Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 181610
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
910 AM MST TUE NOV 18 2014

.SYNOPSIS...AFTER THE COLDEST TEMPERATURES OF THE WEEK THIS MORNING
AND PERHAPS AGAIN WEDNESDAY MORNING...TEMPERATURES WILL MODERATE
TOWARD SEASONAL AVERAGES THE REST OF THE WEEK. A LOW PRESSURE SYSTEM
MOVING ACROSS THE AREA WILL BRING A CHANCE OF SHOWERS FRIDAY
AFTERNOON INTO FRIDAY NIGHT. DRY CONDITIONS WITH COOLER DAYTIME
TEMPERATURES WILL THEN PREVAIL THIS WEEKEND.

&&

.DISCUSSION...IR/VISIBLE SATELLITE IMAGERY AND SURFACE OBSERVATIONS
INDICATED CLEAR SKIES ACROSS NERN SECTIONS...AND SCATTERED TO BROKEN
MOSTLY THIN CIRRIFORM CLOUDS ELSEWHERE. 18/12Z KTWC SOUNDING
DEPICTED A VERY DRY REGIME...WITH TOTAL PRECIP WATER VALUE OF 0.15
INCH. 18/12Z UPPER AIR PLOTS DEPICTED RIDGE AXIS ADJACENT THE WEST
COAST...DEEP TROUGH OVER THE ERN CONUS...AND A 553 DM LOW CENTERED
WEST OF THE NRN CALIFORNIA COAST VICINITY 38N/135W. MODERATE TO
STRONG NWLY FLOW ABOVE 700 MB PREVAILED ACROSS SE AZ.

SUNNY SKIES TO MOSTLY SUNNY SKIES WILL OCCUR TODAY...WITH THE BULK
OF MAINLY THIN CIRRIFORM CLOUDS EXPECTED TO BE SOUTHWEST OF TUCSON.
THE UPPER RIDGE WILL MOVE EWD AND FLATTEN SOMEWHAT ACROSS THE SWRN
CONUS TONIGHT AND WED. MAINLY HIGH CLOUDS WILL INCREASE ACROSS WRN
SECTIONS THIS EVENING FOLLOWED BY PARTLY CLOUDY TO MOSTLY CLOUDY
SKIES AREA-WIDE LATE TONIGHT AND WED. HIGH TEMPS THIS AFTERNOON FROM
TUCSON WWD WILL BE NEARLY IDENTICAL TO TEMPS ACHIEVED MON. HIGH
TEMPS ACROSS ERN SECTIONS THIS AFTERNOON WILL BE ABOUT 2-5 DEGS F
WARMER VERSUS MON.

THERE ARE NO UPDATES PLANNED AT THIS TIME. PLEASE REFER TO THE
ADDITIONAL SECTIONS FOR FURTHER DETAIL.

&&

.AVIATION...VALID THRU 19/18Z.
A RIDGE OF HIGH PRESSURE ALONG THE WEST COAST WILL MOVE EASTWARD
INTO THE AREA WEDNESDAY MORNING. THIS PATTERN WILL YIELD SCATTERED
TO BROKEN CLOUDS ABOVE 20K FT AGL. SURFACE WIND WILL BE MAINLY LESS
THAN 10 KTS WITH AN EASTERLY TO SOUTHEASTERLY COMPONENT. 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. DRY CONDITIONS BUT WITH COOLER
DAYTIME TEMPERATURES WILL OCCUR THIS WEEKEND. EXPECT GUSTY WEST TO
NORTHWEST WINDS SUNDAY AS A DISTURBANCE MOVES NORTH OF THE AREA.

&&

.PREV DISCUSSION...IR SATELLITE IMAGERY SHOWS SOME THIN CIRRUS
CLOUDS CURRENTLY SPILLING EASTWARD ACROSS SOUTHERN PORTIONS OF
ARIZONA. THIS SHOULD CONTINUE THROUGHOUT THE DAY WITH INTERMITTENT
HIGH CLOUDS MOVING ACROSS THE SKY FROM TIME TO TIME TODAY...BUT
STILL MOSTLY SUNNY. HOWEVER...BY WEDNESDAY AS THE RIDGE AXIS SHIFTS
EASTWARD AND WILL GENERALLY EXTEND FROM AZ/NM INTO UTAH AND TOWARD
THE PACIFIC NORTHWEST...A SHORTWAVE TROUGH IMMEDIATELY BEHIND THE
RIDGE WILL MOVE INTO SOUTHERN CALIFORNIA AND WESTERN ARIZONA WITH
SIGNIFICANT MOSTLY HIGH CLOUDS ACROSS A LARGE PART OF ARIZONA...BUT
MOSTLY OVER NORTHERN SECTIONS.

THIS SHORTWAVE WILL SCOOT ACROSS NORTHERN ARIZONA WEDNESDAY AND
INTO NORTHERN NEW MEXICO AND WEST TEXAS THROUGH MIDDAY THURSDAY IN
ZONAL FLOW ALOFT. ANOTHER STRONGER SYSTEM WILL BE ON THE HEELS OF
THIS FIRST ONE...AND WILL MOVE INTO WESTERN ARIZONA LATE THURSDAY OR
EARLY FRIDAY AND WILL SWING THROUGH ARIZONA LATE FRIDAY THROUGH
EARLY SATURDAY. THIS SYSTEM IS EXPECT TO BRING ISOLATED SHOWERS TO
DESERT/VALLEY LOCATIONS AND SCATTERED SHOWERS FOR THE MOUNTAINS ON
FRIDAY AND FRIDAY NIGHT...WITH JUST ISOLATED SHOWERS FOR MOUNTAIN
LOCATIONS SATURDAY THROUGH SUNDAY AS WEAK DISTURBANCES ALOFT IN THE
NORTHWEST FLOW BEHIND THE SYSTEM HELP TO TRIGGER A FEW SHOWERS OVER
THE WEEKEND. BY EARLY NEXT WEEK AS THE HIGH TO THE WEST NUDGES
FARTHER EAST...THE THREAT FOR PRECIPITATION WILL END.

FOR TUCSON...HIGH TEMPS GENERALLY NEAR NORMAL FOR TODAY...THEN
SLIGHTLY ABOVE NORMAL FOR WEDNESDAY AND THURSDAY...THEN AROUND 5
DEGS BELOW NORMAL FOR FRIDAY AND SATURDAY. THEREAFTER...NEAR TO
SLIGHTLY BELOW NORMAL. LOWS TEMPS WEDNESDAY MORNING AROUND 6 TO 8
DEGS BELOW NORMAL...THEN NEAR NORMAL FOR THURSDAY MORNING.
THEREAFTER...LOWS AROUND 3 DEGS ABOVE NORMAL EACH MORNING.

&&

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

&&

$$

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

FRANCIS
PREVIOUS DISCUSSION...MOLLERE





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