Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 230443
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
943 PM MST TUE APR 22 2014

.SYNOPSIS...
BREEZY TO WINDY CONDITIONS WILL SLOWLY DECREASE TONIGHT AS A DRY
WEATHER SYSTEM PASSES ACROSS ARIZONA. ANTICIPATE COOLER HIGH
TEMPERATURES WEDNESDAY WITH READINGS CLOSE TO NORMAL. WARMER
TEMPERATURES WILL MAKE A RETURN THURSDAY AND FRIDAY. ANOTHER LOW
PRESSURE SYSTEM WILL AFFECT THE REGION FRIDAY AND SATURDAY. BREEZY
TO WINDY CONDITIONS CAN BE EXPECTED ALONG WITH MUCH COOLER
TEMPERATURES SATURDAY. THERE IS ALSO A SLIGHT CHANCE OF SHOWERS LATE
FRIDAY NIGHT INTO SATURDAY NIGHT...MAINLY FOR THE HIGHER TERRAIN OF
SOUTH-CENTRAL ARIZONA. ANTICIPATE A WARMING TREND MONDAY AND TUESDAY.

&&

.DISCUSSION...
WELL-DEFINED AND DEEP PACIFIC TROUGH AND SURFACE FRONTAL BOUNDARY
OBSERVED ON EVENING WV/IR IMAGERY AND MSLP ANALYSIS. HIGH CLOUDS
BISECT ARIZONA...WITH THE EASTERN HALF INCLUDING CENTRAL/EASTERN
MARICOPA COUNTY UNDER PARTLY TO MOSTLY CLOUDY SKIES...AND CLEAR SKIES
ACROSS WESTERN ARIZONA TOWARDS THE COLORADO RIVER VALLEY. ELEVATED
DAYTIME WINDS HAVE DIMINISHED THROUGH THE EARLY EVENING
HOURS...HOWEVER SOME ISOLATED STRONGER GUSTS OF 25 TO 30 MPH HAVE
BEEN REPORTED. WINDS WILL REMAIN BREEZY OVERNIGHT AND MAY SEE
ADDITIONAL GUSTS ACROSS CENTRAL ARIZONA AS THE FRONTAL BOUNDARY MOVES
THROUGH THE AREA...BUT GENERALLY FALL UNDER THE SPEEDS OBSERVED
EARLIER TODAY.

00Z NEIGHBOR RAOB DATA INDICATE THE COOL FRONTAL BOUNDARY HAD REACHED
KVEF...WHERE THE LOWER ATMO LAYERS THROUGH 700MB HAD COOLED ABOUT 8
DEGREES. KTUS HAD YET TO INDICATE THE SAME COOLING...WITH TEMPERATURE
PROFILE READINGS SIMILAR TO THOSE OBSERVED 24 HRS AGO. SFC
TEMPERATURES FOR WEDNESDAY EXPECTED COOLER THAN READINGS OBSERVED
THIS AFTERNOON IN LIGHT OF THIS COOLER AIRMASS MOVING THROUGH THE
STATE...FINALLY GIVING THE AREA AN AFTERNOON OF TEMPERATURES CLOSER
TO APRIL NORMALS. ALONG WITH THE COOLER TEMPERATURES...MUCH DRIER AIR
WILL FILTER INTO THE AREA...DROPPING DAYTIME DEWPOINTS INTO THE TEENS
BY THE AFTERNOON. RESULTING HUMIDITIES WILL FALL BELOW 10 PERCENT FOR
MANY LOCATIONS...BUT GENERALLY LIGHTER POST-FRONTAL
WINDS TOMORROW SHOULD KEEP WIDESPREAD CRITICAL FIRE WEATHER
CONDITIONS AT BAY.

FOR TONIGHT...CLOUDS AND THE SURFACE BOUNDARY WILL CONTINUE TO CLEAR
TO THE EAST WITH WINDS REMAINING BREEZY. MINOR ADJUSTMENTS WERE
NEEDED TO THE SKY COVER GRID TO CAPTURE THE THICKER CLOUDS CURRENTLY
OBSERVED AND THEIR EXIT OVER THE NEXT FEW HOURS. DEWPOINTS WERE ALSO
ADJUSTED TO MATCH CURRENT TRENDS AS UPSTREAM READINGS WERE ALREADY
BELOW EVEN THE RAW GRIDDED FORECAST GUIDANCE. REMAINDER OF THE
FORECAST DISCUSSION STILL APPLICABLE FOR WEDNESDAY AND BEYOND.

&&

.PREVIOUS DISCUSSION /ISSUED AT 325 AM MST/PDT/...
WEDNESDAY AND THURSDAY...
BEHIND THE FRONT ON WEDNESDAY LOOK FOR HIGHS IN THE UPPER 80S ACROSS
THE LOWER DESERTS. ANTICIPATE LESS WIND THOUGH A TRAILING SHORT WAVE
WILL MAINTAIN SOME BREEZINESS. A FLAT RIDGE PASSES BY THURSDAY WITH
HIGHS A FEW DEGREES WARMER.

FRIDAY THROUGH SUNDAY...
THE NEXT PACIFIC SYSTEM WILL AFFECT OUR FORECAST AREA FRIDAY AND
SATURDAY. THE GFS CONTINUES TO BE A BIT FASTER THAN THE ECWMF...WITH
THE GEM IN BETWEEN. IN SHORT...BREEZY TO WINDY CONDITIONS DEVELOP
FRIDAY AFTERNOON...WITH BREEZINESS CONTINUING FRIDAY NIGHT AND
SATURDAY. SPEEDS FRIDAY AFTERNOON ARE LOOKING QUITE SIMILAR TO
TODAY...TUESDAY. EVENING AND OVERNIGHT BREEZINESS WILL BE STRONGER
THOUGH. THUS ANTICIPATE RED FLAG POTENTIAL AND POSSIBLY WIND
ADVISORY CONDITIONS SIMILAR TO TODAY. THE NEXT SYSTEM WILL DIG
DEEPER AND BRING EVEN COOLER AIR. MADE SOME SLIGHT DOWNWARD
ADJUSTMENTS TO THE HIGHS FOR SATURDAY WITH LOWER DESERT HIGHS IN
UPPER 70S. ALSO INTRODUCED SOME SLIGHT CHANCE POPS IN PORTIONS OF
OUR FORECAST AREA FOR LATE FRIDAY NIGHT INTO SATURDAY NIGHT...MAINLY
THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA. ANTICIPATE SLIGHTLY
WARMER HIGHS SUNDAY WITH DRY NORTHWEST FLOW ALOFT.

MONDAY AND TUESDAY...
THE FLOW AMPLIFIES EARLY NEXT WEEK FOR RIDGING OVER THE WEST COAST
FOR A WARMING TREND. LINGERING TROUGHING OVER THE CENTRAL CONUS MAY
KEEP THE TEMPS FROM SHOOTING UP EXCESSIVELY...BUT STILL LOOK FOR
HIGHS GETTING INTO THE 90S BY TUESDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
WEST/SOUTHWESTERLY WINDS WILL REMAIN ELEVATED THROUGH MUCH OF THE
OVERNIGHT HOURS AS A DRY SURFACE COOL FRONT PASSES THROUGH CENTRAL
ARIZONA. NEAR 23/09-10Z...LIGHT SPEEDS UNDER 6KTS WITH VRB HEADINGS
POSSIBLE BEFORE TURNING WESTERLY AGAIN AS EARLY AS MIDDAY. HIGH
CLOUDS ALONG THE FRONTAL BOUNDARY WILL QUICKLY CLEAR TO THE
EAST...LEAVING MOSTLY CLEAR SKIES FOR THE TERMINALS BY SUNRISE.

SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
ELEVATED WEST WINDS TO PERSIST OVERNIGHT FOR KIPL AND KBLH...WITH
ISOLATED GUSTS IN THE 20KT RANGE STILL POSSIBLE THROUGH MIDNIGHT
LOCAL. SUSTAINED SPEEDS TO HOLD 10-15KTS GNLY THROUGH SUNRISE BEFORE
DROPPING 8KTS OR LESS FOR WEDNESDAY MORNING. IN THE WAKE OF A DRY
COOL FRONT PASSAGE...SKIES WILL REMAIN MOSTLY CLEAR THROUGH WEDNESDAY
MORNING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
STRONG UPPER LEVEL LOW WILL APPROACH THE AREA ON FRIDAY AND MOVE
THROUGH ARIZONA/CALIFORNIA ON SATURDAY. AHEAD OF THE TROUGH...WINDS
WILL INCREASE QUITE A BIT FRIDAY AFTERNOON AND ITS POSSIBLE CRITICAL
THRESHOLDS COULD BE REALIZED IN SOME PARTS OF THE FORECAST AREA.
STILL NEED A LITTLE BETTER CONSISTENCY IN THE MODELS BEFORE GOING
WITH A FIRE WX WATCH AND WILL HOLD OFF AT THIS POINT. TEMPERATURES
ON SATURDAY AND SUNDAY /POST-TROUGH/ WILL BE SUBSTANTIALLY COOLER
AND HUMIDITIES WILL RECOVER QUITE A BIT...THUS FIRE WEATHER CONCERNS
WILL BE MUCH LESS. TEMPS WILL RECOVER NEXT WEEK AND CONSEQUENTLY
AFTERNOON HUMIDITIES WILL ONCE AGAIN DROP INTO THE SINGLE DIGITS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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DISCUSSION...NOLTE
PREVIOUS DISCUSSION...AJ/MEYERS
AVIATION....NOLTE
FIRE WEATHER...LEINS/MO




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