Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 251000
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
300 AM MST THU DEC 25 2014

.SYNOPSIS...THERE IS A WIND ADVISORY IN EFFECT FROM 10 AM UNTIL 9 PM
TODAY FOR MUCH OF COCHISE...EASTERN SANTA CRUZ...AND EXTREME
SOUTHEASTERN PIMA COUNTIES. A STORM SYSTEM WILL DIG INTO THE DESERT
SOUTHWEST TODAY WITH BREEZY TO WINDY CONDITIONS AND A CHANCE OF
VALLEY RAIN AND MOUNTAIN SNOW THIS EVENING AND OVERNIGHT INTO EARLY
FRIDAY. THIS SHOULD BE A QUICK SHOT OF PRECIPITATION...ENDING IN THE
EASTERN AREAS FRIDAY MORNING. COOL AND DRY WEATHER WILL THEN RETURN
THIS WEEKEND.

&&

.DISCUSSION...WATER VAPOR IMAGERY SHOWS THE RAPIDLY MOVING LOW
PRESSURE SYSTEM THAT IS EXPECTED TO BE OUR NEXT WEATHER MAKER
CURRENTLY EXTENDING FROM EASTERN WASHINGTON/WESTERN IDAHO THROUGH
NEVADA AND INTO SOUTHERN CALIFORNIA. AHEAD OF THIS SYSTEM...IR
IMAGERY SHOWS A SWATH OF MID TO HIGH LEVEL CLOUDS COVERING MUCH OF
SOUTHERN ARIZONA AND NORTHERN MEXICO AND EXTENDING EASTWARD INTO
MUCH OF NEW MEXICO. ADDITIONAL CLOUDINESS CAN BE SEEN CLOSER TO THE
TROUGH AXIS OVER PARTS OF NEVADA...UTAH...COLORADO AND NORTHERN
ARIZONA.

MODELS PROG THE TAIL END OF THIS TROUGH TO SWING INTO NORTHWEST
ARIZONA SHORTLY BEFORE SUNRISE...THEN ACROSS MUCH OF ARIZONA BY LATE
THIS AFTERNOON...WITH THE CENTER OF CIRCULATION OVER EASTERN UTAH.
AS THIS OCCURS A STRONG JET OF AROUND 40-55 KNOTS AT 700MB IS
PROGGED TO MOVE OVER EXTREME SOUTHEASTERN ARIZONA...MORE
SPECIFICALLY COCHISE COUNTY DURING THE LATE MORNING AND INTO THE
LATE AFTERNOON HOURS TODAY. AS A RESULT...EXPECTING BREEZY TO WINDY
CONDITIONS AREA WIDE TODAY. THAT SAID...A WIND ADVISORY WILL BEGIN
TODAY AT 10 AM MST AND CONTINUE THROUGH 9 PM MST FOR COCHISE
COUNTY...EASTERN PARTS OF SANTA CRUZ COUNTY AND EXTREME SOUTHEASTERN
PARTS OF PIMA COUNTY. IN ADDITION TO THE STRONG AND GUSTY WINDS...
ISOLATED SHOWERS WILL DEVELOP THIS AFTERNOON...WITH SCATTERED TO
NUMEROUS SHOWERS BY THIS EVENING AND OVERNIGHT INTO FRIDAY FOR
DESERT AND VALLEY LOCATIONS...WITH NUMEROUS TO CATEGORICAL POPS FOR
THE MOUNTAINS THIS EVENING AND OVERNIGHT. EVEN THOUGH PRECIPITATION
CHANCES WITH THIS SYSTEM ARE EXPECTED TO BE HIGH...PRECIPITATION
AMOUNTS ARE EXPECTED TO ONLY RANGE FROM AROUND A QUARTER OF AN INCH
TO NOT QUITE A HALF INCH...WITH SNOW AMOUNTS RANGING FROM AROUND 2
TO NEAR 5 INCHES FOR ELEVATIONS ABOVE 7000 FEET. THIS SYSTEM WILL
ALSO BE A FAST MOVING ONE WITH THE PRECIPITATION ENDING ABRUPTLY
DURING THE EARLY MORNING HOURS ON FRIDAY.

BY EARLY SATURDAY THE TROUGH WILL LINGER ACROSS THE CENTRAL PLAINS
INTO THE EXTREME SOUTHEAST CORNER OF ARIZONA. COLD AIR BEHIND THIS
SYSTEM WILL RESULT IN A COLD START TO THE MORNING ON SATURDAY WITH
READINGS WELL BELOW FREEZING FOR MOST LOCATIONS...WITH THE EXCEPTION
OF THE FAR WESTERN DESERTS OF PIMA COUNTY NEAR ORGAN PIPE AND AJO.
SIMILAR TEMPS FOR SUNDAY MORNING...ALBEIT A DEGREE OR TWO WARMER...
BUT STILL BELOW FREEZING FOR MOST LOCATIONS.

BRIEF SHORTWAVE RIDGING WILL BUILD IN BEHIND THE SYSTEM ON SATURDAY
BEFORE ANOTHER PACIFIC SYSTEM DROPS TO THE SOUTHEAST ACROSS THE
PACIFIC NORTHWEST LATE SATURDAY AND EARLY SUNDAY. THIS SYSTEM IS
THEN EXPECTED TO DEVELOP INTO A CLOSED LOW OVER NORTHERN PORTIONS OF
THE GREAT BASIN AND NORTHERN ROCKIES BY LATE MONDAY. IT WILL THEN
SWING INTO THE GREAT BASIN AND CENTRAL CALIFORNIA ON TUESDAY...WITH
THE CENTER OF CIRCULATION OVER SOUTHERN NEVADA AND SOUTHEAST
CALIFORNIA LATE TUESDAY/EARLY WEDNESDAY AND WILL BE BODILY OVER
ARIZONA ON WEDNESDAY. THE MODELS ARE IN PRETTY GOOD AGREEMENT WITH
THE GFS/ECMWF AND CANADIAN MODELS ALL SHOWING A SIMILAR SCENARIO
WITH REGARD TO THE TIMING...POSITION AND STRENGTH OF THIS LOW.
MODELS ARE ALSO SUGGESTING THAT THIS STORM WILL BE COLD WITH HIGH
TEMPERATURES POTENTIALLY IN THE LOWER 50S AND PERHAPS A BIT COLDER
BASED ON 850-700MB THICKNESS VALUES. THAT SAID...I INCREASED POPS
FOR THE TUESDAY NIGHT INTO WEDNESDAY TIME FRAME BASED ON RECENT
MODEL SOLUTIONS...AS WELL AS TO BLEND WITH THE SURROUNDING OFFICES.
FOR NOW THE POPS ARE ONLY IN THE SLIGHT CHANCE TO CHANCE CATEGORY...
BUT IF THE SYSTEM DEVELOPS WITH THE KIND OF MOS POP VALUES THAT ARE
CURRENTLY BEING ADVERTISED...THEN MY FORECAST WOULD BE ON THE LOW
SIDE. IN ADDITION...SNOW COULD END UP REACHING THE VALLEY FLOORS FOR
COCHISE AND GRAHAM COUNTIES WEDNESDAY NIGHT OF NEXT WEEK. OF COURSE
THIS IS A LONG WAY OFF...SO STAY TUNED.

FOR TUCSON...HIGH TEMPERATURES GENERALLY A COUPLE OF DEGREES ABOVE
NORMAL TODAY...THEN 10 TO 15 DEGS BELOW NORMAL FOR FRIDAY AND
SATURDAY. FOR THE PERIOD SUNDAY THROUGH WEDNESDAY...HIGHS BELOW
NORMAL EACH DAY...BUT THE COLDEST DAY WILL OCCUR ON WEDNESDAY WHEN
HIGHS COULD BE AROUND 10 DEGS BELOW NORMAL. LOW TEMPS WILL BE BELOW
NORMAL THROUGH THE FORECAST PERIOD...BUT THE COLDEST MORNINGS WILL
OCCUR SATURDAY AND SUNDAY WHEN LOWS WILL RANGE FROM 8 TO 10 DEGS
BELOW NORMAL.

&&

.AVIATION...VALID THRU 26/12Z.
BKN-OVC ABOVE 20 KFT AGL. AFTER 25/18Z...SCT-BKN CLOUDS AT 5-10K FT
AGL MAINLY FROM KTUS WWD/NWD...WITH A SLIGHT CHANCE OF VALLEY
SHRA/MOUNTAIN SHSN. SURFACE WIND SLY/SELY AT 5-15 KNOTS THRU
25/15Z...THEN SURFACE WIND LATE THIS MORNING AND INTO THE AFTERNOON
WILL BE SWLY/WLY AT 18-30 KTS WITH GUSTS TO 30-45 KTS. THE STRONGEST
SURFACE WIND WILL BE EAST OF KTUS AND KOLS...IN THE VICINITY OF
KDUG. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...A STRONG STORM SYSTEM WILL MOVE INTO THE FOUR
CORNERS AREA TODAY...AND CONTINUE EASTWARD INTO NEW MEXICO FRIDAY.
AS THIS SYSTEM APPROACHES THE REGION EXPECT DRY CONDITIONS THROUGH
THIS MORNING...THEN INCREASING PRECIPITATION CHANCES THIS AFTERNOON
AND EVENING...ESPECIALLY ACROSS THE EASTERN HALF OF SOUTHEAST
ARIZONA. A SLIGHT CHANCE OF PRECIPITATION WILL PERSIST ALONG THE NEW
MEXICO BORDER ON FRIDAY. THIS AREA OF LOW PRESSURE WILL ALSO RESULT
IN A SUBSTANTIAL INCREASE IN WINDS TODAY...WITH THE HIGHEST WIND
SPEEDS ACROSS COCHISE...EASTERN SANTA CRUZ AND FAR SOUTHEASTERN PIMA
COUNTIES...WHERE A WIND ADVISORY IS IN EFFECT FROM 10 AM TO 9 PM
TODAY. WIND GUSTS MAY APPROACH 55 MPH AT THE HIGHEST ELEVATIONS AND
30 TO 40 MPH IN VALLEY LOCATIONS. DRY CONDITIONS WILL THEN RETURN
AREAWIDE ON SATURDAY AND PERSIST THROUGH EARLY NEXT WEEK.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY FROM 10 AM TO 9 PM
      MST TODAY FOR AZZ503-507-508-512-513.

&&

$$

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MOLLERE





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