Severe Thunderstorm Warning 87, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
135 PM MST MON AUG 25 2003

.SYNOPSIS...INCREASING MOISTURE ASSOCIATED WITH HURRICANE IGNACIO
WILL TRACK NORTH TOWARD THE DESERT SOUTHWEST EARLY THIS WEEK. THIS
INFLUX IN MOISTURE SHOULD LEAD TO AN UPSWING IN RAINFALL
COVERAGE...ESPECIALLY LATE TUESDAY AND WEDNESDAY. A DRYING TREND
WILL COMMENCE LATER THIS WEEK...LEADING TO LESS THUNDERSTORM
ACTIVITY FOR THE UPCOMING WEEKEND.

.DISCUSSION...THE BIG STORY WEATHER WISE HAS BEEN WHAT HURRICANE
IGNACIO WILL DO FOR SOUTHEAST AZ PRECIP CHANCES THIS WEEK. LATEST
OFFICIAL NHC FORECAST OF IGNACIO HAD IT TRACKING VERY SLOWLY
NORTHWEST AND CROSSING THE BAJA PENINSULA INTO THE EASTERN PACIFIC
BY SATURDAY MORNING. ALL INDICATIONS WERE THAT THE CIRCULATION OF
IGNACIO WILL NOT IMPACT SOUTHEAST ARIZONA THIS WEEK. HOWEVER...THE
LOW PRESSURE SYSTEM AND ASSOCIATED INVERTED TROUGH THAT HAS BEEN
STALLED TO OUR EAST THE PAST FEW DAYS WILL TAP SOME MOISTURE FROM
IGNACIO. IN FACT...SATELLITE IMAGERY WAS ALREADY SUGGESTING THAT
THIS MOISTURE WAS BEING TAPPED AND PULLED NORTHWARD INTO SOUTHWEST
TEXAS TODAY. LATEST MODELS CONTINUED TO DRIFT THE UPPER LOW TO OUR
EAST WESTWARD A BIT TOMORROW AND WEDNESDAY. SUBSEQUENTLY...MOISTURE
WRAPPING INTO THE LOW PRESSURE SYSTEM WILL SHIFT INTO PARTS OF
ARIZONA SOMETIME LATE TUESDAY AND WEDNESDAY. THE MAIN CONCERN AT
THIS POINT WILL BE HOW MUCH PRECIP SERN AZ WILL GET OUT OF THIS
INCREASE IN MOISTURE. THE AIRMASS OVER AZ WAS PRETTY MUCH MOIST
ALREADY...WITH PWATER VALUES RUNNING WELL ABOVE 100 PERCENT OF
NORMAL THE PAST FEW DAYS. THIS ADDITIONAL MOISTURE COMBINED WITH
SOME WEAK LARGE SCALE FORCING ASSOCIATED WITH THE UPPER LOW WILL
SURELY LEAD TO MORE WIDESPREAD RAINFALL WITH EMBEDDED HEAVIER
AMOUNTS FROM THUNDERSTORMS. LATEST MOS POP VALUES WERE SOMEWHAT
SIMILAR TO PREVIOUS RUNS...SO DO NOT ANTICIPATE MAKING MUCH
ADJUSTMENT THERE. TEMPERATURES WILL ALSO BE IMPACTED BY THE INCREASE
IN CLOUDINESS AND PRECIP WITH MOS VALUES RUNNING ABOUT 8 TO 10
DEGREES BELOW NORMAL ON WEDNESDAY. THE MOISTURE WILL LINGER ON
THURSDAY BUT WOULD EXPECT MORE TYPICAL HIT-AND-MISS SHOWERY/
THUNDERSTORM TYPE WEATHER THAT DAY WITH WARMER HIGH TEMPERATURES.

MEANWHILE...SCATTERED SHOWERS AND A FEW THUNDERSTORMS WERE
DEVELOPING ACROSS SERN AZ THIS AFTERNOON. EXPECT FURTHER DEVELOPMENT
WITH STORMS TRACKING WESTWARD THIS EVENING. AS HAS BEEN THE PAST FEW
DAYS...VERY HEAVY RAINFALL FROM SOME OF THE STRONGER STORMS WILL BE
THE MAIN THREAT.

.TWC...NONE.

AZZ019-029>035-261400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1110 AM MST MON AUG 25 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

SYNOPSIS...AS AN UPPER LEVEL INVERTED TROUGH OVER THE TEXAS BIG BEND
CONTINUES TO MOVE VERY SLOWLY TO THE WEST...EXPECT ANOTHER ROUND OF
SCATTERED SHOWERS AND THUNDERSTORMS AS THE ATMOSPHERE REMAINS MOIST
AND UNSTABLE. AS HAS BEEN THE CASE SINCE SATURDAY...THE MAIN THREAT
FROM THE STORMS THAT DEVELOP THIS AFTERNOON AND EVENING WILL BE
HEAVY RAIN THAT MAY LEAD TO FLASH FLOODING. THERE IS A MINIMAL RISK
FOR SEVERE WEATHER ACROSS THE AREA. FOR MORE DETAILS CHECK FOR AN
UPDATE OF THIS OUTLOOK AROUND NOON.

DISCUSSION...STILL LOOKING AT A SIMILAR WEATHER PATTERN AGAIN TODAY
WITH A LOW PRESSURE SYSTEM AND ASSOCIATED INVERTED TROUGH TO OUR
EAST AND THE MOISTURE AXIS RUNNING RIGHT THROUGH AZ. MORNING UPPER
AIR SOUNDINGS SHOWED HIGH PWATER VALUES AND MODERATE INSTABILITY
OVER THE AREA FOR TODAY. DAYTIME SURFACE HEATING AND SOME WEAK UPPER
LEVEL SUPPORT FROM THE TROUGH TO OUR EAST WILL AID IN THE
DEVELOPMENT OF STORMS THIS AFTERNOON AND EVENING. THE MAIN THREAT
FROM THESE STORMS WILL BE FLASH FLOODING...ALTHOUGH DAMAGING WINDS
COULD ACCOMPANY SOME OF THE STRONGER STORMS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

MOISTURE FROM HURRICANE IGNACIO...WHICH WILL MOVE NORTH UP THE GULF
OF CALIFORNIA THIS WEEK...WILL KEEP A VERY MOIST ATMOSPHERE IN PLACE
ACROSS SOUTHEAST ARIZONA. SCATTERED SHOWERS AND THUNDERSTORMS WILL
DEVELOP TUESDAY AND WEDNESDAY WITH THE MAIN THREATS BEING HEAVY
RAINS THAT MAY LEAD TO FLASH FLOODING. A DRIER SOUTHWEST FLOW ALOFT
WILL DEVELOP ACROSS THE DESERT SOUTHWEST LATER IN THE WORK WEEK AND
INTO THE WEEKEND.

.SPOTTER INFORMATION STATEMENT...

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