Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 151651
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
950 AM MST WED OCT 15 2014

.SYNOPSIS...DRY CONDITIONS WITH ABOVE NORMAL DAYTIME TEMPERATURES
WILL PREVAIL THROUGH THURSDAY. A WEAK AREA OF LOW PRESSURE MAY THEN
BRING A FEW SHOWERS EAST OF TUCSON THIS WEEKEND AND EARLY NEXT WEEK.

&&

.DISCUSSION...590 DM HIGH PRESSURE WAS CENTERED OVER NRN SONORA
MEXICO AND RIDGE AXIS EXTENDED NEWD INTO THE NRN CONUS PLAINS THIS
MORNING. MEANWHILE...UPPER TROUGH AXIS WAS ADJACENT THE WEST COAST...
AND A WEAK UPPER LOW WAS CENTERED WELL WEST OF SRN BAJA CALIFORNIA
NEAR 21N/125W. SCATTERED TO BROKEN MOSTLY THIN CIRRIFORM CLOUDS WERE
MOVING NEWD ACROSS SE AZ AT THIS TIME.

PRECIP-FREE CONDITIONS WILL OCCUR THRU THURSDAY NIGHT WITH PERIODS
OF MAINLY HIGH-LEVEL CLOUDINESS UNDER SWLY FLOW ALOFT. THE
AFOREMENTIONED WEAK UPPER LOW IS PROGGED VIA THE 15/12Z GFS AND
15/00Z ECMWF TO BE NEAR THE BAJA SPUR FRI MORNING. THERE MAY BE SOME
VIRGA FRI AFTERNOON AND FRI NIGHT AS THIS SYSTEM MOVES NEWD ACROSS
THE AREA.

THE UPPER LEVEL PATTERN THIS WEEKEND AND EARLY NEXT WEEK IS EXPECTED
TO EVOLVE WITH A RIDGE OVER THE PACIFIC NW...AND A WEAK UPPER TROUGH
OVER THE SWRN CONUS. QUICK GLANCE AT THE 15/12Z GFS YIELDED SIMILAR
QPF/S VERSUS THE 15/00Z ECMWF SAT-SUN. IN ESSENCE...BOTH SOLUTIONS
DEPICTED DRY CONDITIONS SAT...AND LIGHT QPF/S NEAR THE NEW MEXICO
BORDER SUN. BY MON...THE ECMWF DEPICTED MEASURABLE AMOUNTS AS FAR
WEST AS TUCSON. HOWEVER...THE GFS CONTINUED WITH VERY LIGHT QPF/S
NEAR THE NEW MEXICO BORDER. THE DIFFERENCE IS ATTRIBUTED TO THE
PROGGED POSITIONS OF THE SRN STREAM UPPER TROUGH/CLOSED LOW. THE
ECMWF DEPICTED A 574 DM LOW OVER SRN SONORA MON...WHILE THE GFS WAS
FURTHER EAST WITH THE UPPER TROUGH. THE BEST CHANCE FOR MEASURABLE
PRECIP TUE SHOULD OCCUR NEAR THE NEW MEXICO BORDER.

WILL AWAIT RECEIPT OF THE 15/12Z ECMWF PRIOR TO MAKING ANY
SIGNIFICANT ADJUSTMENTS TO THE INHERITED GRIDDED DATA POPS. FOR
NOW...WILL MAINTAIN A SLIGHT CHANCE OF SHOWERS ACROSS THE HIGHER
TERRAIN EAST OF TUCSON SAT...AND A SLIGHT CHANCE OF SHOWERS MAINLY
NEAR THE NEW MEXICO BORDER SUN-MON. WILL ALSO MAINTAIN DRY
CONDITIONS AREA-WIDE TUE.

HIGH TEMPS TODAY WILL GENERALLY AVERAGE ABOUT 2-6 DEGS F OR SO ABOVE
NORMAL...THEN A FEW DEGS OF DAILY COOLING WILL OCCUR THUR-FRI. ONLY
VERY MINOR DAILY TEMP CHANGES WILL THEN PREVAIL SAT-TUE.

&&

.AVIATION...VALID THRU 16/18Z.
EXPECT SCATTERED TO BROKEN CLOUDS ABOVE 20K FT AGL THRU THURSDAY
MORNING. SURFACE WIND THIS MORNING WILL BE MAINLY ELY/SELY AT 8-15
KTS. SURFACE WIND THIS AFTERNOON INTO THURSDAY MORNING WILL BE
TERRAIN DRIVEN AND GENERALLY LESS THAN 10 KTS. AVIATION DISCUSSION
NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...DRY CONDITIONS WILL PREVAIL THROUGH THURSDAY. A WEAK
AREA OF LOW PRESSURE WILL THEN BECOME ESTABLISHED OVER THE DESERT
SOUTHWEST BY THIS WEEKEND AND CONTINUE INTO EARLY NEXT WEEK. THERE
MAY BE ENOUGH MOISTURE TO GENERATE A FEW SHOWERS EAST OF TUCSON
SATURDAY THROUGH MONDAY. DRY CONDITIONS WILL THEN PREVAIL AREA WIDE
EARLY NEXT TUESDAY. 20-FOOT WINDS WILL BE MAINLY EAST TO SOUTHEAST
THIS MORNING FOLLOWED BY NORMAL DIURNAL WIND TRENDS DURING THE
LATTER PART OF THIS WEEK.

&&

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

$$

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

FRANCIS





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