Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 172139
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
237 PM MST THU APR 17 2014

.SYNOPSIS...A PACIFIC LOW PRESSURE SYSTEM WILL 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...A LOW PRESSURE SYSTEM APPROACHING THE SOUTHERN
CALIFORNIA COAST TODAY WILL TRACK THROUGH ARIZONA ON SATURDAY.
MOISTURE ASSOCIATED WITH A WEAK IMPULSE WILL MOVE INTO THE AREA
FRIDAY AHEAD OF THE MAIN SYSTEM. LOW LEVEL MOISTURE WILL BE
LIMITED SO ANY SHOWERS OR THUNDERSTORMS THAT DEVELOP FRIDAY
AFTERNOON AND EARLY EVENING WILL PRODUCE VERY LITTLE RAIN. MODELS
SHOWED DEEPER MOISTURE MOVING INTO SOUTHERN ARIZONA AS THE MAIN LOW
PRESSURE SYSTEM MOVES THROUGH THE STATE ON SATURDAY. THE COLD POOL
ALOFT WILL RESULT IN A LITTLE MORE INSTABILITY SATURDAY AFTERNOON
AND EVENING FOR A BETTER CHANCE OF THUNDERSTORMS COMPARED TO FRIDAY.
A DROP IN DAYTIME TEMPERATURES CAN ALSO BE ANTICIPATED FRIDAY AND
SATURDAY DUE TO THE AFFECTS OF THE SYSTEM. THEREAFTER...A RIDGE OF
HIGH PRESSURE WILL BUILD OVER THE REGION FOR MORE DRY CONDITIONS AND
WARMER DAYTIME TEMPERATURES. MEDIUM RANGE MODELS SHOWED A
SIGNIFICANT CHANGE IN THE WEATHER PATTERN BY THE MIDDLE OF NEXT WEEK
AS A LARGE LOW PRESSURE SYSTEM ENTERS THE WESTERN STATES. MOISTURE
WILL BE LIMITED THIS FAR SOUTH SO NOT EXPECTING ANY SHOWERS BUT WIND
AND COOLER TEMPERATURES FOR SOUTHERN ARIZONA WILL BE THE LIKELY
OUTCOME.

&&

.AVIATION...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...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.

&&

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

&&

$$

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