000
FXUS65 KTWC 200920
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
220 AM MST MON MAY 20 2013

.SYNOPSIS...A BROAD UPPER LEVEL TROUGH OVER THE WESTERN US WILL HOLD
TEMPERATURES NEAR NORMAL LEVELS THROUGH TUESDAY. THEN THE TROUGH
WILL GRADUALLY MOVE EAST ALLOWING FOR A WARMING TREND FROM WEDNESDAY
ONWARD WITH DRY CONDITIONS THROUGH THE WEEK.

&&

.DISCUSSION...A CLEAR SKY PREVAILED ACROSS THE AREA THIS MORNING.
ONE LAST SHORT WAVE TROF WILL BE MOVING THROUGH THE 4 CORNERS REGION
TODAY WHICH IS KEEP AFTERNOON BREEZES AROUND. ONLY WEATHER CONCERN
TODAY WILL BE FIRE WEATHER WHICH IS ADDRESSED IN THE FIRE WEATHER
SECTION BELOW. HIGHS TODAY WILL BE SIMILAR TO WHAT OCCURRED SUNDAY.

TUESDAY...SHORT WAVE RIDGE WILL BE OVER THE STATE. CLEAR START TO
THE DAY THEN RIDGE DIRTIES UP AS HIGH CLOUDS PUSHES IN FROM THE
WEST. HIGHS WILL BE AT OR SLIGHTLY WARMER THAN TODAY.

WEDNESDAY...SHORT WAVE RIDGE PUSHES ON EAST AS GULF OF ALASKA STORM
MOVES INTO THE PACIFIC NW. HIGHS WILL BE THE WARMEST OF THE WEEK
WITH A FEW SPOTS IN THE LOW DESERTS HITTING THE CENTURY MARK. CHECK
CLIMATE SECTION BELOW FOR THE CHANCES FOR TUCSON HITTING 100.

THURSDAY AND FRIDAY...BROAD UPPER LEVEL TROF OVER THE WESTERN CONUS
WILL BRING SLIGHTLY COOLER TEMPERATURES ALONG WITH BREEZY TO
LOCALIZED WINDY CONDITIONS BOTH AFTERNOONS.

SATURDAY AND SUNDAY...WARM WITH AFTERNOON BREEZES.

&&

.AVIATION...SKC THRU TUESDAY MORNING OR 21/12Z...THEN HIGH CLOUD
MOVE IN FROM THE WEST TUESDAY AFTERNOON. SURFACE WIND THIS
AFTERNOON AND EVENING WLY/NWLY 10-15 KTS WITH GUSTS TO NEAR 25
KTS...STRONGEST WIND EAST AND SOUTH OF KTUS. OTHERWISE...SURFACE
WIND LESS THAN 10 KTS. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...SHORT WAVE TROF MOVING THROUGH THE FOUR CORNERS
REGION TODAY WILL BRING GUSTY W-NW WINDS TO NW TO SE ORIENTED
VALLEYS EAST OF TUCSON THIS AFTERNOON. COMBINED WITH AFTERNOON
RELATIVE HUMIDITY VALUES IN THE 6-10% RANGE...A FEW SPOTS MIGHT
APPROACH CRITICAL FIRE WEATHER THRESHOLDS FOR AN HOUR OR TWO.
HOWEVER AREAL COVERAGE NOT LARGE ENOUGH TO WARRANT A RED FLAG
WARNING. OTHERWISE EXPECT A WARMING TREND INTO WEDNESDAY THEN LITTLE
CHANGE IN ABOVE NORMAL TEMPERATURES INTO THE UPCOMING WEEKEND.
NORMAL DIURNAL WINDS TUESDAY AND WEDNESDAY...WITH OCCASIONAL GUSTS
DURING THE AFTERNOON AND EARLY EVENING HOURS DUE TO STRONG DAYTIME
HEATING. SOMEWHAT STRONGER SOUTHWEST WINDS ARE FORECAST TO OCCUR
THURSDAY AND FRIDAY AS A LOW PRESSURE SYSTEM DEEPENS NORTHWEST OF
THE AREA.

&&

.CLIMATE...TUCSON WILL MAKE ANOTHER RUN AT THE FIRST 100 DEGREE DAY
OF 2013 ON WEDNESDAY. MOST OF THE TEMPERATURE GUIDANCE THAT WE
ACCESS TO...FROM MOS GUIDANCE TO BIAS-CORRECTED GUIDANCE TO GFS
ENSEMBLES GUIDANCE...ARE NOT FORECASTING 100 FOR TUCSON THIS WEEK.
HOWEVER THE EC AND UKMET 850-700 MB THICKNESS VALUES ON WEDNESDAY
ARE SHOWING EITHER 99 OR 100 FOR TUCSON. SO THERE IS A SLIGHT
CHANCE...LESS THAN 10%...THAT TUCSON WILL HIT 100 THIS WEEK. WILL
CONTINUE TO KEEP FORECAST HIGH ON WEDNESDAY AT 98. IF FIRST 100
DOESN`T OCCUR ON WEDNESDAY...WILL HAVE TO WAIT UNTIL NEXT MONDAY FOR
NEXT SHOT.

&&

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

&&

$$

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