Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 012128
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
228 PM MST FRI AUG 1 2014

.SYNOPSIS...PLENTY OF SHOWERS AND THUNDERSTORMS ARE EXPECTED THROUGH
SATURDAY NIGHT THANKS TO AN INCREASE IN MOISTURE AND A PASSING UPPER
LEVEL DISTURBANCE. WITH THE ABUNDANT MOISTURE THAT WILL BE
PRESENT...LOCALLY HEAVY RAINFALL IS A POSSIBILITY WITH STRONGER OR
SLOWER MOVING STORMS. DIMINISHING MONSOONAL MOISTURE EARLY NEXT WEEK
WILL RESULT IN LESS THUNDERSTORM ACTIVITY FROM MONDAY ONWARD.

&&

.DISCUSSION...THE CLOUD COVER ACROSS SOUTHEAST ARIZONA HAD SLOWED OR
DELAYED THE REDEVELOPMENT OF SHOWERS AND THUNDERSTORMS SO FAR TODAY.
RECENT RADAR IMAGERY WAS DETECTING A FEW SHOWERS AND THUNDERSTORMS
DEVELOPING THIS AFTERNOON...MAINLY IN THE MOUNTAINS AND IN
SOUTH-CENTRAL PIMA COUNTY NEAR THE INTERNATIONAL BORDER. THE BULK OF
THE RAINFALL WILL LIKELY BE POSTPONED UNTIL LATER AS ANOTHER
THUNDERSTORM COMPLEX DEVELOPS OVER SONORA MEXICO AND TRACKS
NORTHWARD INTO SOUTHERN ARIZONA. THE AIRMASS WAS VERY MOISTURE AND
THE STEERING FLOW REMAINED RATHER LIGHT...SO THE PRIMARY THREAT FROM
THE STRONGER THUNDERSTORMS WILL BE HEAVY RAINFALL AND RUNOFF
PROBLEMS. OTHERWISE...STILL EXPECTING A COUPLE OF DAYS OF HEAVY
RAINFALL ACROSS THE AREA AND IN SONORA MEXICO AND WESTERN NEW MEXICO
WHICH COULD EVENTUALLY RESULT IN ELEVATED FLOWS IN SOME OF THE
LARGER WASHES AND STREAMS. THIS WILL ESPECIALLY BE THE CASE FOR
SANTA CRUZ...GREENLEE...EASTERN GRAHAM AND THE SOUTHERN HALF OF
COCHISE COUNTIES BY SUNDAY AFTERNOON. MODELS DIFFERED A BIT BUT
OVERALL THE BEST TIME FRAME FOR MORE WIDESPREAD HEAVY RAIN WILL BE
SATURDAY AFTERNOON INTO SATURDAY NIGHT AS AN UPPER LOW TRACKS
NORTHWARD INTO SOUTHWEST ARIZONA. THE BEST UPPER LEVEL DYNAMICS TO
SUPPORT SHOWERS AND THUNDERSTORMS WILL BE OVER NORTHERN ARIZONA BY
SUNDAY AFTERNOON. THEREFORE...WOULD EXPECTED CLEARING ACROSS
SOUTHEAST ARIZONA SUNDAY MORNING BUT THERE WILL BE ENOUGH LINGERING
MOISTURE COMBINED WITH DAYTIME HEATING TO SUPPORT AFTERNOON AND
EVENING THUNDERSTORMS. THE GENERAL TREND WILL BE FOR A DRIER
SOUTHWESTERLY FLOW TO DEVELOP ACROSS THE AREA AS AN UPPER LEVEL
TROUGH DIGS INTO THE WEST COAST. THIS WILL REINFORCE THE DRYING
TREND WHICH TRANSLATE TO A DECREASE IN THUNDERSTORM ACTIVITY BY THE
MIDDLE OF NEXT WEEK.

&&

.AVIATION...VALID THRU 03/00Z.
SCATTERED TO LOCALLY NUMEROUS SHOWERS/THUNDERSTORMS WILL CONTINUE TO
DEVELOP THIS AFTERNOON WITH THE POTENTIAL FOR HEAVY RAIN AND GUSTY
WINDS. THE THREAT FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE
TONIGHT AND SATURDAY AS WELL WITH A DISTURBANCE ALOFT NEAR SOUTHERN
ARIZONA. EXPECT LOWERING OF CIGS AND REDUCED VSBYS NEAR
THUNDERSTORMS...WITH MVFR CONDITIONS. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED THROUGH
SATURDAY AS DEEP MOISTURE REMAINS ACROSS SOUTHEAST ARIZONA AIDED BY
A DISTURBANCE ALOFT. EXPECT STRONG...GUSTY AND ERRATIC WINDS WITH
THE STRONGER THUNDERSTORMS. SEASONALLY HIGH MOISTURE VALUES WILL
ALSO TRANSLATE INTO PERIODS OF HEAVY RAINFALL AND COOLER
TEMPERATURES THIS WEEKEND... PARTICULARLY SATURDAY. THEREAFTER...A
DRYING TREND WITH WARMER TEMPERATURES WILL PREVAIL BY THE MIDDLE OF
NEXT WEEK.

&&

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

&&

$$

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