858
FXUS65 KPSR 251204
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
504 AM MST FRI APR 25 2025
UPDATE
UPDATED 12Z AVIATION DISCUSSION.
SYNOPSIS
SEASONABLY WARM TEMPERATURES CONTINUE TODAY AHEAD OF AN APPROACHING
DRY WEATHER SYSTEM. AS THE SYSTEM TRAVERSES THE GREAT BASIN THIS
WEEKEND, BREEZY TO LOCALLY WINDY CONDITIONS WILL MATERIALIZE, WITH
WINDS PEAKING SATURDAY ACROSS THE AREA. LOWER DESERT HIGHS WILL ALSO
COOL INTO THE SEVENTIES FOR MOST PLACES BY SUNDAY. TEMPERATURES ARE
LIKELY TO REBOUND TO NEAR SEASONAL NORMALS BY TUESDAY AS HIGH
PRESSURE BUILDS OVER THE WESTERN UNITED STATES DURING THE UPCOMING
WORKWEEK.
DISCUSSION
EARLY MORNING WATER VAPOR IMAGERY DEPICTS AN UPPER LEVEL TROUGH OFF
THE WEST COAST, WITH SOUTHWEST FLOW ALOFT BEGINNING TO INCREASE OVER
THE FORECAST AREA AHEAD OF THIS FEATURE. THE TROUGH AXIS APPEARS
NEGATIVELY TILTED, AS THE CENTER OF AN UPPER LOW SITS OFFSHORE ALONG
THE NORCAL LATITUDES, AND A SHORTWAVE HAS WRAPPED AROUND TO ITS
SOUTHEAST PERIPHERY, MOVING ONSHORE EARLY THIS MORNING. THIS
SHORTWAVE WILL ACT TO INCREASE REGIONAL PRESSURE GRADIENTS TODAY
AHEAD OF THE APPROACHING CORE OF STRONGER NEGATIVE HEIGHT ANOMALIES,
HELPING TO INCREASE WINDS ACROSS PORTIONS OF THE AREA THIS
AFTERNOON/EVENING. THE TYPICAL WIND PRONE AREAS OF SOUTHEAST CA,
INCLUDING MUCH OF WESTERN IMPERIAL COUNTY, WILL SEE THE STRONGEST
WINDS TODAY, FOCUSED DURING THE EVENING THANKS TO MOUNTAIN ROTOR
ACTIVITY. AS SUCH, A WIND ADVISORY WILL GO INTO EFFECT FOR THE
SOUTHWEST CORNER OF IMPERIAL COUNTY STARTING THIS AFTERNOON (AND
CONTINUING THROUGH SATURDAY), AND ANOTHER HAS BEEN ISSUED FOR THE
ADJACENT DESERTS OF WESTERN IMPERIAL COUNTY JUST FOR THIS EVENING.
WITH THE STRONGEST WINDS, EXPECT SOME AREAS OF DENSER BLOWING DUST.
FORECAST HIGHS THIS AFTERNOON ARE GENERALLY IN THE MIDDLE 80S FOR
THE WESTERN DESERTS AND IN THE UPPER 80S TO AROUND 90F FOR THE
SOUTH-CENTRAL AZ LOWER DESERTS.
ENSEMBLES SHOW THE CORE OF THE UPPER LOW MOVING ONSHORE ALONG THE
CENTRAL CA COAST SATURDAY, WHICH IS WHEN THE FORECAST AREA WILL
LIKELY SEE THE MOST SIGNIFICANT THERMAL AND PRESSURE GRADIENTS
ALOFT, BEFORE THE LOW TRAVERSES THE GREAT BASIN SUNDAY. AS SUCH,
EXPECT WIDESPREAD BREEZY TO LOCALLY WINDY CONDITIONS AREAWIDE
SATURDAY, WITH GUSTS TO BETWEEN 25-35 MPH BECOMING COMMON DURING THE
AFTERNOON ACROSS THE TYPICAL WIND PRONE AREAS. THE ENHANCED
BREEZINESS, COMBINED WITH A VERY DRY AIR MASS IN PLACE, WILL RESULT
IN PERIODS OF ELEVATED TO NEAR CRITICAL FIRE WEATHER CONDITIONS,
PARTICULARLY OVER THE AZ HIGH TERRAIN EAST OF PHOENIX ON SATURDAY.
AS FOR TEMPERATURES, THIS SYSTEM WILL FUNNEL UNSEASONABLY COOL AIR
OVER THE DESERT SOUTHWEST DROPPING TEMPERATURES A GOOD 5-10 DEGREES
BELOW NORMAL, WITH INITIAL COOLING OVER THE WESTERN DESERTS SATURDAY
BEFORE SPREADING FURTHER EAST BY SUNDAY. WIDESPREAD TEMPS IN THE
MIDDLE TO UPPER 70S ARE EXPECTED BY SUNDAY, WITH JUST A FEW SPOTS
MAKING INTO THE LOWER 80S. LINGERING BREEZINESS IS LIKELY ON SUNDAY
AS THE SYSTEM WEAKENS, BUT GUSTS SHOULD REMAIN BELOW THE ADVISORY
LEVEL THRESHOLD.
HEADING INTO THE START OF NEXT WEEK, MODELS DEPICT THE WEEKEND LOW
SPLITTING INTO TWO SEPARATE SYSTEMS, WITH ONE EJECTING TOWARD THE
PLAINS, WHILE THE OTHER HANGS BACK OVER THE SOUTHWESTERN CONUS AND
NORTHERN SONORA. THE GENERAL CONSENSUS IS THAT THIS SECONDARY SYSTEM
WILL NOT BE AS STRONG AS ITS PREDECESSOR, SO LITTLE IN THE WAY OF
IMPACTS ARE ANTICIPATED. AT MOST, PERIODS OF ELEVATED WINDS AND
MAYBE A DELAY IN A MORE NOTICEABLE WARMING TREND WILL BE THE MAIN
IMPACTS. BEYOND THAT, CLUSTERS INDICATE THE RETURN OF HIGH PRESSURE
TO THE WESTERN CONUS BY THE MIDDLE OF NEXT WEEK, USHERING IN THE
RETURN OF BENIGN CONDITIONS AND ABOVE-NORMAL TEMPERATURES.
AVIATION
UPDATED AT 1200Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, KDVT:
THE MAIN AVIATION CONCERN THIS FORECAST PERIOD WILL BE A GUSTY
SOUTHERLY CROSSWIND LATE THIS MORNING THROUGH THE EARLY AFTERNOON
HOURS. WINDS WILL BECOME ELEVATED AROUND 10 KTS OUT OF THE S-SE BY
MID-MORNING, CREATING A CROSS-RUNWAY COMPONENT AT KPHX FOR AT
LEAST 3-4 HRS INTO THE AFTERNOON HOURS UNTIL FINALLY SHIFTING OUT
OF THE SW IN THE LATE AFTERNOON. GUSTS AROUND 20-25 KTS CAN BE
EXPECTED THROUGH THIS AFTERNOON BEFORE DIMINISHING AFTER SUNSET.
THERE IS INCREASED UNCERTAINTY IN REGARDS TO THE WIND DIRECTIONS
AND SPEEDS THROUGH THE OVERNIGHT HOURS TONIGHT FOR AT LEAST KPHX,
AS REFLECTED IN THE VARIABLE WIND GROUP AROUND MIDNIGHT. SKIES
WILL REMAIN MOSTLY CLEAR THROUGH THE PERIOD.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
THE MAIN AVIATION CONCERN WILL BE GUSTY AFTERNOON AND EVENING
WINDS AT BOTH TERMINALS. THERE WILL BE A PERIOD OF LIGHTER SPEEDS
EARLY THIS MORNING BEFORE WINDS INCREASE AGAIN OUT OF THE WEST
THIS AFTERNOON. STRONGER GUSTS UP TO 30 KTS WILL MATERIALIZE
STARTING AROUND 23Z-00Z THIS EVENING AT KIPL AND LAST INTO THE
OVERNIGHT HOURS BEFORE THE STRONGEST GUSTS BEGIN TO SUBSIDE. AT
KBLH, EXPECT WINDS TO REMAIN GENERALLY OUT OF THE S-SW THROUGH
THIS EVENING WITH GUSTS REACHING 20-25 KTS BY THE EARLY AFTERNOON
BEFORE SUBSIDING GOING INTO THE OVERNIGHT HOURS. SKIES WILL
REMAIN MOSTLY CLEAR THROUGH THE PERIOD.
FIRE WEATHER
DRY CONDITIONS WILL PERSIST THROUGH THE NEXT 7 DAYS, WITH ONE MORE
DAY OF NEAR NORMAL TEMPERATURES TO END THE WEEK. AN APPROACHING
LOW PRESSURE SYSTEM WILL INCREASE SOUTHWESTERLY WINDS THROUGH
SATURDAY. WIDESPREAD GUSTS TO BETWEEN 20-35 MPH WILL BECOME COMMON
DURING THE AFTERNOON, LEADING TO ELEVATED TO NEAR CRITICAL FIRE
WEATHER CONDITIONS FOR THE TYPICALLY PRONE AREAS, PARTICULARLY
THE ARIZONA HIGH TERRAIN EAST OF PHOENIX ON SATURDAY. TEMPERATURES
WILL ALSO COOL BELOW NORMAL THIS WEEKEND AS A RESULT OF THE LOW
PRESSURE SYSTEM. AFTERNOON MINRHS WILL GENERALLY FALL INTO THE
LOWER TEENS TODAY BEFORE RISING SLIGHTLY THIS WEEKEND, IN THE
MIDDLE TO UPPER TEENS, THANKS TO THE COOLER TEMPERATURES.
OVERNIGHT RECOVERIES WILL BE POOR TO FAIR, GENERALLY BETWEEN
25-45% THROUGH TONIGHT, INCREASING TO 30-50% FOR THE EASTERN
DISTRICTS BY SATURDAY NIGHT AND SLIGHTLY HIGHER (45-60%) FOR THE
WESTERN DISTRICTS. A WARMING TREND EARLY NEXT WEEK WILL ONCE AGAIN
LOWER HUMIDITIES AND BRING SLIGHTLY ABOVE NORMAL TEMPERATURES BY
THE MIDDLE OF NEXT WEEK.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 5 AM PDT SUNDAY FOR
CAZ562.
WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 10 PM PDT THIS EVENING
FOR CAZ566.
DISCUSSION...WHITTOCK
AVIATION...YOUNG/SALERNO
FIRE WEATHER...WHITTOCK
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