Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 290940
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
235 AM MST SAT AUG 29 2015

.SYNOPSIS...A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS OVER THE
WEEKEND INTO EARLY NEXT WEEK. GRADUALLY DRIER CONDITIONS WILL THEN
LIMIT THUNDERSTORMS TO EAST OF TUCSON THE SECOND HALF OF NEXT WEEK.
HOTTER THAN AVERAGE TEMPERATURES FOR THE NEXT FEW DAYS FOLLOWED BY
TEMPERATURES FALLING TO NEAR AVERAGE AROUND THE MIDDLE OF THE
UPCOMING WEEK.

&&

.DISCUSSION...AFTER THE DOWN DAY YESTERDAY...NOT MUCH CLOUD TO SPEAK
OF OVERNIGHT FOR A CHANGE. JUST SOME DEBRIS CLOUD IN MODEST EASTERLY
OUTFLOW FROM NEW MEXICO STORMS NEAR THE EASTERN BORDER. CIRA LPW
TOTALS AROUND 1.1 TO 1.4 ACROSS SOUTHEAST ARIZONA...A BIT DEEPER IN
WESTERN AREAS. MODEST DRYING TREND FROM THE NORTH IN THE H7-H5 LAYER
NORTHWEST OF US...BUT WE`RE STILL MAINTAINING A DECENT SUPPLY OF
MOISTURE. LOWER LEVELS ARE NOT DOING AS WELL WITH VERY LITTLE
INFLUENCE FROM THE SOUTH TO REINFORCE BOUNDARY LAYER MOISTURE.

THE LARGER SCALE PICTURE IS SHUFFLING A BIT WITH A WEAKENING RIDGE
AXIS NEARLY OVERHEAD AND A VERY STRONG TROUGH THROUGH HIGHER
LATITUDE AND MID TIER STATES NORTHWEST OF THE AREA. THIS WILL HELP
FOCUS OUR ATTENTION FOR STORMS OVER THE NEXT 3 DAYS TO PARTICULAR
AREAS.

FOR TODAY EXPECT THE H7 THETA-E RIDGE NEAR NORTHERN SONORA TO EXTEND
INTO AREAS WEST OF TUCSON THIS AFTERNOON FOR OUR FIRST AREA OF
INTEREST OVER THE TOHONO O`ODHAM NATION. IN ADDITION...SOME WEAK
DIFFLUENCE ALOFT ON THE EASTERN FLANK OF THE H3 RIDGE INFLECTION
WILL HELP WITH STORMS OVER EASTERN AREAS...FOR OUR SECOND MAIN AREA
OF INTEREST OVER COCHISE COUNTY THIS AFTERNOON. STILL WEAK FLOW
OVERALL BUT WE ARE GETTING SOME ADDITIONAL HELP WITH THESE FEATURES
TODAY. WATCH FOR AN ACTIVE OUTFLOW REGIME LATE IN THE AFTERNOON AND
EARLY EVENING WITH POSSIBLE DUST ISSUES IN FAVORED LOCATIONS.

FOR SUNDAY...THE H7 THETA-E RIDGE SHIFTS EASTWARD TO A POSITION NEAR
EASTERN PIMA AND SANTA CRUZ COUNTIES SUNDAY AFTERNOON. THAT WILL BE
OUR MAIN AREA OF FOCUS SUNDAY AFTERNOON.

BY MONDAY AND TUESDAY...THE RIDGE RECONSOLIDATING FURTHER EAST WILL
SEE H7 THETA-E INFLUENCES MOST EVIDENT IN AREAS EAST OF TUCSON.

BY WEDNESDAY THROUGH THE END OF THE WEEK...THE WESTERLY FLOW WILL
HAVE TAKEN IT`S TOLL AS AN ANOMALOUSLY STRONG MEAN TROUGH POSITION
NORTH OF US WILL SLOWLY DRIVE MOISTURE TO THE EAST AND SOUTHEAST.
MOISTURE WON`T BE FAR AWAY...BUT DEFINITELY NOT A GOOD PATTERN FOR
MONSOON ACTIVITY...EVEN LATE IN THE SEASON.

&&

.AVIATION...VALID THRU 30/12Z.
FEW TO SCT MAINLY MID TO HIGH LEVEL CLOUDS...BECOMING MOSTLY SKC
EARLY. BY LATE MORNING CLOUD COVERAGE INCREASING WITH BASES 8 TO 12
KFT. SCT SHRA/TSRA WILL BE POSSIBLE AFTER 29/20Z...INCREASING IN
COVERAGE AS THE AFTERNOON/EVENING PROGRESSES. BRIEF MVFR CONDITIONS
AND GUSTY WINDS OF 30 TO 40 KTS WILL BE POSSIBLE IN AND AROUND
STRONGER STORMS. OUTSIDE OF THUNDERSTORM INFLUENCE SURFACE WINDS
WILL GENERALLY BE UNDER 10 KTS. AVIATION DISCUSSION NOT UPDATED FOR
TAF AMENDMENTS.

&&

.FIRE WEATHER...MORE WIDESPREAD SHOWERS AND THUNDERSTORMS RETURNING
FOR MUCH OF SOUTHEAST ARIZONA THIS AFTERNOON AND EVENING. THIS TREND
WILL CONTINUE INTO EARLY NEXT WEEK...WITH DAILY AFTERNOON AND
EVENING STORMS EXPECTED TO BE THE NORM. STARTING MONDAY STORMS WILL
TEND TO BE MORE FOCUSED OVER EASTERN ZONES...WITH SIGNIFICANTLY
DIMINISHED THUNDERSTORM ACTIVITY FROM WEDNESDAY ON. THUNDERSTORMS
ARE EXPECTED TO BE WET AND AS IS TYPICAL MAY PRODUCE STRONG...GUSTY
AND ERRATIC WINDS WITH THE STRONGER THUNDERSTORMS.

THROUGH SUNDAY GENERALLY LIGHT TERRAIN DRIVEN WINDS ARE EXPECTED.
FROM MONDAY ONWARD A WEST TO SOUTHWEST FLOW WILL GRADUALLY DEVELOP
ACROSS ARIZONA.  THE STRONGEST WINDS WILL BE ACROSS ZONE
150...PEAKING IN THE 15-20 MPH RANGE.  THIS FLOW WILL ALSO STEADILY
PUSH THE MOISTURE OUT OF THE REGION FOR DECREASING CHANCES OF
THUNDERSTORMS WEDNESDAY THROUGH FRIDAY.

&&

.CLIMATE...TUCSON AIRPORT CLOSING IN ON A CONSECUTIVE STREAK RECORD.
YESTERDAY MARKED THE 80TH STRAIGHT DAY THAT THE LOW TEMPERATURE WAS
70 DEGREES OR WARMER. THE RECORD IS 81 STRAIGHT DAYS SET TWO YEARS
AGO. OFFICIAL NWS FORECAST HAS THIS RECORD BEING BROKEN ON SUNDAY.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON

MEYER/HUMPHREYS


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