Severe Thunderstorm Warning 7, NWS Phoenix, AZ

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
250 PM MST TUE JUL 6 1999

.SYNOPSIS...
HIGH PRESSURE ALOFT WILL REMAIN OVER THE COLORADO AND 4 CORNERS AREA
THROUGH THIS WEEK. THIS WILL KEEP A MOIST SOUTHEAST TO EASTERLY FLOW
OVER THE REGION WHICH WILL SPREAD THE MOISTURE WESTWARD. AS A RESULT
SKIES WILL REMAIN PARTLY CLOUDY OVER THE REGION WITH SCATTERED
AFTERNOON AND EVENING THUNDERSTORMS IN SOUTH CENTRAL ARIZONA BECOMING
ISOLATED IN SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA.

.DISCUSSION...
MODELS KEEP UPPER HIGH OVER COLORADO / 4 CORNERS AREA FOR NEXT FEW
DAYS. THIS KEEPS MOIST SOUTHEAST TO EAST FLOW OVER REGION. SATELLITE
PHOTOS SHOW THAT MOISTURE HAS ALREADY SPREAD INTO SW AZ AND PORTIONS
OF SE CA TODAY. IN ADDITION...A 4,000 FT. DEEP GULF SURGE OCCURRED
INT0 YUMA TODAY. MODELS SHOW COUPLE VORMAXS OVER THE NORTHERN GULF
WHICH MODELS TAKE A PIECE OF AND ROTATE INTO THE JOSHUA TREE AREA
TONIGHT/WEDNESDAY WITH SOME PVA EXTENDING UP INTO SW/SOUTH CENTRAL
AZ. THIS SHOULD HELP TO DEVELOP A THUNDERSTORMS TONIGHT OVER CENTRAL
DESERTS AND POSSIBLY ISOLATED IN SW AZ/SE CA AREA. ALTHOUGH AIRMASS
STILL NOT THAT UNSTABLE OVER THE WESTERN...BUT UNSTABLE OVER THE EAST
PORTION OF CWA. SOME THUNDERSTORMS POSSIBLY SEVERE OVER SOUTHEAST AZ
AND CENTRAL DESERTS UNTIL 03Z TONIGHT. OTHERWISE...SCATTERED
AFTERNOON/ EVENING THUNDERSTORMS SOUTH CENTRAL AZ NEXT FEW DAYS AND
ISOLATED IN WESTERN CWA ESPECIALLY WEDNESDAY/THURSDAY. THUNDERSTORMS
OVER SOUTH CENTRAL AZ WILL BE PROPAGATING WESTWARD INTO THE CENTRAL
DESERTS WITH THE EASTERLY FLOW ALOFT. 12Z PHX SOUNDING REMAINS AN
INVERTED V FOR GUSTY WINDS WITH THE STORMS. MRF EXTENDED KEEP UPPER
HIGH NORTH OF REGION FOR CONTINUED MOIST EASTERLY FLOW FOR LITTLE
CHANGE IN CURRENT PATTERN. UK MODEL HOWEVER SHIFTS HIGH CENTER TO
VICINITY LAS BY WEEKEND WHICH...IF IT OCCURS...WOULD BRING STORMS
DOWN OFF RIM INTO CENTRAL DESERTS RATHER THAN FROM THE EAST.

SEE SEL7 FOR SEVERE THUNDERSTORM WATCH BOX. DKS