Severe Thunderstorm Warning 11, NWS Phoenix, AZ

AZZ020>028-CAZ030>033-210545-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX ARIZONA
202 PM MST SUN JUL 20 2003

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO DRIFT WEST ACROSS NORTHERN ARIZONA
TONIGHT...THEN MOVE OVER SOUTHERN NEVADA MONDAY. THERE IS A SLIGHT
CHANCE OF EVENING SHOWERS AND THUNDERSTORMS OVER THE LOWER DESERT OF
SOUTH CENTRAL ARIZONA TONIGHT...AND A BETTER CHANCE FOR STORMS OVER
THE SOUTHWEST AND SOUTH-CENTRAL ARIZONA MONDAY NIGHT. RATHER TYPICAL
LATE JULY WEATHER IS EXPECTED THE REST OF THE WEEK...WITH AFTERNOON
STORMS POSSIBLE OVER THE HIGHER TERRAIN AND EVENING STORMS POSSIBLE
OVER THE LOWER DESERT. TEMPERATURES WILL AVERAGE A FEW DEGREES ABOVE
NORMAL THIS WEEK.

.DISCUSSION...
SAT IMAGERY THIS AFTERNOON CONTINUES TO SHOW MOSTLY CLEAR SKIES
ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA...WITH PARTLY
CLOUDY SKIES OVER THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA.
STEERING FLOW ALOFT REMAINS RATHER LIGHT...AS THE HIGH SLOWLY
TRANSITIONS FROM THE FOUR CORNERS REGION TOWARD NEVADA. ALREADY AN
ACTIVE AFTERNOON FOR OUR NEIGHBORS TO THE NORTH...YET WITH LITTLE
SUPPORT ALOFT AND WEAK STEERING FLOW...WE ARE NOT EXPECTING MUCH
ACTIVITY OVER OUR AREA. THAT SAID...HAVE BACKED OFF ON THE POPS A
BIT FOR TONIGHT...AND WILL HOLD ONTO A SLIGHT CHANCE OF
THUNDERSTORMS FOR THE HIGHER TERRAIN OF SOUTHERN GILA COUNTY...WITH
A SLIGHT CHANCE FOR EVENING THUNDERSTORMS WITH POSSIBLE BLOWING
DUST OVER THE SOUTH-CENTRAL DESERTS.

TEMPS TODAY ARE RUNNING A HANDFUL OF DEG ABOVE THIS TIME YESTERDAY
...WITH DRYING NOTED FROM THE SFC ALOFT. SFC DEW POINTS ARE RUNNING
SEVERAL DEG BELOW YESTERDAY...WITH THE COLORADO RIVER AREAS AND
SOUTHEAST CALIFORNIA DESERTS DOWN ABOUT 10 DEG. MODEL DATA INDICATES
LOW LEVELS WILL STAY DRY INTO TOMORROW...YET FCST SOUNDINGS SHOW
MOISTENING IN THE MID TO UPPER LEVELS...WHICH WOULD BE GOOD FOR
STORMS TO THE NORTH ONCE AGAIN. THE STEERING FLOW ALOFT MON SHOULD
BE OUT OF THE N TO NE MON WHICH COULD LEAD TO AN INCREASED CHANCE OF
STORMS IN THE NORTH AND EAST PORTIONS OF THE VALLEY...AS STORMS
PROPAGATE DOWN OFF THE RIM. MODELS INDICATING ANOTHER SHORTWAVE
TROUGH TO MOVE ACROSS THE STATE MON/TUE...YET WE ARE SKEPTICAL OF
THIS THE GFS AND ETA HAVE BEEN OVERDOING THESE FEATURES THE PAST
COUPLE OF DAYS. EVEN SO...LOOKS LIKE AN UPSWING IN CONVECTIVE
ACTIVITY TOMORROW.

BEYOND MON...THE MID-LEVEL HIGH WILL BE OVER NEVADA/IDAHO THROUGH
TUE...THEN STARTS TO MIGRATE BACK TOWARDS THE FOUR CORNERS AGAIN
WED/THU...AND THEN SOMEWHERE OVER COLORADO/NEW MEXICO FRI. SEEMS TO
BE A BIT MORE DISAGREEMENT AMONG THE MED RANGE MODELS THAN
PREVIOUSLY ADVERTISED...AS THEY EACH HAVE THEIR OWN VARIATION OF
WHERE THE HIGH WILL BE TOWARDS THE END OF THE WEEK. SO...BEST BET
WILL BE A TYPICAL LOW GRADE MONSOON FORECAST FROM ABOUT TUE THROUGH
THE EXTENDED...WITH A CHANCE FOR SHOWERS AND THUNDERSTORMS OVER THE
HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA...WITH A SLIGHT CHANCE
SHOWERS AND THUNDERSTORMS...WITH AREAS OF BLOWING DUST
POSSIBLE...OVER THE DESERTS IN THE AFTERNOON/EVENING.

AS FOR TEMPERATURES...WILL BUMP TEMPS UP A FEW DEG FOR TOMORROW...
AND COOL THINGS OFF A BIT TUE AS SUGGESTED BY BOTH THE AVN/ETA FCST
SOUNDINGS. AFTER TUE...LITTLE VARIATION IN DAY TO DAY TEMPS IS
EXPECTED...AS HIGHS REMAIN SLIGHTLY ABOVE NORMAL FOR THIS TIME OF
YEAR. LW

.PSR...NONE.

AZZ020>028-CAZ030>033-210100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
600 AM MST SUN JUL 20 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWEST AND
SOUTH-CENTRAL ARIZONA...AND SOUTHEAST CALIFORNIA.

.DAY ONE...TODAY

SCATTERED STRONG THUNDERSTORMS WILL DEVELOP OVER THE HIGHER TERRAIN
OF SOUTH CENTRAL ARIZONA THIS AFTERNOON. ISOLATED THUNDERSTORMS AND
AREAS OF DENSE BLOWING DUST WILL BE POSSIBLE OVER THE LOWER DESERT
OF SOUTH CENTRAL ARIZONA TONIGHT. STRONGEST STORMS WILL BE CAPABLE
OF PRODUCING DAMAGING STRAIGHT LINE WIND...INTENSE CLOUD TO GROUND
LIGHTNING...AND BRIEF HEAVY RAIN.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

UPPER LEVEL STEERING FLOW WILL BE FROM THE NORTHEAST...EAST...OR
SOUTHEAST THIS WEEK AS STRONG HIGH PRESSURE ALOFT REMAINS OVER THE
INTERMOUNTAIN WEST. EXPECT STORMS TO DEVELOP OVER THE HIGHER TERRAIN
DURING THE AFTERNOON...THEN OVERSPREAD PORTIONS OF THE LOWER DESERT
EACH EVENING. STRONGEST STORMS MAY PRODUCE DAMAGING STRAIGHT LINE
WIND AS WELL AS BRIEF HEAVY RAIN AND INTENSE CLOUD TO GROUND
LIGHTNING. BLOWING DUST WILL OCCUR NEAR STORMS WHICH DEVELOP OVER
THE LOWER DESERT.