Severe Thunderstorm Warning 74, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
930 AM MST THU AUG 14 2003

.SYNOPSIS...A STRONG LOW PRESSURE SYSTEM WILL MOVE FROM TEXAS INTO
ARIZONA OVER THE NEXT COUPLE OF DAYS...BRINGING AN INCREASE IN
THUNDERSTORMS ACROSS THE AREA THROUGH FRIDAY. EXPECT COOLER
AFTERNOONS TO GO ALONG WITH THE INCREASE IN CLOUD COVER AND
THUNDERSTORMS.

.DISCUSSION...WORKING UP FROM 850 MB THIS MORNING...MOISTURE AXIS
WITH 14C DEW POINT TEMP FROM TUS SOUTHWARD ALONG SIERRA MADRES INTO
MEXICO ALTHOUGH MODELS DO SHOW DRY AIR POCKET FROM CUU TO ELP. AT
700 MB BEST MOISTURE WITH 7 TO 8C DEW POINT TEMPS ACROSS MOST OF
SOUTHEAST ARIZONA AND WESTERN NEW MEXICO WITH DRY AIR AGAIN OVER ELP
WITH A 0 DEW POINT TEMP. TROF AXIS ASSOCIATED WITH UPPER LOW IS FROM
DRT TO MAF. AT 500 MB...-10C TEMP AIR OVER WEST TEXAS...WITH TUS
AMAZINGLY AT -5...COLDEST AIR IS ALL TO THE WEST OF TROF AND WILL
MOVE INTO ARIZONA LATE TODAY AND TONIGHT. A 25 TO 30 KNOT WIND MAX
SHOWN FROM ELP TO ABQ SHOULD ALSO MOVE INTO ARIZONA THIS AFTERNOON.
AT 300 MB...60 KNOT WIND MAX OVER ABQ WITH WEAK WINDS OVER ARIZONA
PROVIDING DIVERGENCE FIELD OVER SOUTHEAST ARIZONA AND PROBABLY
AIDING IN THIS MORNINGS STORMS ACROSS COCHISE COUNTY.

DEALING WITH A COUPLE OF PROBLEMS TODAY...LAST NIGHTS STORMS PUT
DOWN A LOT OF RAIN WEST OF TUCSON AND ANY MORE STORMS TODAY WILL
NOT HAVE TO RAIN A TON TO CAUSE FLASH FLOODING. THATS NOT TO SAY
THAT THE STORMS THAT FORM TODAY CANT DO FLASH FLOODING EVEN WITHOUT
THE ANTECEDENT CONDITIONS SINCE THE AVAILABLE MOISTURE IS SO HIGH.
WILL WAIT TO LOOK AT THE MM5 10 KM RUN WHICH SHOULD BE DONE ABOUT
1030 BEFORE DECIDING ON FLASH FLOOD WATCH...ALSO STORMS MAY FIRE
EARLY SINCE 3 TO 4 C OF COOLING AT H5 WILL NOT REQUIRE MUCH MORE
THAN NINETY DEGREES TO GET STORMS GOING.

THE OTHER PROBLEM IS SEVERE...SHEAR PROFILE WILL SUPPORT SUPERCELL
STORMS SIMILAR TO WHAT WE HAD A WEEK OR SO AGO. THE THREAT WILL
PROBABLY BE LARGE HAIL GIVEN THE COLD TEMPERATURES ALOFT...BUT WILL
NOT RULE ANYTHING OUT GIVEN THIS SCENARIO. THIS IS NOT OUR TYPICAL
INVERTED V SOUNDING WE WILL BE WORKING WITH SO DAMAGING WINDS WILL
BE FROM PRECIPITATION LOADING.

SOME DRY AIR WILL WRAP INTO STATE FROM NEW MEXICO TOMORROW AND WILL
DROP POPS A TAD TO REFLECT THIS...BUT COLD AIR ALOFT STILL GIVES US
POTENTIAL FOR STORMS WITH AFTERNOON HEATING.

.TWC...NONE.

AZZ019-029>035-151400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
12 NOON MST THU AUG 14 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

...FLASH FLOOD WATCH IN EFFECT FROM 2 PM MST THIS AFTERNOON UNTIL 12
MIDNIGHT TONIGHT FOR SOUTHEAST PINAL COUNTY...ALL OF PIMA COUNTY AND
SANTA CRUZ COUNTY...

SYNOPSIS...THUNDERSTORMS SHOULD FORM ON THE RIM TODAY AND MOVE
SOUTHWEST ACROSS THE AREA THIS EVENING. THE POTENTIAL FOR SEVERE
THUNDERSTORMS AND PRECIPITATION IN EXCESS OF ONE INCH IT IS ABOVE
CLIMATOLOGY...ESPECIALLY FROM TUCSON WEST.

DISCUSSION...A FEW LIGHT SHOWERS WERE PRESENT SOUTHEAST OF TUCSON
THIS MORNING AS DEBRIS CLOUD COVER FROM WEDNESDAY NIGHT CONVECTION
CONTINUES TO MOVE SOUTHWEST. THE UPPER LOW THAT WAS IN TEXAS OVER
THE PAST TWO DAYS HAS MIGRATED WEST AND IS SITUATED THIS AFTERNOON
IN CHIHUAHUA MEXICO. MODERATE NORTHEAST FLOW AHEAD OF THIS SYSTEM
WILL MOVE STORMS THAT DEVELOP ON THE RIM COUNTRY DOWN INTO THE LOWER
VALLEYS THIS AFTERNOON AND EVENING AND INTO THE LOW DESERTS WEST OF
TUCSON TONIGHT. THE THREAT OF SEVERE WEATHER (I.E. DAMAGING WINDS
AND HAIL) WILL BE HIGHER THAN NORMAL FROM TUCSON WEST BUT NEAR
CLIMATOLOGY IN THE EAST...WHERE SOME DRIER AIR HAS MOVED IN. A VERY
MOIST ATMOSPHERE IS IN PLACE FROM TUCSON WEST...WHERE PRECIPITABLE
WATER VALUES RANGE FROM 1.50 INCHES TO TWO INCHES. THIS AREA WILL
SEE THE BEST CHANCE OF HEAVY RAIN. THUS THE CHANCE OF ONE INCH
PRECIPITATION IS RATHER HIGH FROM TUCSON WEST...WHERE A FLASH FLOOD
WATCH IS IN EFFECT UNTIL 12 MIDNIGHT...BUT NEAR CLIMATOLOGY EAST OF
TUCSON. MOVEMENT OF THE STORMS WILL BE GENERALLY WEST TO SOUTHWEST
AROUND 10 TO 15 MPH.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

THE UPPER LOW IN CHIHUAHUA MEXICO WILL MOVE INTO THE STATE FRIDAY
AND WILL CONTINUE TO HELP FOCUS THUNDERSTORM DEVELOPMENT FRIDAY AND
FRIDAY NIGHT. THE UPSWING IN THUNDERSTORM COVERAGE WILL CONTINUE AND
THE CHANCE FOR HEAVY RAIN WILL REMAIN AT A LEVEL HIGHER THAN NORMAL.

.SPOTTER INFORMATION STATEMENT...

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