Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 250301
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
800 PM MST FRI OCT 24 2014

.SYNOPSIS...
WELL ABOVE NORMAL TEMPERATURES WILL CONTINUE AS STRONG HIGH PRESSURE
BUILDS NORTHEASTWARD...WITH NEAR-RECORD HIGH TEMPERATURES POSSIBLE
THROUGH SATURDAY ACROSS SOUTH-CENTRAL ARIZONA. A COOLING TREND IS
THEN EXPECTED 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 EXPECTED
BY WEDNESDAY AS HIGH PRESSURE BECOMES REESTABLISHED ACROSS THE
WESTERN STATES.

&&

.DISCUSSION...
STRONG HIGH PRESSURE ALOFT PERSISTED ACROSS THE DESERT SOUTHWEST
EARLY THIS EVENING...AND H5 HEIGHTS WERE QUITE HIGH FOR THIS TIME OF
YEAR...IN EXCESS OF 590DM OVER SRN AZ PER THE 00Z PLOT DATA. IR
IMAGERY AT 8 PM SHOWED CLEAR SKIES ACROSS THE REGION. WITH AMPLE
SUNSHINE AND VERY WARM AIR ALOFT/HIGH HEIGHTS...HIGH TEMPS TODAY
CLIMBED ANOTHER FEW DEGREES AND INTO RECORD TERRITORY OVER THE
WARMER LOWER DESERTS. PHOENIX TIED A RECORD HIGH OF 96 DEGREES
TODAY...A MARK THAT WAS 9 DEGREES ABOVE SEASONAL NORMALS. THE RIDGE
IS FORECAST TO WEAKEN SLIGHTLY OVERNIGHT TONIGHT AS A WEAK LOW OFF
NRN BAJA STARTS TO MOVE INLAND INTO FAR SERN CA BY EARLY SATURDAY.
THE LOW WILL MOVE EAST ACROSS AZ AS A WEAK OPEN WAVE ON SATURDAY...
BRINGING AN INCREASE IN MID CLOUD TO THE SRN DESERTS AND LEADING TO
PARTLY OR EVEN MOSTLY CLOUDY SKIES IN THE PHOENIX AREA BY SATURDAY
AFTERNOON. LITTLE IF ANY PRECIP IS EXPECTED SATURDAY PARTLY DUE TO
EXPECTED VERY DRY AIR THAT WILL PERSIST IN THE LOWER ATMOSPHERE. FOR
THE REST OF TONIGHT EXPECT CLEAR OR MOSTLY CLEAR SKIES...VERY LIGHT
WINDS AND MILD OVERNIGHT TEMPS. NO UPDATES NEEDED TO THE FORECAST.

.PREVIOUS DISCUSSION...
UNSEASONABLY WARM TEMPERATURES CONTINUE TO AFFECT THE REGION THIS
AFTERNOON AS A STRONG 590DM UPPER RIDGE REMAINS POSITIONED OVER THE
AZ/NM BORDER. THE COMBINATION OF ANOMALOUSLY HIGH HEIGHTS...850MB
TEMPS AROUND 22-23C...AND SUNNY SKIES HAVE ALLOWED EARLY AFTERNOON
TEMPERATURES TO RISE INTO THE LOWER 90S AS OF 20Z. WITH A FEW MORE
HOURS OF WARMING...NEAR RECORD TEMPS LOOK LIKE A LOCK BEFORE THE DAY
IS OVER IN THE PHOENIX AREA. TODAY`S RECORD IS IN JEOPARDY IN
PHOENIX WHEREAS YUMA`S RECORD OF 105 WILL REMAIN UNTOUCHED.

NOT LOOKING AT ANY SIGNIFICANT CHANGES TO THE FORECAST ON THIS
SHIFT. THE RIDGE WILL SLIDE EAST TONIGHT AS A WEAK LOW JUST WEST OF
BAJA CALIFORNIA MOVES INTO SOUTHWEST ARIZONA SATURDAY AFTERNOON. THE
MOST RECENT RUNS OF THE GFS...EURO...AND ESPECIALLY THE NAM ARE
INDICATING QUITE A BIT OF MID LEVEL MOISTURE AND BROAD ISENTROPIC
ASCENT ON THE 310-320K SURFACES ALONG WITH MODEST MOISTURE
CONVERGENCE BETWEEN 12Z SAT - 00Z SUN. POINT FORECAST SOUNDINGS FOR
TOMORROW STILL REVEAL A CONSIDERABLE AMOUNT OF DRY AIR IN THE LOWER
LEVELS WITH NEAR SATURATION BETWEEN 700-500MB TOMORROW
AFTERNOON...ESPECIALLY ACROSS SW AZ. WHILE IT DOESN`T LOOK
IMPRESSIVE IN THE LEAST ON SATELLITE AT THE MOMENT...CLOUD COVER
SHOULD FILL IN AS THE LOW MOVES THROUGH THE AREA. I BUMPED UP CLOUD
COVER AND ALSO NUDGED POPS CLOSER TO 10 PERCENT ESPECIALLY ACROSS
WESTERN MARICOPA COUNTY TOMORROW AFTERNOON/EVENING.

THE UPPER LOW WILL DRIFT THROUGH THE REGION SATURDAY NIGHT AS
ANOTHER LOW MOVES THROUGH CALIFORNIA INTO UTAH ON SUNDAY. THIS
SECONDARY TROUGH COULD ALSO KICK OFF A FEW ISOLATED SHOWERS ACROSS
NORTHERN ARIZONA BUT OUR PRECIP CHANCES ACROSS THE DESERTS LOOK SLIM
TO NIL. WILL MAINTAIN LOWER SINGLE DIGIT POPS EAST OF PHOENIX FOR
SUNDAY EVENING...THEN BEGIN A DRYING TREND SUNDAY NIGHT INTO MONDAY
AS A FLAT RIDGE BECOMES ESTABLISHED ACROSS THE AREA.

ON THE SUBJECT OF TEMPERATURES...SHOULD SEE SLIGHTLY COOLER
TEMPERATURES ON SATURDAY COMPARED TO TODAY GIVEN LOWER HEIGHTS AND
MORE CLOUD COVER. HARD TO CALL IT A COOL-DOWN BUT DESERT TEMPS
SHOULD BE ABOUT 2-3 DEGREES COOLER. STILL IN THE LOW/MID 90S.
DISCERNIBLE COOLING TREND WILL BEGIN SUNDAY AS THE AFOREMENTIONED
TROUGH MOVES EASTWARD INTO THE ROCKIES. COOLEST DAY WILL LIKELY BE
MONDAY AS A SOUTHERN STREAM PACIFIC TROUGH AMPLIFIES ACROSS THE
REGION. HOWEVER...TEMPERATURES WILL ONLY DROP TO NEAR OR EVEN
SLIGHTLY ABOVE NORMAL.

WARMING TREND IS LIKELY BEGINNING TUESDAY-WEDNESDAY. DISTINCT
DIFFERENCE IN THE OPERATIONAL GFS/ECMWF IS APPARENT BY MIDWEEK
ACROSS THE WESTERN CONUS. LATEST ECMWF IS FAVORED GIVEN ITS STRONG
PERFORMANCE OVER THE PAST TWO WEEKS AND RELATIVELY LOW ENSEMBLE
SPREAD. CONSEQUENTLY...FORECAST TEMPERATURES HAVE BEEN INCREASED
OWING TO ANOTHER ANOMALOUSLY STRONG RIDGE ACROSS THE WESTERN STATES.
POPS REMAIN NIL THROUGH ALL OF NEXT WEEK.

&&

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

MOSTLY CLEAR SKIES WILL PREVAIL AT ALL TAF SITES THROUGH SATURDAY
MORNING. THERE WILL BE AN INCREASE IN CLOUD COVER STARTING IN THE
EARLY TO MID MORNING SATURDAY AS MOISTURE IS ADVECTED THROUGH
ARIZONA...COULD EVEN BE A FEW SPRINKLES IN SOME SPOTS BUT NOT ENOUGH
COVERAGE/CONFIDENCE TO INCLUDE IN ANY TAFS. IMPACTS WOULD BE MINIMAL
AS CIGS SHOULD REMAIN WELL ABOVE CRITICAL THRESHOLDS. MOST BASES
AFFECTING THE CENTRAL AZ DESERTS SATURDAY WILL BE AOA 8K FEET. AS
FOR WINDS...WINDS WILL BE LIGHT AND WILL FAVOR THE TYPICAL DIURNAL
DIRECTIONS THROUGH SATURDAY EVENING.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.CLIMATE...
RECORD HIGH TEMPERATURES

DATE         PHOENIX
----         -------
FRI OCT 24   96 IN 2007
SAT OCT 25   96 IN 1990

&&

.FIRE WEATHER...
MONDAY THROUGH FRIDAY...
RIDGING WILL RETURN TO THE AREA NEXT WEEK WITH GRADUALLY INCREASING
TEMPERATURES THROUGHOUT THE WEEK. NO MAJOR WIND EVENTS ARE EXPECTED
DURING THIS PERIOD AS ANY TROUGHS WILL BE DISPLACED WELL NORTH OF
THE REGION. AFTERNOON HUMIDITIES WILL FALL INTO THE UPPER 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...CB
PREVIOUS DISCUSSION...LEINS/HIRSCH
CLIMATE...MO/HIRSCH
AVIATION...CB/LEINS
FIRE WEATHER...LEINS








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