Weather Service Report


582 
FXUS65 KTWC 212209
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
310 PM MST TUE APR 21 2015

.SYNOPSIS...DRY WEATHER IS EXPECTED TODAY AND WEDNESDAY WITH NEAR 
NORMAL TEMPERATURES AND A SOUTHWEST BREEZE. A LOW PRESSURE SYSTEM 
WILL BRING COOLER TEMPERATURES AND A CHANCE OF SHOWERS THURSDAY AND 
EARLY FRIDAY WITH GUSTY WINDS THURSDAY. THEN DRIER WEATHER IS 
EXPECTED FOR THE WEEKEND WITH NEAR NORMAL TEMPERATURES.  

&&

.DISCUSSION...MOSTLY CLEAR SKIES PREVAIL OVER SOUTHEAST 
ARIZONA...BUT MID LEVEL CUMULUS IS DEVELOPING ALONG THE MOGOLLON 
RIM. ALSO...THE CUT OFF LOW OVER SOUTHERN CALIFORNIA IS EJECTING 
SOME MID LEVEL MOISTURE IN FAR WESTERN PIMA COUNTY. THIS SHOULD NOT 
TRANSLATE TO PRECIPITATION THOUGH. AS THIS TROUGH SLIDES EAST 
THROUGH TOMORROW...WE WILL START TO EXPERIENCE A COOLING TREND THAT 
WILL LAST THROUGH THE WEEKEND. THE INITIAL TROUGH WILL RECEIVE 
REINFORCED COLD AIR FROM A SYSTEM PUSHING SOUTH OUT OF THE GULF OF 
ALASKA. THE RESULT WILL BE TEMPS ON THE ORDER OF 5 TO 10 DEGREES 
BELOW NORMAL BY THE END OF THE WEEK AND A SMALL CHANCE FOR FREEZING 
CONDITIONS IN THE COLDER VALLEY LOCATIONS FRIDAY AND MAYBE SATURDAY 
MORNING.

IN ADDITION TO THE COLD AIR...AND INCREASE IN MID LEVEL MOISTURE 
WILL BRING PRECIPITATION CHANCES THURSDAY AND FRIDAY. THE COLDER AIR 
ALOFT WILL LEAD TO AN INCREASE IN INSTABILITY SO A FEW LIGHTNING 
STRIKES...AND MAYBE STRONG GUSTY WINDS...ARE NOT OUT OF THE 
QUESTION. 

ARIZONA REMAINS UNDER THE INFLUENCE OF LARGE SCALE TROUGHING SO 
TEMPS WILL REMAIN NEAR OR SLIGHTLY BELOW NORMAL THROUGH THE WEEKEND. 
THEN A HIGHLY AMPLIFIED RIDGE DEVELOPS EARLY NEXT WEEK AND WE SHOULD 
RETURN TO ABOVE NORMAL TEMPERATURES. THE ONLY CAVEAT IS THAT THE 
ECMWF...AND THE GFS TO SOME EXTENT...SHOWS A CUT OFF LOW DEVELOPING 
UNDER THE RIDGE. WILL WAIT AND SEE HOW THAT TRANSPIRES...BUT THIS 
WOULD MEAN A BREAK FROM THE WARM TEMPERATURES WITH LITTLE CHANCE FOR 
PRECIP LATE NEXT WEEK.

&&

.AVIATION...VALID THRU 23/00Z.
VFR CONDITIONS EXPECTED THROUGH THE PERIOD. FEW-SCT CLOUDS AOA 12K 
FT AGL MAINLY N AND E OF KTUS THIS AFTERNOON WITH CLEARING 
OVERNIGHT. SLY/SWLY SURFACE WIND 12-16 KTS AND GUSTS OF AROUND 25 
KTS PSBL THRU 22/02Z WITH THE HIGHEST SPEEDS S AND E OF KTUS. 
SWLY-SELY WINDS 8-12 KTS THROUGH THE OVERNIGHT HOURS WILL BEGIN TO 
INCREASE AROUND 22/16Z IN MOST LOCATIONS. SWLY WINDS WEDNESDAY 
AFTERNOON 14-18 KTS MOST LOCATIONS WITH GUSTS TO NEAR 30 KTS PSBL 
ESP NEAR THE MEXICO BORDER. AVIATION DISCUSSION NOT UPDATED FOR TAF 
AMENDMENTS.   FRENCH

&&

.FIRE WEATHER...DRY CONDITIONS THROUGH WEDNESDAY. A LOW PRESSURE 
SYSTEM APPROACHING THE AREA FROM THE WEST WILL BRING A SLIGHT CHANCE 
OF SHOWERS AND THUNDERSTORMS THURSDAY AND FRIDAY TO AREAS MAINLY 
NORTHWEST TO NORTHEAST OF TUCSON. THIS SYSTEM WILL GENERATE BREEZY 
SOUTHWESTERLY WINDS AS IT APPROACHES AND THEN MOVES ACROSS THE 
REGION...WITH SPEEDS INCREASING EACH DAY. THE STRONGEST WINDS ARE 
EXPECTED THURSDAY AFTERNOON...WHEN SOME LOCALIZED AREAS IN COCHISE 
COUNTY COULD SEE WINDS SPEEDS OF 25-30 MPH AND GUSTS TO 40 MPH. 
SPOTTY AND BRIEF RED FLAG CONDITIONS ARE POSSIBLE EAST OF TUCSON 
WEDNESDAY AND THURSDAY AFTERNOON IN COCHISE COUNTY...ALTHOUGH 
INCREASING MOISTURE AND COOLER TEMPERATURES WILL LIMIT COVERAGE AND 
DURATION OF CRITICAL FIRE WEATHER CONDITIONS. DRY CONDITIONS WITH 
NEAR NORMAL TEMPERATURES AND LESS WIND WILL RETURN THIS WEEKEND.   
FRENCH

&&

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

$$

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