000
FXUS65 KTWC 172113
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
213 PM MST FRI MAY 17 2013

.SYNOPSIS...A LOW PRESSURE SYSTEM WILL MOVE INTO THE REGION TODAY
AND SATURDAY. EXPECT GUSTY WINDS AT TIMES WITH A COOLING TREND TODAY
INTO SATURDAY. HIGH PRESSURE OVER THE WESTERN UNITED STATES WILL
THEN DEVELOP EARLY NEXT WEEK AND GUIDE TEMPERATURES BACK TO WELL
ABOVE AVERAGE.

&&

.DISCUSSION...COOLER AIR...AT LEAST FOR MAY STANDARDS...WILL MOVE
INTO ARIZONA THIS WEEKEND. AN APPROACHING UPPER LEVEL TROUGH IS
PUSHING THE COOLER AIR INTO ARIZONA. THE TROUGH AXIS IS CURRENTLY
STILL WEST OF ARIZONA BY A FEW HUNDRED MILES...BUT THE AXIS SHOULD
REACH WESTERN AZ THIS AFTERNOON OR EVENING. IN ADDITION TO THE
COOLING TREND...ALSO ANTICIPATE INCREASING HIGH CLOUD COVER TONIGHT
THROUGH SATURDAY. OTHERWISE...EXPECT MOSTLY CLEAR SKIES AND
SEASONABLE CONDITIONS EARLY NEXT WEEK AS SHORTWAVE RIDGING SET UP
BEHIND THE EXITING TROUGH.

THE RIDGING WILL ALLOW WARMER CONDITIONS TO DEVELOP TUESDAY THROUGH
THURSDAY AND TUCSON WILL AGAIN FLOAT NEAR TRIPLE DIGITS FOR HIGH
TEMPS. THE AIRMASS IS NOT THAT ANOMALOUS FOR THIS TIME OF YEAR SO
EXPECTING HIGH TEMPS TO RISE ONLY 4 OR 5 DEGREES ABOVE NORMAL. A
DEEP TROUGH WILL DEVELOP OVER THE PACIFIC NORTHWEST SETTING UP AN
OMEGA BLOCK BY LATE IN THE WEEK. THIS WILL KEEP PERSISTENT SW FLOW
ALOFT. THE PRESSURE GRADIENT RESULTING FROM THE DEEPENING NW TROUGH
AND CENTRAL US RIDGE WILL ALSO KEEP BREEZY CONDITIONS IN PLACE OVER
AZ WITH THE STRONGEST WINDS FOCUSED ON THE AFTERNOON HOURS. TEMPS
SHOULD HOVER A FEW DEGREES ABOVE NORMAL AND DRY CONDITIONS WILL
PERSIST. BROST.

&&

.AVIATION...VFR CONDITIONS THROUGH THE NEXT 24 HOURS. HIGH CLOUDS
SHOULD BE THE ONLY SKY COVER. SLY/SWLY SFC WIND 15-25 KTS WITH OCNL
GUSTS OF 30-35 KTS. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...A LOW PRESSURE SYSTEM WILL APPROACH THE REGION
TODAY... PASS THROUGH THE STATE SATURDAY AND BE EAST OF THE REGION
SUNDAY. THIS SYSTEM WILL BE DRY BUT WILL COOL TEMPERATURES AND KICK
UP A BREEZE TODAY THROUGH SUNDAY AFTERNOONS WITH LOCALLY WINDY
CONDITIONS POSSIBLE EACH AFTERNOON. AFTERNOON MIN RH VALUES WILL BE
IN THE 5-15% RANGE BUT OVERALL...EXPECT WINDS TO REMAIN JUST BELOW
RED FLAG THRESHOLDS. HOWEVER...AREAS AROUND ALPINE MAY REACH RED
FLAG THRESHOLDS TODAY. THUS A RED FLAG WARNING IS IN EFFECT FOR THE
ALPINE AREA THIS AFTERNOON INTO EARLY THIS EVENING. DRY CONDITIONS
WILL CONTINUE INTO THE MIDDLE OF NEXT WEEK WITH ABOVE NORMAL
TEMPERATURES INTO WEDNESDAY.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
  RED FLAG WARNING TODAY FROM 12 NOON UNTIL 8 PM MST FOR THE ALPINE
   DISTRICT OF THE WHITE MOUNTAINS IN NORTHERN FIRE WEATHER ZONE 146.

&&

$$

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