178
FXUS65 KPSR 100537
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1037 PM MST FRI MAY 9 2025
UPDATE
UPDATED AVIATION DISCUSSION.
SYNOPSIS
HIGH PRESSURE IS STRENGTHENING OVER THE REGION LEADING TO
TEMPERATURES IN THE TRIPLE DIGITS TODAY LASTING THROUGH THE
WEEKEND, UP TO 105 DEGREES ON SUNDAY. THIS HAS LEAD TO WIDESPREAD
MODERATE HEATRISK AND SOME LOCALIZED MAJOR HEATRISK IN THE
WESTERN PORTIONS OF THE REGION. SKIES WILL REMAIN CLEAR THROUGH
SATURDAY, AFTERWARDS HIGHER LEVEL CLOUD COVERAGE WILL BE COMMON.
BREEZY CONDITIONS WILL ALSO START SATURDAY, CALMING DOWN SLIGHTLY
ON SUNDAY BEFORE RAMPING BACK UP MONDAY AS A LOW PRESSURE SYSTEM
APPROACHES. THIS SYSTEM WILL ALSO HELP BRING TEMPERATURES DOWN.
DISCUSSION
UPPER LEVEL RIDGING HAS BECOME DOMINATE OVER THE REGION AS
TEMPERATURES ARE EXPECTED TO CLIMB JUST OVER 100 DEGREES TODAY AND
CONTINUE TO RISE OVER THE WEEKEND AS THE RIDGE CONTINUES TO BUILD.
PEAK H5 HEIGHTS LOOK TO BE BETWEEN 585-587DM, JUST INTO THE 90TH
PERCENTILE OF CLIMATOLOGY FOR THIS TIME OF YEAR. THIS WILL VERY
LIKELY (>90%) PUT HIGH TEMPERATURES BETWEEN 104-106 OVER THE
WEEKEND. THESE TEMPERATURES HAVE ELEVATED THE HEATRISK TO MODERATE
WIDESPREAD ACROSS A THE DESERT SW, WITH MAJOR HEATRISK IN VERY
LOCALIZED AREAS IN THE WESTERN PORTIONS OF THE REGION STARTING
SATURDAY. WHILE MOST OF THE REGION IS ANTICIPATED TO BE BACK UNDER
MINOR HEATRISK THE PHOENIX METRO HOLDS ONTO MODERATE RISK INTO
MONDAY BEFORE DIPPING BACK DOWN TO MINOR. CLEAR SKIES ARE EXPECTED
THROUGH SATURDAY, WITH HIGHER LEVEL CLOUD COVERAGE STARTING SUNDAY,
WHICH MAY LOWER THE MAX TEMPERATURE OUTPUT BY THE NBM.
WINDS ARE FORECAST TO PICK UP SATURDAY MORNING FROM THE
EAST/SOUTH-EAST ACROSS MUCH OF SOUTHERN AND CENTRAL ARIZONA, WITH
GUSTS AROUND 25-35 MPH. THIS IS MAINLY DUE TO AN INCREASING
GRADIENT BETWEEN OUR HIGH PRESSURE RIDGE AND A STRENGTHENING LOW
OVER THE LOWER MS RIVER VALLEY. WINDS WILL RELAX BY THE AFTERNOON
HOURS AND WILL SEE A SIMILAR TREND SUNDAY.
MODELS SHOW THE RELATIVELY DEEP TROUGH OFF THE PACIFIC NW
AFFECTING H5 HEIGHTS IN THE REGION BY SUNDAY. HOWEVER, TEMPERATURES
ARE VERY UNLIKELY (<10%) TO BE AFFECTED ON SUNDAY. THIS SYSTEM
LOOKS TO WEAKEN AS IT PUSHES FURTHER INLAND, BUT WILL STILL IMPACT
THE REGION ONCE ITS SITUATED OVER THE GREAT BASIN BY MONDAY.
DURING WHICH, AREA WIDE BREEZY CONDITIONS WILL PICK BACK UP.
ENSEMBLES STILL AGREE THIS PACIFIC TROUGH WILL BE FAIRLY SLOW TO
FULLY MOVE THROUGH THE REGION, NOT UNTIL NEXT TUESDAY OR
WEDNESDAY. THERE IS STILL SOME UNCERTAINTY WITH THE EXACT TIMING
AND THE DEPTH OF THE SYSTEM, WITH NBM TEMPERATURES SLOWING THE
COOL DOWN EARLY NEXT WEEK, BUT WE COULD SEE HIGHS EVENTUALLY DROP
INTO THE 80S BY WEDNESDAY.
AVIATION
UPDATED AT 0020Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, KDVT:
EASTERLY WINDS WILL PREVAIL THROUGH THE TAF PERIOD. AN ENHANCED
EASTERLY GRADIENT WIND WILL DEVELOP TONIGHT, SHORTLY AFTER
MIDNIGHT. WINDS ABOVE THE SURFACE AS HIGH AS 30-35 KTS MAY LEAD
LLWS MAGNITUDES UP TO 25-30 KTS BETWEEN 7-14Z, BUT MENTION WILL BE
LEFT OUT OF THE TAF. THE ELEVATED WINDS WILL LEAD TO SURFACE WIND
GUSTS TO AROUND 25-30 KTS SATURDAY, MAINLY BETWEEN 15-20Z. GUST
MAGNITUDES WILL SUBSIDE GRADUALLY THROUGH SATURDAY AFTERNOON.
SKIES WILL REMAIN MOSTLY CLEAR.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
LIGHT DIURNAL WINDS WILL PREVAIL AT BOTH TERMINALS THROUGH
TONIGHT, WITH PERIODS OF LIGHT VARIABILITY AS WELL. AN INCREASED
EASTERLY WIND GRADIENT WILL THEN TAKE HOLD BY LATE MORNING AT BOTH
TERMINALS, WITH SURFACE SPEEDS INCREASING TO AROUND 8-13 KTS WITH
GUSTS UP TO 15-25 KTS THAT WILL CONTINUE THROUGH EARLY AFTERNOON
SATURDAY. MOSTLY CLEAR SKIES WILL PREVAIL, WITH FEW TO SCT HIGH
CLOUDS MOVING IN LATE IN THE AFTERNOON AND EVENING SATURDAY.
FIRE WEATHER
HIGH PRESSURE WILL STRENGTHEN OVER THE REGION INTO THE WEEKEND
LEADING TO HOT TEMPERATURES AND HIGHS TOPPING 100 DEGREES OVER
THE MAJORITY OF THE LOWER DESERTS THROUGH SUNDAY. HUMIDITIES WILL
DROP A BIT FURTHER TODAY WITH MINRHS AROUND 15% BEFORE DROPPING
CLOSER TO 10% BY SUNDAY. AFTER LIGHT WINDS TODAY, WINDS WILL
BECOME QUITE BREEZY OUT OF THE EAST ON SATURDAY WITH PEAK GUSTS
OF 25-35 MPH DURING THE MORNING HOURS ACROSS PORTIONS OF SOUTHERN
ARIZONA. EXPECT ANOTHER ROUND OF EASTERLY BREEZY CONDITIONS
SUNDAY MORNING ACROSS EASTERN ARIZONA BEFORE BREEZY CONDITIONS
EXPAND TO INCLUDE THE WESTERN DISTRICTS SUNDAY AFTERNOON. THESE
CONDITIONS MAY LEAD TO A PERIOD OF ELEVATED FIRE DANGER IN SOME
AREAS THIS WEEKEND. AN APPROACHING LOW PRESSURE SYSTEM EARLY NEXT
WEEK WILL LEAD TO A COOLING TREND, BUT ALSO MORE BREEZY TO WINDY
CONDITIONS WHICH WILL LIKELY BRING A CONTINUATION OF THE ELEVATED
FIRE DANGER.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
DISCUSSION...KUHLMAN/RYAN
AVIATION...BENEDICT
FIRE WEATHER...KUHLMAN/RYAN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page