Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 302154 AAA
AFDPSR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
255 PM MST SAT AUG 30 2014

.UPDATE...
UPDATED AVIATION AND FIRE WEATHER SECTIONS.

&&

.SYNOPSIS...
MOSTLY CLEAR SKIES WITH LOW HUMIDITY VALUES WILL CONTINUE TO PROVIDE
ABOVE NORMAL AFTERNOON TEMPERATURES THROUGH THE MIDDLE OF NEXT WEEK.
THE HOTTEST TEMPERATURES WILL OCCUR THIS WEEKEND. SLIGHT COOLING IS
EXPECTED NEXT WEEK...ALONG WITH AN INCREASING CHANCE OF AFTERNOON
AND EARLY EVENING THUNDERSTORMS OVER EASTERN ARIZONA STARTING AROUND
NEXT THURSDAY.

&&

.DISCUSSION...
CLEAR SKIES AND STRONG RIDGING ALOFT IS AGAIN ALLOWING FOR SOME HOT
TEMPERATURES ACROSS THE REGION. HIGHS THIS AFTERNOON WILL BREAK 110
IN MANY DESERT SPOTS ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST
ARIZONA AND APPROACH 110 ACROSS THE SOUTH-CENTRAL ARIZONA DESERTS
INCLUDING THE PHOENIX AREA. WILL KEEP THE EXCESSIVE HEAT WARNING
GOING THROUGH EARLY THIS EVENING FOR SOUTHEAST CALIFORNIA AND
SOUTHWEST ARIZONA. DRY AIR REMAINS ENTRENCHED ACROSS THE REGION WITH
PRECIPITABLE WATER VALUES TWO STANDARD DEVIATIONS BELOW NORMAL.
SURFACE DEW POINTS GENERALLY IN THE 30S AND 40S WILL CREATE LARGER
THAN TYPICAL DIURNAL TEMPERATURE SWINGS OVER THE NEXT SEVERAL DAYS.

THE FIRST SIGNS OF SOME FLATTENING IN THE UPPER LEVEL RIDGE IS NOW
HAPPENING AS A SERIES OF SHORTWAVES HAVE BEGUN TO CARVE OUT BROAD
SCALE TROUGHING FROM THE GREAT BASIN NORTHWARD INTO SOUTHWEST
CANADA. THIS FLATTENING WILL GRADUALLY BRING DOWN UPPER HEIGHTS
ACROSS THE DESERT SOUTHWEST WITH SOME SLIGHTLY COOLER TEMPERATURES
TO FOLLOW. EXPECTING TO LOSE MAYBE ONE DEGREE ON OUR HIGHS FOR
SUNDAY AND PROBABLY ANOTHER DEGREE OR TWO ON MONDAY. THEN THE BROAD
TROUGHING LIFTS TO THE NORTHEAST...BUT WHILE KEEPING HEIGHTS FAIRLY
STEADY ACROSS OUR REGION MONDAY THROUGH WEDNESDAY. SINCE MODEL
TEMPERATURE GUIDANCE HAS BEEN A BIT TOO COOL THE PAST FEW
DAYS...HAVE KEPT WITH OUR TREND OF GOING SLIGHTLY ABOVE GUIDANCE
WHICH GIVES US HIGHS 2-3 DEGREES ABOVE NORMAL.

FOR THURSDAY AND FRIDAY...MODELS SHOW A FAIRLY STRONG SHORTWAVE
TROUGH MOVING THROUGH THE PACIFIC NORTHWEST ALONG WITH A WEAKER
SHORTWAVE APPROACHING CALIFORNIA FROM THE WEST. THE SUB-TROPICAL
HIGH THEN SHIFTS EASTWARD MAINLY CENTERED OVER THE WESTERN GULF OF
MEXICO. THERE ARE SOME INDICATIONS OF A RETURN TO WEAK SOUTHEASTERLY
LOW LEVEL FLOW OVER NORTHERN MEXICO AND SOUTHEAST ARIZONA...BUT IT
IS STILL TOO EARLY TO SAY WHEN ANY MEANINGFUL MONSOONAL MOISTURE
WILL VENTURE BACK INTO OUR AREA. GIVEN THE EUROPEAN HAS NOT HANDLED
THE MOISTURE RETURN VERY WELL LATELY...LEANING TOWARD THE DRIER GFS
WHICH DOESN/T BRING ANY CHANCES OF RAIN UNTIL FRIDAY. TEMPERATURES
SHOULD COOL DOWN EVEN FURTHER DURING THE LATTER PART OF THE WEEK AS
UPPER HEIGHTS FALL IN RESPONSE TO THE SOUTHERN SHORTWAVE DIGGING
INTO CENTRAL CALIFORNIA AND THE GREAT BASIN.

&&

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

CLEAR SKIES EXCEPT FOR VERY THIN CIRRUS THROUGH SUNDAY. SOUTHWEST
AND WEST WINDS WILL PREVAIL THROUGH SUNDAY OVER SOUTH-CENTRAL
ARIZONA...INCLUDING PHOENIX METRO...WITH GUSTS THIS AFTERNOONS OF
15-20 KTS. SOUTH AND AND SOUTHEAST WINDS WILL PREDOMINATE OVER
SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA WITH SIMILAR GUSTS. WINDS
JUST ABOVE THE LOW LEVEL INVERSION TONIGHT WILL BE FAIRLY STRONG
WITH 20-25 KTS COMMON...FAVORING THE AFOREMENTIONED DIRECTIONS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
TUESDAY THROUGH SATURDAY...
SOUTHERLY FLOW AND SUBSEQUENT LOW LEVEL MOISTURE WILL SLOWLY RETURN
TO THE REGION THROUGH THE WORK WEEK...GRADUALLY NUDGING UP DEWPOINT
READINGS WHILE HELPING TO KEEP TEMPERATURES CLOSER TO NORMAL
READINGS FOR EARLY SEPTEMBER. VERY LIMITED SHOWER AND THUNDERSTORM
ACTIVITY IS EXPECTED TO BEGIN OVER THE SOUTHEASTERN AND FAR EASTERN
AZ HIGHER TERRAIN BY WEDNESDAY...BEFORE SLIGHT CHANCES ENTER THE
FORECAST FOR THE FOOTHILLS AND HIGHER TERRAIN OF SOUTHERN GILA
COUNTY BY FRIDAY. WHILE MOISTURE AT THIS TIME IS NOT PLENTIFUL OVER
THE LOWER DESERT ELEVATIONS...GUSTY OUTFLOW WINDS FROM DISTANT
THUNDERSTORMS MAY REACH LOWER DESERT LOCATIONS. MINIMUM HUMIDITIES
OF 10-15 PERCENT ARE EXPECTED OVER THE LOWER DESERTS THE FIRST HALF
OF THE WEEK INCREASING CLOSER TO 20 PERCENT DURING THE LATTER HALF
OF THE WEEK. SIMILARLY...OVERNIGHT RECOVERY WILL BE FAIR-GOOD THE
FIRST HALF OF THE WEEK AND INCREASE TO GOOD-EXCELLENT AT MOST PLACES
DURING THE LATTER PART OF THE WEEK.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...EXCESSIVE HEAT WARNING AZZ020-021-025-026 UNTIL 8 PM MST TODAY.

CA...EXCESSIVE HEAT WARNING CAZ031>033 UNTIL 8 PM PDT TODAY.

&&

$$

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

DISCUSSION...KUHLMAN
AVIATION...AJ
FIRE WEATHER...AJ/NOLTE






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