101 
FXUS65 KPSR 122121
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
220 PM MST TUE APR 12 2016

.SYNOPSIS...
MUCH WARMER AND DRIER WEATHER WILL RETURN TO THE REGION WEDNESDAY
AND THURSDAY AS HIGH PRESSURE SETTLES OVER THE AREA. ANOTHER PACIFIC
WEATHER SYSTEM WILL MOVE THROUGH THE WESTERN UNITED STATES FRIDAY
AND SATURDAY BRINGING WINDY CONDITIONS AND MUCH COOLER WEATHER BACK
TO THE REGION.

&&

.DISCUSSION...
A NICELY DEFINED COLD CORE SHORTWAVE HAS NOW EJECTED INTO SOUTH
CENTRAL NEW MEXICO WITH HIGHER HEIGHTS AND SUBSIDENCE FEEDING INTO
THE LEFT REAR JET CORE BUILDING INTO SERN CALIFORNIA/SWRN ARIZONA.
THE COMBINATION OF WEAK DEFORMATION...MODESTLY STEEP MIDLEVEL LAPSE
RATES...AND MINOR INSTABILITY (MUCAPE NEARING 500 J/KG) HAVE
SUPPORTED NUMEROUS SHOWERS AND EMBEDDED THUNDERSTORMS ALONG THE
MOGOLLON RIM AND WHITE MOUNTAINS. WHILE STEERING FLOW AND
INSTABILITY PARAMETERS MAY SUPPORT SHOWERS/STORMS PROPAGATING INTO
PARTS OF SRN GILA COUNTY...VERTICAL AND HORIZONTAL MIXING OF DRY
AIR AT LOWER ELEVATIONS ARE CREATING AN ENVIRONMENT MORE HOSTILE
TOWARDS MAINTAINING CONVECTION DIRECTED SOUTH DOWN THE I-17 CORRIDOR.
A BLEND OF RECENT HRRR ITERATIONS AND HIGH RESOLUTION CONVECTIVE
MODELS MOST ACCURATELY DEPICTS THIS EVOLUTION KEEPING CONVECTIVE
ELEMENTS PRIMARILY OVER HIGHER TERRAIN FEATURES INTO EARLY EVENING
BEFORE DISSIPATING ACTIVITY WITH LOSS OF DAYTIME HEATING. 

DAMPENED WEAK RIDGING/QUASI-ZONAL FLOW WILL BECOME ESTABLISHED OVER
SWRN CONUS WEDNESDAY AND THURSDAY WITH H5 HEIGHTS STAY IN A 573-
579DM RANGE. FULL INSOLATION WILL CREATE DEEP BOUNDARY LAYER MIXING
WHILE MODEL H8 TEMPERATURES INCREASE TOWARDS 16-19C RANGE BY
THURSDAY AFTERNOON. MODEL SPREAD HAS DECREASED SOMEWHAT WITH RECENT
MODEL OUTPUT YIELDING BETTER CONFIDENCE IN BEST PERFORMING GUIDANCE
PEAKING AFTERNOON TEMPERATURES IN THE MIDDLE 80S TO LOWER 90S.

FRIDAY AND SATURDAY...
A COLDER PACIFIC WEATHER SYSTEM WILL DESCEND FROM THE PACIFIC
NORTHWEST INTO THE REGION FRIDAY AND FRIDAY NIGHT. DIFFERENCES AMONG
ALL OPERATIONAL AND ENSEMBLE MEMBERS ABOUND WITH LITTLE RUN TO RUN
CONSISTENCY...MUCH LESS AGREEMENT ON TRACK AND INTENSITY. ONE
MEASURE OF CONSISTENCY IS THE CONTINENTAL TRACK OF THE LOW DROPPING
SOUTH OVER GREAT BASIN/ROCKIES...WHICH CONTINUES TO FAVOR SHOWER
CHANCES DURING THE DAYLIGHT HOURS OVER HIGHER TERRAIN WITH MUCH OF
THE LOWER ELEVATION COMMUNITIES CLEARING. 

THE LARGEST IMPACT FROM THIS WEATHER SYSTEM WILL ALMOST CERTAINLY BE
STRONGER WINDS THROUGH SE CALIFORNIA/WRN ARIZONA. OPERATIONAL GFS
WIND ANOMALIES ARE TOWARDS THE STRONGER END OF THE MODEL SPREAD
ENVELOPE (NEAR 40KT AT H8)...HOWEVER EVEN THE NAEFS AVERAGE V-WIND
H8-H7 ANOMALIES LIE TOWARDS THE SEASONALLY EXTREME THRESHOLD.
THUS...THERE IS SUFFICIENT SIGNAL TO START MENTIONING BLOWING DUST
POTENTIAL FRIDAY AFTERNOON IN ADDITION TO ELEVATED FIRE DANGER.
WHILE TAKING A BLENDED APPROACH TO THE EXTENDED FORECAST...COOLER
TEMPERATURES ALSO LOOK TO BE EXTREMELY LIKELY...BUT MOISTURE
CONTINUES TO LOOK VERY LIMITED WITH EACH MODEL RUN SO HAVE TRIMMED
PRECIPITATION CHANCES BACK TOWARDS MAINLY HIGHER TERRAIN AREAS NORTH
AND EAST OF THE PHOENIX METRO.

SUNDAY INTO EARLY NEXT WEEK...
SUBSTANTIAL ENSEMBLE SPREAD EXISTS DURING THIS PERIOD WITH SOME
MEMBERS MORE RAPIDLY EJECTING NEGATIVE HEIGHT ANOMALIES INTO THE
PLAINS...WHILE OTHERS LINGER A CLOSED LOW NEAR THE LOCAL REGION
THROUGH EARLY NEXT WEEK. THUS...FORECAST CONFIDENCE DECREASES
SOMEWHAT DURING THIS TIME FRAME ALBEIT WITH NUMERICAL GUIDANCE NOT
DISPLAYING THE AMOUNT OF SPREAD THAT OTHERWISE WOULD BE ANTICIPATED. 

&&

.AVIATION... 
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
DRIER AIR FILTERING IN FROM THE WEST TO PRETTY MUCH CLEAR ALL
REMAINING CLOUDS BY LATE THIS EVENING...WITH CLEAR SKIES PREVAILING
THROUGH THE REST OF THE TAF PERIOD. WINDS TO REMAIN ON THE LIGHT
SIDE...MAINLY 10 KTS OR LESS. WIND DIRECTIONS TO MAINLY FOLLOW
TYPICAL DIURNAL TRENDS...BUT WITH TYPICAL WESTERLY WINDS PERSISTING
LATER INTO THE EVENING THEN USUAL.

SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
MOSTLY CLEAR SKIES AND LIGHT DIURNALLY-DRIVEN WINDS TO PREVAIL
THROUGH THE TAF PERIOD.

&&

.FIRE WEATHER... 
THURSDAY THROUGH MONDAY...
ABOVE NORMAL TEMPERATURES WILL PERSIST THURSDAY ALONG WITH A SLIGHT
DRYING TREND. THEREAFTER...A STRONG LOW PRESSURE SYSTEM WILL DROP
DOWN OUT OF THE NORTHERN ROCKIES TOWARDS THE FOUR CORNERS. BIGGEST
IMPACT FROM THIS SYSTEM WILL BE AN INCREASE IN WIND. VERY BREEZY TO
WINDY CONDITIONS ARE EXPECTED EACH AFTERNOON BEGINNING THURSDAY AND
CONTINUING THROUGH SATURDAY. ELEVATED FIRE DANGER WILL BE POSSIBLE
FOR A FEW HOURS EACH AFTERNOON THROUGH SATURDAY...PARTICULARLY
ACROSS THE HIGHER TERRAIN OF SOUTHWESTERN ARIZONA AND SOUTHEASTERN
CALIFORNIA. ALTHOUGH THE DRY AIR WILL PERSIST SUNDAY AND INTO NEXT
MONDAY...THE THREAT FOR HAZARDOUS FIRE WEATHER CONDITIONS WILL
DECREASE AS THE LOW PRESSURE SYSTEM MOVES EASTWARD AND WINDS SUBSIDE.

&&

.SPOTTER INFORMATION STATEMENT... 
SPOTTER ACTIVATION IS NOT EXPECTED.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.

&&

$$

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PREVIOUS DISCUSSION...MO/MEYERS
AVIATION...PERCHA
FIRE WEATHER...HIRSCH