Severe Thunderstorm Warning 38, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
245 PM MST SUN JUL 21 2002

.SYNOPSIS...HIGH PRESSURE ALOFT IS EXPECTED TO STRENGTHEN OVER THE
FOUR CORNERS ALLOWING FOR A MOISTURE SURGE FROM THE GULF OF
CALIFORNIA LATER TONIGHT AND MONDAY. AN UPPER LEVEL DISTURBANCE
MOVING WEST FROM TEXAS WILL BEGIN AN UPSWING IN THUNDERSTORMS
MONDAY. SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS WILL
PREVAIL THIS WEEK.

.DISCUSSION...21Z KEMX WSR-88D DETECTED THUNDERSTORMS VICINITY WHITE
MOUNTAINS MOVING SW. OTHER THUNDERSTORMS WERE DETECTED OVER EXTREME
SRN SANTA CRUZ/COCHISE COUNTIES ALSO MOVING SW. VISIBLE SATELLITE
IMAGERY INDICATES PARTLY CLOUDY SKIES ACROSS SE AZ. 21Z SURFACE
ANALYSIS SHOWED DEWPOINTS IN THE LOWER-MID 50S F ACROSS CENTRAL/WRN
SECTIONS WITH DEWPOINTS IN THE UPPER 50S-LOWER 60S F OVER ERN
LOCALES. THUS WOULD EXPECT BEST CHANCE OF THUNDERSTORMS THIS EVENING
TO OCCUR E OF TUS WHERE INCREASED LOW LEVEL MOISTURE RESIDES. ERN
SECTIONS ALSO TO BE INFLUENCED FROM DEFORMATION AXIS ALOFT AND
DIVERGENCE ALOFT FROM CYCLONIC CIRCULATION FEATURE JUST S OF DUG.
NWP PROGS NOT HANDLING THIS FEATURE AS WELL AS CYCLONIC CIRCULATION
CENTRAL GULF CA VERY WELL. STILL APPEARS MON TO PROVIDE INCREASED
CHANCE OF SHOWERS/THUNDERSTORMS TO SE AZ AS ETA/AVN SHOW MOISTURE
INCREASING E-W AREAWIDE. BEST SCENARIO IS THAT SHOWERS/THUNDERSTORMS
TO DEVELOP WHITE MOUNTAINS/RIM AREA MON AFTERNOON MOVING SWWD.
ASSUMING PERFECT PROG BELIEVE THAT BEST CHANCE FOR ACTIVITY TUS
VICINITY TO OCCUR MON NIGHT/TUE AND THUS WILL TREND POPS
ACCORDINGLY. HAVE NOTED THAT INVERTED TROF ANALYZED OVER W CENTRAL
TX WAS ALSO NOT INITIALIZED WELL BY MODELS. THIS FEATURE MAY BECOME
IMPETUS FOR INCREASED CONVECTION AS EARLY AS MON AFTERNOON. AT ANY
RATE ELY FLOW INCREASES AT ALL LEVELS TUE-WED AS UPPER HIGH BUILDS
OVER FOUR CORNERS. GIVEN SCENARIO OF SOMEWHAT WIDESPREAD CONVECTION
TUE...WED COULD BE DOWN-DAY AS CONVECTIVE DEBRIS CLOUDS INHIBIT
INSOLATION NECESSARY FOR DEVELOPMENT. AVN SUGGESTS INCREASED
ACTIVITY THUR AS MID/UPPER FORCING BECOMES MORE PRONOUNCED. WILL NOT
PUT THAT MUCH FAITH IN THOSE DETAILS AT THIS TIME HOWEVER. SO WILL
MAINTAIN SCATTERED MAINLY AFTERNOON/EVENING THUNDERSTORMS AREAWIDE
THROUGH BULK OF WEEK. DAYTIME MAX TEMPS EXPECTED TO REMAIN CLOSE TO
SEASONAL NORMALS FOR LATE JULY.  BF

.TWC...NONE.

AZZ019-029>035-220700-
SOUTHEAST ARIZONA HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1200 PM MST SUN JUL 21 2002

.SYNOPSIS...THE PROBABILITY FOR PRECIPITATION IN EXCESS OF ONE INCH
AND SEVERE THUNDERSTORM WILL BE NEAR CLIMATOLOGY SOUTH AND EAST OF A
LINE FROM SAN MIGUEL TO TUCSON TO SAFFORD...BUT BELOW CLIMATOLOGY
ELSEWHERE.

.DISCUSSION...THE FAVORED AREA FOR THUNDERSTORM ACTIVITY TODAY IS
ACROSS THE FAR SOUTHEAST CORNER OF ARIZONA...MAINLY SOUTH AND EAST
OF A LINE FROM SAN MIGUEL TO TUCSON TO SAFFORD. NOT ONLY DOES THE
GOES-10 PRECIPITABLE WATER IMAGERY INDICATE THIS IS WHERE THE
DEEPER LOW AND MID-LEVEL MOISTURE RESIDES...BUT A WEAK MID-LEVEL
DISTURBANCE IN NORTHWEST CHIHUAHUA WILL SLOWLY PUSH NORTHWEST INTO
THE FAR SOUTHEAST CORNER OF THE FORECAST AREA BY THIS AFTERNOON. THE
TUCSON MORNING UPPER AIR SOUNDING INDICATED A SLIGHTLY MORE UNSTABLE
ATMOSPHERE COMPARED TO YESTERDAY WITH A STABLE CAPPING INVERSION
ALOFT. ALTHOUGH STORMS WILL STRUGGLE TO DEVELOP EARLY THIS
AFTERNOON...A FEW STORMS WILL EVENTUALLY BREAK THROUGH THIS CAPPING
INVERSION BY LATE THIS AFTERNOON RESULTING IN STRONGER STORMS.

THE THREAT FOR PRECIPITATION IN EXCESS OF ONE INCH WILL BE MINIMIZED
TODAY DUE TO A MORE PRONOUNCED STORM MOTION THAN PREVIOUS DAYS.
STORMS WILL INITIALLY DEVELOP OVER THE HIGHER TERRAIN TO THE EAST OF
TUCSON...THEN PUSH SOUTHWEST AT 10 TO 15 MPH INTO THE VALLEYS.

ALTHOUGH MID-LEVELS WERE SLIGHTLY DRIER THAN YESTERDAY...THE LOW
LEVELS HAVE MOISTENED UP A BIT. THIS IS SEEN NOT ONLY IN THE GOES-10
PRECIPITABLE WATER IMAGERY BUT IS ALSO REFLECTED IN THE SURFACE DEW
POINTS IN THE LOWER 60S. THE OVERALL RESULT IS A SLIGHT INCREASE IN
MOISTURE...WHICH WILL DECREASE THE THREAT FOR STRONG THUNDERSTORM
OUTFLOWS. THEREFORE...THE THREAT OF A SEVERE THUNDERSTORM WILL BE
BELOW CLIMATOLOGY ACROSS ALL OF SOUTHEAST ARIZONA. ALTHOUGH THESE
OUTFLOWS WILL BE WEAKER THAN SEVERE LEVEL WINDS...GUSTS TO 40 MPH
WILL ACCOMPANY THE STRONGER STORMS ACROSS THE FAR SOUTHEAST CORNER
OF THE STATE.