Flash Flood Warning 15, NWS Tucson, AZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
950 AM MST FRI JUL 23 2004

SOUTHEAST ARIZONA FORECAST DISCUSSION

.SYNOPSIS...UPPER LEVEL HIGH PRESSURE CONTINUES TO SHIFT TO THE
NORTH...BRINGING A MORE FAVORABLE FLOW AND INCREASED MOISTURE TO
SOUTHEAST ARIZONA. THE RESULT WILL BE AN UPSWING IN THUNDERSTORM
ACTIVITY AND COVERAGE THROUGH THE WEEKEND. ALSO WITH INCREASING
MOISTURE...CLOUDS AND PRECIPITATION TEMPERATURES WILL MODERATE THE
NEXT FEW DAYS. HIGH PRESSURE ALOFT IS THEN EXPECTED TO SHIFT BACK
SOUTHWARD NEXT WEEK...BRINGING A GENERAL DECREASE IN THUNDERSTORM
COVERAGE.
&&

.DISCUSSION...DEBRIS CLOUDS FROM LARGE CONVECTIVE COMPLEX OVER
NORTHERN SONORA LAST NIGHT RAPIDLY DISSIPATING EARLY THIS MORNING...
WITH MODERATE CUMULUS ALREADY FORMING OVER SOME MOUNTAIN CHAINS IN
SOUTHEAST ARIZONA. KEMX RADAR INDICATES LIGHT RETURNS/SHOWERS OVER
FAR WESTERN PIMA ATTM FROM AN OUTFLOW BOUNDARY THAT CAME NORTHWARD
FROM THE COMPLEX LAST NIGHT. THE KTUS 12Z SOUNDING SHOWS AN INCREASE
IN NEARLY ONE-HALF OF PRECIPITABLE WATER VERSUS YESTERDAY...WITH
PRECIPITABLE WATER AT 1.71 INCHES THIS MORNING. FURTHERMORE...THE
12Z KTUS RAOB INDICATES A RATHER UNSTABLE ENVIRONMENT WITH DECENT
SHEAR. WITH THE UPPER HIGH SHIFTING FURTHER NORTH INTO NORTH CENTRAL
ARIZONA...UPPER LEVEL DIFFLUENCE FIELDS ARE FAIRLY IMPRESSIVE FOR
SOUTHEAST ARIZONA OVER THE NEXT 48 HOURS AS CONDITIONS COME TOGETHER
FOR ORGANIZED CONVECTION AND GREATER THUNDERSTORM COVERAGE. THE MOST
FAVORABLE AREA FOR DEVELOPMENT WILL BE SOUTHEAST OF A LINE FROM
HANNAGAN MEADOW...TO SAFFORD...TO TUCSON...TO NOGALES TODAY...BUT
SPREADS WESTWARD TO INCLUDE MUCH OF THE FORECAST AREA TONIGHT AND
SATURDAY AS THE FLOW BECOMES MORE EASTERLY. IN SHORT...WERE LOOKING
FOR A RATHER EARLY START TODAY (ESPECIALLY COMPARED TO THE LAST
COUPLE OF DAYS) WITH THE MODELS HINTING THAT FAR SOUTHEASTERN
PORTIONS OF THE FORECAST AREA COULD BE ON THE EDGE/IN ANY COMPLEXES
THAT DO DEVELOP ON THE PERIPHERY OF THE UPPER HIGH. THIS SEEMS
REASONABLE GIVEN THE TRENDS OVER THE LAST THREE DAYS...WITH EACH
CONVECTIVE COMPLEX IN MEXICO GETTING PROGRESSIVELY CLOSER TO
SOUTHERN ARIZONA.

ULTIMATELY WE NEED TO SHIFT THE HIGH NORTHWARD TO GET BACK INTO FULL
SWING FOR MORE THAN A COUPLE OF DAYS. NOT ONLY IS THIS NOT CERTAIN
BUT THE NEW MEDIUM RANGE TRENDS TRY TO PUSH THE HIGH CENTER BACK
INTO NORTHERN MEXICO THE SECOND HALF OF NEXT WEEK...PUSHING THE
EASTERLIES SOUTH WITH A DRIER SOLUTION FOR MOST OF THE STATE. ABOVE
CLIMO PRECIPITATION CHANCES THROUGH THE WEEKEND...BUT AFTER THAT...
IT COULD GET SPARSE AGAIN.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...NONE.

ZELL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1210 PM MST THU JUL 22 2004

AZZ019-029>035-230700-
NORTHERN GREENLEE COUNTY-UPPER GILA RIVER VALLEY-COCHISE
COUNTY-SOUTHEAST PINAL COUNTY-TUCSON METRO/MARANA/GREEN VALLEY-SANTA
CRUZ COUNTY-TOHONO OODHAM NATION-WESTERN PIMA COUNTY-
1210 PM MST THU JUL 22 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

SYNOPSIS...A NORMAL THREAT EXISTS TODAY ACROSS SOUTHEAST ARIZONA FOR
HEAVY RAINFALL AND STRONG DOWNBURST WINDS. THE HIGHEST RISK OF
SEVERE WEATHER AND HEAVY RAINFALL WILL BE ACROSS THE EASTERN HALF OF
SOUTHEAST ARIZONA TODAY...ROUGHLY SOUTH AND EAST OF A LINE FROM
HANNAGAN MEADOW...TO SAFFORD...TO TUCSON...TO SELLS. HOWEVER...
DAYTIME HEATING COMBINED WITH MOISTURE IN PLACE WILL BE SUFFICIENT
FOR GENERAL AFTERNOON AND EVENING THUNDERSTORM DEVELOPMENT ACROSS
MUCH OF SOUTHEAST ARIZONA.

DISCUSSION...THE UPPER HIGH CONTINUES TO LIFT NORTH WITH THE CENTER
CURRENTLY POSITIONED ACROSS EAST CENTRAL ARIZONA. THIS POSITION
REMAINS UNFAVORABLE FOR LARGE SCALE ORGANIZED CONVECTION ACROSS MUCH
OF SOUTHEAST ARIZONA...ALTHOUGH FAR EASTERN AREAS NEAR THE NEW
MEXICO BORDER AND FAR SOUTHERN AREAS NEAR THE INTERNATIONAL BORDER
MAY BE ON THE EDGE OF ANY COMPLEXES THAT DO DEVELOP ON THE PERIPHERY
OF THE HIGH. PRECIPITABLE WATER VALUES HAVE COME UP A LITTLE DURING
THE LAST 24 HOURS WHILE STABILITY INDICES ARE SIMILAR TO YESTERDAY.
WITH DEBRIS CLOUDS ACROSS MUCH SOUTHERN ARIZONA FROM A LARGE COMPLEX
OVER SONORA LAST NIGHT...WE PROBABLY WILL GET A SLOW START TO
INITIAL DEVELOPMENT. HOWEVER...THERE SHOULD BE ENOUGH BREAKS FOR
SCATTERED SHOWER AND STORM DEVELOPMENT DURING THE AFTERNOON AND
EVENING HOURS. CONVECTION WILL BEGIN SOUTH AND EAST OF THE TUCSON
METRO AREA WITH THE STORMS MOVING TO THE WEST AROUND 10 MPH.

THE BEST AREAL COVERAGE FOR THUNDERSTORMS WILL BE ACROSS GREENLEE...
GRAHAM...COCHISE...SANTA CRUZ AND THE EASTERN HALF OF PIMA COUNTIES.
MORE ISOLATED ACTIVITY IS EXPECTED ELSEWHERE. WITH PRECIPITABLE
WATER VALUES BETWEEN 1.30 AND 1.50 INCHES...DEEP MOISTURE IS IN
PLACE AND STORM MOVEMENT WILL BE SLOW ENOUGH THAT THE MAIN THREAT
WILL BE HEAVY RAINFALL AND FLASH FLOODING. A FEW STORMS WILL ALSO BE
CAPABLE OF PRODUCING STRONG DOWNBURST WINDS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH THURSDAY.

THE UPPER HIGH WILL CONTINUE TO SHIFT NORTH AND WILL BE CENTERED
NEAR THE FOUR CORNERS THIS WEEKEND. AN UPSWING IN THUNDERSTORM
ACTIVITY AND COVERAGE IS EXPECTED THROUGH SATURDAY...WITH HIGH END
SCATTERED TO NUMEROUS PRECIPITATION CHANCES FORECASTED. A MORE
TYPICAL MONSOON PATTERN IS THEN ANTICIPATED LATE IN THE WEEKEND AND
NEXT WEEK AS THE HIGH REMAINS TO OUR NORTH AND EASTERLY FLOW
CONTINUES ACROSS SOUTHERN ARIZONA.

.SPOTTER INFORMATION STATEMENT...

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

ZELL