Wildfire in Arizona, May 21 to 26, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
900 AM MST TUE MAY 21 2013

.SYNOPSIS...A WEAK UPPER LEVEL RIDGE WILL MOVE ACROSS THE STATE
TODAY. A DEEP UPPER LEVEL LOW MOVING INTO THE PACIFIC NORTHWEST
TUESDAY WILL DEEPEN ALONG THE ENTIRE WEST COAST AND LINGER OVER THE
REGION WELL INTO NEXT WEEK. THIS WILL RESULT IN A PROLONGED PERIOD
OF DRY SOUTHWEST FLOW ACROSS SOUTHERN ARIZONA WITH ABOVE NORMAL
AFTERNOON TEMPERATURES AND A FEW GUSTY AFTERNOONS.

&&

.DISCUSSION...12Z KTWC SOUNDING SUPPORTS MIDDLE 90S TODAY WITH
RATHER DRY 1/4 INCH PRECIPITABLE WATER. CURRENT FORECAST IN GOOD
SHAPE.

THIN PATCHY CIRRUS WILL INCREASE OVER THE NEXT 26 HOURS...SPREADING
IN FROM THE WEST AS THE SHORTWAVE RIDGE AXIS PHASES EAST OF THE
AREA. STRONG TROUGH DIGGING INTO THE REGION WEDNESDAY AND THURSDAY.
SOME HEATING JUST AHEAD OF THE MAIN HEIGHT FALLS THIS AFTERNOON AND
WEDNESDAY AFTERNOON...BUT LOOKING LIKE WE ARE ONLY GOING TO BE ABLE
TO TEASE TIA AGAIN WITH A 98 OR 99 WEDNESDAY AFTERNOON BEFORE
DROPPING BACK A FEW DEGREES FOR THE REST OF THE WEEK. GUSTY WINDS
THE MAIN STORY WITH THE TROUGH WITH MAIN DYNAMICS WELL NORTH AND
MOISTURE DRAWN UP EAST OF OUR AREA.

&&

.PREV DISCUSSION...THIN HIGH CLOUDS STARTING TO PUSH INTO WESTERN
ARIZONA THIS MORNING AS WEAK SHORT WAVE RIDGE PUSHES IN FROM THE
WEST. SO EXPECT A MOSTLY SUNNY DAY WITH LESS WIND AND HIGHS AT OR
SLIGHTLY WARMER THAN MONDAY.

WEDNESDAY...SHORT WAVE RIDGE PUSHES ON EAST AS BROAD UPPER LEVEL
TROF BUILDS...WITH CENTER UP IN THE PACIFIC NW...OVER WESTERN
WESTERN CONUS. HIGHS ACROSS THE LOWER DESERTS AT OR 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.

THIS WEEKEND INTO MONDAY...WARM WITH AFTERNOON BREEZES.

&&

.AVIATION...INCREASING HIGH CLOUDS OVERSPREADING THE AREA FROM WEST
TO EAST THIS MORNING...WITH SCT-BKN CLOUDS AOA 20K FT AGL AREAWIDE
AFT 21/15Z. SURFACE WIND LESS THAN 10 KTS THRU 21/17Z...THEN
WLY/NWLY SURFACE WIND AT 9-14 KTS AND GUSTS TO AROUND 20 KTS DURING
THE AFTERNOON AND EARLY EVENING. SURFACE WIND GENERALLY LESS THAN 10
KTS AGAIN AFT 22/03Z. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.

&&

.FIRE WEATHER...HIGH PRESSURE ALOFT WILL CONTINUE ACROSS THE DESERT
SOUTHWEST THROUGH THE WEEK...RESULTING IN DRY CONDITIONS AND WARM
TEMPERATURES WITH ABOVE NORMAL READINGS. EXPECT GUSTY WINDS DURING
THE AFTERNOON AND EARLY EVENING HOURS DUE TO THE STRONG SOLAR
HEATING. HOWEVER...WINDS ARE EXPECTED TO STAY BELOW CRITICAL FIRE
WEATHER THRESHOLDS. THE EXCEPTION MAY BE WEDNESDAY AND THURSDAY IN
EAST CENTRAL MOUNTAIN LOCATIONS OF GREENLEE AND NORTHEAST GRAHAM
COUNTY WHERE CRITICAL FIRE WEATHER THRESHOLDS ARE POSSIBLE.

&&

.CLIMATE...TUCSON WILL MAKE ANOTHER RUN TOWARD THE FIRST 100 DEGREE
DAY OF 2013 ON WEDNESDAY. A LITTLE BIT OF A CHANGE FROM THE DATA I
WAS LOOKING AT ON MONDAY. THE MAJORITY OF THE TEMPERATURE GUIDANCE
THAT WE ACCESS TO...FROM MOS GUIDANCE TO BIAS-CORRECTED GUIDANCE TO
GFS ENSEMBLES GUIDANCE...STILL HAS 98 FOR TUCSON ON WEDNESDAY.
HOWEVER A FEW MORE ARE NOW SHOWING 99 OR 100 FOR TUCSON WITH THE EC
AND UKMET 850-700 MB THICKNESS VALUES ON WEDNESDAY CONTINUING TO
SHOW EITHER 99 OR 100 FOR TUCSON. YESTERDAY I PUT THE CHANCES OF
HITTING 100 FOR TUCSON LESS THAN 10 PERCENT. THIS MORNING I WOULD
SAY THAT THE CHANCES ARE UP TO ABOUT 15 PERCENT. WITH A LITTLE BIT
OF BETTER CONFIDENCE I DECIDED TO UP THE HIGH FOR TUCSON ON
WEDNESDAY TO 99 DEGREES. IF THE FIRST 100 DOESN'T OCCUR ON
WEDNESDAY...WE WILL LIKELY HAVE TO WAIT UNTIL NEXT WEEK FOR THE NEXT
ATTEMPT.

&&

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

&&

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

MEYER/LADER