WRN EDGE OF THE MOIST CONVEYOR AS COLD TEMPERATURES ALOFT BEGIN TO
ADVECT NEWD. DAMAGING WIND GUSTS AND HAIL WILL BE THE PRIMARY
THREATS. A BRIEF ISOLD TORNADO CANNOT BE RULED OUT... ESPECIALLY
ALONG/S OF THE HIGHER RIM COUNTRY WHERE LOCALIZED BACKING OF THE SFC
FLOW WILL EXIST.
..INTERIOR CNTRL/SRN FL...
WHILE THE PRIMARY SYNOPTIC DERIVED CONVECTION MOVES WWD AWAY FROM
THE FL WCOAST...ECOAST SEABREEZE CIRCULATION HAS BEEN IMPETUS FOR
STG TSTMS THIS AFTN. THESE STORMS WILL MIGRATE WWD INTO INTERIOR
CNTRL/SRN FL THROUGH THE EVENING. WEAK FLOW AND RELATIVELY WARM
TEMPERATURES ALOFT WILL PRECLUDE WIDESPREAD SVR WEATHER...BUT ISOLD
STORMS MAY YIELD MARGINALLY SVR HAIL AND/OR DMGG MICROBURSTS.
..CNTRL/UPSTATE NY...
NARROW RIBBON OF INSTABILITY HAS EVOLVED ALONG/AHEAD OF PRE-FRONTAL
CONFLUENCE ACROSS CNTRL/UPSTATE NY...WITH MLCAPES AROUND 500 J/KG.
SUFFICIENT CONVERGENCE AND APPARENT FORCING ALOFT HAS YIELD A FEW
SHOWERS AND TSTMS WILL REMAIN POSSIBLE THROUGH EARLY EVENING FROM
NRN NEW ENGLAND SWWD INTO NCNTRL PA. VWP AT BUF AND CXX SUGGEST
THAT SRN PERIPHERY OF STRONGER FLOW ALOFT WAS SKIRTING ACROSS THE
REGION...SUPPORTIVE FOR BRIEF INTENSIFICATION OF THE TSTMS.
INTENSITY SHOULD PEAK BEFORE 00Z WITH SUBSEQUENT DECREASE AFTER
DARK. ISOLD DMGG WIND GUSTS OR HAIL MAY ACCOMPANY STRONGER
STORMS...BUT OVERALL SVR THREAT APPEARS LIMITED.
.RACY/GUYER.. 09/22/2007
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