Severe Thunderstorm Warning 79, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
200 PM MST THU AUG 21 2003

.SYNOPSIS...HIGH PRESSURE OVER THE CENTRAL AND SOUTHERN ROCKIES
WILL MAINTAIN A FAVORABLE MOIST FLOW FOR SCATTERED SHOWERS AND
THUNDERSTORMS INTO NEXT WEEK. IMPULSES IN THE SOUTHERLY AND EASTERLY
FLOW WILL ENHANCE THUNDERSTORMS FROM TIME TO TIME.

.DISCUSSION...DEBRIS FROM LARGE COMPLEX THROUGH NORTHERN SONORA
OVERNIGHT HAS SLOWED HEATING AND DELAYED CONVECTION ACROSS MUCH OF
PIMA AND SANTA CRUZ COUNTIES. BETTER HEATING TO OUR EAST HAS SEEN
NORMAL DEVELOPMENT OF STORMS OVER EASTERN MOUNTAINS EARLY THIS
AFTERNOON. BORDER AREAS WILL ONCE AGAIN BE VULNERABLE TO SUSTAINED
CONVECTION OVERNIGHT FROM POSSIBLE COMPLEX IN NORTHERN MEXICO.

AS THE HIGH CONTINUES TO CONSOLIDATE TO OUR NORTHEAST...WE WILL PICK
UP A MORE FAVORABLE EASTERLY COMPONENT TO ADD TO OUR CURRENT
SOUTHERLY FLOW AT MOST LEVELS OVER THE NEXT 12 HRS. INITIAL
DEVELOPMENT AND MOVEMENT OF STORM OVER THE CHIRICAHUAS SHOWS WE ARE
ALREADY PICKING UP SOME KIND OF EASTERLY COMPONENT TO OUR FLOW THIS
AFTERNOON. BETTER SHEAR WOULDNT HURT. WAVE DIGGING THROUGH TEXAS
SHOULD WRAP UNDER THE HIGH AND INTO OUR GENERAL VICINITY LATE FRIDAY
INTO EARLY SATURDAY...COULD MAKE FOR A BUSY TIME. AFTER
THAT...ENOUGH FUEL FOR A STANDARD THUNDERSTORM FORECAST FOR LATE
AUGUST. M

.TWC...NONE.

AZZ019-029>035-221400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1155 AM MST THU AUG 21 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

SYNOPSIS...HIGH PRESSURE CENTERED OVER THE CENTRAL AND SOUTHERN
ROCKIES WILL GRADUALLY SHIFT EAST INTO THE CENTRAL AND SOUTHERN
PLAINS BY THE MIDDLE OF NEXT WEEK. THIS WILL MAINTAIN A FAVORABLE
FLOW FOR AFTERNOON AND EVENING THUNDERSTORMS ACROSS SOUTHEAST
ARIZONA. AS THE HIGH MOVES EAST...THE MID AND UPPER LEVEL FLOW WILL
SHIFT FROM OUR CURRENT SOUTHERLY DIRECTION TO MORE OF AN EASTERLY
COMPONENT.

DISCUSSION....A LARGE COMPLEX DEVELOPED OVER SOUTHERN SONORA LAST
NIGHT AND MOVED NORTH INTO NORTHERN SONORA EARLY THIS MORNING. THIS
FEATURE DECAYED QUICKLY THIS MORNING AS IT APPROACHED THE ARIZONA
BORDER...HOWEVER DEBRIS CLOUDS AND SUBSIDENT FIELD FROM THIS FEATURE
ARE CURRENTLY SHIFTING NORTH INTO SOUTH CENTRAL PORTIONS OF THE
FORECAST AREA.

THE 12Z KTUS SOUNDING INDICATES PLENTY OF MOISTURE IN PLACE TODAY...
WITH A PRECIPITABLE WATER VALUE OF 1.5 INCHES. IN ADDITION...
SOUNDING IS FAIRLY UNSTABLE WITH UNMODIFIED LIFTED INDEX AND
POSITIVE ENERGY  VALUES OF -5.7 AND 2143 J/KG RESPECTIVELY. THESE
VALUES ARE A LITTLE MORE UNSTABLE THAN YESTERDAYS VALUES...HOWEVER
THIS MORNINGS SOUNDING INDICATES A WEAK CAP CENTERED AROUND 400 MB.
ALTHOUGH THIS WILL NOT SHUT DOWN STORM DEVELOPMENT TODAY...IT SHOULD
SLOW DOWN THE INITIAL DEVELOPMENT...WITH MOST OF THE ACTIVITY
OCCURRING DURING THE LATE AFTERNOON AND EARLY EVENING HOURS TODAY.

GIVEN REMNANTS OF COMPLEX SHIFTING NORTH AND SOUNDING DATA...EXPECT
MOST FAVORED AREAS FOR DEVELOPMENT TO BE OVER NORTHEASTERN (NORTHERN
COCHISE...GRAHAM AND GREENLEE COUNTIES) AND WESTERN (CENTRAL AND
WESTERN PIMA COUNTY) PORTIONS OF THE FORECAST AREA WHERE THE
STRONGEST SOLAR INSOLATION IS EXPECTED. ANY STORMS THAT DO FORM WILL
HAVE THE CAPABILITY OF PRODUCING HEAVY RAIN GIVEN THE AMOUNT OF
AVAILABLE MOISTURE. IN ADDITION...A FEW STORMS MAY POSSIBLY HAVE
STRONG WINDS DUE TO PRECIPITATION LOADING...ALTHOUGH HAIL IS NOT A
MAJOR CONCERN TODAY DUE TO RELATIVELY WARM TEMPERATURES ALOFT.

THE PROBABILITY OF ONE INCH OR GREATER RAINFALL AND SEVERE WEATHER
WILL BE SLIGHTLY ABOVE NORMAL FOR FAR WESTERN AND NORTHEASTERN
PORTIONS OF THE FORECAST AREA...AND SLIGHTLY BELOW NORMAL ACROSS
CENTRAL PORTIONS OF THE FORECAST AREA. MOVEMENT OF THE STORMS WILL
BE TO THE NORTH AT 10 TO 15 MPH.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

THE MODELS SUGGEST AN INCREASE IN THUNDERSTORM ACTIVITY FRIDAY AND
SATURDAY AFTERNOON AND EVENING...OTHERWISE A STANDARD AFTERNOON AND
EVENING THUNDERSTORM FORECAST IS EXPECTED SUNDAY INTO THE MIDDLE
PART OF NEXT WEEK. AS IS TYPICAL FOR THE END OF AUGUST...A FEW OF
THESE STORMS MAY BE ACCOMPANIED BY LOCALLY HEAVY RAIN AND/OR STRONG
GUSTY WINDS.

.SPOTTER INFORMATION STATEMENT...

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