Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 230406
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
905 PM MST FRI MAY 22 2015

.SYNOPSIS...
A FAIRLY STRONG UPPER LEVEL LOW WILL AFFECT THE REGION TODAY INTO
EARLY SATURDAY BRINGING COOLER TEMPERATURES...AND BREEZY TO LOCALLY
WINDY CONDITIONS. PRECIPITATION CHANCES ARE SLIGHT...SHOWERS AND
THUNDERSTORMS WILL BE CONFINED TO HIGHER TERRAIN AREAS FROM
SOUTHEAST CALIFORNIA NORTHEASTWARD INTO CENTRAL AND NORTHERN
ARIZONA. DRY CONDITIONS AND A WARMING TREND WILL THEN TAKE OVER
THROUGH NEXT WEEK WITH TEMPERATURES CLIMBING TO AROUND SEASONAL
NORMALS BY TUESDAY.

&&

.DISCUSSION... WATER VAPOR IMAGERY AT 8 PM SHOWED THE PRESENCE OF A
LARGE UPPER TROF OVER THE WESTERN CONUS WITH THE MAIN LOW CENTER
LOCATED OVER FAR NWRN ARIZONA. THE LOW HAS BEEN MOVING TOWARDS THE
NORTHEAST...TRACKING WELL TO THE NORTH/NORTHWEST OF PHOENIX AND AS
SUCH THE COLDEST AIR ALOFT AND BEST INSTABILITY HAVE STAYED OVER
NORTHERN ARIZONA AND LOCATIONS TO THE NORTH OF RIVERSIDE COUNTY.
MOST OF THE CONVECTION/SHOWERS/STORMS HAVE STAYED NORTH OF OUR AREA
AND WE HAVE ONLY SEEN A FEW SHOWERS SCRAPE BY THE NORTHERN FRINGES
OF EASTERN RIVERSIDE...LA PAZ AND MARICOPA COUNTIES DURING THE
AFTERNOON AND EARLY EVENING HOURS. EARLIER ISOLATED SHOWERS
DEVELOPED IN A CUMULUS FIELD OVER NORTHERN PINAL COUNTY NEAR CASA
GRANDE BUT THEY MOVED QUICKLY TO THE NORTHEAST AND LITTLE IF ANY
PRECIP WAS GENERATED. LATEST LOOK AT IR IMAGERY SHOWED THE CLOUDS
DISSIPATING ACROSS THE LOWER DESERTS AND AS THE LOW CONTINUES TO
TRACK TOWARDS THE NORTHEAST TONIGHT THE AIRMASS WILL BECOME MORE
SUBSIDENT AND SKIES WILL BECOME MOSTLY CLEAR TO PARTLY CLOUDY.
BREEZY CONDITIONS HAVE ALSO LESSENED FOLLOWING SUNSET AND LACK OF
MIXING...BUT WE WILL CONTINUE TO SEE SOME BREEZY WEST WINDS PERSIST
ACROSS PORTIONS OF IMPERIAL COUNTY THROUGH MIDNIGHT. FORECASTS LOOK
TO BE IN GOOD SHAPE AND NO UPDATES ARE NEEDED AT THIS TIME.

.PREVIOUS DISCUSSION...
FOR TONIGHT...SATELLITE/LIGHTNING DATA SHOW THAT THE UPPER LEVEL LOW
HAS MOVED OVER NW ARIZONA THIS AFTERNOON...SCATTERED THUNDERSTORMS
NOTED BETWEEN LAS VEGAS AND KINGMAN...EXTENDING ACROSS NORTHERN
ARIZONA. NOT MUCH HAS HAPPENED OVER OUR CWA...SOME LOCALIZED BLOWING
DUST NEAR JTNP DUE TO OUTFLOW FROM SHOWERS...AND MAYBE AN ISOLATED
LIGHT SHOWER OR TWO ACROSS THE NORTHERN PORTIONS OF LA PAZ COUNTY.
FOR THE MOST PART...GUSTY SOUTHWEST WINDS UP TO 25-30 MPH HAVE BEEN
THE PRIMARY CONCERN OVER THE SOUTH-CENTRAL ARIZONA DESERTS TODAY.
THE WINDS ELEVATED THE FIRE DANGER...AND HELPED TO QUICKLY SPREAD A
COUPLE OF BRUSH/WILDFIRES THAT STARTED EARLIER IN THE AFTERNOON. THE
WINDS WILL QUICKLY DIMINISH AFTER SUNSET...AND SKIES SHOULD REMAIN
MOSTLY CLEAR OVERNIGHT...WITH LOW TEMPERATURES DROPPING DOWN INTO
THE 50S IN OUTLYING DESERT LOCALES...LOWER 60S IN WARMER URBAN AREAS.

SATURDAY...THE LOW SHOULD CONTINUE TO TRACK OFF TO THE NORTHEAST
THROUGH UTAH LATER THIS EVENING INTO SATURDAY MORNING...AND WITH ITS
DEPARTURE...A MUCH DRIER AND COOLER NORTHWESTERLY FLOW ALOFT WILL
SETTLE IN OVER THE REGION. A LARGE SCALE TROUGH WILL STILL BE THE
DOMINANT FEATURE OVER THE WESTERN CONUS THROUGH THE WEEKEND...AND
WITH THE COOL AIR IN PLACE...HIGHS SATURDAY WILL WARM UP A FEW
DEGREES INTO THE MID 80S.

SUNDAY AND MONDAY...A SHORTWAVE TROUGH IS THEN SHOWN TO QUICKLY MOVE
THROUGH SOUTHERN ARIZONA FROM THE NORTHWEST BY SUNDAY NIGHT...BUT
WITH LITTLE TO NO MOISTURE TO WORK WITH...ONLY SINGLE DIGITS POPS
ARE IN THE FORECAST. TEMPERATURES WILL START TO GET A BOOST SUNDAY
INTO MONDAY...BUT WE WILL STILL BE SEVERAL DEGREES SHY OF NORMAL.

TUESDAY AND BEYOND...NEXT WEEK LOOKS TO BE MORE ON THE QUIET SIDE
WITH NO SIGNIFICANT WEATHER SYSTEMS ON THE HORIZON. QUASI-ZONAL
WESTERLY FLOW WITH GRADUALLY INCREASING UPPER HEIGHTS WILL ALLOW
HIGH TEMPERATURES TO REACH NEAR NORMALS BY THE MIDDLE OF NEXT
WEEK...AND POSSIBLY NEARING 100 DEGREES IN A FEW LOWER DESERT SPOTS
FOR NEXT FRIDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
VERY LITTLE AVIATION CONCERN THROUGH SATURDAY AFTERNOON WITH ONLY
OCCASIONAL CLOUDS AOA 8K FT. GUSTY W/SW WINDS WILL PERSIST INTO
THE EVENING...BEFORE QUICKLY WEAKENING. THE SHIFT TO THE TRADITIONAL
LATE NIGHT EASTERLY DRAINAGE WIND DIRECTION WILL LIKELY BE MORE
DELAYED THAN USUAL...WITH ONLY MODERATE CONFIDENCE IN TIMING. EXPECT
A FEW HIGHER BASED CU TOMORROW AFTERNOON ALONG WITH SOMEWHAT WEAKER
WEST WINDS.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
GUSTY W/SW SFC WINDS WILL BE THE PRIMARY AVIATION CONCERN
THIS EVENING...HOWEVER SPEEDS WILL DECREASE QUICKLY LATER THIS
EVENING AND NOT BE PROBLEMATIC SATURDAY. CHANCES FOR SHOWERS AT KBLH
PRETTY MUCH OVER...BUT THERE MAY BE A SOME SCT CU/SC DECKS NEAR 7-8K
FEET INTO THE EARLY MORNING HOURS. OTHERWISE NO AVIATION CONCERNS
SATURDAY AS SKIES WILL BE MOSTLY CLEAR AND WINDS WILL BE LESS AS
COMPARED TO TODAY...AND STILL FAVORING THE SOUTHWEST TO WEST.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
MONDAY THROUGH FRIDAY...
A FEW WEAK WEATHER DISTURBANCES WILL MOVE THROUGH THE DISTRICT NEXT
WEEK...HOWEVER DRY WEATHER WILL STILL PREVAIL. A GRADUAL WARMING
TREND WILL ALSO GRACE THE REGION BRINGING TEMPERATURES CLOSER TO THE
SEASONAL NORMAL. AS A RESULT...AFTERNOON RELATIVE HUMIDITY VALUES
WILL FALL BACK INTO THE TEENS FOLLOWING FAIR TO GOOD OVERNIGHT
RECOVERY. HOWEVER...WINDS WILL GENERALLY REMAIN LIGHT FOLLOWING
TYPICAL DAILY PATTERNS LEADING TO MINIMAL FIRE WEATHER CONCERNS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.

&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...CB
PREVIOUS DISCUSSION...MEYERS/KUHLMAN
AVIATION...MO/CB
FIRE WEATHER...MO


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