Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 280929
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
230 AM MST FRI AUG 28 2015

.SYNOPSIS...LESS THUNDERSTORM COVERAGE TODAY BEFORE CHANCES INCREASE
OVER THE WEEKEND. WE WILL KEEP ENOUGH MOISTURE FOR A CHANCE OF
THUNDERSTORMS FOR MOST OF NEXT WEEK. HOTTER THAN AVERAGE
TEMPERATURES FOR THE NEXT FEW DAYS BEFORE HIGH PRESSURE WEAKENS AND
TEMPERATURES SLOWLY FALL TO NEAR AVERAGE BY LATE NEXT WEEK.

&&

.DISCUSSION...A RELATIVELY ACTIVE AFTERNOON THURSDAY ALONG WITH A
NICE COMPLEX JUST SOUTH OF THE BORDER IN NORTHERN SONORA...BUT THE
CLEARING TREND PROCEEDING APACE. WE`LL END UP WITH DECENT SOLAR
INSOLATION TODAY. NORMALLY OUR WEAK WESTERLY FLOW WOULD TEND TO DRY
THINGS A BIT...BUT IMMEDIATELY UPSTREAM IN THAT FLOW HAS PLENTY OF
MOISTURE FOR THE TIME BEING. ALL GOOD THINGS FOR THUNDERSTORMS.
HOWEVER...THE WEAK MID LEVEL WARMING TREND WILL PROBABLY CONTINUE
WITH THE RIDGE REORIENTING OVERHEAD TODAY. SO ADD ANOTHER DEGREE OR
SO AT H5. AT THE SAME TIME THE ALREADY WEAK FLOW WILL STAGNATE
FURTHER...SO STORM STRUCTURE WILL STRUGGLE MORE. ALL IN ALL IT LOOKS
LIKE LESS COVERAGE TODAY WITH VALLEY STORMS HAVING A HARD
TIME...ESPECIALLY FROM TUCSON WESTWARD. THIS WILL PROBABLY ALLOW US
TO MIX SURFACE DEW POINTS A LITTLE LOWER IN THE AFTERNOON HOURS...SO
WE`LL ADD A COUPLE OF DEGREES TO THE FORECAST HIGHS IN MANY
LOCATIONS.

SATURDAY AFTERNOON DOESN`T LOOK THAT IMPRESSIVE AS THE HIGH
CONTINUES TO SLOWLY WOBBLE EASTWARD...BUT BY LATE SATURDAY AFTERNOON
AND EARLY SATURDAY EVENING...OUR MID LEVEL FLOW WILL BE IN THE
PROCESS OF PICKING UP A BIT EAST OF TUCSON. THIS WILL FAVOR
ORGANIZED EASTERLY THUNDERSTORM OUTFLOW DEVELOPMENT AND SHOULD PUSH
SOME STORMS DEEPER INTO OUR CWA (INCLUDING THE TUCSON AREA) EARLY
SATURDAY EVENING. HEIGHTS AND THICKNESSES CONTINUE TO SUPPORT HOTTER
THAN AVERAGE TEMPERATURES...BUT MUCH DEPENDS ON TIMING AND LOCATIONS
OF STORMS.

EVEN AS THE RIDGE DEEPENS THROUGH NORTHERN TIER STATES IN OUR REGION
SUNDAY AND MONDAY...WE SHOULD MAINTAIN FAVORABLE THUNDERSTORM
CONDITIONS THROUGH SOUTHEAST ARIZONA AS OUR WEATHER CONTINUES TO BE
DOMINATED BY FEATURES IN SONORA.

THERE`S ONLY SO LONG WE CAN MAINTAIN A WESTERLY COMPONENT TO OUR
FLOW HOWEVER...SO A DRYING TREND WILL KICK IN SOONER OR LATER IF THE
REGION KEEPS THE MEAN TROUGH POSITION THROUGH THE COMING WEEK.

&&

.AVIATION...VALID THRU 29/12Z. ISOLD TO SCTD -TSRA/-SHRA MAINLY E OF
KTUS THIS AFTERNOON AND EVENING. MVFR CONDS AND BRIEF WIND GUSTS OF
35-45 KTS WILL OCCUR WITH THE STRONGER T-STORMS. OTHERWISE...CLOUD
DECKS WILL GENERALLY RANGE FROM 10-15K FT AGL AND SURFACE WIND WILL
MAINLY BE LESS THAN 10 KTS. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...ISOLATED TO SCATTERED THUNDERSTORMS THIS AFTERNOON
AND EVENING...SOMEWHAT LIMITED TO THE MOUNTAINS EAST OF TUCSON.
SCATTERED THUNDERSTORMS WILL RETURN TO MUCH OF SOUTHEAST ARIZONA
SATURDAY...THEN SCATTERED THUNDERSTORMS WILL PREVAIL MAINLY FROM
TUCSON EAST AND SOUTH SUNDAY THROUGH THURSDAY. BRIEF STRONG...GUSTY
AND ERRATIC WINDS WILL ACCOMPANY THE STRONGER THUNDERSTORMS.
OTHERWISE...GENERALLY LIGHT TERRAIN DRIVEN WINDS WILL OCCUR INTO
NEXT WEEK.

&&

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

&&

$$

MEYER/HUMPHREYS

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



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