Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 020911
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
211 AM MST THU OCT 2 2014

.SYNOPSIS...
A PERSISTENT HIGH PRESSURE RIDGE BUILDING INTO THE REGION WILL LEAD
TO A WARMING TREND FOR THE REST OF THE WEEK WITH ABOVE NORMAL
TEMPERATURES PEAKING ON SATURDAY WITH VERY LITTLE CHANGE IN
TEMPERATURES FOR SUNDAY. WEAKENING HIGH PRESSURE NEXT WEEK WILL
RESULT IN A VERY SLOW COOLING TREND TOWARDS MORE NORMAL READINGS FOR
EARLY OCTOBER.

&&

.DISCUSSION...
CLEAR SKIES...MILD TEMPERATURES AND NORTH TO NORTHEASTERLY BREEZES
CONTINUE ACROSS THE FORECAST AREA THIS MORNING AS THE LATEST
PASSING SHORTWAVE DISTURBANCE TREKS TO OUR EAST INTO NM/CO/WY.
LINGERING THERMAL GRADIENT FROM THE WEAK FRONT INTRUSION INTO
NORTHERN AZ AND BUILDING SURFACE HIGH PRESSURE TO OUR NORTH OVER THE
GREAT BASIN WILL KEEP WIND HEADINGS ORIENTED GENERALLY FROM THE
N-NE AREAWIDE...WITH ELEVATED BREEZES AND GUSTS DOWN ALONG THE
COLORADO RIVER AND OVER SOME OF THE MARICOPA/SOUTHERN GILA HIGH
TERRAIN/GAPS. LOCAL SFC WINDS 10-20 MPH ARE LIKELY WITH PERIODS OF
ENHANCED GUSTINESS AT LEAST FOR THE REMAINDER OF THE WORK WEEK AND
SLOWLY TAPERING OFF BY THE WEEKEND.

FORECAST SOUNDINGS INDICATE SUBTLE CHANGES IN THE 850MB-SFC
LAYER...WITH THE SOUTH-CENTRAL DESERTS SEEING VERY SLIGHT WARMING AND
POINT ALONG AND WEST OF THE CO RIVER VALLEY PROGGED FOR SUBTLE
COOLING. WITH BREEZY CONDITIONS EXPECTED TO REMAIN ALONG THE CO RIVER
VALLEY OVERNIGHT KEEPING CONDITIONS A BIT MORE MIXED AND ON THE WARM
SIDE...ONLY MINOR CHANGES IN AFTN TEMPERATURES SHOULD BE OBSERVED
COMPARED TO THOSE ON WEDNESDAY. THE SOUTH-CENTRAL AZ DESERTS MAY SEE
A DEGREE OR TWO OF WARMING IN OUR READINGS...COMING IN AT OR NEAR
NORMAL.

IN THE WAKE OF THIS LATEST SHORTWAVE AND WEAK FROPA/CAA...STRONG
PACIFIC RIDING WILL BUILD ACROSS THE WEST. UPPER RIDGE AXIS WILL
REMAIN MOSTLY TO OUR WEST...KEEPING DRY NORTHWEST FLOW MOVING THROUGH
THE AREA FOR THE MAJORITY OF THE COMING WEEKEND. 1000-500MB
THICKNESSES WILL RAPIDLY REBOUND AND PEAK LATE FRIDAY-SATURDAY IN THE
581-583DM RANGE. TEMPERATURES STILL EXPECTED TO PEAK AREAWIDE
SATURDAY WITH EVEN THE SOUTH-CENTRAL DESERT LOCALES...INCLUDING
PHOENIX...FLIRTING WITH THE CENTURY MARK ALONG WITH THE ALREADY WARM
WESTERN AZ/SOUTHEAST CA DESERTS. AVERAGE LAST 100F HIGH TEMPERATURE
OVER THE LAST NORMAL PERIOD OF 1981-2010 IN PHOENIX HAS BEEN OCT
3RD AND OCT 5TH FOR YUMA.

BY EARLY NEXT WEEK...HIGH PRESSURE WILL BEGIN TO WEAKEN AND THE UPPER
FLOW BECOMES MORE ZONAL AS THE PACIFIC STORM TRACK APPROACHES AND
BEGINS TO DIP INTO THE WEST COAST. THE COMBINATION OF LOWER
HEIGHTS...POTENTIAL FOR INCREASING CLOUDS AND A RETURN OF SLIGHTLY
ELEVATED HUMIDITIES WILL SUPPORT A SLOW COOLING TREND OF AFTERNOON
TEMPERATURES...KNOCKING OFF A DEGREE OR TWO EACH AFTERNOON THROUGH
THE REST OF THE WEEK.

&&

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

A WEAK DRY COLD FRONT WILL SLOWLY SAG SOUTHWARD INTO SOUTHERN
ARIZONA AND FAR SOUTHEAST CALIFORNIA TONIGHT AND THURSDAY.
HOWEVER...STRENGTHENING HIGH PRESSURE TO THE NORTH WILL LEAD TO A
TIGHTENING PRESSURE GRADIENT FAVORING NORTH AND NORTHEAST
WINDS...MOST NOTICEABLY AFTER 16Z. SURFACE WIND WILL BE STRONGEST
OVER THE LOWER COLORADO RIVER VALLEY AND NEAR FOOTHILL LOCATIONS ON
THE EDGES OF THE PHOENIX METRO AREA WITH GUSTS OF 20-25 KTS. LOWER
LEVEL WINDS ABOVE THE INVERSION WILL STRENGTHEN TO 20-25 KTS AFTER
08Z AND WEAKEN CONSIDERABLY AFTER 14Z. LOCATIONS WITH CALM SURFACE
WINDS OR WINDS WITH A SOUTHERLY COMPONENT BETWEEN 09Z-13Z MIGHT
EXPERIENCE SOME LOW LEVEL WIND SHEAR. CONFIDENCE TOO LOW IN STRENGTH
OF NEAR SURFACE WINDS TO REFLECT LLWS IN THE TAFS. OTHERWISE...CLEAR
SKIES.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
A RIDGE OF HIGH PRESSURE WILL BE THE PREDOMINANT WEATHER FEATURE
ACROSS THE SOUTHWEST THROUGH THE MIDDLE NEXT WEEK. DRIER THAN NORMAL
CONDITIONS WILL PREVAIL AND NO PRECIPITATION IS EXPECTED.
TEMPERATURES WILL BE ABOVE AVERAGE THROUGH SUNDAY...FOLLOWED BY A
SLIGHT COOLING TREND EARLY NEXT WEEK AS HIGH PRESSURE WEAKENS AND
MEAGER MOISTURE RETURNS TO THE AREA. MINIMUM HUMIDITIES WILL FALL
INTO THE SINGLE DIGITS AND TEENS OVER THE WEEKEND...BEFORE TRENDING
UP VERY SLIGHTLY NEXT WEEK. WINDS WILL REMAIN UNUSUALLY LIGHT...WITH
ONLY OCCASIONAL UPSLOPE GUSTINESS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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

DISCUSSION...NOLTE
AVIATION...AJ
FIRE WEATHER...MO/HIRSCH




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