Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 120937
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
230 AM MST FRI SEP 12 2014

.SYNOPSIS...MOISTURE MOVING INTO THE AREA FROM THE EAST WILL RESULT
IN MORE THUNDERSTORMS TODAY...ESPECIALLY EAST OF TUCSON. STRONG AND
GUSTY EAST WINDS DEVELOPING TONIGHT INTO SATURDAY...THEN SEVERAL
DEGREES OF COOLING ALONG WITH A REDUCED CHANCE OF STORMS THIS
WEEKEND. THE CHANCE FOR THUNDERSTORMS WILL INCREASE EARLY NEXT WEEK
AS MOISTURE INCREASES ACROSS THE AREA FROM THE SOUTH...ESPECIALLY
TUESDAY AND WEDNESDAY.

&&

.DISCUSSION...MOISTURE GRADIENT ACROSS SE AZ WITH PRECIPITABLE WATER
VALUES AROUND 1.3 INCHES IN SOUTHWEST NEW MEXICO TO VALUES BELOW 1
INCH IN WESTERN AREAS. THIS WILL DRIVE OUR THUNDERSTORM COVERAGE
TODAY WITH BEST COVERAGE IN EASTERN AREAS. A FEW STRONG STORMS AND
LOCALLY HEAVY RAIN UNDER CORES. GUSTY OUTFLOWS.

DECENT SYSTEM PUSHING THROUGH THE NORTHERN AND CENTRAL PLAINS WITH
TRAILING FRONTAL BOUNDARY INTO NEW MEXICO. EXPECT AN EASTERLY
GRADIENT AS THE PERIPHERY OF THIS AIR MASS TRIES TO BACK INTO THE
AREA FROM THE EAST FRIDAY NIGHT INTO SATURDAY WITH A SURFACE HIGH
BUILDING DOWN THE FRONT RANGE. BREEZY TO LOCALLY WINDY EAST TO
SOUTHEAST WINDS FRIDAY NIGHT THROUGH THE FIRST HALF OF THE WEEKEND.
EXPECT ELEVATED OVERNIGHT LOWS SATURDAY MORNING AS MANY VALLEY
LOCATIONS FROM TUCSON EASTWARD FAIL TO DECOUPLE. THIS WILL TAMP DOWN
THE MOISTURE A BIT AND FILTER IN SOME RELATIVELY COOLER AIR INTO
EASTERN ZONES SATURDAY. AN EXAGGERATED SPATIAL TREND IN TEMPERATURES
SATURDAY WITH VERY LITTLE COOLING OUT WEST CONTRASTED WITH AROUND 10
DEGREES OF COOLING IN EASTERN ZONES.

TROPICAL STORM ODILE CURRENTLY DOWN AROUND 15.5N 104.9W OR ABOUT 245
MILES SOUTH OF MANZANILLO WILL CONTINUE TO STRENGTHEN AND PUSH
NORTHWEST TOWARD THE TIP OF BAJA OVER THE NEXT 5 DAYS. SHE WILL
LIKELY HELP PROVIDE A MOISTURE INCREASE FOR BETTER SHOWER AND
THUNDERSTORM COVERAGE FOR OUR AREA AROUND TUESDAY AND WEDNESDAY OF
NEXT WEEK...BUT SHE DOESN`T HAVE ALL OF THE ADVANTAGES NORBERT DID.
FOR ONE...THERE IS A DEVELOPING RIDGE AXIS THAT WILL PROBABLY BE A
LITTLE TOO DOMINANT OVER THE DESERT SOUTHWEST EARLY NEXT WEEK. FOR
NORBERT THE RIDGE WAS SET UP EAST OF OUR AREA WITH STRONGER AND
DEEPER SOUTHERLY TO SOUTHEASTERLY FLOW AROUND IT. ANOTHER FACTOR IS
NORBERT ALSO WAS ABLE TO HELP GUIDE ADDITIONAL TROPICAL MOISTURE
FROM A DECAYING GULF OF MEXICO SYSTEM INTO OUR AREA...AND WE DON`T
REALLY HAVE THAT THIS TIME. ODILE WILL VERY LIKELY ENHANCE OUR
MOISTURE WITH INCREASED STORM COVERAGE FOLLOWING...BUT AT THIS POINT
IT DOESN`T LOOK LIKE IT WILL BE QUITE AS SIGNIFICANT AS NORBERT WAS.

SO...INCREASING MOISTURE FOR BETTER STORM COVERAGE FROM TUCSON
EASTWARD TODAY...GUSTY EAST WINDS FRIDAY NIGHT INTO SATURDAY WITH
BELOW AVERAGE TEMPERATURES SATURDAY...THEN ENHANCED MOISTURE FOR
MUCH BETTER STORM COVERAGE BY TUESDAY AND WEDNESDAY.

&&

.AVIATION...VALID THRU 13/09Z.
AN EASTERLY WIND WILL IMPORT HIGHER MOISTURE TO LOCATIONS MAINLY
EAST OF TUCSON FRIDAY. THIS WILL RESULT IN SCATTERED LOW-LEVEL
CLOUDS /7-11K FT AGL/ AND SCATTERED TO BROKEN MID-LEVEL CLOUDS
/12-16K FT AGL/ WITH SCATTERED AFTERNOON AND EVENING SHRA/TSRA.
SURFACE WIND GENERALLY LESS THAN 10 KTS...EXCEPT GUSTY IN VCNTY OF
SHRA/TSRA. GUSTY EAST WINDS DEVELOPING LATE FRIDAY NIGHT INTO
SATURDAY. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...THERE WILL BE A CHANCE OF SHOWERS AND THUNDERSTORMS
ACROSS THE EASTERN HALF OF THE FORECAST AREA FRIDAY. WINDS WILL
GENERALLY BE OUT OF THE EAST FRIDAY...WITH EXCEPT ERRATIC OUTFLOWS
ASSOCIATED WITH THUNDERSTORMS.

FRIDAY EVENING WILL SEE A SHIFT IN THE WINDS TO AN EAST/SOUTHEAST
DIRECTION WITH A BACKDOOR FRONTAL PASSAGE. EXPECT WIND SPEEDS TO BE
ELEVATED INTO SUNDAY...GENERALLY BETWEEN 10 AND 20 MPH...WITH SOME
LOCALLY HIGHER SPEEDS POSSIBLE. PRECIPITATION CHANCES WILL LOWER
OVER THE UPCOMING WEEKEND INTO THE SLIGHT CHANCE CATEGORY.

TROPICAL MOISTURE WILL THEN BE ON THE INCREASE NEXT WEEK...WITH
TROPICAL STORM ODILE INFLUENCE REACHING THE FORECAST AREA. EXPECT
AN INCREASE IN SHOWER AND THUNDERSTORM ACTIVITY AND AREAL COVERAGE
BY THE MIDDLE OF NEXT WEEK.

&&

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

&&

$$

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MEYER/MEADOWS





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