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276
FXUS65 KPSR 251542
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
842 AM MST SAT OCT 25 2014

.SYNOPSIS...
HIGH PRESSURE WILL GRADUALLY TRANSITION EAST OF THE AREA TODAY...BUT
NOT BEFORE SUPPORTING ANOTHER ROUND OF WELL-ABOVE AVERAGE HIGH
TEMPERATURES. A COOLING TREND IS FROM SUNDAY INTO EARLY NEXT WEEK AS
LOW PRESSURE MOVES INLAND INTO THE GREAT BASIN...WITH TEMPERATURES
FALLING BACK TO NEAR SEASONAL NORMALS. A RETURN TO ABOVE NORMAL
TEMPERATURES IS THEN EXPECTED FROM WEDNESDAY ONWARD THROUGH THE END
OF NEXT WEEK AS HIGH PRESSURE BECOMES REESTABLISHED ACROSS THE
WESTERN STATES.

&&

.DISCUSSION...
CONSIDERABLE CU FIELDS ALREADY NOTED ON AREA WEBCAMS AND THE FIRST
FEW FRAMES OF VISIBLE SATELLITE IMAGERY THIS AM. NEIGHBOR AM RAOBS
AND FORECAST SOUNDINGS INDICATE MOISTURE MOSTLY THROUGHOUT THE MID
LEVELS AROUND 700MB...WITH DRY SUB-CLOUD LAYERS/INVERTED V SOUNDING
TRACES BELOW. THIS SOMEWHAT NARROW MOISTURE LAYER...ALTHOUGH MOIST
ENOUGH TO WARRANT 3-4 STANDARD DEV ABOVE NORMAL ON NAEFS ANOMALIES
TABLES TODAY...WILL PERSIST LAYERS OF CU THROUGHOUT THE DAY AREAWIDE
AS MOISTURE CONTINUES TO TRACK NORTHWARD IN RESPONSE TO LOW PRESSURE
MOVING INTO THE GREAT BASIN. WITH PWATS STILL PROGGED TO NEAR THE 1
INCH MARK...CANNOT RULE OUT VIRGA AND MAYBE AN ISOLATED SPRINKLE TO
TWO OUT OF THE SOME OF THE THICKER CLOUDS THROUGH THE DAYLIGHT
HOURS...BUT NOT ENOUGH COVERAGE TO WARRANT ANY WEATHER-GENERATING
POPS IN FOR THE GRIDS TODAY.

HIGH PRESSURE RIDGE...RESPONSIBLE FOR OUR LATEST STRETCH OF ABOVE
NORMAL TEMPERATURES...HAS BEGUN TO TRANSITION EASTWARD AS PACIFIC
LOW PRESSURE TROUGH APPROACHES THE WA/OR COAST. PROGRESSION OF
LOWERING 500MB HEIGHTS IN RESPONSE TO THE TROUGH ARE ALREADY AHEAD
12Z GFS/NAM FORECASTS AND COOLING IN THE MODEL SOUNDING PROFILES ALSO
SEEM TO BE JUST A FEW DEGREES WARMER/BEHIND THAN 12Z RAOBS. THOSE
FACTORS...COUPLED WITH THE PERIODS OF CLOUDINESS SHOULD SUPPORT A FEW
DEGREES OF COOLING AT THE SURFACE TODAY. WHILE TEMPERATURES ARE
MOSTLY SHY OF RECORDS TODAY...THEY WILL STILL BE 8 TO 10 DEGREES
ABOVE NORMAL.

MINOR UPDATES WERE NEEDED TO ALIGN THE SKY COVER GRIDS TO CURRENT
TRENDS WHILE SOLIDLY PLACING MUCH OF THE FORECAST AREA INTO PARTLY
SUNNY TO PARTLY CLOUDY WORDING FOR MUCH OF THE DAY. CU FIELDS SHOULD
TRANSITION EASTWARD THROUGH THE DAY...BUT ANOTHER AREA OF PACIFIC
MOISTURE IN THE MID TO HIGH LEVELS MAY STREAM OVER THE AREA TONIGHT
FROM THE SOUTHWEST...PERSISTING SOME AREAS OF CIRRUS OVERNIGHT. NO
OTHER UPDATES NEEDED...REST OF FORECAST REMAINS ON TRACK.

&&

.PREVIOUS DISCUSSION /ISSUED AT 300 AM MST/PDT...
THE STRONG RIDGING ALOFT THAT BROUGHT RECORD HIGH TEMPERATURES TO
SOUTH-CENTRAL ARIZONA YESTERDAY IS NOW BEGINNING TO WEAKEN AND SHIFT
OFF TO THE EAST AS A RATHER STRONG UPPER TROF BEGINS TO PUSH INLAND
INTO CENTRAL/NORTHERN CA. IT APPEARS THAT ONE MORE DAY OF NEAR-RECORD
HIGHS IS IN THE CARDS FOR SOUTH-CENTRAL ARIZONA TODAY. HOWEVER...A
COMBINATION OF INCREASING CLOUDINESS...A DEGREE OR SO OF COOLING IN
THE 850-700 MB LAYER...AND A SLIGHT LOWERING OF 500MB HEIGHTS SHOULD
KEEP PHOENIX SKY HARBOR A COUPLE OF DEGREES SHORT OF TODAY/S RECORD
HIGH OF 96F.

SCATTERED TO BROKEN MID-HIGH LEVEL CLOUD LAYERS...A RESULT OF A
MOISTURE PLUME THAT IS EXPECTED TO BRIEFLY SURGE NORTHWARD AHEAD OF
THE APPROACHING UPPER TROF...ARE EXPECTED TO PROGRESS EASTWARD
ACROSS ARIZONA TODAY AND TONIGHT. ALTHOUGH PWATS COULD BRIEFLY
REACH/EXCEED 1 INCH ACROSS SOUTHERN ARIZONA TODAY...A DRY SUBCLOUD
LAYER IS EXPECTED TO LIMIT ANY RAINFALL TO AN ISOLATED
SPRINKLE...WITH ONLY A REMOTE CHANCE THAT ANY LOCATION WILL SEE
MEASURABLE RAINFALL. THE APPROACHING TROF WILL ALSO INCREASE THE
USUAL AFTERNOON WESTERLY BREEZES A BIT ACROSS SE CA AND SW AZ...BUT
SUSTAINED WIND SPEED ARE EXPECTED TO REMAIN MAINLY AOB 10 KTS. A
SLOW DRYING/CLEARING TREND IS THEN EXPECTED ON SUNDAY AS THE MAIN
MOISTURE PLUME MOVES OFF TO THE EAST AS DRIER AIR BEGINS TO MOVE
INTO THE REGION FROM THE NORTHWEST.

ALTHOUGH A COOLING TREND IS EXPECTED FROM SUNDAY ONWARD INTO
TUESDAY AS THE LONG-WAVE UPPER-LEVEL TROF SHIFTS EASTWARD ACROSS THE
GREAT BASIN INTO THE CENTRAL ROCKIES...IT STILL APPEARS THAT
TEMPERATURES WILL ONLY FALL TO AROUND...OR SLIGHTLY ABOVE SEASONAL
NORMALS ON MONDAY AND TUESDAY...SINCE 850MB TEMPERATURES ARE ONLY
EXPECTED TO FALL ABOUT 4-5C FROM TODAY/S READINGS...WITH EVEN LESS
COOLING INDICATED AT 700 AND 500MB. SKIES ARE EXPECTED TO BE MOSTLY
SUNNY THROUGH THIS PERIOD AS PWATS FALL INTO THE 0.40-0.60 INCH
RANGE.

AS FAR AS THE FORECAST OF THE MIDDLE AND END OF NEXT WEEK IS
CONCERNED...THE GFS IS NOW COMING INTO BETTER AGREEMENT WITH THE
EURO ON THE IDEA OF A RETURN TO WARMER TEMPERATURES AS HIGH PRESSURE
REBUILDS BACK OVER THE REGION...BUT IT IS STILL NOT AS AGGRESSIVE AS
THE EURO IS ON THE MAGNITUDE OF THE UPCOMING WARMING TREND. WHILE
THE EURO CONTINUES TO PUSH HIGH TEMPERATURES BACK INTO THE LOW TO
MID 90S ACROSS THE LOWER DESERTS BY THE END OF NEXT WEEK...THE GFS
STILL HOLDS HIGHS BACK DOWN IN THE UPPER 80S DUE TO ITS FORECAST OF
SOMEWHAT LOWER 500MB HEIGHTS. IT THIS POINT...STILL GIVING THE NOD
TO THE BETTER-PERFORMING EURO...WITH MANY LOWER DESERT LOCATIONS
SEEING AT LEAST 90F ON FRIDAY AND SATURDAY UNDER MOSTLY SUNNY SKIES
WITH LIGHT WINDS.

&&

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

MOISTURE SPREADING NORTHWARD AHEAD OF A UPPER LOW CENTER THAT WILL
BE MOVING INLAND INTO CENTRAL/NORTHERN CA IS EXPECTED TO PRODUCE
SCATTERED-BROKEN MID-HIGH CLOUD LAYERS TODAY AND TONIGHT...WITH THE
LOWEST CIGS/GREATEST CLOUD COVERAGE TO BE ACROSS SOUTH-CENTRAL
ARIZONA...WITH EVEN AN OUTSIDE CHANCE OF A FEW SPRINKLES AT ONE...OR
MORE OF THE PHX AREA TERMINALS. THE AFOREMENTIONED UPPER LOW CENTER
IS ALSO EXPECTED TO ENHANCE TYPICAL AFTERNOON WESTERLY WINDS
TODAY...BUT SPEEDS ARE STILL EXPECTED TO REMAIN MAINLY AOB 10
KTS...WITH TYPICAL DIURNAL TRENDS RETURNING TONIGHT THROUGH SUNDAY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.CLIMATE...
RECORD HIGH TEMPERATURES

DATE         PHOENIX
----         -------
SAT OCT 25   96 IN 1990

&&

.FIRE WEATHER...
MONDAY THROUGH FRIDAY...
AFTER A BRIEF PERIOD OF NEAR-NORMAL TEMPERATURES ON MONDAY AND
TUESDAY...A WARMING TREND IS EXPECTED THROUGH THE REST OF NEXT WEEK
AS HIGH PRESSURE SLOWLY BUILDS BACK EASTWARD ACROSS THE
REGION...WITH MANY LOWER DESERT LOCATIONS SEEING HIGHS NEAR 90F BY
FRIDAY. MAINLY CLEAR SKIES AND LIGHT WINDS ARE EXPECTED THROUGH THE
FORECAST PERIOD...WITH AFTERNOON HUMIDITIES FALLING INTO THE MID
TEENS TO LOWER 20 PERCENT RANGE EACH DAY...WITH GOOD OVERNIGHT
RECOVERIES EXPECTED.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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

DISCUSSION...NOLTE
PREVIOUS DISCUSSION...PERCHA
AVIATION....PERCHA
FIRE WEATHER...PERCHA






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