Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 070426
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
926 PM MST MON JUL 6 2015

.SYNOPSIS...A GRADUAL DRYING TREND WILL PREVAIL DURING THE NEXT
SEVERAL DAYS. HOWEVER...THERE WILL STILL BE ENOUGH MOISTURE TO
SUPPORT ISOLATED TO SCATTERED AFTERNOON AND EVENING THUNDERSTORMS
MAINLY EAST OF TUCSON. SOME INCREASE IN SHOWERS AND THUNDERSTORMS
WILL THEN OCCUR THIS WEEKEND AND EARLY NEXT WEEK. HIGH TEMPERATURES
WILL GENERALLY AVERAGE A FEW DEGREES BELOW NORMAL INTO THIS WEEKEND.

&&

.DISCUSSION...THE UPPER PATTERN IS DEFINED BY AN UPPER LOW SITUATED
OFF THE CALIFORNIA COAST AND A BROAD RIDGE OF HIGH PRESSURE EXTENDING
ACROSS NORTHERN MEXICO. IN GENERAL...THE STRONGER SOUTHWEST TO WEST
FLOW ASSOCIATED WITH THE UPPER LOW NOT ONLY IMPORTED DRIER AIR INTO
THE DESERT SOUTHWEST LIMITING COVERAGE...BUT THE ASSOCIATED STORM
TILT LIMITED THE ABILITY FOR THE STORMS TO EXPERIENCE SUSTAINED DEEP
CONVECTION. HOWEVER...A COUPLE OF WEAK DISTURBANCES IN THE FLOW WERE
INSTRUMENTAL IN ENHANCING THUNDERSTORMS THIS AFTERNOON...ESPECIALLY
IN SOUTHWEST COCHISE COUNTY WHERE PORTIONS OF THE HUACHUCA MOUNTAINS
RECEIVED 2.72 INCHES OF RAINFALL /ASH CANYON/. IN ANY EVENT...STORMS
DIED OFF EARLIER THIS EVENING SO I UPDATED THE GRIDS TO SHOW ONLY A
SLIGHT CHANCE OF WEAK SHOWERS ACROSS SOUTHERN COCHSIE COUNTY
OVERNIGHT.

&&

.PREV DISCUSSION...

A GRADUAL DRYING TREND IS THEN EXPECTED TO OCCUR TUESDAY THRU FRIDAY
IN RESPONSE TO GENERALLY SWLY FLOW ALOFT. A WEAK UPPER LOW NEAR THE
CALIFORNIA COAST NEAR 38N/130W TUE MORNING WILL MOVE TO NEAR THE SAN
FRANCISCO AREA WED AFTERNOON. THE UPPER LOW IS PROGGED VIA THE
06/12Z GFS/ECMWF/CMC TO THEN MOVE NEWD ACROSS THE GREAT BASIN AS AN
OPEN-WAVE TROUGH FRI. ALTHOUGH DEEPER MOISTURE WILL BE SHUNTED WELL
EAST OF THE AREA...THERE SHOULD BE ENOUGH MOISTURE TO MAINTAIN
ISOLATED TO SCATTERED SHOWERS/TSTMS FROM TUCSON EWD/SWD TUE-FRI.

THEREAFTER...06/12Z GFS/ECMWF WERE SIMILAR WITH BACKING THE MID-
LEVEL FLOW TO SLY OR PERHAPS SELY THIS WEEKEND AND EARLY NEXT WEEK.
THIS PATTERN SHOULD PROVIDE SOME INCREASE IN MOISTURE AND SOMEWHAT
GREATER COVERAGE OF SHOWERS/TSTMS. HOWEVER...FOR CONTINUITY WITH
NEIGHBORING WFO/S...HAVE ONLY DEPICTED A VERY MODEST INCREASE IN
SHOWER/TSTM CHANCES SAT-MON.

HIGH TEMPS TUE-WED WILL TREND CLOSE TO SEASONAL NORMALS FOLLOWED BY
SOME VERY MODEST COOLING THUR-FRI. SLIGHTLY WARMER TEMPS ARE ON TAP
SAT-MON.

&&

.AVIATION...VALID THRU 08/06Z.
ISOLATED TO SCATTERED -TSRA/-SHRA WILL PREVAIL MAINLY EAST OF KTUS
TUESDAY AFTERNOON AND EVENING. LOCAL MVFR CONDITIONS AND BRIEF WIND
GUSTS OF 25-35 KTS MAY ACCOMPANY THE STRONGER TSRA. SCATTERED MID-
CLOUDS AROUND 10-14K FT AGL THIS EVENING BECOMING CLEAR TO SCATTERED
HIGH CLOUDS ABOVE 20K FT AGL LATE TONIGHT. SURFACE WIND WILL
GENERALLY BE LESS THAN 10 KTS APART FROM THUNDERSTORM INFLUENCES.
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...EXPECT MARKEDLY REDUCED COVERAGE OF SHOWERS AND
THUNDERSTORMS TUESDAY THROUGH FRIDAY. THERE WILL BE ENOUGH MOISTURE
FOR ISOLATED TO SCATTERED THUNDERSTORMS MAINLY EAST OF TUCSON. SOME
INCREASE IN THUNDERSTORM ACTIVITY SHOULD OCCUR THIS WEEKEND AND
EARLY NEXT WEEK. GENERALLY LIGHT TERRAIN DRIVEN WINDS WILL OCCUR
OUTSIDE OF THUNDERSTORM INFLUENCES.

&&

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

&&

$$

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