Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 282025
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
125 PM MST FRI NOV 28 2014

.SYNOPSIS...
UNSEASONABLY WARM AND DRY WEATHER WILL PREVAIL ACROSS THE REGION
THROUGH THE WEEKEND UNDER STRONG HIGH PRESSURE. WITH MOSTLY SUNNY
SKIES...TEMPERATURES WILL ONLY SLOWLY COOL THROUGH EARLY NEXT WEEK.
A LOW PRESSURE SYSTEM WILL AFFECT THE WESTERN UNITED STATES NEXT
WEEK WITH A FEW LIGHT SHOWERS POTENTIALLY AFFECTING PARTS OF
SOUTHEAST CALIFORNIA AND CENTRAL ARIZONA TUESDAY INTO WEDNESDAY.

&&

.DISCUSSION...
STRONG UPPER LEVEL HIGH PRESSURE RIDGE CONTINUES IN PLACE ACROSS THE
DESERT SOUTHWEST...WITH H5 HEIGHTS RUNNING 585DM ACROSS THE CENTRAL
DESERTS. GIVEN VERY DRY AIR IN PLACE AND FULL SUNSHINE...HIGH TEMPS
TODAY WILL AGAIN RUN 10 DEGREES OR MORE ABOVE SEASONAL NORMALS AND
MAY APPROACH RECORDS IN SOME LOCALES. FOR TONIGHT THROUGH THE
WEEKEND THE RIDGE WILL REMAIN MORE OR LESS IN PLACE...BUT WILL
SLOWLY WEAKEN WITH TIME AS SHORT WAVE ENERGY MOVES OUT OF THE ERN
PACIFIC AND RIDES OVER THE TOP OF THE RIDGE. ONE SUCH SHORT WAVE
QUICKLY RACES EAST ACROSS THE RIDGE SUNDAY...BRINGING A BATCH OF
THICKER HIGH CLOUDS FOR PARTLY SUNNY SKIES. TEMP TRENDS OVER THE
WEEKEND SHOW A STEADY FALLOFF WITH HIGHS RETREATING INTO THE MID 70S
BY SUNDAY...STILL 5 DEGREES OR MORE ABOVE CLIMO.

12Z MEDIUM RANGE MODELS HAVE CONTINUED THE TREND OF DEEPENING A WAVE
EMANATING OVER THE ALEUTIAN CHAIN...INTO A CUTOFF FEATURE SPINNING
WELL WEST OF THE CALIFORNIA COAST THROUGH THE MIDDLE OF NEXT WEEK.
SUBJECTIVELY...DPROG/DT TRENDS APPEAR TO HAVE THE CNTRL CIRCULATION
EVEN FURTHER TO THE WEST WHILE THE SUBTROPICAL MOISTURE TAP GETS
PULLED MORE TO THE NORTH AND WEST TOWARDS THE LA BASIN VERSUS THE
LOCAL FORECAST AREA. THE KEY PLAYERS APPEAR TO LIE IN THE NORTHERN
STREAM WHERE WAVE ENERGY FIRST BYPASSES THE CUTOFF IN SWRN
CANADA...AND THEN UPSTREAM ENERGY THROUGH THE NORTHERN PACIFIC IS
INSUFFICIENT TO ACT AS AN EFFECTIVE KICKER. 00Z NAEFS ENSEMBLE
OUTPUT SHOWS FAR LESS MEMBER DISPERSION THAN THE PRIOR 12Z
ITERATIONS...WITH THE MEAN SOLUTION NOW NEARLY MIRRORING THE
OPERATIONAL GFS/GEM/ECMWF (YIELDING INCREASINGLY BETTER FORECAST
CONFIDENCE).

GIVEN THESE AFOREMENTIONED MODEL TRENDS...HAVE MADE SOME NOTABLE
INCREASES TO HIGH TEMPERATURES THROUGH THE MID/END OF WEEK PERIOD AS
DOWNSTREAM SHORTWAVE RIDGING EAST OF THE CUTOFF SHOULD MAINTAIN
LOCAL H5 HEIGHTS SOMEWHERE IN A 576-582DM RANGE. DESPITE THE
POTENTIAL FOR OCCASIONAL THICKER CIRRUS COVER SPILLING EAST FROM THE
PACIFIC...LOW LEVEL THERMAL FIELDS REMAINS QUITE WARM AND WOULD
ARGUE FOR TEMPERATURES IN THE NEAR TO ABOVE NORMAL RANGE. HAVE ALSO
SELECTIVELY BUMPED LOW TEMPERATURES UP ON MORNINGS MOST LIKELY TO
EXPERIENCE THE THICKER INSULATING CLOUD COVER.

DESPITE THE MAJORITY OF ENERGY REMAINING WELL REMOVED FROM THE
FORECAST AREA...THERE STILL IS ADEQUATE EVIDENCE OF DEEPER
SUBTROPICAL MOISTURE SEEPING INTO THE FORECAST AREA. THIS
ATMOSPHERIC RIVER WILL BE PULLED NORTH THROUGH A SOUTHERN EXTENSION
OF A SUBTROPICAL JET...THOUGH THE BULK OF THE HIGH QUALITY MOISTURE
WILL BE WRUNG OUT IN THE OROGRAPHIC ASCENT TO THE WEST OF THE CWA.
HOWEVER...THE MAGNITUDE AND DEPTH OF THIS MOISTURE BAND SHOULD BE
LARGE ENOUGH TO ALLOW RESIDUAL SHOWERS TO SURVIVE INTO PARTS OF THE
FORECAST AREA TUESDAY AND WEDNESDAY...ALBEIT LIKELY WIDELY SCATTERED
IN NATURE AND NOT OVERWHELMING IN QUANTITY. POPS MAY BE REFINED
SOMEWHAT IN THE FUTURE...HOWEVER WITHOUT A SINGLE STRONGLY FORCED
FEATURE TO ACT ON THE MOISTURE FEED...THIS PATTERN GENERALLY ARGUES
FOR A FEW LIGHT SHOWERS OVER SEVERAL PERIODS WITH LIMITED
PREDICTABILITY.

&&

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

HIGH PRESSURE TO REMAIN OVERHEAD...KEEPING SKIES GNLY CLEAR AND SFC
WINDS LIGHT. EXPECT TYPICAL DIURNAL TRENDS IN THE AM WITH VARIABLE
AFTN HEADINGS GNLY LESS THAN 6KTS. VSBY ISSUES HAVE BEEN
PERIODICALLY POPPING UP FOR KIWA...MOST LIKELY DUE TO RESIDENTIAL
FIREPLACE SMOKE. CERTAINLY POSSIBLE THAT SMOKE IMPACTS MAY
OCCASIONALLY IMPACT FIELD VSBYS...CIGS OR SLANT VSBYS FOR BRIEF
PERIODS BEFORE MIXING OCCURS LATER INTO THE DAY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SUNDAY THROUGH THURSDAY...
LITTLE CHANGE IN THE WEATHER PATTERN THROUGH THE EARLY WEEK AS HIGH
PRESSURE REMAINS THE DOMINANT FEATURE OVER THE SOUTHWEST. AS A
RESULT...DRY AND WARM CONDITIONS WILL PERSIST UNDER MOSTLY CLEAR
SKIES. BY TUESDAY...A LARGE STORM SYSTEM WILL BE DEVELOPING OVER THE
PACIFIC AND CA COAST...SPREADING INCREASING CLOUDS AND PRECIPITATION
CHANCES INTO CA BY LATE TUESDAY. SLIGHT DIFFERENCES IN THE TIMING
AND OVERALL AMOUNTS OF PRECIPITATION STILL REMAIN WITHIN MODEL
FORECASTS. BUT OVERALL...SLIGHT PRECIP CHANCES WILL EXPAND FROM WEST
TO EAST ACROSS THE FIRE ZONES TUESDAY THROUGH WEDNESDAY. LOOK FOR
COOLER TEMPERATURES AND INCREASING DEWPOINTS WHICH WILL HELP
AFTERNOON HUMIDITIES FALL ONLY INTO THE 20 TO 30 PERCENT
RANGE...POSSIBLY RICHER IN THE HIGHER TERRAIN LOCALES. LOOK FOR
PRECIP CHANCES TO DISSIPATE HEADING INTO THURSDAY WITH ZONAL
SOUTHWEST UPPER LEVEL FLOW REMAINING OVER THE AREA.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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

DISCUSSION...CB/MO
AVIATION...NOLTE
FIRE WEATHER...NOLTE














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