516
FXUS65 KPSR 022358
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
458 PM MST FRI JAN 2 2026
.UPDATE..UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- DRY WEATHER WILL RETURN TO THE REGION THROUGH THE WEEKEND WITH
TEMPERATURES HOVERING A FEW DEGREES ABOVE NORMAL.
- AN UNSETTLED PATTERN IS FORECAST TO SET UP OVER THE DESERT SOUTHWEST
BY THE MIDDLE OF NEXT WEEK, RESULTING IN MUCH COOLER AND WETTER
CONDITIONS.
SHORT TERM /TODAY THROUGH SATURDAY/
LATEST MID-LVL WV IMAGERY AND 500 MB STREAMLINE ANALYSIS REVEALS A
TROUGH OF LOW PRESSURE SITUATED SEVERAL HUNDRED MILES OFF THE COAST
OF CALIFORNIA WHILE SHORTWAVE RIDGING IS NOW BUILDING INLAND OVER
THE DESERT SOUTHWEST. THE UPPER-LVL RIDGE WILL BE THE PREDOMINANT
FEATURE OVER THE REGION THROUGH THIS WEEKEND, WHICH WILL PROMOTE DRY
AND TRANQUIL WEATHER. EARLY MORNING FOG HAS BURNED OFF, LEAVING
PARTLY CLOUDY SKIES ACROSS THE LOWER DESERTS. SKIES MAY NOT FULLY
CLEAR UNTIL LATE THIS AFTERNOON AS ABUNDANT MOISTURE REMAINS TRAPPED
IN THE BOUNDARY LAYER. SINCE THIS LOW-LVL MOISTURE WILL BE SLOW TO
ERODE, WE COULD SEE ANOTHER ROUND OF PATCHY FOG OVERNIGHT,
PARTICULARLY IN THE SAME LOCATIONS AS THIS MORNING INCLUDING THE
LOWER COLORADO AND GILA RIVER VALLEYS. THE MAIN CAVEAT WILL BE
ABUNDANT HIGH CLOUDS WHICH WILL BEGIN TO OVERSPREAD WESTERN PORTIONS
OF THE FORECAST AREA EARLY SATURDAY MORNING WHICH COULD INHIBIT FOG
DEVELOPMENT. TEMPERATURES ARE EXPECTED TO REMAIN AROUND 5 TO 7
DEGREES ABOVE NORMAL THROUGH SATURDAY WITH HIGHS AGAIN RANGING FROM
THE MID 60S TO LOWER 70S AND LOWS MAINLY IN THE UPPER 40S TO LOW
50S ACROSS THE LOWER DESERTS.
LONG TERM /SUNDAY THROUGH THURSDAY/
THE HEMISPHERIC LONGWAVE PATTERN WILL ONLY BE SLOW TO ADVANCE
THROUGH THE MIDDLE OF NEXT WEEK OWING TO STUBBORN DOWNSTREAM NORTH
ATLANTIC BLOCKING. ENSEMBLE MEMBERSHIP REMAINS IN EXCELLENT
AGREEMENT INDICATING LOW AMPLITUDE RIDGING PREVAIL ACROSS THE SW AND
CENTRAL CONUS WHILE EAST PACIFIC TROUGHING ONLY SLOWLY EDGES TOWARDS
THE WEST COAST. A SERIES OF LEAD SHORTWAVES WILL ALMOST CERTAINLY
EJECT FROM THE LONGWAVE TROUGH POSITION EARLY IN THE WEEK, HOWEVER
ONLY DE-AMPLIFY AND LIFT INTO THE GREAT BASIN BRINGING A COLD FRONT
ONSHORE INTO CNTRL/SRN CALIFORNIA, BUT NO FURTHER. A MORE DEFINED
COLD CORE SHOULD DROP TOWARDS A DEVELOPING WEAKNESS IN THE MIDLEVEL
HEIGHT FIELD INTO THE SOUTHWEST DURING THE MIDDLE OF THE WEEK. WHILE
A HANDFUL OF ENSEMBLE MEMBERS STILL DEPICT AN EARLIER ARRIVAL
(PARTICULARLY IN THE CMC SUITE), THE TREND AMONG THE PREPONDERANCE
OF MEMBERSHIP SUGGESTS A SLOWER PV PASSAGE SOMETIME IN THE WEDNESDAY
TIME FRAME.
WHILE LOW LEVEL MOISTURE WILL NOT COMPLETELY BE ELIMINATED EARLY IN
THE WEEK, WARMER AIR ALOFT AND RAIN SHADOW EFFECTS FROM PREVAILING
W/SW FLOW WILL LIMIT ANY INLAND DEEP SATURATION AND RAIN CHANCES. AS
USUAL, NBM POP BIAS IN SE CALIFORNIA BECOMES EVIDENT BLEEDING HIGHER
CHANCES OFF MOUNTAINS TO THE WEST, AND HAVE TRIMMED VALUES BACK
APPROPRIATELY. IT WOULD NOT BE UNCOMMON FOR THICKER CIRRUS DECKS TO
IMPACT DAILY HIGHS AT SOME POINT EARLY IN THE WEEK, HOWEVER
NUMERICAL GUIDANCE REMAINS CONSISTENT IN ADVERTISING READINGS A FEW
DEGREES ABOVE THE DAILY NORMALS INTO THE MIDDLE OF THE WEEK.
UNCERTAINTY IN THE PRECISE TRACK AND INTENSITY OF THE PV ANOMALY
MOVING INTO THE REGION MIDWEEK LIMITS A LARGER POP MENTION IN THE
OFFICIAL FORECAST WITH THE MAJORITY OF MODEL OUTPUT LEANING TOWARDS
ANOTHER WEAKENING WAVE AND LIMITED ASCENT/PRECIPITATION POTENTIAL.
AVIATION
UPDATED AT 1800Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
VFR CONDITIONS AND VERY LIGHT WINDS ARE EXPECTED THROUGH THE TAF
PERIOD. LOWER CLOUDS CLEAR THIS EVENING AND WILL LIKELY REMAIN
CLEAR THROUGH THE TAF PERIOD. THERE WILL BE AN INCREASE IN HIGH
CLOUDS THROUGH THE PERIOD. FOG IS LIKELY TO FORM SOUTH OF PHOENIX
SATURDAY MORNING BETWEEN 11-17Z, BUT IS NOT EXPECTED TO SPREAD TO
ANY OF THE TERMINALS. WINDS WILL FAVOR A LIGHT EAST THROUGH THE
OVERNIGHT AND MORNING HOURS FOLLOWED BY A LIGHT WEST SATURDAY
AFTERNOON, WITH SPEEDS AT OR BELOW 6 KTS.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
POTENTIAL REDUCTIONS IN VISIBILITY IN FOG SATURDAY MORNING WILL BE
THE PRIMARY AVIATION WEATHER CONCERN THROUGH THE TAF PERIOD. ODDS
OF FOG AT THE TERMINALS ARE LOWER THAN FRIDAY MORNING, WITH MID
AND HIGH CLOUDS INCREASING OVER THE AREA TONIGHT. WIND DIRECTIONS
WILL PRIMARILY BE NW'RLY THROUGH THE EVENING AND INTO THE
OVERNIGHT HOURS, BUT GO MORE W/SW OVERNIGHT (KIPL)/TOMORROW
MORNING (KBLH). HOWEVER, WITH THE LIGHT WINDS, EXTENDED PERIOD OF
LIGHT AND VARIABLE TO CALM CONDITIONS ARE EXPECTED.
FIRE WEATHER
MOISTURE LEVELS WILL REMAIN ELEVATED THROUGH MUCH OF NEXT WEEK WITH
MINIMUM AFTERNOON HUMIDITY ONLY FALLING INTO A 40-60% RANGE. THIS
WILL FOLLOW EXCELLENT OVERNIGHT RECOVERY GREATER THAN 75% REGION-
WIDE. VERY LIGHT WINDS WITH SPEEDS AOB 10 MPH WILL BE COMMON OVER
THE NEXT SEVERAL DAYS AND DIRECTIONS SHOULD FOLLOW NORMAL DIURNAL
TRENDS. A DRY WEATHER PATTERN THROUGH THE FIRST PART OF NEXT WEEK
WILL LIKELY BECOME MORE UNSETTLED PATTERN DURING THE MIDDLE OF THE
WEEK WITH INCREASED CHANCES FOR WETTING RAIN.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...SALERNO
LONG TERM...18
AVIATION...BENEDICT
FIRE WEATHER...SALERNO/18
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