Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 210933
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
233 AM MST SAT FEB 21 2015

.SYNOPSIS...WEST TO SOUTHWESTERLY FLOW ALOFT WILL RESULT IN MILD
WEATHER THROUGH SUNDAY WITH PERIODS OF CONSIDERABLE MID AND HIGH
LEVEL CLOUDINESS. AFTERNOON BREEZES ARE EXPECTED EAST OF TUCSON
TODAY...THEN AREAWIDE ON SUNDAY. A WEAK WEATHER DISTURBANCE WILL
WILL MOVE THROUGH LATE TONIGHT AND SUNDAY RESULTING IN A SLIGHT
CHANCE OF SHOWERS EAST OF TUCSON. ANOTHER SYSTEM WILL MOVE INTO THE
AREA FROM THE NORTH AND WEST MONDAY NIGHT INTO TUESDAY WITH SOMEWHAT
COOLER TEMPERATURES AND A CHANCE OF VALLEY RAIN AND MOUNTAIN SNOW
SHOWERS.

&&

.DISCUSSION...THE RELATIVELY QUIET WEATHER PATTERN WE`VE SEEN LATELY
WILL BECOME A BIT MORE ACTIVE OVER THE FORECAST PERIOD. LOOKING AT
THE LATEST IR/WV SATELLITE IMAGERY....WEST TO SOUTHWESTERLY FLOW
ALOFT CONTINUES ACROSS ARIZONA WITH CONSIDERABLE MID AND HIGH LEVEL
CLOUDINESS. HOWEVER...LOOKING UPSTREAM ACROSS FAR SOUTHWEST ARIZONA/
NORTHERN BAJA AND JUST OFFSHORE...SKIES ARE MOSTLY CLEAR. THUS...WE
EXPECT MORE SUNSHINE TODAY COMPARED TO WHAT OCCURRED ACROSS THE AREA
ON FRIDAY. TEMPERATURES WILL REMAIN MILD AS WELL WITH HIGHS IN THE
MID TO UPPER 70S FOR THE DESERTS AND LOW TO MID 70S IN THE VALLEYS
TO THE SOUTH AND EAST OF TUCSON. AFTERNOON BREEZES ARE EXPECTED
ESPECIALLY FOR EASTERN AREAS.

AN UPPER LOW IN THE SUBTROPICAL JET STREAM NOW NEAR 25N/125W WILL
CONTINUE TO MOVE TOWARDS THE NORTHEAST AND GRADUALLY SHEAR OUT AS IT
DOES SO OVER THE NEXT DAY OR SO. HOWEVER...THERE WILL BE JUST ENOUGH
MOISTURE AND LIFT WITH THIS SYSTEM AS IT CLIPS THE AREA LATE TONIGHT
AND SUNDAY FOR A SLIGHT CHANCE OF SHOWERS...MAINLY TO THE SOUTH AND
EAST OF TUCSON. NOTE THAT THE MODELS ARE HANDLING THIS SYSTEM RATHER
POORLY. FOR THIS FORECAST CYCLE...HAVE LEANED TOWARDS THE SLIGHTLY
WETTER NAM SOLUTION. MEANWHILE...THE OTHER STORY SUNDAY WILL BE
WIDESPREAD SOUTH TO SOUTHWEST AFTERNOON BREEZES AS THE GRADIENT
TIGHTENS.

BY MONDAY...AN UPPER LOW IS EXPECTED TO BE CENTERED NEAR CALIFORNIA
AND NEVADA WITH CONTINUED WEST TO SOUTHWEST FLOW ALOFT AND AFTERNOON
BREEZES MAINLY FOR EASTERN AREAS. TEMPERATURES WILL DROP CLOSER TO
NORMAL VALUES FOR THIS TIME OF YEAR AS HEIGHTS AND THICKNESSES
LOWER.

THE LATEST TRENDS IN THE 00Z GLOBAL MODEL SUITE FOR THIS SYSTEM IS
TO DIG IT FARTHER SOUTH MONDAY NIGHT AND TUESDAY WITH THE UPPER LOW
CENTER ACROSS NORTHERN ARIZONA. THIS WOULD BE CLOSE ENOUGH TO BRING
INCREASED MOISTURE AND A BONA FIDE COLD FRONT THROUGH THE AREA WITH
A SLIGHT CHANCE TO CHANCE OF VALLEY RAIN AND MOUNTAIN SNOW AND BELOW
NORMAL TEMPERATURES ON TUESDAY.

MAINLY DRY NORTHWESTERLY FLOW IS EXPECTED ON WEDNESDAY BEFORE
ANOTHER TROUGH DIGS INTO THE DESERT SOUTHWEST BY LATE THURSDAY OR
FRIDAY WITH PERHAPS SOME INCREASED BREEZES AND THE NEXT CHANCE OF
PRECIPITATION.

&&

.AVIATION...DRY CONDITIONS WILL PREVAIL INTO THIS EVENING FOLLOWED
BY A SLIGHT CHANCE OF SHOWERS EAST OF KTUS LATE TONIGHT INTO EARLY
SUNDAY MORNING. OTHERWISE...EXPECT SCT-BKN CLOUDS ABOVE 15K FT AGL
THRU 22/12Z. SURFACE WIND THIS AFTERNOON WILL BE SWLY/WLY AT 12-18
KTS WITH GUSTS OF 20-25 KTS. SURFACE WIND WILL BE MAINLY LESS THAN
10 KTS AT OTHER TIMES. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...A SERIES OF DISTURBANCES WILL BRING OCCASIONAL
VALLEY RAIN AND HIGHER ELEVATION SNOW CHANCES THROUGH TUESDAY. THERE
IS A SLIGHT CHANCE OF SHOWERS LATE TONIGHT INTO SUNDAY NIGHT EAST OF
TUCSON. PRECIPITATION CHANCES WILL INCREASE NORTH OF TUCSON
MONDAY...THEN ISOLATED TO SCATTERED SHOWERS SHOULD OCCUR TUESDAY.
DRY CONDITIONS WILL PREVAIL FOR MOST SECTIONS WEDNESDAY AND
THURSDAY. THERE IS A SLIGHT CHANCE OF SHOWERS FROM TUCSON EASTWARD
TO THE NEW MEXICO BORDER NEXT FRIDAY. THIS FAIRLY ACTIVE PATTERN
WILL ALSO BRING AFTERNOON BREEZINESS...ESPECIALLY EAST AND SOUTH OF
TUCSON.

&&

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

&&

$$

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