Severe Thunderstorm Warning 28, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
208 PM MST SAT AUG 4 2001

.SYNOPSIS...A SUBTROPICAL DISTURBANCE WILL MOVE ACROSS SOUTHERN
ARIZONA TONIGHT AND INTO NORTHERN BAJA ON SUNDAY. IN ITS WAKE...THE
ATMOSPHERE SHOULD STABILIZE AND LEAD TO LESS THUNDERSTORM COVERAGE
ON SUNDAY AND POSSIBLY INTO MONDAY. MEANWHILE...HIGH PRESSURE WILL
REMAIN OVER THE GREAT BASIN...WHICH MAY ALLOW ANOTHER DISTURBANCE TO
MOVE WEST INTO THE REGION BY MID WEEK.

.DISCUSSION...SWOMCD/QPFERD/SWODY1 SUM THINGS UP WELL, ALTHOUGH I'M
STARTING TO SEE A COUPLE OF THINGS WHICH ARE BOTHERING ME. ANVILS
ARE MOVING AHEAD OF THE STORMS SO FAR, WHICH MEANS THAT IF THE MID
LEVEL FLOW DOESN'T PICK UP SOON, THE ANVILS MIGHT WIN AND REDUCE THE
TSTM COVERAGE SIGNIFICANTLY. ALSO, MUCH LIKE YESTERDAY, SUSTAINED
UPSLOPING FROM THE NW HASN'T DEVELOPED AS YET. KTUS HAS BEEN TRYING
TO SHIFT AROUND FOR A COUPLE OF HOURS NOW, AND KPHX AREA IS STILL S
OR LIGHT AND VARIABLE. IF THOSE MINUSES CAN BE OVERCOME, WE'RE
LOOKING AT AN ACTIVE LATE AFTERNOON/EVENING. DESERTS ARE NOW OVER
100+F, AND THE LEADING EDGE OF THE EASTERLY WAVE IS APPROACHING THE
NM/AZ BORDER. A COUPLE OF MOUNTAIN HUGGERS HAVE STARTED TO GET
PRETTY STRONG. CLOSER TO THE UPPER LOW, A CLUSTER CROSSING THE NM
BORDER E OF KDUG APPEARS TO HAVE GONE SURFACE-BASED. WE HAVE
HEIGHTENED WORDING AND MID-HIGH GRADE POPS IN OUR DRAFT ZONES, WHICH
WE MAY ADJUST UP OR DOWN DEPENDING ON HOW THINGS GO OVER THE NEXT
HOUR AND A HALF. UPPER LEVEL DIVERGENCE REMAINS FIXED OVER SE AZ
UNTIL 06Z WHEN IS IS PROGGED BY THE 18Z ETA TO SHIFT S OF THE
BORDER. GIVEN THE APPROACHING SUBTROPICAL LOW, WE'LL PROBABLY GET AN
MCS GOING RIGHT ALONG OUR BORDER TO JUST TO OUR S, WHICH WOULD KEEP
SPOTTY SHOWERS GOING FOR MUCH OF THE NIGHT. WE'LL WORD THE FORECAST
ACCORDINGLY.

MODELS ARE CONSISTENT IN WARMING OUR MID LEVELS ON SUN IN THE WAKE
OF THIS SUBTROPICAL LOW. THIS, IN ADDITION TO GETTING WORKED OVER
THIS EVENING, SHOULD LEAD TO A NOTICEABLE DOWN DAY SUN. I'D DROP
POPS EVEN MORE, BUT 20-25KT 500MB FLOW HAS ME CONCERNED THAT
ANYTHING THAT TRIES TO DEVELOP ON THE MOUNTAINS WILL STILL BE ABLE
TO MOVE INTO THE VALLEYS, ESPECIALLY LATE IN THE DAY WHEN OUR LOW
LEVELS WILL HAVE HAD A LITTLE TIME TO RECOVER. MON DOESN'T LOOK VERY
ACTIVE, EITHER, AS MID LEVEL TEMPS REMAIN WARM AND WE GET INTO WEAK
UPPER RIDGING AHEAD OF THE NEXT WAVE EXPECTED TO FORM OVER THE
EASTERN GULF OF MEXICO. THE MODELS, OF COURSE, USUALLY HAVE A ROUGH
TIME TRYING TO PICK UP THESE WAVES, LET ALONE TIME THEM PROPERLY.
THE ONE MOVING INTO US NOW MARCHED IN 24HRS FASTER THAN THE AVN
INDICATED ON THU. I'LL GO FOR A SLIGHT UPTICK ON MON SINCE THE
DESERTS WILL HAVE HAD TIME TO RECOVER, FOLLOWED BY A STANDARD
MID/HIGH GRADE FORECAST INTO THE EXTENDED. HOWEVER, I WOULDN'T BE
SURPRISED IF WE HAVE TO SPEED THE TIMING UP ON THE NEXT WAVE AS
WELL. POSITIONING OF THE UPPER HIGH IS GREAT FOR AN ACTIVE MONSOON
INTO THE END OF THE WEEK. HOWEVER, WE'LL HAVE TO KEEP AN EYE ON THE
MUCH DRIER AIR OVER S TX WHICH COULD ENTRAIN INTO THE EASTERN ZONES,
AND POSSIBLE REAMPLIFIwCATION OF THE WEST COAST TROUGH IN DAYS 6/7.
PYTLAK

.TWC...NONE.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TUCSON ARIZONA
0353 PM MST SAT AUG 4 2001

TIME (MST) .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0352 PM    5N RIO RICO               AZ   1 3/4 INCH HAIL
08/04/01   SANTA CRUZ                     DPS REPORTED DAMAGE TO VEHICLE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TUCSON ARIZONA
0358 PM MST SAT AUG 4 2001

TIME (MST) .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0352 PM    5N RIO RICO               AZ   1.75 INCH HAIL
08/04/01   SANTA CRUZ                     DPS REPORTED DAMAGE TO VEHICLE