Severe Thunderstorm Warning 27, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
305 PM MST WED JUL 23 2003

.SYNOPSIS...HIGH PRESSURE CENTERED OVER NEVADA WILL SLOWLY MOVE
TOWARD THE FOUR CORNERS REGION BY FRIDAY. WEAK DISTURBANCES ROTATING
AROUND THE HIGH WILL PROVIDE SCATTERED AFTERNOON AND EVENING SHOWERS
AND THUNDERSTORMS THROUGH FRIDAY. AN INCREASE IN SHOWERS AND
THUNDERSTORMS IS EXPECTED BY SUNDAY AS A STRONGER DISTURBANCE MOVES
TOWARD SOUTHEAST ARIZONA.

.DISCUSSION...KEMX WSR-88D DETECTED SCATTERED MOSTLY LESS THAN 40
DBZ ECHOES MAINLY NEAR THE ERN MOUNTAINS MOVING SLOWLY NWWD AT
2140Z. CELL E BENSON APPROACHED 60 KG/M2 WORTHY OF SEVERE TSTM
WARNING. VISIBLE SATELLITE IMAGERY INDICATED GENERALLY CLEAR SKIES
ACROSS WRN SECTIONS WITH CUMULIFORM CLOUDINESS OVER CENTRAL/ERN
LOCALES. DEWPOINTS WERE IN THE LOWER-MID 50S F ERN SECTIONS WHILE
REMAINING AROUND 60 F TUS VICINITY WWD. BELIEVE SHOWERS/TSTMS WILL
DEVELOP DURING THE NEXT FEW HOURS BUT WILL BE SLOW TO MOVE TOWARD
VALLEYS. BEST CHANCE PRECIP TUS VICINITY SHOULD BE AFTER 01-02Z OR
SUCH PER LATEST MESO-ETA/MM5 OUTPUT. WILL OPT FOR SCATTERED EVENING
SHOWERS/THUNDERSTORMS WITH EXPECTATION OF ACTIVITY WANING EARLY ERN
SECTIONS THOUGH PERHAPS LINGERING ACROSS CENTRAL LOCALES. ONLY
ISOLATED EVENING THUNDERSTORMS EXPECTED ZONES 31/32. 23/12Z NWP
MODELS WERE WELL INITIALIZED PER PMDHMD. ETA/GFS CONCUR THAT AN
INCREASE IN CONVECTIVE DEVELOPMENT TO OCCUR THUR AFTERNOON/NIGHT AS
DEPICTED BY H5-H3 OMEGA/DIVERGENCE/TOTAL DEFORMATION FIELDS. THUS
WILL TREND POPS UPWARD MAINLY THUR EVENING TO REFLECT THIS SCENARIO.
UPPER HIGH TO MOVE TOWARD SRN CO BY SAT. AVN DEPICTS INVERTED TROF
TO ROTATE AROUND SE PERIPHERY OF HIGH ACROSS TX SAT AND TOWARD SE AZ
BY SUN. PER COORD WITH WFO/S PSR/FGZ WILL ADJUST POPS UPWARD SUN AND
TREND DOWNWARD SLIGHTLY MON AS SYSTEM MOVES WWD. LOW CONFIDENCE WITH
REGARD TO GFS/MRF TUE-WED SOLUTION PERTAINING TO SWRN CONUS/NRN BAJA
TROF. SO WILL MAINTAIN GENERIC POP SCENARIO FOR THE MOMENT. WILL
TREND DAYTIME MAX TEMPS DOWNWARD STARTING FRI WITH EXPECTATION THAT
SUN WILL BE COOLEST DAY GIVEN PROGGED PRECIPITATION.  BF

.TWC...NONE.

AZZ019-029>035-241400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1230 PM MST WED JUL 23 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

SYNOPSIS...THUNDERSTORMS LAST NIGHT COOLED THE LOWER LAYERS OF THE
ATMOSPHERE WHICH GENERALLY LEADS TO LESS ACTIVITY ON THE FOLLOWING
DAY. THIS SHOULD CONFINE THE THUNDERSTORM ACTIVITY TO MAINLY THE
MOUNTAINS THIS AFTERNOON WITH THUNDERSTORMS MOVING INTO THE VALLEYS
THIS EVENING. NUMERICAL MODELS DO NOT INDICATE SIGNIFICANT ORGANIZED
CONVECTION TODAY...ALTHOUGH STORMS WILL PRODUCE LOCALLY HEAVY RAIN
DUE TO THE HIGH MOISTURE CONTENT OF THE ATMOSPHERE.

.DISCUSSION...TUCSON SOUNDING SIMILAR TO YESTERDAY ALTHOUGH LOW
LEVELS COOLED SOMEWHAT...ESPECIALLY PHOENIX SOUNDING WHICH DOES NOT
APPEAR ABLE TO SUPPORT SURFACED BASED STORMS. THE ONLY FACTOR THAT
MAY PUSH STORMS OFF THE MOUNTAINS IS FAIRLY STRONG MID LEVEL WINDS
OF 20 KNOTS OR SO. FIRST STORMS WILL DEVELOP...RAIN...AND MOVE OFF
MOUNTAINS AND THEN DISSIPATE AFTER THEY MOVE INTO VALLEYS. BY
EVENING...STORMS SHOULD BE ABLE TO MOVE INTO VALLEYS. AT THIS TIME
IT DOES NOT LOOK LIKE STORMS WILL PUSH MUCH FARTHER OUT IN THE
DESERTS THAN MARANA...BUT THE TUCSON VALLEY AS WELL AS THE I-19
CORRIDOR SEEM TO HAVE THE BEST POTENTIAL FOR THE HEAVIEST RAINS.

STORM MOTION WILL BE TO THE WEST TO NORTHWEST AT 15 MPH.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH WEDNESDAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

SUFFICIENT MOISTURE WILL BE IN PLACE FOR A STANDARD SUMMERTIME
THUNDERSTORM SEASON FORECAST. EXPECT SCATTERED MAINLY AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS.

.SPOTTER INFORMATION STATEMENT...

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