Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 182056
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
155 PM MST SAT APR 18 2015

.SYNOPSIS... MOSTLY CLEAR SKIES AND WARMING TEMPERATURES ARE
EXPECTED THROUGH THE REMAINDER OF THE WEEKEND WITH DESERT HIGHS
CLIMBING INTO THE LOW 90S BY SUNDAY. LOOK FOR DRY AND WARM WEATHER
TO PERSIST INTO THE MIDDLE OF NEXT WEEK. BIG CHANGES ARE POSSIBLE
WEDNESDAY INTO FRIDAY...AS AN APPROACHING STORM SYSTEM BRINGS COOLER
TEMPERATURES AND A SLIGHT CHANCE OF SHOWERS INTO THE REGION.

&&

.DISCUSSION...SLUGGISH UPPER LEVEL CLOSED LOW CONTINUED TO PUSH OFF
TO THE EAST EARLY THIS AFTERNOON AND BEHIND THE EXITING LOW A DRY
NORTHWEST FLOW ALOFT OVERSPREAD THE DESERTS LEADING TO SUNNY SKIES
ALONG WITH WARMING TEMPERATURES. IR IMAGERY AT 2 PM SHOWED A BIT OF
HIGH BASED CUMULUS OVER SRN GILA COUNTY...MAINLY EAST OF GLOBE...A
RESULT OF MOISTURE CONTINUING TO WRAP AROUND THE BACKSIDE OF THE
DEPARTING LOW. TEMPS OVER THE CENTRAL DESERTS AT 2 PM WERE RUNNING 6
TO 10 DEGREES WARMER THAN 24 HOURS AGO AND WE CAN EXPECT HIGHS TO
TOP OUT IN THE UPPER 80S TO NEAR 90.

HIGHER PRESSURE WILL CONTINUE TO BUILD IN FROM THE WEST SUNDAY AND
DRY WESTERLY FLOW ALOFT WILL KEEP SKIES SUNNY. HIGH TEMPS SHOULD
CLIMB ANOTHER DEGREE OR TWO AND WE ARE LOOKING AT HIGHS REACHING
INTO THE LOWER 90S OVER MOST OF OUR LOWER DESERTS.

FOR NEXT MONDAY INTO TUESDAY...A SPLIT IN THE FLOW WILL DEVELOP
ALONG THE WEST COAST WITH HIGH PRESSURE SITUATED OVER THE PAC
NORTHWEST WHILE A BAGGY SOUTHERN BRANCH TROF SETS UP OFF THE NRN
BAJA/SRN CA COAST. THIS SOUTHERN BRANCH FEATURE WILL BRING A DRY
SOUTHWEST FLOW ALOFT TO SERN CA AND ARIZONA...FOR CONTINUED SUNNY OR
MOSTLY SUNNY SKIES. HIGH TEMPS WILL PEAK ON MONDAY WITH WARMER
DESERTS REACHING THE LOW TO MID 90S...AND THEN TAPER OFF SLIGHTLY
TUESDAY AS H5 HEIGHTS START TO FALL OFF. DESPITE THE SLIGHT COOLING
THE GREATER PHOENIX AREA WILL STILL APPROACH 90 ON TUESDAY.

MODELS CONTINUE TO ADVERTISE BIG CHANGES FOR THE LATER HALF OF THE
WEEK. SIGNIFICANT COOLING IS LIKELY...WITH SOME MODEL GUIDANCE
INDICATING HIGHS WILL REMAIN IN THE UPPER 70S ACROSS MUCH OF THE
AREA ON THURSDAY. THERE IS ALSO GREATER CONFIDENCE OF RAINFALL
ACROSS THE REGION. CLIMATOLOGICALLY SPEAKING...VERY LITTLE RAIN
NORMALLY FALLS DURING THE MONTH OF APRIL. LAST YEAR ONLY A TRACE
FELL AT PHOENIX SKY HARBOR AND IN 2013 AND 2012 ONLY .06 AND .05
INCHES FELL RESPECTIVELY. SLIGHTLY OVER A QUARTER OF AN INCH FELL IN
2011...BUT YOU HAVE TO GO ALL THE WAY BACK TO 2004 TO FIND ANY
SIGNIFICANT RAINFALL. THAT YEAR WE MEASURED .68 INCHES. THIS FAR OUT
THERE STILL IS QUITE A BIT OF UNCERTAINTY...BUT SOME MODELS ARE
INDICATING TOTALS UP TO HALF AN INCH ARE POSSIBLE IN NORTHERN
MARICOPA COUNTY. THE BULK OF THIS IS EXPECTED TO FALL THURSDAY
AFTERNOON INTO FRIDAY MORNING. DID MAKE SOME ADJUSTMENTS TO OUR POPS
IN THESE PERIODS...WITH INCREASES TO ACCOUNT FOR GREATER CONFIDENCE
OF RAINFALL. FOR SATURDAY...PROGS SUGGEST HIGHER PRESSURE ALOFT AND
A DRIER WESTERLY FLOW WILL BUILD IN FROM THE WEST...ALLOWING HIGH
TEMPS TO CLIMB TOWARDS SEASONAL NORMALS UNDER PARTLY SUNNY SKIES.

&&

.AVIATION... SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND
KSDL...SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND
KBLH...

AFTER SOME WESTERLY BREEZES LATE THIS AFTERNOON/EARLY
EVENING...STRONG HIGH PRESSURE AT THE SFC AND ALOFT ALONG WITH A
VERY DRY AIRMASS TO KEEP SKIES MAINLY CLEAR AND WINDS ON THE LIGHT
SIDE...MOSTLY AOB 8 KTS THROUGH THE REMAINDER OF THE TAF
PERIOD...MAINLY FOLLOWING TYPICAL DIURNAL TRENDS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
TUESDAY THROUGH SATURDAY...HIGH PRESSURE OVER THE REGION WILL KEEP
TEMPERATURES ABOVE NORMAL AND WINDS ON THE LIGHT SIDE THROUGH
WEDNESDAY. A PACIFIC LOW CENTER MOVING INLAND INTO THE REGION WILL
THEN BRING COOLER TEMPERATURES...AFTERNOON BREEZINESS...AN INCREASE
IN THE CLOUD COVER...AND EVEN A SLIGHT CHANCE FOR SHOWERS ON
THURSDAY. HIGH PRESSURE BUILDING BACK INTO THE DESERT SOUTHWEST WILL
THEN BRING BACK WARMER AND DRIER CONDITIONS BACK TO THE REGION ON
FRIDAY AND SATURDAY. MINIMUM HUMIDITIES IN THE 5 TO 15 PERCENT RANGE
ON TUESDAY WILL RISE INTO THE 20 TO 30 PERCENT RANGE BY
THURSDAY...THEN DROP BACK DOWN INTO THE 15 TO 25 PERCENT RANGE BY
SATURDAY...WITH FAIR TO GOOD OVERNIGHT RECOVERIES.


&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.
CA...NONE.

&&

$$

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

DISCUSSION...CB/MCLANE
AVIATION...PERCHA
FIRE WEATHER...PERCHA


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