Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 221646
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
945 AM MST MON SEP 22 2014

.SYNOPSIS...DRIER CONDITIONS WILL LEAD TO REDUCED COVERAGE OF
SHOWERS AND THUNDERSTORMS BY MIDWEEK. THE CHANCES FOR SHOWERS AND
THUNDERSTORMS WILL THEN INCREASE DURING THE LATTER PART OF THE WEEK.
A GRADUAL WARMING TREND WILL OCCUR THROUGH WEDNESDAY FOLLOWED BY
COOLER TEMPERATURES THIS WEEKEND.

&&

.DISCUSSION...IR/VISIBLE SATELLITE IMAGERY AND SURFACE OBSERVATIONS
INDICATED SUNNY SKIES ACROSS WRN PIMA COUNTY...AND MOSTLY CLEAR
SKIES TO PARTLY CLOUDY SKIES ELSEWHERE. DEWPOINTS AT LOWER
ELEVATIONS VALID 16Z WERE GENERALLY IN THE LOWER-MID 60S F...AND
THESE TEMPS WERE NEARLY IDENTICAL TO 24 HOURS AGO. 22/12Z KTWC
SOUNDING PRECIP WATER VALUE WAS 1.39 INCHES...DOWN NEARLY 0.10 INCH
VERSUS 24 HOURS AGO. THE ENVIRONMENT WAS MARGINALLY UNSTABLE WITH
LIFTED INDEX OF MINUS 1...AND UNMODIFIED SBCAPE OF 1391 J/KG. 22/12Z
UPPER AIR PLOTS INDICATED WEAK UPPER LOW CENTERED OVER SRN IDAHO
WITH 592 DM HIGH PRESSURE CENTERED OVER THE TEXAS BIG BEND AREA.
LIGHT TO MODERATE WLY FLOW PREVAILED ABOVE 500 MB.

MOISTURE WILL REMAIN SUFFICIENT TO JUSTIFY A CONTINUED CHANCE OF
SHOWERS/TSTMS THIS AFTERNOON AND EVENING ACROSS GREENLEE...GRAHAM
AND COCHISE COUNTIES. THERE IS THE POTENTIAL FOR LOCALLY HEAVY
RAINFALL TO OCCUR WITH THE STRONGER TSTMS. ISOLATED SHOWERS/TSTMS
WILL BE POSSIBLE THIS AFTERNOON/EVENING FOR THE TUCSON METRO AREA...
AND DRY CONDITIONS WILL CONTINUE FURTHER WEST ACROSS WRN/CENTRAL
PIMA COUNTY. A SLIGHT CHANCE OF SHOWERS/TSTMS WILL CONTINUE LATE
TONIGHT MAINLY NEAR THE NEW MEXICO BORDER WITH DRY CONDITIONS
ELSEWHERE.

HIGH PRESSURE ALOFT CENTERED OVER THE NRN GULF OF CALIFORNIA TUE IS
PROGGED TO AMPLIFY OVER THE SWRN CONUS WED. WARMER MID-LEVEL TEMPS
IN COMBINATION WITH DECREASED MOISTURE WILL TRANSLATE INTO MARKEDLY
REDUCED PRECIP CHANCES TUE-WED. ISOLATED SHOWERS AND THUNDERSTORMS
WED AFTERNOON/EVENING SHOULD BE CONFINED TO NEAR THE HIGHER TERRAIN
EAST AND SOUTH OF TUCSON.

LOWER AND MID-LEVEL MOISTURE IS PROGGED TO INCREASE THUR-SAT AHEAD
OF A DEEPENING UPPER TROUGH OVER THE WRN CONUS. THERE REMAINED SOME
DIFFERENCES BETWEEN THE 22/00Z GFS/ECMWF REGARDING THE EVOLUTION OF
THIS TROUGH BY THIS WEEKEND. ALTHOUGH THE GFS CONTINUED TO DEPICT A
SOMEWHAT MORE-PROGRESSIVE SYSTEM VERSUS THE ECMWF...THESE SOLUTIONS
WERE ACTUALLY FAIRLY SIMILAR WITH THE MID/UPPER LEVEL PATTERN AND
ASSOCIATED QPF/S FOR THIS WEEKEND.

AT ANY RATE...ISOLATED SHOWERS/TSTMS THUR SHOULD INCREASE TO
SCATTERED COVERAGE OF SHOWERS/TSTMS BY SAT. THE PRESENCE OF A
NEGATIVELY-TILTED TROUGH AXIS AND STRONG DIFFLUENCE ALOFT MAY
ENHANCE THE POTENTIAL FOR SEVERE TSTMS TO OCCUR SAT. THEREAFTER...
DEEPER MOISTURE IS PROGGED TO BE SHUNTED EWD ACROSS MUCH OF NEW
MEXICO SUNDAY. HOWEVER...THERE APPEARS TO BE ENOUGH RESIDUAL
MOISTURE TO MAINTAIN ISOLATED SHOWERS/TSTMS SUN MAINLY FROM TUCSON
EASTWARD TO THE NEW MEXICO BORDER.

HIGH TEMPS THIS AFTERNOON WILL BE SIMILAR TO TEMPS ACHIEVED SUN...
THEN EXPECT A DEGREE-OR-TWO OF DAILY WARMING TUE-WED. DAYTIME TEMPS
WILL THEN FALL TO BELOW SEASONAL NORMALS THIS WEEKEND.

&&

.AVIATION...VALID THRU 23/18Z.
EXPECT SCATTERED -SHRA/-TSRA FROM KTUS VICINITY EAST AND SOUTH THIS
AFTERNOON AND THIS EVENING. MVFR CONDITIONS AND BRIEF WIND GUSTS TO
AROUND 35 KTS WILL OCCUR WITH THE STRONGER THUNDERSTORMS. ISOLATED
-SHRA/-TSRA WILL THEN BE CONFINED MAINLY NEAR THE NEW MEXICO BORDER
LATE TONIGHT INTO TUESDAY MORNING. OTHERWISE...SURFACE WIND WILL BE
MAINLY LESS THAN 10 KTS THRU TUESDAY MORNING. AVIATION DISCUSSION
NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...SCATTERED SHOWERS AND THUNDERSTORMS WILL OCCUR
MAINLY FROM TUCSON EASTWARD AND SOUTHWARD THIS AFTERNOON AND THIS
EVENING. DRIER CONDITIONS WILL PRODUCE MARKEDLY LESS COVERAGE OF
SHOWERS AND THUNDERSTORMS TUESDAY AND WEDNESDAY. INCREASING CHANCES
FOR SHOWERS AND THUNDERSTORMS WILL THEN PREVAIL THURSDAY INTO THIS
WEEKEND. BRIEF GUSTY OUTFLOWS WILL OCCUR WITH THE STRONGER
THUNDERSTORMS. OTHERWISE...20-FOOT WINDS WILL GENERALLY BE LESS THAN
15 MPH THIS WEEK.

&&

.HYDROLOGY...PRETTY EXTENSIVE AREA OF RAINFALL THIS MORNING FROM
CENTRAL GREENLEE COUNTY EAST INTO WESTERN GRANT COUNTY IN NEW
MEXICO. DOPPLER RADAR INDICATED THAT OVER TWO AND A HALF INCHES HAD
FALLEN EAST OF CLIFTON WITH A COUPLE OF GAUGES NEAR AND NW OF VIRDEN
NEW MEXICO RECORDING BETWEEN 1"-2". RUNOFF FROM THESE HEAVY RAINS
FLOWED INTO THE SAN FRANCISCO AND GILA RIVERS THIS MORNING. AS A
RESULT...THE GILA RIVER AT THE CLIFTON GAUGE...WHICH IS
APPROXIMATELY 6 MILES SOUTH OF THE TOWN OF CLIFTON...INDICATED A
RISE TO 17.1 FEET EARLIER THIS MORNING WITH A FLOW OF JUST UNDER
11,000 CFS. THIS FLOW WILL CONTINUE DOWN THE GILA RIVER AND WILL
AFFECT THE SOLOMON...SAFFORD AND PIMA AREAS LATE THIS AFTERNOON AND
EARLY EVENING. AS THE WATER REACHES THE SAFFORD AREA...SOME OF THE
APPROACHES TO BRIDGES MAY BE AFFECTED BY THE RISING WATER.
THEREFORE...A HYDROLOGIC ADVISORY IN THE FORM OF A SMALL STREAM
FLOOD ADVISORY WAS ISSUED THROUGH 830 PM MST THIS EVENING...WHICH
INCLUDES SOLOMON...SAFFORD AND PIMA.

&&

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

&&

$$

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

FRANCIS
HYDROLOGY...MOLLERE





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