Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 032132
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
232 PM MST MON AUG 3 2015

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

&&

.DISCUSSION...WATER VAPOR IMAGERY AND 03/12Z UPPER-AIR PLOTS SHOW
RIDGING EXTENDING ACROSS THE EASTERN PACIFIC WATERS...ACROSS THE
NORTHERN BAJA PENINSULA AND NORTHERN SONORA/CHIHUAHUA INTO TEXAS AND
THE WESTERN GULF OF MEXICO. MEANWHILE...A SHORTWAVE TROUGH IS OVER
THE CENTRAL ROCKIES AND LIFTING TO THE NORTHEAST. A LARGE SWATH OF
DRY MID-UPPER LEVEL AIR CAN BE SEEN IN WV IMAGERY THAT EXTENDS FROM
THE EASTERN PACIFIC THROUGH MUCH OF THE BAJA PENINSULA AND EASTERN
PARTS OF ARIZONA INTO NORTHWESTERN NEW MEXICO AND SOUTHERN COLORADO.

IR AND VISIBLE IMAGERY SHOWS CUMULUS CLOUDS THAT HAVE DEVELOPED OVER
THE MOUNTAINS OF SOUTHEAST ARIZONA. ISOLATED THUNDERSTORMS HAVE
DEVELOPED OVER THE CHIRICAHUA MOUNTAINS OF EAST CENTRAL COCHISE
COUNTY..AS WELL AS OVER THE HUACHUCA MOUNTAINS OF EXTREME
SOUTHWESTERN COCHISE COUNTY.

WITH A DRIER AIRMASS IN PLACE (12Z KTWC SOUNDING SHOWING A PW OF 1.2
INCHES AND THE U OF A GPS PW INDICATING A VALUE OF JUST A TAD OVER 1
INCH AS OF 1745Z)...NOT EXPECTING MORE THAN JUST ISOLATED ACTIVITY
MOSTLY OVER THE MOUNTAINS AND MAINLY NEAR THE INTERNATIONAL AND NEW
MEXICO BORDERS FOR THIS AFTERNOON AND EARLY THIS EVENING.

MODELS SHOW THE HIGH TO OUR SOUTH SHIFTING NORTH TO NEARLY OVERHEAD
TUESDAY RESULTING IN EVEN A LESSER THREAT FOR SHOWERS AND
THUNDERSTORMS...ALONG WITH WARMER TEMPERATURES. A SIMILAR SITUATION
WILL OCCUR WEDNESDAY AS THE HIGH IS PROGGED TO BE IN THE SAME
GENERAL LOCATION...WITH MOISTURE STILL RESIDING TO OUR SOUTH. GIVEN
THAT...I JUST HAVE SINGLE DIGIT POPS IN THE GRIDS/FORECAST FOR
TUESDAY AND ISOLATED ACTIVITY ON WEDNESDAY MAINLY BETWEEN NOGALES
AND DOUGLAS AS WELL AS THE WHITE MOUNTAINS...BUT ANY MOUNTAIN TOP IS
FAIR GAME FOR THUNDERSTORMS TO DEVELOP WEDNESDAY AFTERNOON.

BY THURSDAY...THE HIGH IS PROGGED TO SHIFT A BIT FARTHER EAST OVER
NEW MEXICO OR THE TEXAS PANHANDLE...WHICH WILL RESULT IN A SOUTH TO
SOUTHEAST MID LEVEL RETURN FLOW ON THE WESTERN FLANK OF THE
HIGH...WHICH WILL PULL IN ADDITIONAL MOISTURE FOR A BETTER CHANCE OF
SHOWERS AND THUNDERSTORMS. FOR NOW ONLY LOOKING AT SLIGHT CHANCES
AREA-WIDE...WITH SLIGHTLY HIGHER CHANCES FOR THE MOUNTAINS.

BY FRIDAY THE HIGH WILL HAVE SHIFTED TO A POSITION OVER THE SOUTHERN
PLAINS WITH DISTURBANCES EMBEDDED IN THE RETURN FLOW HELPING TO
TRIGGER STORMS DURING THE AFTERNOON AND EVENING.

FOR SATURDAY ANOTHER SHORTWAVE WILL MOVE THROUGH THE GREAT BASIN
WHICH WILL SHUNT THE HIGH A TAD SOUTH AND EAST AND RESULT IN A
SLIGHT DECREASE IN RAIN CHANCES FROM W TO E...BUT STILL ISOLATED TO
SCATTERED ACTIVITY FROM TUCSON EASTWARD. A SIMILAR FORECAST FOR
SUNDAY AND MONDAY...ALTHOUGH MODELS DIFFER THAT FAR OUT WITH THE
ECMWF WETTER THAN THE GFS. HOWEVER...BOTH MODELS SHOW AN INVERTED
TROUGH POTENTIALLY MAKING ITS WAY TOWARD THE DESERT SOUTHWEST LATE
IN THE FORECAST PERIOD...SO STAY TUNED.

FOR TUCSON...HIGHS WILL BE SEVERAL DEGREES ABOVE NORMAL EACH DAY
THROUGH THE FORECAST PERIOD...ALTHOUGH THE WARMEST DAYS WILL OCCUR
TUESDAY THROUGH THURSDAY...WHEN HIGHS WILL RUN 6 TO 8 DEGS ABOVE
NORMAL. OTHERWISE...HIGHS AROUND 3 TO 5 DEGS ABOVE NORMAL. LOW TEMPS
WILL GENERALLY RANGE FROM 3 TO 5 DEGS ABOVE NORMAL EACH DAY.

&&

.AVIATION...VALID THRU 05/00Z.
SCT-BKN CLOUDS AT 9-12K FT AGL E OF A KTUS-KOLS LINE...WITH MOSTLY
CLEAR SKIES ELSEWHERE. ISOLATED -SHRA/-TSRA MAINLY SE OF A KSAD-KOLS
LINE. BRIEF MVFR CONDITIONS AND ERRATIC WIND GUSTS TO 40 KTS PSBL 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.
EXPECT DRY CONDITIONS WITH MOSTLY CLEAR TO PARTLY CLOUDY CONDITIONS
ON TUESDAY. 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. DRY CONDITIONS
WILL LIKELY OCCUR AREA-WIDE ON TUESDAY. THIS DRY AIR COMBINED WITH
ABOVE NORMAL TEMPERATURES WILL RESULT IN DAYTIME MINIMUM RELATIVE
HUMIDITY VALUES FALLING INTO THE 10 TO 20 PCT RANGE 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.

&&

$$

PUBLIC...MOLLERE
AVIATION/FIRE WEATHER...FRENCH

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



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