Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 311648
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
947 AM 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...RADAR WAS SHOWING A FEW LINGERING SHOWERS IN THE WHITE
MOUNTAINS THIS MORNING...WITH CLOUDS ALREADY STARTING TO BUILD UP IN
THE MOUNTAINS ELSEWHERE ACROSS SOUTHEAST ARIZONA. STILL LOOKING AT A
RATHER ACTIVE DAY THUNDERSTORM WISE ACROSS THE AREA...WITH LOCALLY
HEAVY RAINFALL AND STRONG WINDS BEING THE MAIN CONCERNS TODAY.
CURRENT FORECAST SEEMED TO HANDLE THE TRENDS WELL...SO NO UPDATES
NECESSARY THIS MORNING. PLEASE REFER TO THE ADDITIONAL SECTIONS IN
THIS PRODUCT FOR MORE DETAILS.

&&

.AVIATION...VALID THRU 01/18Z.
BECOMING SCT-BKN IN THE AFTERNOON...DECKS GENERALLY 8 TO 12 KFT. SCT
SHRA/TSRA WILL AGAIN BE POSSIBLE THIS AFTERNOON. 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...THOUGH SOME WEST-SOUTHWEST
AFTERNOON BREEZINESS IS NOT OUT OF THE QUESTION. AVIATION DISCUSSION
NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...ANOTHER ROUND OF SCATTERED SHOWERS AND THUNDERSTORMS
IN STORE FOR TODAY...WITH THE ACTIVITY SHIFTING A BIT MORE EAST.
GENERALLY FROM ZONES 503...504 AND 536 EAST. PRIME CONCERN TODAY IS
STRONG WINDS AND HEAVY RAIN DUE TO SLOW MOTIONS.  THIS BASIC IDEA
WILL CONTINUE EARLY THIS WEEK...WITH DAILY AFTERNOON AND EVENING
STORMS EXPECTED.  STARTING TUESDAY STORMS WILL TEND TO BE MORE
FOCUSED OVER EASTERN ZONES...WITH DIMINISHED THUNDERSTORM ACTIVITY
FROM WEDNESDAY ON.  THUNDERSTORMS ARE EXPECTED TO BE WET AND AS IS
TYPICAL MAY PRODUCE STRONG...GUSTY AND ERRATIC WINDS WITH THE
STRONGER THUNDERSTORMS.

OUTSIDE OF THUNDERSTORMS GENERALLY LIGHT TERRAIN DRIVEN WINDS ARE
EXPECTED...WITH A WEST TO SOUTHWEST FLOW WILL DEVELOPING TODAY
ACROSS ARIZONA. THE STRONGEST WINDS WILL BE ACROSS ZONE
150...PEAKING IN THE 15-20 MPH RANGE.

&&

.PREV DISCUSSION...THE MID LEVEL AND STORM FLOW REMAIN WEAK WITH THE
TROUGHINESS THROUGH THE REGION NORTH OF US NOT DIGGING MUCH...AND
THE NEARBY RIDGE CONTINUING TO WEAKEN WITH THE REMNANT CENTER
HANGING ON IN CHIHUAHUA. WE HAVE PLENTY OF MOISTURE FOR THE TIME
BEING WITH PRECIPITABLE WATER LEVELS ACROSS THE SOUTHERN HALF OF THE
STATE RANGING FROM 1 INCH NEAR THE NEW MEXICO BORDER TO 1.6 INCHES
IN SOUTH CENTRAL AREAS WEST AND NORTHWEST OF TUCSON.

FOR TODAY WE SHOULD BENEFIT FROM A LITTLE MORE COOLING IN THE MID
LEVELS AS THE HIGH PRESSURE CONTINUES TO WEAKEN. THIS SHOULD SUPPORT
VALLEY STORMS A LITTLE BETTER COMPARED TO YESTERDAY. WE HAD BUILT UP
SOLID ELEVATED CONVECTIVE POTENTIAL BY YESTERDAY AFTERNOON...WE JUST
DIDN`T HAVE QUITE ENOUGH TO OVERCOME THE INHIBITION IN SOME VALLEY
LOCATIONS. EXPECT BETTER COVERAGE TODAY WITH INCREASED SUPPORT FOR
VALLEY STORMS EAST OF SELLS. THIS IS SUPPORTED WELL BY 00Z UOFA WRF
RUNS.

FOR TUESDAY AND WEDNESDAY WE`LL CONTINUE TO SEE SOME MOISTURE
EROSION FROM THE WEST...WITH AREAS IMMEDIATELY UPSTREAM IN THE WEAK
BUT CONTINUING WESTERLY TO SOUTHWESTERLY FLOW STARTING TO LOSE
MOISTURE. MAIN AREA OF FOCUS EAST OF TUCSON TUESDAY AND WEDNESDAY
AFTERNOONS.

BY THURSDAY THE WEAKER MOISTURE FIELDS WILL HAVE TAKEN THEIR TOLL
WITH MORE LIMITED COVERAGE...STILL FAVORING AREAS EAST OF TUCSON.

LATER IN THE WEEK AND INTO THE WEEKEND...SEPTEMBER IS HERE AND IT`S
TIME TO WATCH FOR TROPICAL INFLUENCES. THE ACTIVITY OFF THE WEST
COAST OF MEXICO HAS BEEN PICKING UP STEAM AGAIN...GENERATING 3 NAMED
STORMS OVER THE PAST WEEK. AS IS OFTEN THE CASE IN AUGUST...THESE
STORMS HAVE BEEN MAKING A BEELINE FOR THE CENTRAL PACIFIC WITHOUT
DOING MUCH FOR OUR AREA. ANOTHER IS COOKING ABOUT 650 MILES SOUTH-
SOUTHWEST OF MANZANILLO WITH AN AREA OF LOW PRESSURE BECOMING BETTER
ORGANIZED SINCE YESTERDAY. CONDITIONS ARE CONDUCIVE FOR CONTINUED
DEVELOPMENT WITH THIS STORM EXPECTED TO BECOME A DEPRESSION DURING
THE NEXT DAY OR TWO. IF IT ENDS UP GETTING A NAME...IT WILL BE
KEVIN. WITH THE MEAN TROUGH POSITION HANGING ON THROUGH THE NORTHERN
AND CENTRAL GREAT BASIN...WE MIGHT BE ABLE TO COAX SOME TROPICAL
INFLUENCES IN OUR GENERAL DIRECTION BY THEN. AT THE VERY LEAST
MEDIUM RANGE MODELS ONCE AGAIN INCREASE OUR MOISTURE BY NEXT WEEKEND.

&&

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

&&

$$

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