Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 182212
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
310 PM MST SAT APR 18 2015

.SYNOPSIS...DRY CONDITIONS WITH ABOVE NORMAL DAYTIME TEMPERATURES
WILL PREVAIL INTO THE MIDDLE OF THE UPCOMING WEEK. GUSTY WINDS
SHOULD RETURN WEDNESDAY AND CONTINUE INTO THURSDAY AS A LOW PRESSURE
SYSTEM MOVES TOWARD THE AREA FROM THE WEST. COOLER TEMPERATURES WILL
ALSO OCCUR THURSDAY...AND THERE IS A SLIGHT CHANCE OF SHOWERS
THURSDAY AND THURSDAY NIGHT...MAINLY NORTH OF TUCSON.

&&

.DISCUSSION...SUNNY SKIES PREVAIL ACROSS SE ARIZONA THIS AFTERNOON
EXCEPT FOR SCATTERED TO BROKEN CUMULOFORM CLOUDS ACROSS THE WHITE
MOUNTAINS. GUSTY NWLY WINDS WILL ALSO OCCURRING...ESPECIALLY ACROSS
ERN SECTIONS. THE WINDS WILL DIMINISH EARLY THIS EVENING...AND THE
CLOUDS ACROSS THE WHITE MOUNTAINS WILL ALSO DISSIPATE WITH THE LOSS
OF DAYTIME HEATING. THUS...EXPECT CLEAR SKIES MOST SECTIONS TONIGHT
EXCEPT FOR MOSTLY CLEAR SKIES ACROSS THE WHITE MOUNTAINS. A SIMILAR
SCENARIO IS ON TAP SUNDAY WITH ABUNDANT SUNSHINE FOR MOST OF THE
AREA. MOSTLY SUNNY SKIES TO PARTLY CLOUDY SKIES WILL OCCUR AGAIN
ACROSS THE WHITE MOUNTAINS. ANY MEASURABLE RAINFALL SHOULD REMAIN
JUST NORTH OF THIS FORECAST AREA.

A SHORTWAVE RIDGE AXIS OVER THE AREA MON WILL MOVE EWD INTO THE SRN
ROCKIES TUE AHEAD OF A DEVELOPING UPPER TROUGH EXTENDING FROM SRN
CALIFORNIA/NRN BAJA CALIFORNIA WWD TO AROUND 130W. FLOW ALOFT WILL
BECOME INCREASINGLY SWLY TUE AND BECOME MORE PRONOUNCED WED AS THE
UPPER TROUGH CONTINUES TO DEEPEN WEST OF THE AREA. PRECIP-FREE
CONDITIONS WILL OCCUR TUE INTO WED NIGHT.

THEREAFTER...THE 18/12Z GFS/ECMWF WERE FAIRLY SIMILAR WITH DEPICTING
A 558-559 DM LOW TO BE CENTERED OVER FAR SWRN ARIZONA/EXTREME NWRN
SONORA MIDDAY THUR. THESE SOLUTIONS DEPICTED SIMILAR MOISTURE FIELDS
THUR AFTERNOON...WITH THE BULK OF MEASURABLE PRECIP TO OCCUR MAINLY
NORTH OF THIS FORECAST AREA ACROSS CENTRAL/NRN ARIZONA. HAVE NOTED
THAT THE 18/12Z CMC WAS CONSIDERABLY DRIER VERSUS THE GFS/ECMWF. THE
UPPER LOW IS THEN PROGGED TO FILL AND LIFT RAPIDLY NEWD INTO NRN NEW
MEXICO BY EARLY FRI MORNING.

BASED ON THESE SOLUTIONS...HAVE ONLY MADE VERY MINOR MODIFICATIONS
TO THE INHERITED GRIDDED DATA POP FIELDS. THUS...THERE IS A SLIGHT
CHANCE OF SHOWERS THUR GENERALLY NW OF A HANNAGAN MEADOW-TUCSON-SELLS
LINE. A SLIGHT CHANCE OF SHOWERS EXISTS ACROSS MUCH OF THE AREA THUR
NIGHT. SOME VERY LIGHT SNOW ACCUMULATIONS MAY OCCUR BY DAYBREAK FRI
ABOVE 8000 FEET. HAVE MAINTAINED A SLIGHT CHANCE OF SHOWERS FRI
ACROSS THE WHITE MOUNTAINS AND ACROSS THE GALIURO/PINALENO MOUNTAINS
OF GRAHAM COUNTY. OTHERWISE...DRY CONDITIONS SHOULD OCCUR FRI BEHIND
THE DEPARTING SYSTEM.

THEREAFTER...THERE WERE CONSIDERABLE DIFFERENCES BETWEEN THE GFS/
ECMWF REGARDING THE NEXT SHORTWAVE TROUGH/UPPER LOW WEST OF THE AREA
FRI NIGHT-SAT. THE ECMWF DEPICTED A DEEPER UPPER TROUGH TO BE OVER
SRN CALIFORNIA MIDDAY SAT. MEANWHILE...THE GFS DEPICTED A MUCH
WEAKER SYSTEM TO BE WELL SW OF THE SRN CALIFORNIA COAST. EITHER
SOLUTION MAINTAINED DRY CONDITIONS NEXT FRI NIGHT-SAT.

EXPECT THE WARMING TREND TO CONTINUE SUN-MON...WITH DAYTIME TEMPS
MON (THE WARMEST DAY) TO AVERAGE NEARLY 2-5 DEGS F ABOVE NORMAL. A
COOLING TREND WILL THEN OCCUR TUE-THUR...WITH HIGH TEMPS THUR TO BE
ABOUT 3-7 DEGS F BELOW NORMAL. EXPECT WARMER TEMPS TO RETURN SAT.

&&

.AVIATION...VALID THRU 20/00Z.
SCT CLOUDS AROUND 6-10K FT AGL OVER THE WHITE MTNS THROUGH 19/04Z
AND AGAIN SUNDAY AFTERNOON. OTHERWISE...CLEAR SKIES THROUGH SUNDAY.
SURFACE WIND EAST OF KTUS WILL BE NWLY AT 12-18 KTS WITH GUSTS OF
20-30 KTS THRU 19/02Z. SURFACE WIND ELSEWHERE WILL GENERALLY BE LESS
THAN 10 KTS. THEN A NEAR REPEAT IN THE WIND SUNDAY AFTERNOON WITH NW
WINDS 8-15 KTS DEVELOPING AFT 19/20Z. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...A RED FLAG WARNING REMAINS IN EFFECT THROUGH 7 PM
MST THIS EVENING FOR A SLIVER OF NE FIRE WEATHER ZONE 152 FOR
MARGINAL RED FLAG CONDITIONS.

EXPECT WARM AND DRY CONDITIONS THROUGH WEDNESDAY AS AN UPPER LOW
DEVELOPS OFF THE SOUTHERN CALIFORNIA COAST. THIS LOW WILL BRING
INCREASINGLY STRONG SW WINDS TO THE AREA MONDAY THROUGH WEDNESDAY.

THE UPPER LOW WILL MOVE ACROSS THE AREA THURSDAY INTO EARLY FRIDAY
BRINGING A CHANCE OF SHOWERS...COOLER TEMPERATURES AND GUSTY SW
WINDS. ELEVATED RH CONDITIONS ARE EXPECTED TO PREVENT RED FLAG
CONDITIONS FROM OCCURRING DURING THIS PERIOD DESPITE THE STRONG
WINDS.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
    RED FLAG WARNING UNTIL 7 PM MST THIS EVENING FOR AZZ152
    (THE PORTION INCLUDING SAFFORD...EASTERN GRAHAM COUNTY AND
     SOUTHERN GREENLEE COUNTY).

&&

$$

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

DISCUSSION...FRANCIS
AVIATION/FIRE WEATHER...CERNIGLIA





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