Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 011035
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
335 AM MST SAT AUG 1 2015

.SYNOPSIS...ENOUGH MOISTURE WILL LINGER TODAY TO BRING A CHANCE OF
MAINLY AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS TO MUCH OF
SOUTHEAST ARIZONA. THEREAFTER A DRYING TREND WILL OCCUR WHICH WILL
RESULT IN MORE ISOLATED SHOWER AND THUNDERSTORM ACTIVITY CONFINED
MAINLY TO AREAS SOUTH AND EAST OF TUCSON.

&&

.DISCUSSION...IR SATELLITE LOOPS SHOW GRADUALLY CLEARING SKIES
ACROSS SOUTHERN PORTIONS OF THE CWA...WITH MOSTLY CLOUDY CONDITIONS
ELSEWHERE AS OVERNIGHT CONVECTIVE DEBRIS CONTINUES TO THIN. SURFACE
OBSERVATIONS FROM AROUND THE REGION EARLY THIS MORNING SHOW
DEWPOINTS GENERALLY IN THE LOW TO MID 60S F...MORE OR LESS UNCHANGED
FROM 24 HOURS AGO (PERHAPS A SHADE DRIER)...WITH AN IMPRESSIVE 71 F
DEWPOINT AT KPHX THANKS IN PART TO EARLIER SHOWERS AND STORMS. THE
CIRA PRECIPITABLE WATER PRODUCT SHOWS THAT WE`RE STILL QUITE MOIST
THROUGH THE ATMOSPHERIC COLUMN...WITH PW VALUES OF AROUND 1.3-1.4
INCHES NEAR TUCSON AND A TOUCH HIGHER TO THE WEST.

ALOFT...LATEST ANALYSES REVEAL A PRETTY CHAOTIC UPPER-AIR
PATTERN...WITH SEVERAL HIGH PRESSURE CENTERS STRUNG OUT ACROSS THE
GREAT BASIN AND SOUTHEASTWARD INTO THE TRANS-PECOS REGION OF TEXAS.
WATER VAPOR LOOPS IMPLY A LOCAL ENHANCEMENT TO THE UPPER-LEVEL FLOW
PUNCHING INTO CENTRAL PORTIONS OF THE BAJA PENINSULA AND GULF OF
CALIFORNIA...WHICH IS BACKED-UP BY THE LATEST RAP ANALYSIS. THE NOSE
OF THIS SUBTLE JET STREAK MAY PLAY A ROLE IN INITIATING CONVECTION
LATER TODAY ACROSS CENTRAL AND POSSIBLY WESTERN PORTIONS OF THE CWA.

SOME ISSUES TO CONTEND WITH FOR TODAY`S FORECAST REVOLVE AROUND
SLIGHTLY WARMER MID-LEVEL TEMPERATURES...POSSIBLE ISSUES WITH ANVIL
SHADING OWING TO A SOUTH TO SOUTHEASTERLY STEERING FLOW...AND THE
WIDE VARIETY OF SOLUTIONS OFFERED UP BY VARIOUS CONVECTIVE ALLOWING
MODELS. HOWEVER...BOTH THE 05Z RUN OF THE HRRRX (EXPERIMENTAL HRRR)
AND THE 00Z UNIV. OF AZ WRF-NAM SOLUTIONS PAINT A FAIRLY SIMILAR
PICTURE FOR TODAY...WITH THE MAIN CONVECTIVE FOCUS ACROSS PARTS OF
PINAL...PIMA...AND SANTA CRUZ COUNTIES AND GENERALLY MORE ISOLATED
COVERAGE OUT EAST. THESE SOLUTIONS GENERALLY LINE UP WITH THE RECENT
RUNS OF THE NAM/GFS WHICH SHOW THE BEST INSTABILITY LINING UP FROM
TUCSON AND POINTS WEST...EFFECTIVELY WITHIN THE ZONE OF HIGHER PW
AIR AS MENTIONED EARLIER.

FOR SUNDAY AND BEYOND...THE GENERAL PATTERN IS FORECAST TO BEGIN A
RE-ORGANIZATION PHASE AS THE UPPER-HIGH RECONSOLIDATES...EVENTUALLY
NEAR THE FOUR-CORNERS REGION BY THE MIDDLE TO END OF NEXT WEEK. IN
THE MEAN TIME...SOUTHWESTERLY OR WESTERLY MID-LEVEL FLOW WILL USHER
DRIER AIR INTO THE AREA WHICH WILL RESULT IN MARKEDLY REDUCED
PRECIPITATION CHANCES...PARTICULARLY BY TUESDAY. THEREAFTER...MORE
FAVORABLE SOUTHEASTERLY FLOW SHOULD ONCE AGAIN BEGIN TO PUMP
MOISTURE...AND AS A RESULT SOMEWHAT BETTER SHOWER AND STORM
COVERAGE...BACK INTO THE REGION. THE ROLLER COASTER RIDE THAT IS THE
MONSOON 2015 CONTINUES...

&&

.AVIATION...VALID THRU 02/12Z.
DECREASING CLOUD COVER THIS MORNING. SCT TO BKN CLOUDS 7-10K FT AGL
RE-DEVELOPING DURING THE LATE-MORNING ALONG WITH ISOLD-SCT SHRA/TSRA
DEVELOPING AFTER 01/19Z. THE GREATEST COVERAGE TODAY LOOKS TO OCCUR
NEAR THE KTUS AND KOLS TERMINALS AND NEAR THE HIGH TERRAIN NORTHEAST
OF KSAD. BRIEF MVFR CONDITIONS WITH ERRATIC WIND GUSTS TO 40 KTS
POSSIBLE IN AND AROUND THE STRONGER TSRA. OUTSIDE OF STORM
INFLUENCES SFC WINDS WILL GENERALLY BE LESS THAN 12 KTS WITH A FEW
HIGHER GUSTS IN THE AFTERNOON/EARLY EVENING HOURS. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...ENOUGH MOISTURE WILL LINGER TODAY FOR A CHANCE OF
AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS WITH THE GREATEST
COVERAGE FROM NEAR TUCSON AND POINTS WEST. THEN...MORE SOUTHWESTERLY
WINDS ALOFT ON SUNDAY WILL BRING DRIER AIR INTO THE REGION FOR
ISOLATED TO SCATTERED THUNDERSTORM COVERAGE TO BEGIN NEXT
WEEK...WITH A FOCUS MAINLY SOUTH AND EAST OF TUCSON. OUTSIDE OF
THUNDERSTORM WIND GUSTS...20-FT WINDS WILL GENERALLY BE TERRAIN
DRIVEN AND LESS THAN 15 MPH. HOWEVER SOME AFTERNOON AND EARLY
EVENING BREEZINESS IS LIKELY DUE TO DAYTIME HEATING...ESPECIALLY
THROUGH THE GILA VALLEY NEAR SAFFORD.

&&

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

&&

$$

CARLAW

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