Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 291603
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
902 AM MST TUE JUL 29 2014

.SYNOPSIS...A DRYING TREND WILL LIMIT THUNDERSTORMS TO MAINLY NEAR
THE NEW MEXICO AND INTERNATIONAL BORDERS EAST TO SOUTHEAST OF TUCSON
THROUGH THURSDAY. INCREASING CHANCES OF THUNDERSTORMS WILL THEN
OCCUR ON FRIDAY FOLLOWED BY SCATTERED MAINLY AFTERNOON AND EVENING
THUNDERSTORMS THIS WEEKEND. EXPECT WARMER DAYTIME TEMPERATURES
THROUGH WEDNESDAY...THEN A MODERATION IN HIGH TEMPERATURES WILL
PREVAIL THIS WEEKEND.

&&

.DISCUSSION...SATELLITE IMAGERY WAS SHOWING A DECAYING THUNDERSTORM
COMPLEX OVER SONORA MEXICO JUST SOUTH OF DOUGLAS THIS MORNING. SOME
CLOUDINESS WAS SPREADING NORTHWARD INTO FAR SOUTHEAST ARIZONA...BUT
OVERALL THE MORNING STARTED OUT WITH MOSTLY CLEAR SKIES AREAWIDE.
LATEST MODEL SOLUTIONS WERE STILL SUGGESTING THAT THE NEXT COUPLE OF
DAYS WILL SEE LIMITED THUNDERSTORM ACTIVITY AS THE AIRMASS REMAINS
RELATIVELY STABLE UNDER A WESTERLY STEERING FLOW. CURRENT FORECAST
LOOKED ON TRACK FOR TODAY WITH THUNDERSTORMS DEVELOPING AND
REMAINING NEAR THE MOUNTAINS AND SOUTH OF TUCSON NEAR THE
INTERNATIONAL BORDER. PLEASE REFER TO THE PREVIOUS DISCUSSION IN
THIS PRODUCT FOR MORE DETAILS.

&&

.AVIATION...VALID THRU 30/18Z.
ISOLATED -TSRA/-SHRA WILL BE MAINLY NEAR THE MOUNTAINS THIS
AFTERNOON AND THIS EVENING. OTHERWISE...MOSTLY CLEAR SKIES THRU MID-
MORNING THEN A FEW TO OCCASIONALLY BROKEN CLOUDS AROUND 8-12K FT AGL
INTO THIS EVENING. CLEARING SKIES MOST SECTIONS AFTER ABOUT
30/04Z. SURFACE WIND WILL BE MOSTLY LESS THAN 10 KTS INTO EARLY
WEDNESDAY MORNING. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...EXPECT THUNDERSTORMS TO BE LIMITED TO MAINLY NEAR
THE MOUNTAINS THROUGH THURSDAY. THEREAFTER...SCATTERED MOSTLY
AFTERNOON AND EVENING THUNDERSTORMS WILL RETURN STARTING FRIDAY AND
CONTINUE THIS WEEKEND AS DEEPER MOISTURE MOVES INTO THE AREA.
OTHERWISE...NORMAL DIURNAL WIND TRENDS WILL OCCUR WITH OCCASIONAL
GUSTS DURING THE AFTERNOON HOURS DUE TO DAYTIME HEATING.

&&

.PREV DISCUSSION...GIVEN THE VERY WEAK GENERALLY WLY STORM STEERING
FLOW...ANY SHOWERS/ TSTMS THAT DEVELOP THIS AFTERNOON/EVENING WILL
LIKELY BE CONFINED TO NEAR THE MOUNTAINS. CONTINUED MID-LEVEL DRYING
TO OCCUR WED DUE TO A LIGHT GENERALLY NWLY FLOW REGIME. ANY
SHOWERS/TSTMS THAT OCCUR WED AFTERNOON/EVENING SHOULD BE NEAR THE
NEW MEXICO/INTERNATIONAL BORDERS EAST-TO-SOUTHEAST OF TUCSON.

29/00Z GFS/ECMWF DEPICTED THE LIGHT WLY/NWLY MID-LEVEL FLOW REGIME
TO CONTINUE THUR. HAVE REDUCED THE INHERITED POPS SOMEWHAT FOR THUR
AFTERNOON/EVENING. THE OFFICIAL FORECAST DEPICTS CHANCE-CATEGORY
POPS EAST-TO-SOUTH OF TUCSON THUR AFTERNOON/EVENING...WITH A SLIGHT
CHANCE OF SHOWERS FURTHER NW INTO WRN PIMA/SOUTH CENTRAL PINAL
COUNTIES. HOWEVER...THIS SCENARIO MAY BE OVERDONE AND ADDITIONAL
DOWNWARD POP ADJUSTMENTS FOR THUR MAY YET OCCUR.

THEREAFTER...GFS/ECWMF/CANADIAN MODELS WERE SIMILAR WITH DEPICTING
INCREASING MOISTURE STARTING FRI AND CONTINUING INTO THE WEEKEND AS
THE MID-LEVEL FLOW BECOMES MORE SELY. SCATTERED SHOWERS/TSTMS WILL
RETURN TO MUCH OF SE AZ FRI AFTERNOON/EVENING. GIVEN THIS FLOW
PATTERN...A POTENTIAL SCENARIO OF GUSTY OUTFLOWS PRODUCING BLOWING
DUST IS A FAIRLY DISTINCT POSSIBILITY. SCATTERED MAINLY AFTERNOON/
EVENING SHOWERS/TSTMS WILL THEN CONTINUE THIS WEEKEND. GFS/ECMWF
WERE FAIRLY SIMILAR WITH DEPICTING ANOTHER DRYING TREND MON. THUS...
SCATTERED SHOWERS/TSTMS MON SHOULD BE LIMITED TO ERN SECTIONS WITH
LESSER COVERAGE OF SHOWERS/TSTMS FROM TUCSON WWD INTO WRN PIMA
COUNTY.

HIGH TEMPS THIS AFTERNOON WILL GENERALLY BE ABOUT 5 DEGS F WARMER
VERSUS TEMPS ACHIEVED MON. SLIGHTLY WARMER DAYTIME TEMPS WILL OCCUR
WED FOLLOWED BY A COOLING TREND FRI-SUN.

&&

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

&&

$$

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

PREV DISCUSSION...FRANCIS







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