Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 190922
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
220 AM MST FRI DEC 19 2014

.SYNOPSIS...A DRY NORTHWEST FLOW PATTERN WILL RESULT IN SOME PASSING
HIGH LEVEL CLOUDS AND SOMEWHAT COOLER THAN NORMAL TEMPERATURES
THROUGH THE WEEKEND.  THEN TEMPERATURES WILL RISE TO ABOVE NORMAL
LEVELS THROUGH THE MIDDLE OF NEXT WEEK DUE TO A PASSING UPPER LEVEL
RIDGE.  UNSETTLED AND COOLER WEATHER LOOKS LIKELY FOR THE END OF
NEXT WEEK.

&&

.DISCUSSION...SKIES CLEARED OUT LAST EVENING WHICH HAS ALLOWED
TEMPERATURES TO DROP NICELY WITH FOG BEGINNING TO FORM ACROSS FAR
EASTERN AREAS.  WITH THE CURRENT TEMP/DEWPOINT SPREADS WOULD EXPECT
THE FOG OR SOME VERY LOW CLOUDS TO CONTINUE TO DEVELOP AND BECOME
SOMEWHAT MORE WIDESPREAD MAINLY EAST AND SOUTH OF TUCSON THIS
MORNING.  THIS WILL BEGIN TO BURN OFF AN HOUR OR TWO AFTER SUNRISE
AND BE PRETTY MUCH GONE BY LATE MORNING.  WITH THE COOL AIR MASS IN
PLACE AND THE EFFECTS OF THE MORNING FOG HIGH TEMPERATURES WILL BE
3-7 DEGREES COOLER THAN NORMAL THIS AFTERNOON DESPITE THE SUNSHINE.

FOR THE WEEKEND...A COUPLE OF WEAK AND DRY SHORTWAVES WILL DROP
SOUTHEAST ACROSS THE REGION WHICH WILL PAVE THE WAY FOR NW UPPER
LEVEL FLOW EARLY NEXT WEEK.  THESE WEAK WAVES WILL BE GOOD FOR SOME
HIGH CLOUDS PASSING BY AT TIMES BUT THATS ABOUT IT.  EACH DAY WILL
BE A COUPLE OF DEGREES WARMER THAN THE PREVIOUS ONE SO THAT BY
SUNDAY TEMPERATURES WILL BE RIGHT ABOUT SEASONAL NORMS.

AN UPPER LEVEL RIDGE ALONG THE WEST COAST WILL NOSE OVER THE AREA
EARLY NEXT WEEK WHICH WILL ALLOW FOR A STEADY WARMING TREND MONDAY
THROUGH WEDNESDAY UNDER MOSTLY CLEAR SKIES.  BY WEDNESDAY AFTERNOON
TEMPERATURES WILL BE 3-7 DEGREES WARMER THAN NORMAL WITH MORNING
LOWS ANYWHERE FROM 5-10 DEGREES WARMER THAN NORMAL.

HOWEVER...THE REASON FOR THE RIDGE NOSING OVER OUR AREA IS BECAUSE A
SIGNIFICANT UPPER LEVEL TROUGH IS SHOVING IT OUT OF THE WAY AS IT
DIGS SOUTHEAST ACROSS THE WESTERN US AND WILL POTENTIALLY AFFECT OUR
AREA CHRISTMAS DAY AND FRIDAY.  THIS FEATURE HAS BEEN INDICATED IN
THE MODELS FOR THE LAST SEVERAL DAYS BUT THERE HAS BEEN A FAIR
AMOUNT OF INCONSISTENCY IN THE DEPTH OF THE TROUGH.  THE ECMWF
CONTINUES DEPICT THE DEEPEST TROUGH ALTHOUGH TODAYS SOLUTION IS A
GOOD DEAL WEAKER THAN YESTERDAY.  AT THIS POINT WENT WITH SLIGHT
CHANCE POPS OVER THE WHITE MOUNTAINS AND DROPPED TEMPERATURES BACK
SEVERAL DEGREES CHRISTMAS DAY AND FRIDAY.  IT IS LIKELY THAT WE WILL
ALSO HAVE SOME BREEZY AFTERNOON WINDS THOSE TWO DAYS.  WILL HAVE TO
WAIT AND SEE HOW THIS ALL UNFOLDS OVER THE NEXT COUPLE OF DAYS.
CERNIGLIA


&&

.AVIATION...VALID THRU 20/12Z.
MOSTLY CLEAR SKIES EARLY THIS MORNING AS THE SYSTEM THAT BROUGHT
RAIN AND MOUNTAIN SNOW CONTINUES TO EXIT THE REGION TO THE EAST.
HOWEVER...ENOUGH LINGERING LOW LEVEL MOISTURE THAT SOME TERMINALS
WILL EXPERIENCE DETERIORATING CONDITIONS DUE TO FOG AND/OR STRATUS
DEVELOPMENT...WITH IFR CONDITIONS IN SOME AREAS THIS MORNING
PARTICULARLY ALONG THE INTERNATIONAL BORDER SUCH AS KOLS AND KDUG.
SURFACE WIND WILL GENERALLY REMAIN LESS THAN 10 KTS THROUGH THE
PERIOD. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...DRY CONDITIONS WILL PREVAIL TODAY THROUGH NEXT
WEDNESDAY. 20-FT WINDS WILL GENERALLY BE LIGHT AND TERRAIN DRIVEN
THROUGH THE MIDDLE OF NEXT WEEK. HOWEVER...SOME NORTHWEST BREEZES
WILL OCCUR MONDAY AFTERNOON ACROSS THE UPPER GILA RIVER VALLEY
INCLUDING SAFFORD. THE NEXT SIGNIFICANT WEATHER MAKER MAY ENTER THE
REGION LATE NEXT WEEK WITH POSSIBLE GUSTY WINDS AND ANOTHER CHANCE
FOR VALLEY RAIN AND MOUNTAIN SNOW.

&&

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

&&

$$

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