Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 190932
AFDTWC
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
230 AM MST SUN OCT 19 2014

.SYNOPSIS...A WEAK WEATHER SYSTEM WILL BRING A CHANCE OF SHOWERS AND
THUNDERSTORMS TODAY...ESPECIALLY EAST OF TUCSON. WE WILL KEEP A
CHANCE OF SHOWERS IN THE FORECAST UNTIL IT MOVES EAST OF THE REGION
BY WEDNESDAY. STRONG HIGH PRESSURE WILL THEN BRING DRIER CONDITIONS
THE SECOND HALF OF THE WEEK ALONG WITH MUCH WARMER TEMPERATURES.

&&

.DISCUSSION...WEAK LOW UNDERCUTTING THE LARGER SCALE RIDGE DRIVING
OUR WEATHER THE NEXT COUPLE OF DAYS...ESPECIALLY LATER TODAY INTO
THIS EVENING. CUT-OFF IMPULSE VERY SLOWLY PUSHING ACROSS THE
NORTHERN GULF OF CALIFORNIA INTO NORTHWEST SONORA THIS MORNING.
FAVORABLE UPPER LEVEL DIFFLUENT FIELDS IN NORTHEAST QUADRANT AHEAD
OF THE LOW FIRING OFF CONVECTION THIS MORNING INTO EAST CENTRAL AND
NORTHEAST ARIZONA. AVAILABLE MOISTURE HAS CREPT UP TO A LITTLE OVER
.75 OF AN INCH WITH .9 TO 1 INCH IN CLOSER PROXIMITY TO THE LOW. AS
IT SLOWLY PUSHES EASTWARD TODAY A LITTLE DEEPER INTO NORTHERN SONORA
NEAR THE INTERNATIONAL BORDER...EXPECT AN ACTIVE REGION TO CONTINUE
ON THE NORTHEAST QUADRANT...BASICALLY AREAS NORTH AND EAST OF
NOGALES TO POSSIBLY INCLUDE TUCSON BY LATE THIS AFTERNOON OR EARLY
EVENING. BETTER CHANCES IN EASTERN AREAS SUCH AS COCHISE COUNTY.
SOME STORMS MAY GET A LITTLE FRISKY TODAY SO WE`LL NEED TO KEEP AN
EYE ON THE RADAR FOR POTENTIAL SMALL HAIL AND STRONG WINDS AS WELL
AS BRIEF LOCALLY HEAVY RAIN.

FAVORABLE AREA FOR CONVECTION WILL SHIFT SLOWLY EASTWARD DEEPER INTO
NEW MEXICO LATER TONIGHT INTO MONDAY MORNING AS THE LOW WOBBLES
SLOWLY ACROSS NORTHERN SONORA. IT WILL REMAIN CUT OFF FOR 48 TO 72
HOURS BEFORE BEING DRAWN INTO HIGHER LATITUDE SUPPORT ENERGY LATE
TUESDAY INTO WEDNESDAY.

STRONG RIDGE...VERY STRONG RIDGE BUILDING IN THROUGH ARIZONA FROM
THE SOUTH LATER THIS WEEK. ECMWF HEIGHTS AND THICKNESSES SUPPORT MID
90S AS WE FLIRT WITH VERY LATE SEASON 95S FOR TIA FRIDAY AND
SATURDAY (THE LATEST 95 AT TIA IS OCT 26 IN 2001). STRENGTH OF ECMWF
PREFERRED BASED ON VERY FAVORABLE ENSEMBLE MEAN TRENDS AND
NORMALIZED STANDARD DEVIATION TRENDS OVER THE PAST 30 DAYS. SO...WE
WILL TRY TO STEAL SOME POINTS FROM MOS BY LENDING LESS WEIGHT TO
LATE OCTOBER CLIMO AND MORE TO WHAT SEASONAL THICKNESS REGRESSION
ANALYSIS ACTUALLY SUGGESTS FOR 850MB-700MB THICKNESS VALUES AROUND
165.5 TO 166.0DAM.

&&

.AVIATION...VALID THRU 20/09Z.
SKC-SCT CLOUDS MAINLY ABOVE 10K FT AGL SOUTH OF KTUS AND SCT-BKN
NORTH OF KTUS THROUGH 19/18Z AND THERE WILL BE ENOUGH MOISTURE FOR
ISOLD -SHRA/-TSRA EAST OF KTUS.  INCREASING CLOUDS AFT 19/18Z
BECOMING SCT-BKN AROUND 10K FT ALL AREAS WITH A CHANCE OF
-SHRA/-TSRA DEVELOPING FROM AROUND KTUS EASTWARD.  SFC WINDS
GENERALLY LESS THAN 10 KTS THROUGH SUNDAY EXCEPT SOUTHEAST WIND TO
15 KT EASTERN AREAS SUNDAY AFTERNOON.  GUSTY WINDS ARE POSSIBLE
IN/NEAR TSRA THIS AFTERNOON AND EARLY EVENING. AVIATION DISCUSSION
NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...A TROUGH OF LOW PRESSURE MOVING INTO THE AREA IN
COMBINATION WITH A MODEST MOISTURE INCREASE WILL RESULT IN A CHANCE
OF SHOWERS AND THUNDERSTORMS THROUGH TUESDAY OR WEDNESDAY...MAINLY
TUCSON EASTWARD.  DRY CONDITIONS WILL THEN OCCUR AREA WIDE THE
SECOND HALF OF THE WEEK WITH SIGNIFICANTLY ABOVE NORMAL HIGH
TEMPERATURES.  20-FOOT WINDS WILL GENERALLY BE DIURNAL AND LESS THAN
15 MPH THIS WEEKEND AND INTO NEXT WEEK.  SOME GUSTY WINDS ARE
POSSIBLE NEAR ANY THUNDERSTORMS.

&&

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

$$

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

MEYER/MEADOWS









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