Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 180338
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
845 PM MST WED DEC 17 2014

.SYNOPSIS...AFTER A PARTIAL BREAK IN THE EARLY MORNING HOURS...A LOW
PRESSURE SYSTEM WILL CONTINUE TO BRING PERIODS OF VALLEY RAIN AND
MOUNTAIN SNOW TO THE AREA THROUGH THURSDAY EVENING. SEASONABLY COOL
THE NEXT FEW NIGHTS...OTHERWISE EXPECT DRIER CONDITIONS WITH A
GRADUAL WARMING TREND INTO CHRISTMAS EVE.

&&

.DISCUSSION...SOLID SHOT OF VALLEY RAIN AND MOUNTAIN SNOW THIS
AFTERNOON AND EVENING. WIDESPREAD RAINFALL AMOUNTS IN THE .3 TO .6
OF AN INCH RANGE ACROSS TUCSON METRO. FIRST IMPULSE LAST NIGHT
LOWERED OUR SNOW LEVELS SO THAT ELEVATIONS ABOVE 7500 FEET STARTED
WITH SNOW INSTEAD OF RAIN WITH THIS SECOND STRONGER IMPULSE DURING
THE AFTERNOON HOURS. REPORTS OF 4 TO 5 INCHES OF SNOW AT SUMMERHAVEN
AS OF 4:30 PM JUST BEFORE A SECOND BAND OF MODERATE SHOWERS MOVED
THROUGH THE AREA. STILL SOME LIGHT TO MODERATE ACTIVITY UP THERE AS
OF 830 PM BUT SLOWING CONSIDERABLY FROM WEST TO EAST. CAMERAS ON MT
GRAHAM INDICATED 5 TO 6 INCHES OF SNOW AT AN ADOT YARD RIGHT AT
SUNSET AND THE SNOTEL SENSOR AT HANNAGAN MEADOWS WAS AT 4 INCHES AS
OF 7PM. WE WILL PROBABLY BE ABLE TO CANCEL THE SNOW ADVISORY EARLY
FOR THOSE LOCATIONS...AS WE SHOULD CONTINUE TO SEE A DECREASE IN
COVERAGE AND INTENSITY AFTER MIDNIGHT.

A PARTIAL BREAK IN BETWEEN IMPULSES DURING THE EARLY MORNING
HOURS...BUT THE FINAL IMPULSE WILL COMBINE WITH NICE TERRAIN/UPSLOPE
FEATURES FOR SHOWERS TO ONCE AGAIN BLOSSOM BETWEEN 15Z AND 00Z
TOMORROW (EMPHASIS ON LATE MORNING TO AFTERNOON HOURS). SNOW LEVELS
STILL ABOVE 6000 TO 6500 FEET BUT THEY COULD SEE ANOTHER 2-4 INCHES
ABOVE 7000 FEET. BLEND OF ECMWF/NAMDNG5/SREF HAS BEEN HANDLING
TIMING...COVERAGE AND INTENSITIES PRETTY WELL.

RATHER COOL THE NEXT COUPLE OF NIGHTS...ESPECIALLY THURSDAY NIGHT
INTO FRIDAY MORNING...BUT NOTHING EXTREME. PATCHY FOG POSSIBLE THE
NEXT COUPLE OF MORNINGS WITH THE RESIDUAL BOUNDARY LAYER MOISTURE
FROM THE PRECIP AND COOL AIRMASS.

STRONG RIDGE SETTING UP IN THE EASTERN PACIFIC OVER THE NEXT 72
HOURS...PUSHING TOWARD THE WEST COAST OVER THE WEEKEND. STORM TRACK
RECEDES TO HIGHER LATITUDES AS WE SEE DRY CONDITIONS AND A WARMING
TREND EARLY NEXT WEEK. SOME HINTS OF THE FLOW BUCKLING AND ANOTHER
TROUGH IMPACTING MUCH OF THE REGION LATE NEXT WEEK NEAR TO JUST
AFTER CHRISTMAS. WE`LL SEE IF IT CAN DIG DEEP ENOUGH TO BRING WINTER
WEATHER TO OUR NECK OF THE WOODS.

&&

.AVIATION...VALID THRU 19/04Z.
ISOLATED TO SCATTERED VALLEY RAIN/MOUNTAIN SNOW SHOWERS WILL
CONTINUE THRU THIS EVENING WITH PERHAPS AN ISOLATED RUMBLE OF
THUNDER. BKN-OVC CLOUDS AT 4-6K FT AGL WITH MULTIPLE BKN-OVC LAYERS
ABOVE. EXPECT LOCAL MVFR CONDITIONS AT GENERALLY 2-3K FT ESP IN THE
VICINITY OF SHOWERS THRU THIS EVE. SFC WINDS DIMINISHING THIS
EVENING...BECOMING DIURNAL AND TERRAIN DRIVEN FROM LATE THIS EVENING
THROUGH TOMORROW AFTERNOON. ANOTHER ROUND OF SCATTERED VALLEY
RAIN/MOUNTAIN SNOW SHOWERS WILL SPREAD INTO THE AREA BY LATE
THURSDAY MORNING WITH SKY CONDITIONS QUITE SIMILAR TO TODAY.
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...UNSETTLED WEATHER WILL CONTINUE THROUGH THURSDAY IN
THE FORM OF VALLEY RAIN AND MOUNTAIN SNOW WITH SOMEWHAT OF A BREAK
IN THE PRECIPITATION TONIGHT. SNOW LEVELS WILL BE AS LOW AS 6000 FT
WITH ACCUMULATING SNOWS OCCURRING GENERALLY ABOVE 7000 FT AND
SEVERAL INCHES POSSIBLE. BREEZY SOUTHWESTERLY WINDS NEAR THE
INTERNATIONAL BORDER THIS AFTERNOON SHOULD TAPER OFF DURING THE
EARLY EVENING HOURS WITH LIGHTER WESTERLY WINDS OCCURRING THURSDAY.
MOSTLY DRY CONDITIONS ARE EXPECTED THROUGH THE COMING WEEKEND WITH
PLENTY OF PASSING HIGHER CLOUDS AND FAIRLY LIGHT NORTH TO NORTHWEST
WINDS.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...WINTER WEATHER ADVISORY AZZ510-
     511-514 ABOVE 7000 FEET UNTIL 5AM THURSDAY MORNING.

&&

$$

VISIT US ON FACEBOOK...TWITTER...YOUTUBE...AND AT WEATHER.GOV/TUCSON

DISCUSSION...MEYER
AVIATION/FIRE WEATHER...81




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