000
FXUS65 KTWC 201554
AFDTWC

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

.SYNOPSIS...A BROAD UPPER LEVEL TROUGH OVER THE ROCKY MOUNTAIN
STATES WILL HOLD TEMPERATURES NEAR NORMAL LEVELS THROUGH TUESDAY.
THEN THE TROUGH WILL MOVE EAST ALLOWING FOR A WARMING TREND FROM
WEDNESDAY ONWARD WITH DRY AND OCCASIONALLY BREEZY CONDITIONS
CONTINUING THROUGH THE WEEKEND.

&&

.DISCUSSION...A BROAD UPPER LEVEL TROUGH OVER THE ROCKY MOUNTAIN
STATES WILL GRADUALLY SHIFT EAST OVER THE CENTRAL US THROUGH
TUESDAY.  A SHORT WAVE ROTATING AROUND THE BASE OF THE TROUGH WILL
SWING ACROSS ARIZONA THIS AFTERNOON AND WILL BE FOLLOWED BY A
SHORTWAVE RIDGE TUESDAY AFTERNOON AND EVENING.  THE ONLY NOTICEABLE
AFFECT OF THE SHORT WAVE PASSAGE WILL BE AN ENHANCEMENT OF THE NW
BREEZE THIS AFTERNOON WHICH WOULD BE A CONCERN PRIMARILY FOR THE
FIRE FIGHTING COMMUNITY.  THE TROUGH WILL HOLD AFTERNOON HIGH
TEMPERATURES NEAR TO WHAT WE HAD YESTERDAY.

THE SHORT WAVE RIDGE PASSING ACROSS THE AREA TUESDAY WILL ALSO HAVE
LIMITED AFFECT ON THE SENSIBLE WEATHER OTHER THAN ALLOWING
TEMPERATURES TO BE A DEGREE OR TWO WARMER AND SLIGHTLY LESS WIND
THAN THIS AFTERNOON.  BUT THE PASSING OF ITS AXIS WILL OPEN THE DOOR
TO THE INFLUENCE OF THE DEEP LATE SEASON UPPER LOW/TROUGH THAT WILL
SETTLE IN ALONG THE WEST COAST AND REMAIN IN THAT GENERALLY AREA IN
ONE FORM OR ANOTHER WELL INTO NEXT WEEK.

THE FIRST HINT OF THAT TROUGH INFLUENCE WILL BE THE HIGH CLOUDS THAT
WILL SPREAD ACROSS THE AREA LATER TUESDAY INTO TUESDAY NIGHT.  THEY
WILL CLEAR OUT DURING THE DAY WEDNESDAY BUT FROM THE LOOK OF THINGS
BANDS OF HIGH LEVEL MOISTURE WILL STREAM ACROSS ARIZONA FROM TIME TO
TIME FROM LATE WEDNESDAY INTO NEXT WEEK.  DUE TO THE POSITION OF THE
LOW AND FLOW DIRECTION NOT SEEING ANY POTENTIAL FOR PRECIPITATION
OVER OUR NECK OF THE WOODS.  THE GREATEST IMPACT FOR OUR AREA FROM
THIS SETUP WILL BE THE OCCASIONAL BREEZY/WINDY PERIODS THAT WE WILL
GET AS FEATURES ROTATE AROUND THE BASE OF THE TROUGH.  THE BASIC
IDEA IS DRY...SOMEWHAT WARMER THAN NORMAL WITH GUSTY WINDS NOW AND
THEN THURSDAY INTO EARLY NEXT WEEK WHICH IS MORE OF A FIRE WEATHER
CONCERN THAN FOR THE GENERAL PUBLIC.  CERNIGLIA

&&

.AVIATION...SKC THRU TONIGHT OR 21/12Z...WITH A THICKENING HIGH
CLOUD TREND TUESDAY. SURFACE WIND THIS AFTERNOON AND EVENING
WLY/NWLY 10-15 KTS WITH GUSTS TO NEAR 25 KTS...NW WINDS AND GUSTS
5-10 KTS STRONGER IN NW-SE VALLEYS SUCH AS NEAR KSAD...THEN SURFACE
WIND LESS THAN 10 KTS AFT 21/03Z. AVIATION DISCUSSION NOT UPDATED
FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...UPPER TROUGH EXITING SOUTHERN ROCKIES WILL BRING NW
WINDS TODAY WITH ENHANCED GUSTS OVER MT TOPS AND NW-SE ORIENTED
VALLEYS EAST OF TUCSON. COMBINED WITH AFTERNOON RELATIVE HUMIDITY
VALUES IN THE SINGLE DIGITS...GUSTS COULD PUSH A FEW SPOTS ACROSS
CRITICAL FIRE WEATHER THRESHOLDS FOR AN HOUR OR TWO.
LIGHTER...MEANING MORE NORMAL DIURNAL WINDS...AND WARMER
TEMPERATURES ARE FORECAST TUESDAY AND WEDNESDAY UNDER HIGH
PRESSURE.  AS A LARGE AREA OF LOW PRESSURE SETS UP ALONG THE WEST
COAST...SOMEWHAT STRONGER SOUTHWEST WINDS ARE FORECAST TO OCCUR
THURSDAY THROUGH THE HOLIDAY WEEKEND YIELDING OCCASIONAL CRITICAL
FIRE WEATHER CONDITIONS ACROSS SE AZ AS DRY WEATHER PERSISTS...KD

&&

.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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