Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 031016
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
316 AM MST MON AUG 3 2015

.SYNOPSIS...DRIER AIR WILL CONTINUE TO MOVE INTO THE REGION. AS A
RESULT EXPECT CONSIDERABLY LESS THUNDERSTORM ACTIVITY ALONG WITH
WARMER DAYTIME TEMPERATURES THROUGH MID WEEK. INCREASING MOISTURE
WILL THEN BRING A RETURN OF SCATTERED MAINLY AFTERNOON AND EVENING
THUNDERSTORMS THURSDAY INTO NEXT WEEKEND. HIGH TEMPERATURES WILL
ALSO TREND CLOSER TO SEASONAL AVERAGES BY NEXT WEEKEND.

&&

.DISCUSSION...IR SATELLITE IMAGERY SHOWS CLEAR TO MOSTLY CLEAR SKIES
ACROSS MUCH OF THE CWA EARLY THIS MORNING...SAVE FOR SOME LINGERING
(BUT THINNING) CLOUD COVER SOUTHEAST OF A SAFFORD-TUCSON LINE. WATER
VAPOR LOOPS SHOW MARKEDLY DRIER MID- AND UPPER-LEVEL AIR CONTINUING
TO INFILTRATE MUCH OF AZ ON DEEPENING WESTERLY/SOUTHWESTERLY FLOW
ALOFT. THE 00Z KTWC RAOB NICELY SHOWS THE DRYING ATMOSPHERIC COLUMN
ABOVE ABOUT 600 MB WITH THE PWAT VALUE DOWN TO 1.15 INCH. THE CIRA
PWAT PRODUCT SHOWS VALUES EARLY THIS MORNING EVEN A TOUCH LOWER
EARLY THIS MORNING--DOWN TO AROUND ONE INCH.

AT THE SURFACE...WE`RE STILL HOLDING ONTO SOME MOISTURE WITH
DEWPOINTS GENERALLY RUNNING NEAR 60 DEGS F. THAT SAID...WE`LL LIKELY
WORK THESE DOWN INTO THE 40S AND LOWER 50S TODAY AS WE MIX INTO THE
INCREASINGLY DRY AIR ALOFT. AS A RESULT...JUST ISOLATED SHOWER AND
THUNDERSTORMS TODAY SHOULD BE CONFINED SOUTH AND EAST OF THE TUCSON
METRO AND IN PARTICULAR ACROSS THE WHITE MOUNTAINS AND NEAR THE
INTERNATIONAL BORDER WHERE REMAINING LOW-LEVEL MOISTURE HASN`T BEEN
COMPLETELY SCOURED OUT.

FOR TOMORROW...MADE NO CONSIDERABLE CHANGES TO THE PREVIOUS FORECAST
AND SHOW PRECIP-FREE CONDITIONS OVER THE ENTIRE CWA AS THE
SUBTROPICAL HIGH CENTER PIVOTS ALMOST DIRECTLY OVERHEAD. THE
RESULTANT LARGE THICKNESS VALUES AND DRY AIRMASS WILL RESULT
IN VERY WARM TEMPERATURES DURING THE MIDDLE OF THE WEEK...SOME 8 TO
11 DEGREES ABOVE NORMAL...NEAR-RECORD HEAT.

WEDNESDAY LOOKS TO BE OUR TRANSITION DAY AS THE MID-LEVEL HIGH
CENTER BEGINS TO SHIFT EASTWARD INTO NM. SOME DISCREPANCIES STILL
EXIST AMONG THE VARIOUS NWP SOLUTIONS...WITH THE 03/00Z ECMWF THE
SLOWEST IN MOVING THE HIGH EASTWARD. REGARDLESS...THE GFS/CMC AND
GFS ENSEMBLE SHOWS THE HIGH STILL IN AN UNFAVORABLE POSITION FOR
CONVECTION. AS SUCH...TRIMMED POPS A BIT TO LOW-END SLIGHT CHANCES
CONFINED TO THE HIGH TERRAIN AND INTERNATIONAL BORDER.

FOR THE END OF THE WEEK AND SATURDAY...WE`LL SEE ANOTHER UPSWING
IN CONVECTIVE COVERAGE AS DEEPER MOISTURE RETURNS TO SOUTHEAST
AZ...PARTICULARLY ON FRIDAY...BEFORE YET ANOTHER UPPER-LOW
APPROACHING THE WEST COAST SHUNTS THE MID-LEVEL HIGH BACK INTO THE
SOUTHERN GREAT PLAINS. THE ENSUING SOUTHWESTERLY FLOW WILL ONCE
AGAIN ADVECT DRYER AIR INTO THE REGION...RESULTING IN DECREASING
PRECIPITATION CHANCES ON SUNDAY AND INTO EARLY NEXT WEEK.

&&

.AVIATION...VALID THRU 04/12Z.
LINGERING CLOUD-COVER EAST OF KTUS WILL CONTINUE TO THIN THROUGH THE
MORNING. SCT-BKN CLOUDS AT 9-12 KFT AGL REDEVELOPING DURING THE LATE
MORNING AND EARLY AFTERNOON. ISOLATED -SHRA/-TSRA DEVELOPING AFTER
03/19Z MAINLY SE OF A KSAD-KOLS LINE. BRIEF MVFR CONDITIONS AND
ERRATIC WIND GUSTS TO 40 KTS IN AND NEAR STRONGER TSRA. -SHRA/-TSRA
WILL DISSIPATE AFTER 04/02Z. OUTSIDE OF STORM INFLUENCES SFC WINDS
WILL GENERALLY BE LESS THAN 12 KTS WITH A FEW HIGHER GUSTS IN THE
AFTERNOON/EARLY EVENING HOURS. AVIATION DISCUSSION NOT UPDATED FOR
TAF AMENDMENTS.

&&

.FIRE WEATHER...DRIER AIR WILL CONTINUE TO INFILTRATE THE REGION
EARLY THIS WEEK. FAR SOUTHEASTERN ARIZONA AND THE WHITE MOUNTAINS
CAN EXPECT ISOLATED SHOWERS AND THUNDERSTORMS TODAY. AT THIS
TIME...IT APPEARS AS IF PRECIPITATION-FREE CONDITIONS WILL THEN
OCCUR ON TUESDAY. ALONG WITH THE DRIER AIR...TEMPERATURES WILL
RUN ABOVE TO WELL-ABOVE NORMAL THIS WEEK...RESULTING IN MINIMUM
RELATIVE HUMIDITY VALUES FALLING INTO THE LOWER TEENS TO NEAR 20
PERCENT THROUGH WEDNESDAY. HIGH PRESSURE THEN RETURNS TO A MORE
FAVORABLE LOCATION FOR DAILY CHANCES OF SHOWERS AND THUNDERSTORMS
THURSDAY INTO THE UPCOMING WEEKEND. OUTSIDE OF THUNDERSTORM WIND
GUSTS...20-FT WINDS WILL GENERALLY BE TERRAIN DRIVEN AND LESS THAN
15 MPH. HOWEVER TYPICAL AFTERNOON AND EARLY EVENING BREEZINESS IS
LIKELY...ESPECIALLY THROUGH THE GILA VALLEY NEAR SAFFORD.

&&

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

&&

$$

CARLAW

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