Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 171518
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
817 AM MST THU APR 17 2014

.SYNOPSIS...DRY CONDITIONS WITH ABOVE NORMAL DAYTIME TEMPERATURES
WILL PREVAIL ONCE AGAIN TODAY. A PACIFIC LOW PRESSURE SYSTEM WILL
THEN BRING A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS FRIDAY
AFTERNOON INTO SATURDAY. COOLER TEMPERATURES WILL ALSO OCCUR FRIDAY
FOLLOWED BY A WARMING TREND EARLY NEXT WEEK. GUSTY WINDS WILL RETURN
TO THE AREA NEXT TUESDAY AND WEDNESDAY.

&&

.DISCUSSION...CURRENT FORECAST LOOKED ON TRACK WITH CLEAR SKIES THIS
MORNING IN ADVANCE OF A LOW PRESSURE SYSTEM APPROACHING THE SOUTHERN
CALIFORNIA COAST. SEE ADDITIONAL SECTIONS IN THIS PRODUCT FOR MORE
DETAILS. NO UPDATES NECESSARY THIS MORNING.

&&

.AVIATION...HIGH PRESSURE ALOFT WILL PROVIDE CLEAR SKIES THIS
MORNING FOLLOWED BY A FEW TO SCATTERED CLOUDS ABOVE 20K FT AGL THIS
AFTERNOON. A WEAK UPPER LEVEL LOW PRESSURE SYSTEM NEAR THE SOUTHERN
CALIFORNIA COAST THIS EVENING WILL MOVE INTO THE AREA FRIDAY. EXPECT
BROKEN TO OVERCAST CLOUD DECKS MOSTLY ABOVE 12K FT AGL LATE TONIGHT
AND FRIDAY. ISOLD-SCT -SHRA SHOULD DEVELOP FRIDAY AFTERNOON. THERE
IS ALSO A SLIGHT CHANCE OF -TSRA FRIDAY AFTERNOON. SURFACE WIND
THROUGH TONIGHT WILL BE MOSTLY LESS THAN 10 KTS. SURFACE WIND FRIDAY
WILL BE SLY/SWLY 12-18 KTS WITH GUSTS TO AROUND 25 KTS. BRIEF WIND
GUSTS TO NEAR 40 KTS MAY OCCUR NEAR THUNDERSTORMS. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...DRY CONDITIONS WITH FAIRLY LIGHT GENERALLY SOUTHERLY
TO WESTERLY SURFACE WINDS WILL OCCUR TODAY. A WEAK UPPER LEVEL LOW
PRESSURE SYSTEM WILL THEN MOVE EAST ACROSS THE AREA FRIDAY THROUGH
SATURDAY. THERE APPEARS TO BE ENOUGH MOISTURE TO JUSTIFY ISOLATED TO
SCATTERED SHOWERS FRIDAY AFTERNOON THROUGH SATURDAY. THERE ALSO
APPEARS TO BE ENOUGH INSTABILITY TO SUPPORT A SLIGHT CHANCE OF
THUNDERSTORMS FRIDAY AFTERNOON AND FRIDAY EVENING...AND AGAIN
SATURDAY AFTERNOON. RAINFALL AMOUNTS ARE EXPECTED TO BE QUITE LIGHT.

HOWEVER...THE MAIN CONCERN WILL BE FOR THE POTENTIAL OF GUSTY AND
ERRATIC WINDS ASSOCIATED WITH ANY THUNDERSTORMS THAT OCCUR. DRY
CONDITIONS WILL THEN PREVAIL SATURDAY NIGHT THROUGH WEDNESDAY.
EXPECT NORMAL DIURNAL WIND TRENDS SUNDAY AND MONDAY...WITH
OCCASIONAL GUSTS DURING THE AFTERNOON HOURS DUE TO DAYTIME HEATING.

CRITICAL FIRE WEATHER CONDITIONS MAY RETURN AS EARLY AS TUESDAY...
THOUGH MORE LIKELY NEXT WEDNESDAY WHEN STRONGER WINDS ARE FORECAST
TO OCCUR. THE STRONGEST WINDS WILL BE ACROSS GREENLEE...GRAHAM AND
COCHISE COUNTIES EAST OF TUCSON.

&&

.PREV DISCUSSION...A CLEAR SKY PREVAILED ACROSS THE AREA THIS
MORNING UNDER DRY NW FLOW ALOFT. UPPER RIDGE TO OUR WEST WILL BUILD
OVER THE AREA TODAY WITH RIDGE AXIS EXTENDING FROM CHIHUAHUA MEXICO
NW INTO NV. HIGHS TODAY WILL BE SLIGHTLY WARMER THAN WEDNESDAY. SOME
HIGH CLOUDS WILL PASS THROUGH LATER TODAY.

TONIGHT...CLOUDS WILL BE ON THE INCREASE LATE IN ADVANCE OF UPPER
TROF THAT WILL BE OFF SRN CA/NRN BAJA COAST. OVERNIGHT LOWS WILL BE
RATHER MILD...RUNNING 6-10 DEGREES ABOVE NORMAL.

FRIDAY AND SATURDAY...UPPER LEVEL TROF WILL BE SLOWLY MOVING EAST
ACROSS THE STATE. MODELS ARE PROGGING PRECIPITABLE WATER VALUES OF
0.60"-0.80"...WHICH IS AROUND TWO STANDARD DEVIATIONS ABOVE NORMAL
FOR APRIL. BEST CHANCES OF MEASURABLE PRECIPITATION WILL BE IN THE
MOUNTAINS WITH A SLIGHT CHANCE OF THUNDERSTORMS FRIDAY AND SATURDAY
AFTERNOON. QPF VALUES WILL BE RATHER LIGHT WITH SNOW LEVELS BEING
RATHER HIGH WITH THIS SYSTEM. COOLER FRIDAY WITH HIGHS BEING 4-8
DEGREES COOLER THAN TODAY. HIGHS ON SATURDAY WILL BE 2-4 DEGREES
WARMER THAN FRIDAY.

SUNDAY...SLIGHTLY WARMER AND DRY WITH FRI/SAT SYSTEM HEADING INTO
THE PLAINS.

MONDAY...UPPER RIDGE OVER THE AREA RESULTING IN HIGHS BEING 4-6
DEGREES WARMER THAN SUNDAY.

TUESDAY AND WEDNESDAY...STRONG UPPER TROF MOVING THROUGH THE
INTERMOUNTAIN WEST WILL BRING A RETURN TO BREEZY TO WINDY CONDITIONS
TO SE ARIZONA WITH WEDNESDAY BEING THE WINDIEST DAY. IF MODELS ARE
RIGHT ON WIND SPEEDS...CRITICAL FIRE WEATHER CONDITIONS WILL BE A
CONCERN. THIS IS ADDRESSED IN FIRE WEATHER SECTION BELOW.

&&

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

&&

$$

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