Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 312130
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
230 PM MST MON AUG 31 2015

.SYNOPSIS...ANOTHER GOOD CHANCE OF SHOWERS AND THUNDERSTORMS TODAY.
A WEAK DRYING TREND AND WEAK FLOW WILL TEND TO LIMIT MOST
THUNDERSTORM ACTIVITY TO AREAS EAST OF TUCSON THE SECOND HALF OF THE
WEEK. BY THIS WEEKEND...A MOISTURE INCREASE FROM THE SOUTH WILL
BRING A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS.

&&

.DISCUSSION...ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
CONTINUED TO DEVELOP THIS AFTERNOON. RAINFALL AMOUNTS HAVE GENERALLY
BEEN ON THE ORDER OF .25 TO .50 OF AN INCH...WITH A FEW OF THE
STRONGER ONES PRODUCING UP TO 1.5 INCHES IN AN HOUR. EXPECTING THIS
ACTIVITY TO DIMINISH SIGNIFICANTLY AFTER SUNDOWN. THEREAFTER...THE
GFS AND ECMWF DIFFER ON HOW MUCH DRYING TAKES PLACES AS A LOW
PRESSURE TROUGH DEEPENS ALONG THE WEST COAST...AND THE SOUTHWESTERLY
FLOW ALOFT INCREASES ACROSS THE AREA. FOR NOW...WILL CONTINUE TO
ADVERTISE A DECREASE AND EASTERLY SHIFT IN RAIN CHANCES FOR TOMORROW
INTO AT LEAST FRIDAY. FORECAST BECOMES MORE UNCERTAIN THIS WEEKEND
AS THE GFS AND ECMWF SHOWED WIDELY DIFFERENT SOLUTIONS IN THE
STRENGTH AND TRACK OF A SYSTEM MOVING INTO THE PACIFIC NORTHWEST.
FOR NOW...WILL LEAN MORE TOWARD THE GFS SOLUTION WHICH SUGGESTED
THAT THERE MIGHT BE SOME TROPICAL INFLUENCE FROM THE EASTERN PACIFIC
AS A POSSIBLE SYSTEM HELPS PUSH DEEPER MOISTURE BACK INTO THE AREA
BY THE WEEKEND. OTHERWISE...HIGH TEMPERATURES WILL BE NEAR
SEASONABLE READINGS THIS WEEK.

&&

.AVIATION...VALID THRU 02/00Z. SCT-BKN GENERALLY 8-12 KFT WITH SCT
SHRA/TSRA THRU 01/05Z. BRIEF MVFR CONDITIONS AND GUSTY WINDS TO 45
KTS WILL BE POSSIBLE IN AND AROUND THE STRONGER STORMS.  OUTSIDE OF
THUNDERSTORM INFLUENCE SURFACE WINDS WILL GENERALLY BE UNDER 10 KTS.
 SKIES WILL CLEAR AFT 01/06Z WITH CONVECTION BUILDING AGAIN AFT
01/18Z.  AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...SCATTERED AFTERNOON AND EARLY EVENING THUNDERSTORMS
WILL CONTINUE THROUGH THURSDAY WITH A BIT OF AN EASTWARD SHIFT IN
THE ACTIVITY EACH DAY. WITH SW FLOW ALOFT STORMS WILL GENERALLY MOVE
TOWARD THE NE OUTSIDE THE INFLUENCE OF OUTFLOWS.  FOR THE MOST PART
STORMS WILL BE DECENT RAINERS WITH WIND GUSTS IN THE 25-40 MPH
RANGE...WHILE A COUPLE EACH DAY WILL BE STRONGER.  THROUGH MUCH OF
THE COMING WEEK WINDS WILL BE LIGHT WITH A WEST TO SOUTHWEST 10-15
MPH BREEZE EACH AFTERNOON.

FROM FRIDAY ONWARD THERE IS THE POTENTIAL FOR THE SW FLOW ALOFT TO
CAPTURE REMNANT TROPICAL SYSTEMS AND DIRECT THAT MOISTURE UP ACROSS
OUR AREA FOR PERIODS OF ENHANCEMENT TO THE PRECIPITATION POTENTIAL.

&&

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

&&
.AVIATION/FIRE WEATHER...CERNIGLIA

$$

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


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