Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 191620
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
920 AM MST WED NOV 19 2014

.SYNOPSIS...DRY CONDITIONS WITH SEASONABLE DAYTIME TEMPERATURES WILL
OCCUR THROUGH THURSDAY. A LOW PRESSURE SYSTEM MOVING ACROSS THE AREA
WILL BRING A CHANCE OF VALLEY RAIN AND MOUNTAIN SNOW SHOWERS FRIDAY
AFTERNOON AND EVENING. ONLY LIGHT PRECIPITATION AMOUNTS ARE
EXPECTED. DRY CONDITIONS WITH BELOW NORMAL DAYTIME TEMPERATURES WILL
THEN PREVAIL LATE THIS WEEK AND EARLY THIS WEEKEND.

&&

.DISCUSSION...UPPER RIDGE AXIS EXTENDED FROM SRN ARIZONA NWWD INTO
CENTRAL WASHINGTON THIS MORNING. MEANWHILE...THE BACK EDGE OF MAINLY
MID AND HIGH-LEVEL CLOUDS REPRESENTING A SHORTWAVE TROUGH WAS
ADJACENT THE CALIFORNIA COAST. THE SHORTWAVE TROUGH WILL MOVE EWD
ACROSS THE GREAT BASIN AND ARIZONA TODAY. THERE WILL BE ENOUGH
MOSTLY CIRRIFORM CLOUDS FOR PARTLY CLOUDY TO PERHAPS MOSTLY CLOUDY
SKIES TODAY. THE SHORTWAVE TROUGH WILL MOVE EWD INTO WRN NEW MEXICO
THIS EVENING. CLEAR SKIES OR SOME CIRRUS CLOUDS WILL PREVAIL BEHIND
THIS SYSTEM TONIGHT AND THUR.

THE FOCUS OF ATTENTION THEN TURNS TOWARD A STRONGER UPSTREAM
SHORTWAVE TROUGH PROGGED VIA THE 19/00Z GFS/ECWMF/CANADIAN TO BE
OVER THE GREAT BASIN/SRN CALIFORNIA REGION THUR NIGHT. THIS SYSTEM
WILL MOVE EWD ACROSS THE AREA FRI...WITH THE MID-LEVEL TROUGH AXIS
TO BE OVER ERN NEW MEXICO EARLY SAT MORNING. GFS/ECMWF/CANADIAN
REMAINED SIMILAR RELATIVE TO PREVIOUS SOLUTIONS REGARDING PRECIP
POTENTIAL FOR SE AZ...WITH THE BEST CHANCE OF PRECIP TO OCCUR FRI
AFTERNOON/EVENING.

GIVEN THE RAPID PROGRESSION OF THIS SYSTEM AND THE LACK OF
SIGNIFICANT LOWER LEVEL MOISTURE...LIQUID AMOUNTS SHOULD BE QUITE
LIGHT. SNOW LEVELS BY FRI EVENING SHOULD GENERALLY RANGE FROM 6000-
7000 FEET...AND SNOW ACCUMULATIONS SHOULD BE LIMITED TO ONLY AN INCH
OR SO ACROSS THE HIGHEST PEAKS. DRY CONDITIONS UNDER NWLY FLOW ALOFT
WILL OCCUR SAT AND SAT NIGHT. THE NEXT SHORTWAVE TROUGH WILL MOVE
RAPIDLY SEWD ACROSS THE CENTRAL ROCKIES SUN. EXPECT DRY CONDITIONS
SUN EXCEPT FOR A SLIGHT CHANCE OF SNOW SHOWERS ACROSS THE WHITE
MOUNTAINS. A TIGHT MID-LEVEL GRADIENT WILL PRODUCE GUSTY WLY/NWLY
WINDS SUN. THE ORIENTATION OF THE MID-LEVEL GRADIENT FAVORS THE
UPPER GILA VALLEY WITH THE STRONGER WINDS. DRY CONDITIONS WILL THEN
OCCUR MON-TUE AS NWLY FLOW ALOFT CONTINUES OVER THE AREA.

SEASONABLE DAYTIME TEMPS WILL OCCUR ACROSS SE AZ TODAY FOLLOWED BY
VERY MINOR COOLING THUR. EXPECT AN ADDITIONAL 5 DEGS OR SO OF
COOLING FRI FOLLOWED BY NO SIGNIFICANT CHANGE IN DAYTIME TEMPS SAT.
A GRADUAL WARMING TREND WILL THEN PREVAIL EARLY NEXT WEEK.

&&

.AVIATION...VALID THRU 20/12Z.
A WEAK DISTURBANCE MOVING EASTWARD ACROSS THE AREA WILL BRING
SCATTERED TO BROKEN CLOUDS ABOVE 15K FT AGL TODAY. CLEAR SKIES OR A
FEW CLOUDS ABOVE 20K FT AGL WILL OCCUR BEHIND THIS SYSTEM TONIGHT
INTO THURSDAY MORNING. SURFACE WIND WILL BE MAINLY LESS THAN 10 KTS
THROUGH THURSDAY MORNING. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...DRY CONDITIONS WITH LIGHT GENERALLY TERRAIN DRIVEN
WINDS WILL PREVAIL THROUGH THURSDAY. A LOW PRESSURE SYSTEM WILL THEN
BRING ISOLATED TO SCATTERED VALLEY RAIN AND MOUNTAIN SNOW SHOWERS
FRIDAY AFTERNOON AND FRIDAY NIGHT. PRECIPITATION AMOUNTS WILL BE
QUITE LIGHT. ANOTHER LOW PRESSURE SYSTEM WILL BRING A SLIGHT CHANCE
OF SHOWERS TO THE WHITE MOUNTAINS SUNDAY. EXPECT GUSTY WEST TO
NORTHWEST WINDS SUNDAY AS THIS SYSTEM MOVES NORTHEAST OF THE AREA.
THE UPPER GILA VALLEY WILL BE A FAVORED AREA FOR THE STRONGER WINDS.
DRY CONDITIONS WITH LESS WIND WILL THEN OCCUR EARLY NEXT WEEK.

&&

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

&&

$$

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FRANCIS





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