Severe Thunderstorm Warning 12, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
133 PM MST SUN JUL 13 2003

.SYNOPSIS...A STRONG RIDGE OF HIGH PRESSURE OVER THE DESERT
SOUTHWEST WILL PROVIDE THE AREA WITH MORE UNSEASONABLY WARM HIGH
TEMPERATURES EARLY THIS WEEK. THESE WARMER THAN NORMAL TEMPERATURES
COMBINED WITH LIMITED MOISTURE WILL SUPPORT ISOLATED TO SCATTERED
AFTERNOON AND EVENING THUNDERSTORMS THE NEXT FEW DAYS. TEMPERATURES
WILL MODERATE SOME BY MID WEEK AS THE HIGH PRESSURE RIDGE BROADENS
AND BECOMES CENTERED OVER THE CENTRAL UNITED STATES. THIS TRANSITION
OF THE HIGH PRESSURE SYSTEM WILL LEAD TO AN INCREASE IN MOISTURE...
AND AN UPSWING IN THUNDERSTORM ACTIVITY AROUND WEDNESDAY INTO THE
WEEKEND.

.DISCUSSION...CURRENTLY RADARS ARE ALREADY DETECTING THUNDERSTORMS
IN THE RIM COUNTRY OF NORTHERN GREENLEE COUNTY. EXPECT TO SEE THIS
ACTIVITY FORM IN A FASHION SIMILAR TO YESTERDAY. THE ONE DIFFERENCE
FROM YESTERDAY IS EVIDENT IN BOTH WATER VAPOR IMAGERY AND GOES
PRECIPITABLE WATER IMAGERY...WHICH IS DRIER LOW TO MID LEVEL AIR
FILTERING INTO THE REGION FROM SOUTHERN NEW MEXICO. THIS COULD PUT A
DAMPER ON DEVELOPMENT OVER THE EXTREME SOUTHERN PORTION OF THE
FORECAST AREA...BUT THE LINE OF DEMARCATION OF DRY AIR AND
RELATIVELY MOIST AIR COULD SEE STORMS TRIGGER ALONG THE INTERFACE
BETWEEN THE TWO. I SUSPECT THAT THIS ZONE WILL STILL RESIDE
WITHIN COCHISE COUNTY...SO WILL LEAVE POPS AS IS FOR NOW.

DEWPOINTS ACROSS SOUTHERN NEW MEXICO ARE IN THE 40S AT THIS TIME AND
THE MODELS/MOS GUIDANCE SHOW NO INDICATION THAT THIS DRIER AIR WILL
BE ABLE TO FILTER INTO THE REGION ON MONDAY. IN THE UPPER LEVELS THE
MODELS KEEP THE CENTER OF THE HIGH GENERALLY JUST SOUTH OF THE FOUR
CORNERS REGION...OR WOBBLING OVER THIS AREA THROUGH EARLY TUESDAY
THEN IT MOVES RIGHT OVER THE FOUR CORNERS AREA BY LATE TUESDAY. FOR
MONDAY THE MODELS AT THE 300MB LEVEL ARE SHOWING SOME DIVERGENCE
ACROSS SE ARIZONA BY THE LATE AFTERNOON AND EARLY EVENING WHICH MAY
AID IN THE DEVELOPMENT OF STORMS. MOISTURE IS ALSO PROGGED TO BE IN
PLACE WITH MODELS INDICATING THAT THE MEAN RH IN THE 700-300MB LAYER
WILL BE IN THE 50-65 PERCENT RANGE DEPENDING ON MODEL PREFERENCE. BY
TUESDAY THIS INCREASES TO BETWEEN 65 TO NEAR 80 PERCENT...UPPER
LEVEL DIVERGENCE IS ALSO PRESENT...AS WELL AS SOME DECENT OMEGA
VALUES.

HAVE INCREASED POPS GENERALLY ABOUT 10 PERCENT OR SO IN SOME PLACES
FOR THIS AFTERNOON THROUGH TUESDAY. STILL ONLY LOOKING AT 10 PERCENT
CHANCES WEST...20 PERCENT CENTRAL AND 30 PERCENT EAST. THINGS SHOULD
IMPROVE (BETTER RAIN CHANCES) AT LEAST SLIGHTLY FOR THE LATTER HALF
OF THE WEEK AS THE HIGH MIGRATES FARTHER EAST AND EASTERLY FLOW SETS
UP OVER THE AREA. HAVE UPPED POPS FOR THE PERIOD THURSDAY THROUGH
SUNDAY IN THE GRIDS/ZONES...ALTHOUGH NOT A DRAMATIC INCREASE SINCE
GUIDANCE VALUES ARE ONLY IN THE 20-30 PERCENT RANGE EVEN THROUGH
LATE WEEK AND INTO THE WEEKEND. WILL JUST HAVE TO MAKE MINOR
ADJUSTMENTS TO POPS ON A DAY-TO-DAY BASIS AS MORNING SOUNDINGS
REVEAL NEW INSIGHTS TO THE DAILY CHALLENGE OF DETERMINING POPS FOR
THE DAY.

TEMPS OVER THE NEXT COUPLE OF DAYS SHOULD REMAIN HOT AS THE HIGH
STAYS PARKED OVER ARIZONA. I BEGIN TO TRIM TEMPS BACK DOWN STARTING
TUESDAY AND THIS TREND CONTINUES THROUGH THE END OF THE WEEK WHEN
TEMPS SHOULD BE AROUND THE 100 DEGREE MARK FOR THE CENTRAL DESERTS
(TUCSON) BY LATE WEEK.

MOLLERE

.TWC...NONE.

AZZ019-029>035-141400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1200 PM MST SUN JUL 13 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY
THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

SYNOPSIS...THE AIRMASS OVER SOUTHEAST ARIZONA IS BASICALLY SIMILAR
TO YESTERDAY. THE MAIN BODY OF MOISTURE IS FROM TUCSON WEST WITH
SLIGHTLY DRIER AIR MOVING INTO COCHISE AND GRAHAM COUNTIES. THE
BIGGEST PROBLEM WITH ANY THUNDERSTORMS TODAY WILL BE WIND GUSTS.
POTENTIALLY THESE GUSTS COULD EXCEED 60 MPH. PRECIPITATION AMOUNTS
ARE EXPECTED TO BE LESS THAN INCH.

DISCUSSION...THE PRECIPITABLE WATER IMAGES SHOWS COCHISE...GRAHAM
AND SANTA CRUZ COUNTIES HAVE DROPPED TO LESS THAN 1 INCH. PIMA AND
PINAL COUNTIES ARE STILL HANGING ON TO AMOUNTS SLIGHTLY OVER AN
INCH. GIVEN THIS TREND MOST ACTIVITY EXPECTED FROM TUCSON WEST AND
IN OROGRAPHICALLY FAVORED AREAS SUCH AS THE MOGOLLON RIM. THE 12Z
SOUNDING AT TUCSON SHOWS A SLIGHT INCREASE IN STABILITY WHEN
COMPARED TO YESTERDAY.  SLIGHTLY WARMER ALOFT AND SLIGHTLY COOLER IN
THE LOWER LAYERS. HOWEVER THE AIRMASS IS MORE SIMILAR THAN
DIFFERENT. AS YESTERDAY..WIND GUSTS IN EXCESS OF 60 MPH WILL
PROBABLY OCCUR SOMEWHERE GIVEN THESE CONDITIONS...ALTHOUGH NO
SIGNIFICANT FOCUSING MECHANISM IS PRESENT.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

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

GWS