Severe Thunderstorm Warning 69, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
926 PM MST TUE AUG 12 2003

.SYNOPSIS...TEMPERATURES WILL FINALLY DROP BACK TO NEAR OR BELOW
SEASONAL NORMALS THE SECOND HALF OF THE WEEK AS AN UNUSUALLY STRONG
LOW PRESSURE SYSTEM MOVES WESTWARD FROM TEXAS INTO ARIZONA. AS IT
DOES...EXPECT A STRONG UPSWING IN THUNDERSTORM ACTIVITY AS WELL.

.DISCUSSION...A LITTLE MORE SHOWER AND THUNDERSTORM ACTIVITY THIS
AFTERNOON AND EVENING...MAINLY IN OUR EASTERN ZONES EAST OF TUCSON
AND NOGALES. THIS EARLIER ACTIVITY WAS NOW SWITCHING OVER TO A MORE
STRATIFORM TYPE RAIN WHICH WAS CONTINUING TO EXPAND IN AREAL
COVERAGE ACROSS GRAHAM...COCHISE AND EASTERN SANTA CRUZ COUNTIES.
LATEST RADAR IMAGERY INDICATED THAT THE NEW THUNDERSTORM DEVELOPMENT
WAS ALONG THE WESTERN EDGE OF THIS STRATIFORM RAIN AREA. EXPECT THIS
ACTIVITY TO SPREAD WESTWARD THE REST OF THIS EVENING AND
OVERNIGHT...WITH GENERALLY LIGHT TO MODERATE RAINFALL EXPECTED.
HOWEVER...WILL LIKELY SEE A FEW EMBEDDED THUNDERSTORMS WITH LOCALLY
HEAVY RAINFALL THROUGH AT LEAST 2 AM MST WED. OTHERWISE...EXPECTING
A FAIR AMOUNT OF DEBRIS CLOUDINESS TO LINGER INTO THE EARLY
MORNING HOURS WEDNESDAY. THIS CLOUDINESS SHOULD DISSIPATE RATHER
QUICKLY AS SUBSIDENCE ALOFT AHEAD OF THE APPROACHING SYSTEM MOVES
OVER THE REGION. THE TIMING SHOULD BE JUST RIGHT TO PROVIDE ENOUGH
SURFACE HEATING WEDNESDAY AFTERNOON TO SUPPORT THUNDERSTORMS. THE
UPPER LEVEL DYNAMICS ASSOCIATED WITH THE WESTWARD MOVING LOW
PRESSURE SYSTEM WILL ALSO AID IN FORCING AND ORGANIZING THE
THUNDERSTORM ACTIVITY TOMORROW AFTERNOON AND NIGHT. WEDNESDAY
THROUGH EARLY THURSDAY MORNING STILL LOOKS LIKE WIDESPREAD SHOWER
AND THUNDERSTORM ACTIVITY. BY THURSDAY AFTERNOON...MODELS SUGGESTED
THAT THE MAIN MOISTURE AXIS WILL HAVE SHIFTED FARTHER WEST. THIS
INDICATED THAT THE WESTERN PORTION OF OUR CWA WILL BE THE ACTIVITY
AREA THURSDAY EVENING. CURRENT FORECAST LOOKS ON TRACK...SO NO
UPDATES THIS EVENING.

.TWC...NONE.

AZZ019-029>035-131400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1206 PM MST TUE AUG 12 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

SYNOPSIS...THE THREAT OF SEVERE THUNDERSTORMS PRODUCING DAMAGING
WINDS WILL BE THE MAIN CONCERN TODAY ACROSS THE EASTERN VALLEYS.
THE POTENTIAL FOR PRECIPITATION IN EXCESS OF ONE INCH IS NEAR OR
SLIGHTLY ABOVE CLIMATOLOGY IN THE WESTERN DESERTS.

DISCUSSION...SOUTHEAST ARIZONA WILL EXPERIENCE A LOW GRADE MONSOON
DAY THIS AFTERNOON AND EVENING AS THE COMBINATION OF DRY AIR TO THE
EAST AND WARM MID LEVEL TEMPERATURES PUSHING INTO THE SOUTHEASTERN
PORTION OF THE STATE FROM NEW MEXICO WILL INHIBIT WIDESPREAD
CONVECTION. THE GOES-10 PRECIPITABLE WATER IMAGERY INDICATED THAT A
GRADIENT OF MOISTURE EXISTS FROM WEST TO EAST ACROSS SOUTHEAST
ARIZONA...WITH AS MUCH AS 1.50 INCHES OF PRECIPITABLE WATER SPREAD
ACROSS THE WESTERN DESERTS TO AROUND AN INCH ALONG AND EAST OF A
LINE FROM SAFFORD TO DOUGLAS. THE MORNING UPPER AIR BALLOON SOUNDING
INDICATED WARM TEMPERATURES ALOFT WHICH WILL DELAY CLOUD FORMATION
UNTIL THE AFTERNOON HOURS. STORMS WILL THEN BEGIN TO DEVELOP OVER
THE HIGHER TERRAIN BY MID AFTERNOON WITH SCATTERED THUNDERSTORM
COVERAGE OVER THE MOUNTAINS AND ISOLATED STORM COVERAGE ACROSS THE
VALLEYS.

ALTHOUGH STORM MOTION WILL INITIALLY BE TOWARDS THE WEST AT 5 TO 10
MPH...THEN SHIFT TOWARDS THE SOUTHWEST THIS EVENING.

WITH DIRER LOW LEVEL MOISTURE OUT EAST...THE THREAT OF SEVERE
THUNDERSTORM GENERATED DAMAGING WINDS WILL EXIST...WITH A REDUCED
THREAT FURTHER WEST WHERE DEEPER MOISTURE RESIDES. CONVERSELY...THE
CHANCE FOR PRECIPITATION IN EXCESS OF ONE INCH FALLING IS SLIGHTLY
ABOVE CLIMATOLOGY ACROSS THE WESTERN DESERTS...AND BELOW CLIMATOLOGY
EAST.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

A STRONG IMPULSE WILL SPREAD INTO THE AREA FROM THE EAST THURSDAY
AND THURSDAY NIGHT...WITH A SUBSEQUENT INCREASE IN BOTH THE COVERAGE
OF THUNDERSTORMS AND THE STRENGTH OF SOME STORMS. THE CHANCE FOR
HEAVY RAIN IS EXPECTED TO INCREASE.

.SPOTTER INFORMATION STATEMENT...

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