Severe Thunderstorm Warning 33, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
250 PM MST FRI JUL 25 2003

.SYNOPSIS...DISTURBANCES ROTATING AROUND THE UPPER LEVEL HIGH
LOCATED OVER THE FOUR CORNERS AREA WILL ENHANCE THE DEVELOPMENT OF
SHOWERS AND THUNDERSTORMS TODAY AND SATURDAY. AN INCREASE IN STORMS
IS EXPECTED SUNDAY AND MONDAY AS THE HIGH PRESSURE CENTER WEAKENS
AND A STRONGER DISTURBANCE MOVES TOWARD SOUTHEAST ARIZONA.
TEMPERATURES ARE ALSO EXPECTED TO DECREASE ON SUNDAY AND MONDAY BUT
WILL THEN SLOWLY REBOUND NEXT WEEK.

.DISCUSSION...TUCSON 12Z MORNING SOUNDING A BIT MORE MOIST AND MORE
UNSTABLE THAN 24 HOURS AGO. GOES-10 PRECIPITABLE WATER IMAGES THIS
MORNING SHOWED DEEPEST MOISTURE FROM TUCSON WEST. 12Z UPPER AIR
PLOTS THIS MORNING SHOWED UPPER HIGH CENTERED NEAR ALBUQUERQUE WHICH
IS KEEPING MOIST E-SE FLOW ALOFT ACROSS THE AREA. 500 MB ALSO SHOWED
A COOL -8C POOL FROM EL PASO DOWN TO CHIHUAHUA...WHICH NONE OF THE
MODELS INITIALIZED AT ALL (TO WARM). THIS COOL AIR SHOULD ADVECT
INTO THE AREA OVER THE NEXT 12-18 HOURS TO HELP DESTABILIZE THE
ATMOSPHERE A BIT MORE. 24 HOUR SATELLITE DIFFERENCES...AS OF 2
PM...SHOW THAT ACTIVITY IS MORE SOUTH OF TUCSON...ESPECIALLY ACROSS
EASTERN SONORA MEXICO WHERE A BIG MCS IS LIKELY TO DEVELOP TONIGHT.
STILL LOOKING AT SIMILAR ACTION TO WHAT OCCURRED THURSDAY WITH
SCATTERED EVENING THUNDERSTORMS...SOME STORMS APPROACHING SEVERE
LIMITS...ALONG WITH LOCALLY HEAVY RAINFALL....WITH ACTION PUSHING
OUT INTO THE LOWER DESERTS OVERNIGHT.

LOOKS LIKE THE WEEKEND AND EARLY NEXT WEEK WITH BE VERY ACTIVE WITH
PLENTY OF MOISTURE IN PLACE WITH SUNDAY NIGHT/MONDAY LOOKING LIKE
THE BEST DAYS. THIS DUE TO INVERTED UPPER TROF...CURRENTLY NEAR THE
THE EASTERN MEXICO COAST (SOUTH OF BROWNSVILLE TEXAS). THIS FEATURE
IS PROGGED TO MOVE WEST ACROSS MEXICO AS UPPER HIGH...CURRENTLY NEAR
ABQ...SHIFTS WEST INTO NEVADA. AS HAS BEEN THE CASE WITH PREVIOUS
FORECASTS...HAVE HIT SUNDAY NIGHT HARD...WITH THE HIGHEST POPS.
COULD SEE SOME SIGNIFICANT RAINFALL TOTALS SUNDAY INTO MONDAY.
TEMPERATURES ARE ALSO A FORECAST PROBLEM IN THAT IT WILL BE
DEPENDENT ON HOW ACTIVE THE AREA GETS AND HOW MUCH THE ATMOSPHERE
WILL BE WORKED OVER. HAVE LEANED TOWARD GFS GUIDANCE WHICH IS MUCH
COOLER THAN NGM/ETA MOS GUIDANCE. THAT MEANS AFTERNOON HIGHS ON
SUNDAY AND MONDAY MAY BE IN THE 80S TO LOWER 90S. THE REMAINDER OF
THE FORECAST CYCLE...TUESDAY THROUGH FRIDAY...WILL MAINTAIN STANDARD
MONSOON FORECAST. G

.TWC...NONE.

AZZ019-029>035-261400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1150 AM MST FRI JUL 25 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

SYNOPSIS...HIGH PRESSURE CENTERED OVER NORTHERN NEW MEXICO WILL
ALLOW A COUPLE OF WEAK DISTURBANCES TO ROTATE AROUND THE HIGH
TODAY...ENHANCING THE DEVELOPMENT OF SCATTERED AFTERNOON SHOWERS AND
THUNDERSTORMS. THUNDERSTORM WILL DEVELOP MAINLY EAST OF TUCSON THIS
AFTERNOON THEN MOVE INTO THE WESTERN DESERTS BY EARLY THIS EVENING.
THE MAIN WEATHER CONCERN WILL BE THE POTENTIAL FOR A FEW OF THE
STORMS TO PRODUCE STRONG GUSTY WINDS...SMALL HAIL AND LOCALIZED
HEAVY RAINFALL AS THE STORMS DEVELOP...ESPECIALLY DURING THE EVENING
HOURS ACROSS THE WESTERN DESERTS.

DISCUSSION...THE GOES-10 PRECIPITABLE WATER IMAGERY INDICATED AN
AREA OF MODERATELY DEEP LOW TO MID LEVEL MOISTURE EXTENDED ALONG AND
WEST OF A LINE FROM ELOY TO DOUGLAS...WITH DRIER AIR PUSHING INTO
THE EASTERN PORTIONS OF ARIZONA. IN FACT...THE MORNING UPPER AIR
SOUNDING INDICATED A PRECIPITABLE WATER VALUE OF 1.48 INCHES IN
TUCSON...UP 0.18 INCHES OVER THE PAST 24 HOURS. THIS MOISTURE WILL
BE ENOUGH TO ALLOW THUNDERSTORMS TO DEVELOP ACROSS SOUTHEAST ARIZONA
TODAY.

THE UPPER AIR ANALYSIS PLOT INDICATED THAT A POOLING OF COOL AIR IN
THE MID TO UPPER LEVELS EXTENDED FROM EL PASO INTO THE MEXICAN
STATE OF CHIHUAHUA. THIS COOLER AIR...AS WELL AS A WEAK MID LEVEL
COL WILL MOVE NORTHWEST AROUND THE BASE OF THE UPPER HIGH...MOVING
INTO THE FAR SOUTHEAST CORNER OF THE STATE BY MID AFTERNOON AND INTO
THE WESTERN DESERTS BY EARLY THIS EVENING. BOTH OF THESE FEATURES
WILL AID IN DESTABILIZING THE ATMOSPHERE AND AID THUNDERSTORM
DEVELOPMENT TODAY.

EXPECT THUNDERSTORMS TO BEGIN DEVELOPING OVER THE EASTERN MOUNTAINS
BY THE EARLY AFTERNOON...THEN PUSH NORTHWEST AT 10 TO 15 MPH INTO
THE EASTERN VALLEYS BY MID AFTERNOON...AND FINALLY INTO THE WESTERN
DESERTS BY THE EARLY EVENING.

WATER VAPOR IMAGERY INDICATED THAT AN AREA OF DRY AIR...MAINLY AT
MID TO UPPER LEVELS HAD PUSHED INTO THE EASTERN PORTIONS OF ARIZONA
THIS MORNING...WITH THE STRONGEST GRADIENT EXTENDING ALONG A LINE
FROM SASABE TO ELOY. THIS MOISTURE DISCONTINUITY LINE IS PROGGED BY
THE MODELS TO STAY RATHER STATIONARY THROUGHOUT THE DAY AND SHOULD
SERVE AS BOUNDARY TO AID THUNDERSTORM DEVELOPMENT LATER THIS
EVENING. GIVEN THE DEEPER LOW-LEVEL MOISTURE AND HIGHER PRECIPITABLE
WATER VALUES TO THE WEST OF THIS LINE...ANY THUNDERSTORM THAT DOES
DEVELOP IS CAPABLE OF PRODUCING VERY HEAVY RAINFALL. THEREFORE...THE
CHANCE OF RECEIVING PRECIPITATION IN EXCESS OF ONE INCH IS ABOVE
CLIMATOLOGY WEST OF TUCSON.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

SUFFICIENT MOISTURE WILL BE IN PLACE FOR AT LEAST A STANDARD
SUMMERTIME THUNDERSTORM SEASON FORECAST WITH SCATTERED MAINLY
AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS SATURDAY.
HOWEVER...SUNDAY AND MONDAY...ATMOSPHERIC MODELS ARE INDICATING THAT
AN EASTERLY WAVE WILL PUSH IN FROM THE WESTERN GULF COAST REGION...
THROUGH MEXICO AND INTO THE DESERT SOUTHWEST. AS A RESULT...EXPECT
AN INCREASE IN SHOWER AND THUNDERSTORM ACTIVITY THAN NORMALLY
ASSOCIATED WITH THE MONSOON.

.SPOTTER INFORMATION STATEMENT...

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