Severe Thunderstorm Warning 17, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
230 PM MST FRI JUL 12 2002

.SYNOPSIS...HIGH PRESSURE OVER UTAH WILL KEEP DEEP EASTERLY FLOW
OVER THE REGION INTO THE WEEKEND. THIS WILL GUIDE A SERIES OF
DISTURBANCES OFF THE GULF OF MEXICO AND SOUTHERN PLAINS...LEADING TO
A DAILY RISK OF THUNDERSTORMS THROUGH EARLY NEXT WEEK.

.DISCUSSION...LITTLE BIT OF A DRY PUNCH PUSHING IN FROM THE THE
NORTHEAST EVIDENT ON WATER VAPOR IMAGERY AND GOES SOUNDER PW
ESTIMATES...BUT NOT ENOUGH TO INHIBIT CONVECTION OVER THE EAST
CENTRAL MOUNTAINS. OTHERWISE...PRECIPITABLE WATER VALUES IN THE 12Z
KTUS SOUNDING SIMILAR TO RECENT DAYS...IN THE 1.2 TO 1.3 INCH RANGE.
SURFACE DEWPTS HAVE AGAIN MIXED OUT TO THE LOWER 50S ACROSS THE AREA
THIS AFTERNOON. MAKES FOR A LOW SCATTERED MOUNTAIN / ISOLATED VALLEY
THUNDERSTORM DAY WITH ONE OR TWO POTENTIALLY SEVERE. WELL NEED TO
WATCH AS OUTFLOW COMES OFF THE RIM AS WELL.

NICE LITTLE COMPLEX OVER CENTRAL TO SOUTHERN SONORA FORMED OVERNIGHT
AND PUSHED OFF INTO THE GULF OF CALIFORNIA. SLIGHT TO MODERATE
PRESSURE DIFFERENTIAL DOWN THE GULF AS WELL (SEEMS TO BE FILLING IN
FAIRLY RAPIDLY TODAY THOUGH). LOOKING MORE AND MORE LIKE WELL SEE
A SURGE ENHANCEMENT THROUGH THE LOWER DESERTS OVER THE NEXT 36HRS AS
HINTED AT BY THE MESO-ETA. THIS WOULD BE ON TOP OF THE 10 TO 15KTS
UP TO 4K FT ALREADY EVIDENT ON THE YUMA VWP. WELL FOCUS ON SUNDAY
AND/OR SUNDAY NIGHT AS AN UP TIME FOR STORMS WITH MORE WIDESPREAD
CONVECTION. ON THE LARGER SCALE...POSITIONING OF THE HIGH CENTER BY
EARLY IN THE WEEK OPENS THE DOOR EVEN FURTHER FOR A DEEPER SOUTHERLY
FLOW. EXPECT HEAVIER RAINFALL RATES AS WE GET INTO THE DEEPER
MOISTURE. M

.TWC...NONE.

AZZ019-029>035-130700-

SOUTHEAST ARIZONA HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1150 AM MST FRI JUL 12 2002

.SYNOPSIS...SOUTHEAST ARIZONA WILL HAVE BELOW CLIMATOLOGICAL
PROBABILITIES FOR PRECIPITATION IN EXCESS OF ONE INCH...WITH THE
GREATEST CHANCE FOR HEAVY PRECIPITATION IN THE WESTERN DESERTS. THE
PROBABILITY FOR SEVERE THUNDERSTORMS WILL BE NEAR TO BELOW
CLIMATOLOGY.

.DISCUSSION...SATELLITE IMAGERY AND UPPER AIR DATA INDICATE DEEP
MOISTURE ACROSS ALL OF SOUTHERN ARIZONA...WITH THE BEST MOISTURE
OVER FAR WESTERN PIMA COUNTY. WITH NO SPECIFIC DISTURBANCE OR
TRIGGERING MECHANISM IN PLACE...THUNDERSTORM DEVELOPMENT WILL HAVE
TO RELY ON SOLAR HEATING TO DESTABILIZE THE ATMOSPHERE. THEREFORE...
THUNDERSTORMS WILL MAINLY BE CONFINED TO THE PERIOD BETWEEN THE MID
AFTERNOON AND EARLY EVENING HOURS.

SOME DRIER AIR IS NOTED OVER FAR WESTERN NEW MEXICO AND THIS IS
EXPECTED TO WORK INTO EASTERN PORTIONS OF SOUTHERN ARIZONA DURING
THE AFTERNOON HOURS. ALTHOUGH THIS WILL NOT INHIBIT THUNDERSTORM
DEVELOPMENT...IT WILL LESSEN THE CHANCES OF HEAVY PRECIPITATION WITH
THE STORMS THAT DO DEVELOP. THEREFORE...THE BEST CHANCES FOR STORMS
WITH GREATER THAN ONE-INCH POTENTIAL WILL BE OVER WESTERN PORTIONS
OF SOUTHERN ARIZONA. AS FOR THE SEVERE POTENTIAL...WITH NO SPECIFIC
TRIGGERING MECHANISM...THIS SHOULD LESSEN THE CHANCES OF SEVERE
STORMS. THEREFORE...THE PROBABILITY OF SEVERE THUNDERSTORMS WILL BE
NEAR TO BELOW CLIMATOLOGY TODAY.

THUNDERSTORM MOTION WILL BE TOWARDS THE SOUTHWEST AT 10 TO 15 MPH.