Severe Thunderstorm Warning 33, NWS Tucson, AZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
950 AM MST SUN AUG 1 2004

SOUTHEAST ARIZONA FORECAST DISCUSSION

.SYNOPSIS...HIGH PRESSURE ALOFT WILL CONTINUE THE POSSIBILITY OF
AFTERNOON AND EVENING THUNDERSTORMS THROUGH THE WEEK. ALSO... NEAR
NORMAL TEMPERATURES ARE EXPECTED.

&&

.DISCUSSION...SOME HIGH CLOUDS CONTINUE OVER PORTIONS OF SOUTHEAST
ARIZONA THIS MORNING BROUGHT ABOUT BY THUNDERSTORM DEVELOPMENT OVER
MEXICO EARLIER. AS ONE CAN SEE VIA SATELLITE IMAGERY... THE MID AND
UPPER LEVEL FLOW HAS BECOME SOUTHEAST TO SOUTH ADVECTING MOISTURE
NORTHWARD INTO THE STATE. DEW POINTS HAVE RESPONDED WITH REPORTS
AROUND THE AREA UP 2 TO 8 DEGREES OVER 24 HOURS AGO. THE MOIST FLOW
IS A RESULT OF AN UPPER LEVEL HIGH THAT CONTINUES TO SHIFT TO THE
EAST AS A LOW PRESSURE TROUGH STRENGTHENS ALONG THE WEST COAST. THIS
HAS PLACE SOUTHEASTERN ARIZONA IN UPPER LEVEL DIVERGENCE ENHANCING
THE UPWARD MOVEMENT. ALSO... CONVERGENCE AT LOWER LEVELS WILL HELP
INCREASE THE INSTABILITY LATER TODAY. OTHER FACTORS WHICH WILL
CONTRIBUTE TO A GREATER THUNDERSTORM THREAT TODAY ARE POSITIVE
VORTICITY ADVECTION FROM A SHORT WAVE TROUGH ROTATING AROUND THE
HIGH AND THE DEVELOPMENT OF A WEAK THETA-E RIDGE. HOWEVER... THE
ATMOSPHERE HAS SOME INHIBITORS TO OVERCOME. THERE IS A WEAK
INVERSION AT 430 MB... SOME WARMING ALOFT AND THE CLOUD COVER
MENTIONED PREVIOUSLY. AS THE CLOUD COVER DIMINISHES TOWERING CUMULUS
WILL BEGIN TO WORK ON THE INVERSION. ONCE THE INVERSION HAS BEEN
BREACHED THUNDERSTORMS WILL BE POSSIBLE... MOST LIKELY LATE IN THE
DAY. SINCE THE MID AND LOWER LEVELS ARE RELATIVELY DRY THE THREAT OF
DOWNBURSTS EXISTS.

BEYOND TODAY... THE UPPER LEVEL TROUGH TO THE WEST PUSHES THE CENTER
OF THE HIGH INTO TEXAS ON TUESDAY RESULTING IN A SOUTHWESTERLY FLOW
ALOFT. THIS WILL RELAX THE MOISTURE PUSH INTO ARIZONA... BUT
RESIDUAL MOISTURE WILL REMAIN FOR THE POSSIBILITY OF DAILY
THUNDERSTORMS. ON WEDNESDAY THE HIGH BEGINS TO SHIFT WESTWARD
ALLOWING THE SOUTHEASTERLY FLOW TO RETURN ONCE AGAIN ENHANCING THE
MOISTURE POTENTIAL.

NAME IOP#5 WILL CONTINUE THROUGH 00Z MON.

&&

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

EVANS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1130 AM MST SUN AUG 1 2004

AZZ019-029>035-010700-
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-
1130 AM MST SUN AUG 1 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

SYNOPSIS...A SIGNIFICANT PATTERN CHANGE OVER THE PAST COUPLE OF DAYS
HAS ALLOWED A DECENT AMOUNT OF UPPER LEVEL MOISTURE TO MAKE ITS WAY
INTO SOUTHEAST ARIZONA FROM NORTHERN MEXICO. THIS MOISTURE WILL
ALLOW FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS...MAINLY
LATE THIS AFTERNOON AND EVENING. THE MAIN CONCERN WITH STORMS THAT
DO DEVELOP WILL BE THE POTENTIAL FOR STRONG WINDS ASSOCIATED
WITH DOWNBURSTS. THE POTENTIAL FOR HEAVY RAINFALL IS BELOW NORMAL
TODAY.

DISCUSSION...THE FLOW ACROSS SOUTHEAST ARIZONA HAS BECOME SOUTH TO
SOUTHEAST...WHICH HAS ALLOWED FOR THE ADVECTION OF MOISTURE FROM
NORTHERN MEXICO. THIS MOIST FLOW IS DUE TO THE POSITION OF THE UPPER
LEVEL HIGH WHICH CONTINUES TO SHIFT EAST AS A TROUGH OF LOW PRESSURE
STRENGTHENS OFF THE WEST COAST. THE MID AND HIGH LEVEL CLOUDS
PRESENT ACROSS MOST OF SOUTHEAST ARIZONA THIS MORNING WILL SLOW THE
DEVELOPMENT OF THUNDERSTORMS...AT LEAST A LITTLE BIT. ANOTHER
INHIBITOR TO THE STORMS TODAY IS AN INVERSION AT ABOUT 430 MB.
HOWEVER...ONCE THE STORMS OVERCOME THESE TWO THINGS...THERE IS
DECENT MOISTURE AND GOOD DYNAMICS IN THE AREA FOR CONVECTION.

STRONGER WINDS ALOFT TODAY INCREASES THE POTENTIAL FOR STRONGER
WINDS AT THE SURFACE. THE POTENTIAL FOR DOWNBURSTS IS ALSO INCREASED
DUE TO THE LOWER LEVELS STILL APPEARING TO BE A LITTLE DRY.
HOWEVER...THE STRONGER WINDS WILL KEEP THE STORMS MOVING AND HENCE
REDUCE THE RISK OF LOCALLY HEAVY RAIN OCCURRING. STORMS WILL LIKELY
DEVELOP IN AREAS SOUTH OF TUCSON FIRST...AS THEY HAVE ALREADY
RECEIVED A SIGNIFICANT JUMP IN MOISTURE. HOWEVER...DO BELIEVE THAT
STORMS WILL DEVELOP ON THE MOUNTAINS IN MOVE INTO THE VALLEYS LATER
THIS AFTERNOON AND EVENING FOR MOST OF SOUTHEAST ARIZONA.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SUNDAY.
A FEATURE OVER NORTHERN MEXICO COULD MOVE THROUGH SOUTHEAST ARIZONA
ON MONDAY AND ENHANCE THE DEVELOP OF THUNDERSTORMS ACROSS THE AREA.
THE MOISTURE WILL CONTINUE TO FILTER INTO THE STATE...UNTIL THE HIGH
IS PUSHED A LITTLE FURTHER EAST BY THE WEST COAST TROUGH. ONCE THIS
HAPPENS...AROUND TUESDAY...ARIZONA SHOULD SEE THE WINDS SHIFT TO
BECOME MORE FROM THE SOUTHWEST. THIS SHOULD SLOW THE INFLUX OF
MOISTURE...HOWEVER THERE WILL BE ENOUGH MOISTURE IN THE AREA TO
CONTINUE AFTERNOON AND EVENING THUNDERSTORM DEVELOPMENT. THE HIGH
WILL SHIFT WESTWARD AGAIN BY MID WEEK AND ALLOW ARIZONA TO REGAIN
THE SOUTH FLOW AND HENCE MORE MOISTURE.

.SPOTTER INFORMATION STATEMENT...

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

ELSLAGER