Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 111600
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
900 AM MST FRI JUL 11 2014

.SYNOPSIS...SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE
EXPECTED TODAY THROUGH THIS WEEKEND...ESPECIALLY FROM TUCSON
EASTWARD. OTHERWISE...A CHANCE OF THUNDERSTORMS WILL CONTINUE INTO
NEXT WEEK. MOST STORMS WILL OCCUR DURING THE AFTERNOON AND EVENING
HOURS BUT SOME WILL LINGER OVERNIGHT. SOME STORMS WILL PRODUCE
LOCALLY HEAVY RAINFALL AND STRONG WINDS.

&&

.DISCUSSION...AFTER AN ACTIVE OVERNIGHT PERIOD...ESPECIALLY FOR
COCHISE COUNTY THE LATEST SATELLITE TRENDS SHOW MOSTLY SUNNY TO
PARTLY CLOUDY SKIES ACROSS MOST OF SOUTHEAST ARIZONA WITH A BIT OF
RESIDUAL DEBRIS CLOUDINESS. THE LATEST SATELLITE TRENDS SHOW THESE
CLOUDS HAVE BEEN QUICKLY LESSENING IN COVERAGE OVER THE PAST COUPLE
OF HOURS. NOTE THAT THERE IS A WEAK CIRCULATION LEFTOVER FROM THE
CONVECTION ALONG IN SW GRAHAM COUNTY MOVING NORTHWESTWARD.

THE 12Z KTWC SOUNDING CAME IN QUITE MOIST AGAIN WITH A 1.71 INCH
PWAT VALUE. THE WIND FLOW PROFILE IS A BIT CHOPPY BUT GENERALLY
SOUTHERLY FROM 700MB TO 400 MB...HOWEVER THIS FLOW IS EXPECTED TO
CHANGE CONSIDERABLY AS THE DAY PROGRESSES TO A MORE UNIFORM EAST TO
SOUTHEAST FLOW BY LATER THIS AFTERNOON. MODIFYING THE SOUNDING FOR A
T=100F AND TD=55F YIELDS 1200 J/KG OF CAPE SO THERE IS CERTAINLY
PLENTY OF MOISTURE AND INSTABILITY TO WORK WITH TODAY.

IT IS SHAPING UP TO BE QUITE AN INTERESTING DAY AS WE HAVE SOME
SYNOPTIC SCALE FEATURES TO START LATCHING ONTO. LOOKING AT WV
IMAGERY...THERE IS A DISTURBANCE PUSHING SOUTHWESTWARD INTO CENTRAL
NM AND ALSO AN INVERTED TROUGH JUST SOUTH OF THE BIG BEND OF TEXAS.
AS THESE FEATURES PUSH WESTWARD /ESPECIALLY THE CLOSER DISTURBANCE
OVER NM/ THE WIND FLOW WILL BECOME MORE EASTERLY THROUGH THE DAY BUT
MORE IMPORTANTLY SOME ENHANCED SYNOPTIC SCALE LIFTING SHOULD HELP
INITIATE MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ESPECIALLY
EAST OF TUCSON IN THIS AFTERNOON. AFTER CONSIDERABLE RAINFALL
OVERNIGHT IN COCHISE COUNTY WE HAVE BEEN CONTEMPLATING THE IDEA OF
FLASH FLOOD WATCH FOR GRAHAM/GREENLEE/COCHISE COUNTIES TODAY/THIS
EVENING BUT CONFIDENCE IS NOT QUITE HIGH ENOUGH IN WIDESPREAD FLASH
FLOODING TO PULL THE TRIGGER. REGARDLESS...THE STORMS TODAY WILL
HAVE THE POTENTIAL TO PRODUCE HEAVY RAINFALL AND LOCALIZED FLASH
FLOODING. THE STORM THREAT FOR THE TUCSON METRO AREA WILL LIKELY BE
GREATEST IN THE LATE AFTERNOON AND EVENING WHERE WE EXPECT ISOLATED
TO SCATTERED STORM COVERAGE...WITH CONSIDERABLY LESSER CHANCES OVER
THE WESTERN DESERTS WHERE THERE IS SOMEWHAT DRIER AIR.

HEADING INTO THIS WEEKEND...WE WILL BE WATCHING THE INVERTED TROUGH
NOW JUST SOUTH OF THE TEXAS BIG BEND TO PUSH WEST. EXPECT DEEP LAYER
EAST TO NORTHEAST FLOW SATURDAY WHICH IS NORMALLY FAVORABLE...BUT
PWAT VALUES WILL BE DOWN CONSIDERABLY TO NEAR 1.2 INCHES ACROSS MUCH
OF THE AREA WITH PERHAPS LESSER STORM COVERAGE AS THE ANVILS ALSO
PUSH OUT AHEAD OF THE STORMS. IN ADDITION...IF TODAY ENDS UP BEING
QUITE ACTIVE IT COULD BE A DOWN DAY WITH THAT DRIER AIR AS WELL.

BY SUNDAY...MOISTURE VALUES ARE PROGGED TO BE UP AGAIN WITH PWAT
VALUES IN EXCESS OF 1.5 INCHES. THIS IN COMBINATION WITH STRONGER
EAST TO SOUTHEAST STEERING FLOW SHOULD RESULT IN BETTER COVERAGE OF
SHOWERS AND THUNDERSTORMS...WITH THE POTENTIAL OF GETTING ALL THE
WAY INTO THE WESTERN DESERTS AS WELL. THE FLASH FLOODING THREAT WILL
LIKELY BE REDUCED SOMEWHAT THIS WEEKEND AS WELL DUE TO QUICKER STORM
MOTIONS WITH PERHAPS AN INCREASED SEVERE STORM THREAT.

FOR NEXT WEEK...AN OVERALL ACTIVE PERIOD IS EXPECTED TO START THE
WEEK...PERHAPS TRENDING BACK TOWARDS A LOW TO MID GRADE MONSOON
PATTERN BY THE MIDDLE OF NEXT WEEK AS THE MID/UPPER LEVEL HIGH
CENTERS ITSELF MORE OVER ARIZONA.

&&

.AVIATION...EXPECT SCTD TSRA/SHRA FROM KTUS E AND S LATER THIS
AFTERNOON INTO THIS EVENING...WITH A LESSER CHANCE OF STORMS W OF
KTUS. MVFR VSBY NEAR +TSRA...AS WELL AS WIND GUSTS MOSTLY AROUND
35-40 KTS. OTHERWISE...CLOUD DECKS WILL BE AROUND 8-15K FT AGL.
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...MOISTURE WILL REMAIN SUFFICIENT TO PROVIDE SCATTERED
TO PERHAPS NUMEROUS MAINLY AFTERNOON AND EVENING THUNDERSTORMS INTO
NEXT WEEK.

&&

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

&&

$$

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