Severe Thunderstorm Warning 65, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
245 PM MST FRI AUG 8 2003

.SYNOPSIS...HIGH PRESSURE OVER EASTERN NEW MEXICO WILL MAINTAIN A
FAVORABLE FLOW FOR MOISTURE AND THUNDERSTORM DEVELOPMENT INTO THE
WEEKEND. THE HIGH PRESSURE CENTER WILL MOVE TOWARD THE FOUR CORNERS
AREA EARLY NEXT WEEK. THIS SYSTEM WILL MAINTAIN THE CHANCE OF MAINLY
AFTERNOON AND EVENING THUNDERSTORMS. DAYTIME HIGH TEMPERATURES WILL
REMAIN ABOVE SEASONAL NORMALS FOR EARLY AUGUST.

.DISCUSSION...KEMX WSR-88D DETECTED MOSTLY LESS THAN 40 DBZ ECHOES
MAINLY NEAR THE MOUNTAINS COCHISE/SRN GRAHAM/ERN PIMA/ERN SANTA CRUZ
COUNTIES MOVING SLOWLY NWWD AT 2140Z. VISIBLE SATELLITE IMAGERY
INDICATED CUMULIFORM CLOUDINESS MAINLY NEAR MOUNTAINS OF CENTRAL/ERN
SECTIONS WHILE GENERALLY CLEAR SKIES PREVAILED W. NWP PROGS SIMILAR
WITH REGARD TO ENDING PRECIP ACROSS ERN SECTIONS THIS EVENING BUT
MAINTAINING PRECIP ACROSS CENTRAL/WRN LOCALES. THUS BELIEVE SHOWER/
THUNDERSTORM DEVELOPMENT WILL CONTINUE THIS AFTERNOON WITH ACTIVITY
GRADUALLY MOVING AWAY FROM MOUNTAINS ESPECIALLY DURING THE EVENING.
BEST CHANCE PRECIP TUS VICINITY THIS EVENING MAINLY BETWEEN 09/00-06Z.
SIMILAR SCENARIO EXPECTED SAT BEFORE A SUBTLE PATTERN CHANGE PROGGED
STARTING SUN. UPPER HIGH PRESENTLY OVER E CENTRAL NM TO MIGRATE
TOWARD THE FOUR CORNERS EARLY NEXT WEEK. INFLUENCE OF ERN PACIFIC
TROUGH APPEARS TO BE LESS PRONOUNCED VIA 08/12Z NWP MODEL GUIDANCE.
THUS WOULD EXPECT MAINLY AFTERNOON/EVENING THUNDERSTORMS DURING THE
EARLY-MID WEEK PERIOD. SPECULATION AT THIS STAGE BUT PATTERN
SUGGESTS THAT DEVELOPMENT ON ANY GIVEN AFTERNOON WOULD OCCUR ALONG
RIM THEN MOVE SWWD SIMILAR TO EARLY JULY. THAT OF COURSE IS ASSUMING
NWP PROGS ARE ACCURATE WITH REGARD TO POSITION OF UPPER HIGH AND
ASSOCIATED MID-LEVEL STEERING FLOWS. A GRADUAL INCREASE IN DAYTIME
TEMPS EXPECTED THIS WEEKEND/EARLY NEXT WEEK AS MID-LEVEL HEIGHTS
RISE. MON-TUE SHOULD BE WARMEST DAYS THEN WILL SLOWLY TAPER MAX
TEMPS WED-FRI. AT ANY RATE A RATHER WARM PERIOD ON TAP THIS WEEKEND
INTO NEXT WEEK WITH DAYTIME MAX TEMPS REMAINING ABOVE SEASONAL
NORMALS FOR EARLY AUG.  BF

.TWC...NONE.

AZZ019-029>035-091400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1215 PM MST FRI AUG 8 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

SYNOPSIS...HIGH PRESSURE ALONG THE CENTRAL NEW MEXICO/ARIZONA BORDER
WILL SHIFT NORTH TOWARDS THE FOUR CORNERS REGION BY LATE IN THE
WEEKEND. THIS WILL MAINTAIN A FAVORABLE FLOW FOR ADVECTING MOISTURE
INTO THE REGION...BRINGING THE CHANCE OF AFTERNOON AND EVENING
THUNDERSTORM DEVELOPMENT THROUGH THE WEEKEND. DAYTIME HIGH
TEMPERATURES WILL REMAIN ABOVE SEASONAL NORMALS FOR EARLY AUGUST...
WITH READINGS EXPECTED TO TOP OUT IN THE SUNDAY THROUGH TUESDAY TIME
FRAME.

DISCUSSION...TODAYS SCENARIO IS SIMILAR TO YESTERDAY...WITH THE
KTUS 12Z SOUNDING INDICATING NEARLY IDENTICAL VALUES (VERSUS 24 HRS
AGO) WITH RESPECT TO STABILITY INDICES AND THE AMOUNT OF POTENTIAL
ENERGY. THE 12Z KTUS SOUNDING ALSO SHOWS THAT WE MOISTENED UP A
LITTLE...WITH 1.47 INCHES OF PRECIPITABLE WATER.

CURRENT SATELLITE IMAGERY INDICATES SLIGHTLY DRIER AIR WORKING INTO
THE REGION FROM THE EAST/SOUTHEAST. THIS IS DUE TO THE POSITION OF
THE UPPER HIGH...WHICH IS CURRENTLY CENTERED ALONG THE CENTRAL
ARIZONA/NEW MEXICO BORDER. WEAK SOUTHEASTERLY STEERING FLOW AROUND
THE HIGH IS ALLOWING THE DRIER AIR OVER NEW MEXICO TO SLOWLY PUSH
INTO THE REGION...ALTHOUGH SIGNIFICANT DRYING ACROSS SOUTHERN
ARIZONA IS NOT EXPECTED. LOOKING AT AREA RAOBS...PRECIPITABLE WATERS
DECREASE FROM 1.9 INCHES AT PHOENIX...TO 1.47 IN TUCSON...TO 0.86
INCHES AT EL PASO.

THE COMPLEX WHICH MOVED ACROSS THE REGION LATE LAST NIGHT AND EARLY
THIS MORNING HAS PROVIDED SOMEWHAT OF A STABILIZING EFFECT TO THE
AIRMASS BEHIND IT...AS THE LOWER LAYERS COOLED OFF AND A SLIGHT
WARMING IS NOTED IN THE MID LEVELS. THIS IS NOT EXPECTED TO SHUT US
DOWN...BUT WILL SLOW THE INITIAL DEVELOPMENT TODAY...WITH MOST OF
THE ACTIVITY EXPECTED TO OCCUR DURING THE LATE AFTERNOON AND EARLY
EVENING HOURS. CONVECTIVE INITIATION SHOULD OCCUR OVER AN AREA
BOUNDED BY SAFFORD...DOUGLAS...TUCSON...AND NOGALES...WITH THE
STORMS PROPAGATING TO THE WEST/NORTHWEST AT 10 TO 15 MPH.

OVERALL...WITH A LESS THAN OPTIMAL STEERING FLOW...A SLIGHTLY DRYING
AIRMASS...AND NO SIGNIFICANT FORCING FEATURES...THERE IS THE
EXPECTATION OF A LOW GRADE THUNDERSTORM FORECAST OVER THE NEXT 24 TO
48 HOURS. THE MAIN THREAT OF SEVERE WEATHER WILL BE ACROSS EASTERN
AND CENTRAL SECTIONS OF SOUTHERN ARIZONA (FROM TUCSON EASTWARD) LATE
THIS AFTERNOON AND EVENING. THIS IS DUE TO THE SLIGHTLY DRIER LOW
LEVEL AIR WORKING IN FROM THE EAST...INCREASING THE THREAT OF STRONG
WINDS. THE MAIN THREAT FOR HEAVY RAINFALL WILL BE OVER CENTRAL AND
WESTERN PORTIONS OF SOUTHERN ARIZONA (FROM TUCSON WESTWARD) LATE
THIS AFTERNOON AND EVENING...WHERE THE DEEPEST MOISTURE RESIDES.
HOWEVER...BOTH THE SEVERE WEATHER THREAT AND THE THREAT FOR
PRECIPITATION AMOUNTS GREATER THAN ONE INCH ARE EXPECTED TO BE NEAR
CLIMATOLOGICAL NORMALS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

SEASONAL SCATTERED THUNDERSTORM ACTIVITY WILL CONTINUE THROUGH THE
WEEKEND...WITH THE NORMAL IMPLIED THREAT OF HEAVY RAIN AND STRONG
WINDS. A SLIGHTLY DRIER REGIME IS EXPECTED EARLY NEXT WEEK...WITH AN
INCREASED CHANCE OF THUNDERSTORMS RETURNING BY THE MIDDLE PORTION OF
NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

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