Severe Thunderstorm Warning 89, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
945 AM MST TUE AUG 26 2003

.SYNOPSIS...ABUNDANT MOISTURE IN COMBINATION WITH DAYTIME HEATING
WILL PROVIDE ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THIS
AFTERNOON AND CONTINUE INTO TONIGHT. LOCALLY HEAVY RAINS WILL OCCUR
WITH THE STRONGER STORMS. THE POTENTIAL FOR HEAVY RAINFALL WILL
CONTINUE WEDNESDAY AS AMPLE MOISTURE IS MAINTAINED ACROSS THE AREA.

.DISCUSSION...VISIBLE SATELLITE IMAGERY INDICATED PARTLY CLOUDY
SKIES ACROSS SE AZ THIS MORNING WITH THE THICKEST CLOUDINESS OVER
NERN SECTIONS AND ACROSS FAR WRN PIMA COUNTY. DEWPOINTS WERE IN THE
LOWER-MID 60S F WHICH WERE ABOUT 3-7 DEGS F HIGHER VERSUS 24 HOURS
AGO. 26/12Z TUS SOUNDING WAS QUITE MOIST AS EVIDENCED IN PRECIP
WATER VALUE NEAR 1.60 INCH WHICH WAS AN INCREASE FROM ABOUT 1.45
INCH OF 25/12Z. SOUNDING WAS WEAKLY CAPPED AT H8 BUT WITH AMPLE
SUNSHINE PROVIDING DIFFERENTIAL HEATING WOULD EXPECT SHOWERS/
THUNDERSTORMS TO DEVELOP THIS AFTERNOON NEAR CENTRAL/ERN MOUNTAINS.
STORMS SHOULD MOVE WWD GIVEN THE 10-20 KT H7-H5 FLOW. FOR NOW WILL
MAINTAIN CURRENT FORECAST WHICH INDICATES SCATTERED AFTERNOON
THUNDERSTORMS WITH SHOWERS/THUNDERSTORMS LIKELY FROM TUS VICINITY
WWD TONIGHT. AM CONSIDERING FLASH FLOOD WATCH TONIGHT FOR ALL ZONES
EXCEPT 019/030/ERN 035 AND WILL COORDINATE WITH WFO/S PSR/FGZ LATER
THIS MORNING FOR ADDITIONAL INPUT. 26/12Z ETA INDICATES DEEP
MOISTURE TO REMAIN ACROSS SE AZ WED. THUS LIKELIHOOD FOR LOCALLY
HEAVY RAINS TO PERSIST AS INDICATED IN INHERITED FORECAST PACKAGE. A
VERY GRADUAL DECREASE IN MOISTURE PROGGED BEGINNING THUR WITH MORE
SIGNIFICANT DRYING INDICATED ESPECIALLY ACROSS NRN/WRN SECTIONS THIS
WEEKEND. WILL EVALUATE THIS NOTION FURTHER FOR AFTERNOON DISCUSSION.
NO CHANGES NECESSARY TO FORECASTS THIS UPDATE.  BF

.TWC...NONE.

AZZ019-029>035-271400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1210 PM MST TUE AUG 26 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

SYNOPSIS...HIGH PRESSURE ALOFT CENTERED TO OUR NORTH WILL BRING AN
EASTERLY FLOW ALOFT TODAY AND THEN MORE OF A SOUTHERLY DIRECTION ON
WEDNESDAY AS THE HIGH BEGINS TO SHIFT EAST. THERE WILL ALSO BE AN
INCREASE IN MOISTURE INTO WEDNESDAY FROM THE REMNANTS TO HURRICANE
IGNACIO...WHICH IS EXPECTED TO MOVE SLOWLY NORTHWEST UP THE BAJA
COAST. IN ADDITION...AN UPPER LEVEL INVERTED TROUGH ACROSS FAR WEST
TEXAS AND NEW MEXICO WILL SHIFT WESTWARD INTO THE REGION TONIGHT AND
WEDNESDAY. THE COMBINATION OF THESE FACTORS WILL BRING INCREASING
CHANCES OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON...CONTINUING
THROUGH TONIGHT AND INTO WEDNESDAY. HEAVY RAIN WILL BE POSSIBLE
DURING THIS TIME FRAME. THUS...A FLASH FLOOD WATCH HAS BEEN ISSUED
FOR A GOOD PORTION OF SOUTHEAST ARIZONA...STARTING THIS AFTERNOON
AND CONTINUING THROUGH TONIGHT AND INTO WEDNESDAY.

DISCUSSION...MANY FACTORS ARE COMING TOGETHER TODAY/TONIGHT AND EVEN
INTO WEDNESDAY THAT IS EXPECTED TO BRING A SIGNIFICANT ROUND OF
SHOWERS AND THUNDERSTORMS TO MOST OF SOUTHEAST ARIZONA DURING THIS
TIME FRAME. ABUNDANT MOISTURE CONTINUES IN PLACE...WITH AREA RAOBS
AND GOES PWAT IMAGERY INDICATING 1.2 TO 2.1 INCHES OF PRECIPITABLE
WATER ACROSS THE FORECAST AREA. IN ADDITION...MORNING SOUNDINGS ALSO
INDICATE MODERATE INSTABILITY VALUES...WITH AN UNMODIFIED LIFTED
INDEX OF MINUS 4.5 AND A POSITIVE ENERGY VALUE OF 1941 J/KG. IN
ADDITION...THE REMNANTS OF HURRICANE IGNACIO NEAR THE SOUTHERN TIP
OF BAJA CONTINUES TO MOVE VERY SLOWLY TO THE NORTHWEST...WITH
COPIOUS AMOUNTS OF MOISTURE BEING PUSHED NORTH OVER MEXICO AND INTO
SOUTHERN ARIZONA. AN INVERTED TROUGH TO OUR EAST IS FORECASTED TO
MOVE WEST INTO ARIZONA TONIGHT AND WEDNESDAY...WITH STRETCHING AND
DEFORMATION IN THE UPPER WIND FIELDS AHEAD OF THIS FEATURE AIDING
STORM DEVELOPMENT.

THE COMBINATION OF THESE FACTORS IS EXPECTED TO BRING A SIGNIFICANT
ROUND OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON/TONIGHT AND INTO
WEDNESDAY...WITH THE MAIN THREAT FOR HEAVY RAINS THAT MAY LEAD TO
FLASH FLOODING. THERE WILL ALSO BE A MINIMAL RISK FOR SEVERE WEATHER
ACROSS THE AREA MAINLY DURING THE AFTERNOON HOURS. THEREFORE...THE
CHANCE OF SEVERE THUNDERSTORMS WILL BE SLIGHTLY BELOW CLIMATOLOGY
TODAY AND TONIGHT. HOWEVER...THE CHANCE FOR GREATER THAN ONE INCH OF
RAINFALL TODAY AND TONIGHT WILL BE ABOVE CLIMATOLOGY...ESPECIALLY
WEST OF A LINE FROM SIERRA VISTA...TO WILLCOX...TO MAMMOTH...TO
WINKELMAN. THE MOVEMENT OF THE SHOWERS AND STORMS WILL BE TO THE
WEST AROUND 15 MPH.

A FLASH FLOOD WATCH IS IN EFFECT FROM 200 PM THIS AFTERNOON THROUGH
TONIGHT FOR THE FOLLOWING LOCATIONS...WESTERN COCHISE...SANTA
CRUZ...SOUTHEAST PINAL AND PIMA COUNTIES. THE WATCH INCLUDES THE
FOLLOWING CITIES...GREEN VALLEY...MARANA...NOGALES...ORO VALLEY...
SELLS...SIERRA VISTA...BISBEE...WILLCOX AND THE TUCSON METRO AREA

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

ON WEDNESDAY...MOISTURE FROM FORMER HURRICANE IGNACIO WILL CONTINUE
TO MOVE NORTH INTO THE REGION...KEEPING A VERY MOIST ATMOSPHERE IN
PLACE ACROSS SOUTHEAST ARIZONA. THE MAIN THREAT FROM THE STORMS THAT
DEVELOP ON WEDNESDAY WILL AGAIN BE HEAVY RAIN THAT MAY LEAD TO FLASH
FLOODING.

A FLASH FLOOD WATCH CONTINUES IN EFFECT WEDNESDAY FOR THE FOLLOWING
LOCATIONS...WESTERN COCHISE...SANTA CRUZ...SOUTHEAST PINAL AND PIMA
COUNTIES. THE WATCH INCLUDES THE FOLLOWING CITIES...GREEN VALLEY...
MARANA...NOGALES...ORO VALLEY...SELLS...SIERRA VISTA... BISBEE...
WILLCOX AND THE TUCSON METRO AREA

SCATTERED SHOWERS AND THUNDERSTORMS ARE STILL EXPECTED ACROSS
EASTERN PORTIONS OF SOUTHERN ARIZONA IN THE THURSDAY THROUGH MONDAY
TIME FRAME...WHILE SOME DRYING IS EXPECTED OVER FAR WESTERN PORTIONS
OF THE STATE OVER THE WEEKEND AS A DRIER SOUTHWEST FLOW ALOFT BEGINS
TO DEVELOP ALONG THE WEST COAST AND PUSH EASTWARD.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

FOR MORE INFORMATION...SEE THE LATEST WEATHER BULLETINS:
                                AWIPS ID        WMO ID
FLASH FLOOD WATCH               PHXFFATWC       WGUS65 KTWC

ZELL