584
FXUS65 KPSR 101009
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
309 AM MST TUE JUN 10 2025
KEY MESSAGES
- DRY CONDITIONS THROUGH THE PERIOD WITH ABOVE NORMAL TEMPERATURES
THROUGH THE WEEK, PEAKING UPWARDS OF 7-10 DEGREES OVER THE
WEEKEND
- FAIRLY WIDESPREAD MODERATE HEATRISK THROUGH THE ENTIRE WEEK WITH
INCREASING MAJOR HEATRISK STARTING BY SUNDAY
DISCUSSION
EARLY MORNING IR SATELLITE DEPICTS CLEAR SKIES ACROSS THE REGION,
WHILE A SLUG OF ENHANCED MOISTURE LEVELS IN NORTHERN ARIZONA,
EVIDENT IN WV IMAGERY, IS CREEPING SOUTHWARD INTO THE NORTHERN
PORTIONS OF SOUTH-CENTRAL ARIZONA. THESE ENHANCED MOISTURE LEVELS
AIDED IN SOME SHOWER AND THUNDERSTORM ACROSS THE HIGHER COUNTRY OF
NORTHERN ARIZONA YESTERDAY BY A WEAK TROUGHING FEATURE THAT
CONTINUES TO DEEPEN ACROSS THE STATE TODAY. THIS TROUGH WILL AID
IN MORE ROBUST CONVECTIVE ACTIVITY INTO NEW MEXICO TODAY, WITH
SOME HIGH COUNTRY SHOWERS AND THUNDERSTORMS NORTH OF THE REGION.
CONDITIONS ARE TOO DRY AND STABLE ACROSS THE IMMEDIATE REGION TO
WARRANT ANY CHANCES OF SHOWER/STORM POTENTIAL TODAY.
THIS TROUGHING FEATURE CONTINUES TO CAP LOWER DESERT HIGH
TEMPERATURES IN THE MID TO UPPER 100S THROUGH THE MIDDLE OF THIS
WEEK, WITH CONTINUED WESTERLY TO NORTHWESTERLY FLOW KEEPING HIGH
TEMPERATURES IN THIS GENERAL RANGE THROUGH THE REST OF THE WEEK
UNDER FAIRLY WIDESPREAD MODERATE HEATRISK. LATE IN THE WEEK, A
CLOSED LOW IN THE GULF OF ALASKA WILL BEGIN TO AMPLIFY AND DEEPEN
ACROSS THE PACIFIC NORTHWEST, RESULTING IN THE SUBTROPICAL RIDGE
CURRENTLY CENTERED OFFSHORE FROM THE BAJA PENINSULA TO BUILD INTO
THE DESERT SOUTHWEST GOING INTO THIS WEEKEND. THIS CHANGE IN THE
PATTERN WILL RESULT IN ANOTHER WARMING PERIOD ACROSS THE REGION,
AS PROBABILITIES OF TEMPERATURES EXCEEDING 110 DEGREES ACROSS THE
LOWER DESERTS ARE BECOMING MUCH MORE LIKELY OVER THE WEEKEND AND
EVEN INTO EARLY NEXT WEEK DEPENDING ON THE LOWER DESERT LOCATION
(60-100% CHANCE).
THE INCREASING ALIGNMENT AMONGST THE ENSEMBLE MEMBERS ARE
RESULTING IN CONTINUED WARMING NBM DETERMINISTIC TEMPERATURE
OUTPUTS FOR THE LOWER DESERTS, WITH INCREASING MAJOR HEATRISK
COVERAGE, PARTICULARLY ON SUNDAY AND MONDAY, AS HIGH SOAR INTO AT
LEAST THE LOWER 110S. THUS, THERE IS INCREASING CONCERN ABOUT THE
FIRST IMPACTFUL HEAT EVENT OF THE SEASON THAT WILL LIKELY RESULT
IN THE FIRST EXTREME HEAT PRODUCTS OF THE YEAR SHOULD THESE TRENDS
HOLD, SO STAY TUNED.
THE EVOLUTION OF THE AFOREMENTIONED TROUGHING FEATURE IN THE
PACIFIC NORTHWEST WILL DICTATE THE LENGTH OF THIS HEAT EVENT, AS
ENSEMBLES BEGIN TO DIVERGE BY A DECENT AMOUNT STARTING ON MONDAY
AS TO HOW MUCH THIS TROUGH WILL DISLODGE THE SUBTROPICAL THE
RIDGING IN PLACE THROUGH THE MIDDLE OF NEXT WEEK. SO, WHILE
TEMPERATURES WOULD COOL UNDER THIS PATTERN TRANSITION, HOW QUICKLY
AND THE MAGNITUDE OF COOLING IS MUCH MORE UNCERTAIN AT THIS TIME,
AS EVIDENCED BY THE SIX DEGREE IQR SPREAD IN NBM HIGH
TEMPERATURES FOR PHOENIX BY NEXT TUESDAY.
AVIATION
UPDATED AT 0530Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, KDVT; AND
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR WEATHER ISSUES WILL EXIST THROUGH TUESDAY EVENING UNDER
MOSTLY CLEAR SKIES. TRENDS IN WIND SPEEDS AND DIRECTIONAL SHIFTS
WILL BE NEARLY IDENTICAL TO THE PAST 24 HOURS. THIS WILL INCLUDE
PERIODIC AFTERNOON/EARLY EVENING GUSTS 15-20KT (SLIGHTLY
STRONGER, 20-25 KTS, AT KBLH) WITH MINIMAL OPERATIONAL IMPACTS.
FIRE WEATHER
DRY CONDITIONS WILL CONTINUE THROUGH THE WEEK WITH ABOVE NORMAL
TEMPERATURES. MIN RHS WILL BE AROUND 10-15% THROUGH MUCH OF THE
WEEK, WHILE MAX RHS RANGE BETWEEN 20-50% (POOREST IN THE EASTERN
DISTRICTS). WINDS WILL TEND TO FOLLOW THEIR TYPICAL DIURNAL
TENDENCIES WITH PERIODS OF MODEST AFTERNOON UPSLOPE GUSTINESS.
TEMPERATURES ARE FORECAST TO FURTHER HEAT UP THIS UPCOMING WEEKEND
WITH AFTERNOON HIGHS IN EXCESS OF 110 DEGREES LIKELY BY SUNDAY
ACROSS THE LOWER DESERTS AS MIN RHS LOWER IN THE 5-10% RANGE.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
DISCUSSION...YOUNG
AVIATION...WHITTOCK
FIRE WEATHER...YOUNG/SMITH
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