Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 272218
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
320 PM MST THU NOV 27 2014


.SYNOPSIS...
A WARM AND DRY STRETCH OF WEATHER WILL AFFECT THE REGION THROUGH THE
UPCOMING WEEKEND UNDER HIGH PRESSURE ALOFT. HIGH TEMPERATURES WILL
BE THE WARMEST TODAY AND THEN SLOWLY COOL THROUGH EARLY NEXT WEEK
WHILE STILL REMAINING WELL ABOVE SEASONAL NORMALS. A LOW PRESSURE
SYSTEM IS EXPECTED TO AFFECT THE WESTERN STATES NEXT WEEK BRINGING A
SLIGHT CHANCE OF LIGHT SHOWERS TUESDAY INTO WEDNESDAY AND COOLER
TEMPERATURES.

&&

.DISCUSSION...
REST OF TODAY THROUGH SUNDAY...
THE REST OF THE WARMTH IN THE LOWER LEVELS CERTAINLY REACHED THE
SURFACE THIS AFTERNOON LIKELY AIDED BY THE PRESSURE GRADIENT ACROSS
MUCH OF ARIZONA. TEMPERATURES IN THE PHOENIX AREA HAVE ALREADY
CLIMBED WELL INTO THE 80S WITH SKY HARBOR TYING A RECORD FOR THE
DATE AT 86 DEGREES. FRIDAY WILL ONLY BE A LITTLE BIT COOLER AS THE
RIDGE STARTS TO WEAKEN AND WE HAVE SOME HIGH CLOUDS. THIS VERY
GRADUAL TREND CONTINUES THROUGH THE WEEKEND. ANTICIPATE MORE HIGH
CLOUDS ON SUNDAY AS A WEAKENED SHORT WAVE MOVES THROUGH THE
SOUTHWESTERLY FLOW ALOFT. MEANWHILE...A NEW LOW PRESSURE SYSTEM
TAKES SHAPE OFF THE WEST COAST BECOMING CENTERED WEST OF NORTHERN
CALIFORNIA BY SUNDAY AFTERNOON. ALSO BY THIS TIME...MOISTURE FROM
TROPICAL LATITUDES MOVES NORTHEASTWARD TOWARD THE BAJA PENINSULA.

MONDAY THROUGH THURSDAY...
DIFFERENCES IN THE MEDIUM RANGE MODELS BECOME MORE EVIDENT BY MONDAY
WITH THE GFS POSITIONING THE UPPER LOW CLOSER TO THE COAST THAN THE
ECMWF AND GEM. THE LATTER ALSO DEPICT A MORE CUTOFF SITUATION WITH
THE LOW. THE GFS ALSO HAS A MORE SUBSTANTIAL SUBTROPICAL JET AND
MOISTURE PLUME THAN THE THE ECMWF AND GEM. HOWEVER...THE LOW WEAKENS
AS IT MOVES INLAND. WHILE THE GFS HAS TRENDED DOWN SUBSTANTIALLY IN
ITS QPF THE PAST COUPLE DAYS...IT SEEMS TO HAVE SETTLED ON A WINDOW
OF TUESDAY AFTERNOON INTO WEDNESDAY FOR PRECIP OVER OUR AREA. THE
EXPERIMENTAL GFS-13KM ALSO SUPPORTS THIS. THE GEFS PROBABILITIES ARE
ALSO WELL INTO THE DOUBLE DIGITS. CONTRAST THAT WITH THE ECWMF AND
GEM WHICH KEEP AT LEAST SOME MEASURE OF RIDGING OVER US AS THE
SYSTEM DISSIPATES MOVING INTO THE PACIFIC NORTHWEST. THE ECENS MEAN
SUPPORTS THE IDEA OF WEAKENING AND SOME SORT OF RIDGING THOUGH A BIT
LESS THAN THE OPERATIONAL RUN. WITH THE PERSISTENCE OF THE GFS/GEFS
IN HOLDING ON TO POPS...LEFT THE EXTENDED AS IS. IF WE WIND UP
GETTING PRECIP NEXT WEEK IT IS NOT LOOKING LIKE IT WILL BE MUCH.
OTHERWISE THERE SHOULD AT LEAST BE SOME THICK CLOUD COVER AROUND
TUE/WED TO NUDGE HIGH TEMPS DOWNWARD. EXTENDED TEMPS MAY NEED SOME
UPWARD ADJUSTMENT IF LESS TROUGHING PANS OUT.


&&

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

UPPER LEVEL RIDGE OVER THE DESERT SOUTHWEST WILL ALLOW FOR MOSTLY
CLEAR SKIES AND LIGHT WINDS AT ALL TERMINALS THROUGH AT LEAST
FRIDAY. WINDS WILL FAVOR TYPICAL DIURNAL TRENDS AT ALL
SITES...GENERALLY 5 KTS OR LESS. REGARDING THE MULCH FIRE NEAR LUKE
AIR FORCE BASE...THIS SHOULD ONLY HAVE AN IMPACT ON SLANT VSBYS AS
WINDS SHOULD BE TOO LIGHT TO CARRY DENSE SMOKE TO ANY OF THE MAIN
PHOENIX TERMINALS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH MONDAY...RESULTING IN A
CONTINUED PERIOD OF MOSTLY CLEAR SKIES AND DRY CONDITIONS. SINGLE
DIGIT HUMIDITIES WITH FAIR OVERNIGHT RECOVERIES WILL BE COMMON
THROUGH THE WEEKEND. STILL MONITORING THE POTENTIAL FOR A LARGE
UPPER LEVEL STORM SYSTEM TO MOVE THROUGH THE AREA BY THE MIDDLE OF
NEXT WEEK. SOME MODEL DIFFERENCES HAVE BECOME MORE AND MORE EVIDENT
OVER THE PAST FEW RUNS...THUS CONFIDENCE IN EXACTLY HOW THE FORECAST
WILL EVOLVE NEXT WEEK IS LOW. STILL HANGING ONTO THE IDEA OF
INCREASING RAIN CHANCES AND ELEVATED HUMIDITIES BY
TUESDAY/WEDNESDAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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

DISCUSSION...AJ
AVIATION...LEINS
FIRE WEATHER...LEINS






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