Severe Thunderstorm Warning 45, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
230 PM MST SUN JUL 27 2003

.SYNOPSIS...A SERIES OF DISTURBANCES ROTATING AROUND THE UPPER HIGH
IN THE GREAT BASIN WILL CONTINUE TO FOCUS THUNDERSTORM ACTIVITY AT
TIMES INTO MONDAY. OTHERWISE...EXPECT SCATTERED MAINLY AFTERNOON AND
EVENING THUNDERSTORMS THROUGH THE COMING WEEK.

.DISCUSSION...WATER VAPOR THIS AFTERNOON CONTINUED TO SHOW A
DISTINCT INVERTED TROF APPROACHING US FROM THE EAST....WITH
SUBSIDENCE AREA OVER NOW OVER EXTREME SOUTHEAST ARIZONA AND
NORTHEAST SONORA. SATELLITE TRENDS SHOW THAT THIS FEATURE IS MOVING
WEST AROUND 15 KTS AND WILL MOVE ALONG THE INTERNATIONAL BORDER AND
BE IN NORTHWEST MEXICO (SOUTH OF ORGAN PIPE) LATE TONIGHT. WESTERN
EDGE OF FEATURE FIRED OFF THUNDERSTORMS SOUTH OF BORDER THIS MORNING
...WHICH CONTINUED SOUTHWEST TOWARD HERMOSILLO THIS AFTERNOON. MY
CONCERN FOR THE DAY IS WHERE TO HAVE THE BEST POPS THIS FOR TONIGHT?
LOOKING AT WATER VAPOR IMAGERY FROM THE PAST 24 HOURS...NOT A WHOLE
LOT OF ACTIVITY OCCURRED IN THE CORE OF THIS TROF...WHERE SUBSIDENCE
FIELD IS AT (EL PASO 12Z SOUNDING SHOWED SUBSIDENCE AT AROUND 450
MB). ACTIVITY LAST NIGHT WAS PLACED WELL WEST OF CORE...OVER GRAHAM
AND COCHISE COUNTIES IN AZ AND OVER SW NM. THIS AREA SHOULD SHIFT
INTO PIMA/PINAL AND SANTA CRUZ COUNTIES TONIGHT WHERE BEST DIFFLUENT
FIELD WILL BE AT. MAIN THREAT FROM STORMS WILL BE LOCALIZED DAMAGING
WINDS...HAIL WITH HEAVY RAIN DUE TO VERY MOIST ATMOSPHERE IN PLACE.
40-50KT 300 MB JET CORE ALSO WILL HELP IN STORM DEVELOPMENT AND
INCREASED WIND SHEAR WITH SPC HAVING MOST OF THE AREA UNDER SLIGHT
RISK. LOOKING BACK AT SOMEWHAT OF A SIMILAR DAY BACK IN 2001 WHERE
AN INVERTED TROF WAS JUST EAST OF THE FORECAST AREA...THE BEST
THUNDERSTORM COVERAGE WAS FROM TUCSON WEST WITH ISOLATED TO LOW
SCATTERED IN THE EAST. HOWEVER THERE IS STILL THE POTENTIAL FOR
LOCALIZED HEAVY RAIN EAST OF TUCSON TONIGHT. STANDARD MONSOON
FORECAST WILL BE CONTINUED FOR THE FORESEEABLE FUTURE WITH AFTERNOON
TEMPERATURES THIS WEEK REMAINING BELOW NORMAL. JRG

.TWC...NONE.

AZZ019-029>035-281400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1130 PM MST SUN JUL 27 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

SYNOPSIS...A STRONG UPPER LEVEL DISTURBANCE SOUTHEAST OF DOUGLAS
WILL CONTINUE TO MOVE WESTWARD ACROSS NORTHERN MEXICO. THIS WILL
TEND TO SUPPRESS THUNDERSTORM ACTIVITY EAST OF TUCSON AND ENHANCE
STORMS FROM TUCSON WEST. MID LEVEL WIND SPEEDS ARE FAIRLY STRONG AS
THIS WILL LIMIT THE FLASH FLOOD POTENTIAL UNLESS STORMS ARE
LARGE...BUT THE POTENTIAL FOR SEVERE WEATHER INCREASES DUE TO THE
STRONG MID LEVEL WINDS.

DISCUSSION...UPPER LOW SOUTHEAST OF DOUGLAS MOVING WESTWARD 10 KNOTS
OR SO...WITH SOME DRY AIR WRAPPING AROUND SYSTEM IN THE MID LEVELS.
THIS WOULD GENERALLY PUT THE EASTERN ZONES IN A LESS FAVORABLE
ENVIRONMENT BUT FROM ABOUT SIERRA VISTA TO TUCSON AND WESTWARD THE
AREA IS IN FAVORABLE DYNAMIC POSITION IN RELATION TO UPPER LOW. THIS
IS NOT TO DOWNPLAY THE POTENTIAL FOR SEVERE IN THE OTHER AREAS BUT
THE HIGHER POTENTIAL IS FARTHER WEST. ANOTHER PART OF THE
EQUATION...THERMO...LOWER LEVELS NEED TO GET TO MID 90S IN
VALLEYS...A LITTLE WARMER FARTHER WEST...TO GET SURFACE BASED
CONVECTION. SO ITS KIND OF A RACE BETWEEN SOLAR HEATING AND
CLOUDINESS SINCE MOUNTAINS WILL PROBABLY FIRE STORMS BY 1 PM. OF A
LITTLE MORE INTEREST IS THE STRONG MID LEVEL WINDS...15 TO 25 KNOTS
FROM THE NORTHEAST. THIS WILL HELP PUSH STORMS OFF MOUNTAINS AND AID
IN SEVERE WEATHER POTENTIAL. FINALLY...NGM MOS SEVERE WEATHER
CHANCES FOR TUCSON ARE HIGHER THAN NORMAL. TEND TO RESPECT THESE
NUMBERS SINCE THE STATISTICS ARE GENERALLY BETTER THAN MAV AND MET
MOS.

CHANCE OF HEAVY RAIN WILL BE A FUNCTION OF HOW LARGE STORMS GET AND
RAINFALL RATE...SINCE THE SOUTHWEST MOVEMENT OF STORMS AT 15 MPH
WILL LIMIT THE AMOUNT OF TIME THEY WILL HAVE OVER ANY ONE LOCATION.

THEREFORE...THE CHANCE OF SEVERE STORMS IS HIGHER THAN CLIMATOLOGY
FROM TUCSON WEST...THE CHANCE OF HEAVY RAIN IS SLIGHTLY BELOW
CLIMATOLOGY.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

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.