485
FXUS65 KPSR 082115
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
215 PM MST THU MAY 8 2025
SYNOPSIS
HIGH PRESSURE IS BUILDING IN THE REGION TODAY AND WILL CONTINUE TO
STRENGTHEN, PEAKING BY THIS WEEKEND. THIS WILL LEAD TO TEMPERATURES
RAPIDLY INCREASING ACROSS THE DESERT SOUTHWEST WITH HIGHS BETWEEN
100 AND 105 STARTING FRIDAY THROUGH THE WEEKEND. THIS WILL ELEVATE
HEATRISK TO MODERATE FOR THE PHOENIX METRO AND MODERATE TO MAJOR
IN THE WESTERN PART OF THE REGION. SLIGHT RELIEF IS EXPECT BY
EARLY NEXT WEEK, LIKELY BY TUESDAY, AS LOW PRESSURE SYSTEM IS
APPROACHING, AND SHOULD BRING TEMPERATURES DOWN SLIGHTLY BELOW
NORMAL.
DISCUSSION
THE LOW PRESSURE SYSTEM THAT SLOWLY MOVED THROUGH THE REGION AND
BROUGHT SOME WELL NEEDED PRECIPITATION HAS EXITED THE REGION TO
THE EAST. BEHIND THE PREVIOUSLY MENTIONED SYSTEM UPPER LEVEL
RIDGING HAS STARTED TO BUILD AND WILL BE STRONGEST THROUGH THE
WEEKEND WITH H5 HEIGHTS FORECASTED TO BE BETWEEN 584-587DM. DRIER
AIR IS ALSO ANTICIPATED TO FILTER INTO THE REGION SEEING SURFACE
DEW POINTS BACK IN THE LOW TO MID-40S.
THIS WEEKEND'S ANTICIPATED WARMING EVENT WILL BE REPRESENTATIVE
OF A FAIRLY STRONG HIGH PRESSURE RIDGE FOR THIS TIME OF YEAR AS
HEIGHTS REACH JUST INTO THE 90TH PERCENTILE OF CLIMATOLOGY. THE
NBM HAS VERY LITTLE SPREAD, 1-3 DEGREES FROM THE 25TH AND 75TH
INTERQUARTILE RANGES, SHOWING TEMPERATURES IN THE TRIPLE DIGITS
STARTING FRIDAY. OVER THE WEEKEND MOST OF THE DESERT SW WILL SEE
TEMPERATURES 3-7 DEGREES ABOVE THE CENTURY MARK, AND THE HIGHER
TERRAINS IN THE MID TO HIGH 90S. WHILE NOT RECORD BREAKING, THESE
TEMPERATURES ARE 10-15 DEGREES ABOVE NORMAL. OVERNIGHT
TEMPERATURES WILL ALSO INCREASE UNDER THE RIDGING PATTERN. LOWS
FRIDAY WILL GENERALLY BE IN THE UPPER 60S AND STEADILY INCREASING
WITH LOWS OVER THE WEEKEND IN THE MID TO UPPER 70S. THESE
TEMPERATURES HAVE ELEVATED HEATRISK TO MODERATE STARTING FRIDAY
FOR THE LOWER DESERT REGIONS AND INCREASES TO MAJOR HEATRISK OUT
WEST STARTING SATURDAY FOR PLACES SUCH AS YUMA, IMPERIAL, AND
BLYTHE. WE ARE STILL HOLDING OFF ON ISSUING ANY HEAT PRODUCTS, BUT
ANY ADDITIONAL BUMP IN THE TEMPERATURES WOULD LIKELY TRIGGER A
WATCH OR WARNING FOR SOME AREAS. CLEAR SKIES ON SATURDAY BEFORE WE
START TO SEE SOME HIGHER LEVEL CLOUDS MOVING OVER THE AREA
SATURDAY NIGHT THROUGH SUNDAY.
MODELS ARE SHOWING AN INCREASE IN SE WINDS STARTING SATURDAY
MORNING ACROSS EASTERN AZ AS A BACKDOOR COLD FRONT FROM THE SE ATTEMPTS
TO PUSH INTO THE REGION. THIS IS NOT EXPECTED TO IMPACT THE
TEMPERATURES BUT MAY DISRUPT THE TYPICAL DIURNAL TRENDS LEADING
TO MORE EASTERLY WINDS DURING THE AFTERNOON. THESE WINDS SHOULD
ALSO PROVIDE A SLIGHT UPTICK IN LOWER LEVEL MOISTURE WHICH MAY
EVEN BE ENOUGH FOR A FEW ISOLATED AFTERNOON SHOWERS OVER THE WHITE
MTNS AND MAYBE FURTHER TO THE NORTHWEST ALONG THE RIM ON
SATURDAY.
BY SUNDAY H5 HEIGHTS BEGIN TO FALL AS ANOTHER TROUGHING FEATURE
OFF THE PACIFIC NW INCHES CLOSER, HOWEVER, HEAT FROM THE RIDGE
WILL STILL DOMINATE ACROSS THE REGION. AS THIS NEXT SYSTEM
APPROACHES WE WILL SEE AN INCREASE IN WESTERLY WINDS, ESPECIALLY
ACROSS THE WESTERN DESERT. MONDAY TEMPERATURES COME DOWN SLIGHTLY
BUT WILL GENERALLY STILL BE IN THE UPPER 90S. TUESDAY THE REGION
WILL SEE A MORE SUBSTANTIAL DROP IN TEMPERATURE ALONG WITH
BREEZIER CONDITIONS AS THE LOW PRESSURE FROM THE SYSTEM WILL BE
OVER THE GREAT BASIN. GUIDANCE IS STILL UNCERTAIN WITH THE TIMING
AND THE DEPTH OF THE SYSTEM, BUT WE WILL CERTAINLY SEE A GOOD COOL
DOWN BY THE MIDDLE OF NEXT WEEK. NBM FORECAST HIGHS ARE SEEN
DROPPING INTO THE UPPER 90S ON MONDAY TO MOST LIKELY IN THE 85-90
DEGREE RANGE BY NEXT TUESDAY AND/OR WEDNESDAY.
AVIATION
UPDATED AT 1735Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, KDVT:
NO AVIATION WEATHER CONCERNS ARE ANTICIPATED THROUGH THE FORECAST
PERIOD UNDER CLEAR SKIES. WINDS ARE EXPECTED TO REMAIN LIGHT AND
FOLLOW TYPICAL DIURNAL TENDENCIES. EXPECT LIGHT WESTERLY WINDS
THIS AFTERNOON FOLLOWED BY A RETURN TO THE EASTERLY AT KPHX, KIWA,
AND KDVT TERMINALS BY 06Z-07Z TOMORROW. KSDL WILL REMAIN LIGHT
AND VARIABLE THROUGHOUT THE FORECAST PERIOD. SPEEDS SHOULD REMAIN
AOB 6 KTS.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION WEATHER CONCERNS ARE ANTICIPATED AT THE SOUTHEAST CA
TERMINALS. WINDS WILL BE PRIMARILY LIGHT AND VARIABLE WITH A
NORTHERLY COMPONENT AT KBLH AND WESTERLY AT KIPL, ALTHOUGH THERE
WILL ALSO LIKELY BE EXTENDED PERIODS OF LIGHT AND VARIABLE AT
THIS TERMINAL. MOSTLY CLEAR SKIES ARE ANTICIPATED THROUGH THE
FORECAST PERIOD.
FIRE WEATHER
HIGH PRESSURE WILL BUILD OVER THE REGION OVER THE NEXT COUPLE OF
DAYS LEADING TO A QUICK WARM UP AND DRIER CONDITIONS. TEMPERATURES
ARE EXPECTED TO BE WELL ABOVE NORMAL BY FRIDAY WITH HIGHS AROUND
100 DEGREES AND UP TO AROUND 105 DEGREES OVER THE WEEKEND.
HUMIDITIES WILL ALSO DROP QUICKLY WITH MINRHS RANGING BETWEEN
15-20% TODAY AND REMAINING BETWEEN 10-15% THROUGH THE WEEKEND.
WINDS WILL REMAIN FAIRLY LIGHT THROUGH FRIDAY BEFORE WINDS BECOME
QUITE BREEZY OUT OF THE EAST FOR THE FIRST PART OF THE WEEKEND.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
DISCUSSION...KUHLMAN/RYAN
AVIATION...95/YOUNG
FIRE WEATHER...KUHLMAN/RYAN
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