Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 280918
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
218 AM MST THU AUG 28 2014

.SYNOPSIS...
DRIER AIR WILL CONTINUE TO MOVE INTO THE REGION TODAY DROPPING
HUMIDITIES TO WELL BELOW TYPICAL MONSOON SEASON LEVELS. HIGH
PRESSURE WILL SET UP TO THE WEST ALLOWING FOR PERSISTENTLY DRY AND
WARMER AIR TO MOVE INTO THE DESERT SOUTHWEST THROUGH AT LEAST EARLY
NEXT WEEK. AFTER NEAR NORMAL HIGH TEMPERATURES TODAY...TEMPERATURES
WILL RISE A COUPLE MORE DEGREES INTO FRIDAY...PEAKING BETWEEN 105
AND 110 FRIDAY AND SATURDAY. A SLIGHT COOLDOWN BUT CONTINUED DRY
CONDITIONS ARE EXPECTED FOR THE MIDDLE OF NEXT WEEK.

&&

.DISCUSSION...
SKIES HAVE FOR THE MOST PART COMPLETELY CLEARED ACROSS THE STATE
WITH THE EXCEPTION OF A SMALL AREA OF ACCAS FROM PHOENIX THROUGH THE
WHITE MOUNTAINS. AT THIS HOUR...THERE ARE EVEN SOME WEAK RADAR
RETURNS FROM THE ACCAS OVER PHOENIX...WITH A FEW LOCATIONS OVER THE
NORTH PHOENIX AREA SEEING SOME LIGHT RAIN. DON/T EXPECT THIS TO LAST
VERY LONG AND WILL LIKELY DIMINISH BY 4 AM. DRY AIR CONTINUES TO
WORK ITS WAY INTO THE CWA AS EVIDENT ON WATER VAPOR IMAGERY.
HOWEVER...MOISTURE BELOW 700MB IS STILL PRESENT...ON THE ORDER OF
7-8 G/KG PER THE 03Z PHOENIX RAOB. ONCE FULL MIXING OCCURS BY THIS
AFTERNOON...EXPECT SURFACE DEW POINTS TO CRASH...LIKELY DROPPING
INTO THE 30S ACROSS OUR WESTERN ZONES AND 40S ELSEWHERE. THIS WILL
BE A SIGN OF WHATS TO COME THROUGH THE UPCOMING WEEKEND AS THE
MONSOON MOISTURE STAYS WELL SOUTH INTO MEXICO.

AS THE SUBTROPICAL HIGH BUILDS JUST OFF THE SOUTHERN CALIFORNIA
COAST TODAY INTO FRIDAY...AREA 500MB HEIGHTS AND HIGH TEMPERATURES
WILL GET A BOOST. SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA LOWER
DESERTS WILL PEAK NEAR 110 STARTING TODAY...LIKELY LASTING THROUGH
SATURDAY WHILE THE LOWER DESERTS OF SOUTH-CENTRAL ARIZONA WILL
GENERALLY SEE 105-108 DURING THE PERIOD. AREA PWATS DROP FROM AROUND
ONE INCH CURRENTLY TO BETWEEN 0.5 AND 0.75 INCHES FOR FRIDAY AND
SATURDAY WHICH IS AROUND TWO STANDARD DEVIATIONS BELOW NORMAL.
SHOULD SEE SOME HIGH CIRRUS MOVE INTO CENTRAL ARIZONA STARTING
FRIDAY AFTERNOON AS SOME UPPER LEVEL MOISTURE GETS PEELED OFF OF NOW
TROPICAL STORM MARIE AND GETS CAUGHT UP IN OUR WESTERLY FLOW ALOFT.

BY LATE SATURDAY INTO SUNDAY...THE UPPER RIDGE TO OUR WEST GETS
FLATTENED BY BROAD SCALE TROUGHING OVERTAKING THE NORTHWESTERN
UNITED STATES. ALTHOUGH WE WILL REMAIN UNDER DRY WEST NORTHWESTERLY
FLOW ALOFT...500MB HEIGHTS START TO DECREASE AND HIGH TEMPERATURES
DROP DOWN TO AROUND NORMAL INTO EARLY NEXT WEEK. FORECAST CONFIDENCE
FOR THE MIDDLE OF NEXT WEEK IS STILL SOMEWHAT LOW AS SOME MODEL
DIFFERENCES REMAIN...BUT MAINLY DUE TO THE DIFFICULTY OF TIMING ANY
POSSIBLE MOISTURE RETURN. BOTH THE EUROPEAN AND THE GFS SHOW SOME
HINT OF MOISTURE BELOW 700MB WORKING INTO SOUTHEAST ARIZONA STARTING
MONDAY WITH THE EUROPEAN ALREADY SHOWING THIS WITH PREVIOUS RUNS AND
HAVING BETTER RUN TO RUN CONSISTENCY LATELY. HOWEVER...THE HIGH
CENTER DOESN/T SHIFT QUITE FAR ENOUGH NORTH INTO NEW MEXICO AND
SOUTHEASTERLY FLOW WILL REMAIN WEAK ONLY ADVECTING VERY LIMITED
AMOUNTS OF MOISTURE INTO SOUTHEAST AND EAST-CENTRAL ARIZONA. FEEL
KEEPING SOME MENTION OF SLIGHT CHANCE POPS OVER THE HIGH TERRAIN OF
EASTERN PORTIONS OF GILA COUNTY IS STILL WARRANTED WHILE NEAR ZERO
POPS ARE FORECAST ELSEWHERE.

&&

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

DRY WESTERLY FLOW ALOFT CONTINUES ACROSS THE LOWER DESERTS...AND
FOLLOWING SUNSET THE BOUNDARY LAYER CUMULUS HAD RAPIDLY DISSIPATED.
EXPECT GENLY CLEAR SKIES AT THE TERMINALS NEXT 24 HOURS...THO THERE
MAY BE A FEW HIGH BASED CU AGAIN TOMORROW AFTERNOON ACROSS SOUTH
CENTRAL AZ...WITH BASES AOA 9K FEET. WINDS TO BE ON THE LIGHT SIDE
FAVORING NORMAL DIURNAL SPEEDS AND DIRECTIONS. NO AVIATION IMPACTS
NEXT 24 HOURS AT THE TAF SITES.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
NORTHWEST FLOW AND DRY CONDITIONS WILL PREVAIL ACROSS THE AREA
THROUGH EARLY NEXT WEEK...WITH NO STORM CHANCES EXPECTED ACROSS THE
REGION. MOISTURE WILL RETURN TO FAR EASTERN ARIZONA BY THE MIDDLE OF
NEXT WEEK BUT UNTIL THEN...THERE WILL BE A BREAK IN THE TYPICAL
MONSOON PATTERN. AFTERNOON HUMIDITIES WILL DROP INTO THE TEENS EACH
DAY WITH FAIR OVERNIGHT RECOVERY EXPECTED. RECOVERIES WILL SLOWLY
IMPROVE AS MOISTURE INCREASES NEXT WEEK. WINDS WILL BE LIGHT THROUGH
NEXT WEEK WITH NO MAJOR WIND EVENTS EXPECTED.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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

DISCUSSION...KUHLMAN
AVIATION...CB
FIRE WEATHER...LEINS










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