Hail and Damaging Wind in Arizona, August 17, 2001

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
210 PM MST FRI AUG 17 2001

.SYNOPSIS...HIGH PRESSURE OVER NORTHWEST ARIZONA WILL GRADUALLY
SHIFT INTO NEW MEXICO THROUGH SUNDAY. MEANWHILE...AN UPPER LEVEL
LOW PRESSURE AREA OVER BAJA WILL GRADUALLY MOVE WEST INTO THE
PACIFIC. ALTHOUGH STORM COVERAGE THROUGH SUNDAY WILL BE SOMEWHAT
LIMITED AND FAVOR THE EVENING HOURS...THEY COULD BE ON THE STRONG
SIDE. BY SUNDAY...THE PATTERN WILL FAVOR MORE TYPICAL AFTERNOON AND
EVENING THUNDERSTORMS...WHICH WILL CONTINUE INTO THE END OF THE
WEEK.

.DISCUSSION...TSTMS ALREADY FIRING IN THE WHITES AND SE COCHISE
COUNTY. ANVIL DRIFT CONTINUES TO SHOW DIFFLUENCE ALOFT, WITH THE
DIFFUENCE AXIS EXTENDING FROM NE SONORA INTO PINAL COUNTY. LAPS DATA
SHOWS CONVECTIVE INHIBITION PRETTY MUCH GONE OVER THE E AND
WEAKENING RAPIDLY IN THE W. THIS SUPPORTS THE 18Z ETA WHICH
COMPLETELY RELOADS OUR BOUNDARY LAYER BY 00Z. I DONT SEE ANY
DISTINCT FOCUSING MECHANISM OTHER THAN OUTFLOWS AND IMPRESSIVE UPPER
DIVERGENCE, SO WELL HOLD COVERAGE NEAR CLIMO (LOW-MID SCATTERED)
WHILE USING HEIGHTENED WORDING. SWODY1 OUTLOOK LOOKS VERY GOOD.
0-6KM SHEAR IS PROGGED TO BE AS HIGH AS 40KTS TONIGHT (IT WAS AROUND
30KTS ON THE 12Z SOUNDING) WHICH MEANS ANY STORMS THAT GET SOME
DEPTH WILL TRY TO ORGANIZE INTO SMALL LINES OR BOW SEGMENTS. AT
LEAST THAT WILL KEEP THE RISK OF HEAVY RAIN ON THE LOW SIDE. GOES-10
RAPID SCAN UPDATE WILL RUN FROM 22Z-07Z TONIGHT.

UPPER HIGH IS CONTINUING TO BRIDGE TO OUR N, AND ONCE THE PLAINS
TROUGH LIFTS OUT, IT WILL REFORM OVER THE 4-CORNERS. MODELS INSIST
ON RAMPING PRECIP WATERS ABOVE 1.5 BY SUN NIGHT AND TURNING OUR
30KT E FLOW AT 500MB TO 15KT SE. THAT WILL SHIFT US BACK INTO
GREATER COVERAGE/HEAVY RAINER MODE IN THE EXTENDED. FORECASTS HAVE
BEEN ADVERTISING THIS TREND ALL WEEK, AND I SEE LITTLE REASON TO
DEVIATE. ID GO A LITTLE HIGHER WITH POPS SUN, BUT MODELS SUGGEST
ANOTHER BIG NIGHT SAT NIGHT, AND WITH THE FLOW WEAKENING ON SUN, WE
MAY HAVE A HARDER TIME RELOADING THE DESERTS AND VALLEYS. WELL HAVE
TO WATCH THE DAY 6-7 AS MRF CONTINUES TO DROP A TROUGH DOWN THE WEST
COAST. THERES ISNT STRONG TELECONNECTIVE SUPPORT FOR SUCH AN
AMPLIFIED TROUGH, AND EVEN IF IT HAPPENS, WED PROBABLY TAKE A
COUPLE OF DAYS TO DRY DOWN. FOR NOW, IM INCLINED TO LET THE CURRENT
EXTENDED RIDE. PYTLAK

.TWC...NONE.

AZZ019-029>035-180700-

SOUTHEAST ARIZONA HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
12 NOON MST FRI AUG 17 2001

.SYNOPSIS...SOUTHEAST ARIZONA WILL REMAIN WEDGED BETWEEN AN UPPER
LEVEL LOW OVER BAJA AND HIGH PRESSURE OVER NORTHERN ARIZONA. THIS
HAS BEEN A FAVORED AREA FOR STRONG THUNDERSTORM DEVELOPMENT ALL
WEEK...AND MAY ONCE AGAIN LEAD TO SIGNIFICANT DEVELOPMENT LATE THIS
AFTERNOON AND ESPECIALLY TONIGHT.

.DISCUSSION...MOST OF SOUTHEAST ARIZONA RECEIVED THUNDERSTORMS
THURSDAY EVENING. NORMALLY...THIS WOULD LEAD TO A DECREASE ON BOTH
STORM COVERAGE AND STRENGTH TODAY. IN FACT...THE MORNING SOUNDINGS
ACROSS ARIZONA REFLECTED A STABILIZED ATMOSPHERE. HOWEVER...THE EAST
WIND FLOW TODAY REMAINS RATHER STRONG...ESPECIALLY IN THE MID
LEVELS. THIS IS IMPORTING ADDITIONAL MOISTURE FROM SOUTHWEST NEW
MEXICO AND WILL CAUSE THE ATMOSPHERE TO DESTABILIZE FAIRLY RAPIDLY
LATER THIS AFTERNOON. ISOLATED THUNDERSTORMS WERE ALREADY DEVELOPING
OVER THE WHITE MOUNTAINS. THAT AREA WAS SPARED FROM THE STRONGER
STORMS YESTERDAY.

ALTHOUGH IT WILL TAKE SEVERAL MORE HOURS FOR THE VALLEYS TO
RECOVER...ABOVE NORMAL AFTERNOON TEMPERATURES...BELOW NORMAL
TEMPERATURES ABOVE 15000 FEET...RATHER STRONG STEERING WINDS...AND
THE PRESENCE OF DIVERGENCE ALOFT ALL SUGGEST ANOTHER ACTIVE LATE
AFTERNOON AND EVENING. VALLEY DEVELOPMENT WILL NOT OCCUR UNTIL LATE
IN THE AFTERNOON OR THIS EVENING...BUT SOME OF THE STORMS COULD LAST
WELL PAST MIDNIGHT...ESPECIALLY OVER THE WESTERN DESERTS. LIKE THE
PAST COUPLE OF DAYS...STORM COVERAGE WILL NOT BE AS GREAT AS USUAL
FOR MID AUGUST BECAUSE PRECIPITABLE WATERS ARE A BIT LOW. HOWEVER...
ANY STORMS THAT DEVELOP WILL BE ABLE TO FORM INTO SHORT LINES OR BOW
SEGMENTS WHICH WOULD BE CAPABLE OF DAMAGING WINDS. THE MID LEVEL
TEMPERATURES ARE ALSO COLD ENOUGH TO SUPPORT HAIL UP TO AROUND AN
INCH IN DIAMETER. THE RISK OF FLASH FLOODING IS BELOW CLIMATOLOGY
BECAUSE OF THE RAPID STORM MOTIONS WHICH ARE EXPECTED.

STORM MOVEMENT WILL BE GENERALLY SOUTHWEST AT 20 TO 25 MPH.

PYTLAK