218
FXUS65 KPSR 180527
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1027 PM MST WED JUN 17 2026
UPDATE...UPDATED 06Z AVIATION DISCUSSION
KEY MESSAGES
- ISOLATED TO WIDELY SCATTERED THUNDERSTORMS WILL RETURN THIS
AFTERNOON, MAINLY OVER THE FOOTHILLS OF MARICOPA COUNTY, BUT A
FEW STORMS COULD FORM IN THE LOWER DESERTS WITH THE MAIN THREATS
BEING GUSTY OUTFLOW WINDS AND BLOWING DUST.
- TEMPERATURES UP TO 8 DEGREES ABOVE NORMAL WILL COOL CLOSER TO
THE SEASONAL AVERAGE BY THE END OF THE WEEK ALLOWING MODERATE
HEATRISK TO BE REDUCED TOWARDS A MINOR CATEGORY.
- AN APPROACHING EAST PACIFIC WEATHER DISTURBANCE LATE THIS WEEK
WILL DRY OUT THE REGION, WHILE BRINGING INCREASINGLY BREEZY
CONDITIONS AND COOLING TEMPERATURES.
SHORT TERM /TODAY THROUGH THURSDAY/
LATEST MID-LVL WV IMAGERY AND 500 MB STREAMLINE ANALYSIS REVEALS
AN AREA OF LOW PRESSURE SITUATED OVER THE AZ/CA BORDER ALLOWING
MUCH DRIER AIR TO ADVECT INTO THE WESTERN HALF OF THE FORECAST
AREA. OUT AHEAD OF THIS FEATURES IN SOUTH-CENTRAL AND SOUTHEASTERN
AZ, SFC MOISTURE REMAINS RELATIVELY HIGH WITH DEWPOINTS HOVERING
IN THE MID 50S. PWAT VALUES ARE ALSO AROUND 1.2"-1.5" OR AROUND
175% OF NORMAL FOR MID-JUNE. THE MOISTURE IN PLACE COUPLED WITH
DIFFLUENCE ALOFT AHEAD OF THE APPROACHING LOW WILL PROVIDE A FOCUS
FOR WIDELY SCATTERED SHOWER AND THUNDERSTORM ACTIVITY BY THIS
AFTERNOON. LATEST HIGH-RES GUIDANCE, ESPECIALLY THE HRRR DOES
SUGGEST HIGHER COVERAGE THAN PREVIOUS RUNS WITH THE MAIN FOCUS
AREAS FOR INITIATION IN SOUTHERN YAVAPAI AND CENTRAL PINAL
COUNTIES. LATEST VISIBLE SATELLITE IMAGERY DOES CONFIRM INITIATION
UNDERWAY IN THESE AREAS. CAPE VALUES IN EXCESS OF 1500 J/KG
ACROSS THE LOWER DESERTS MAY SUPPORT WELL DEFINED OUTFLOW
BOUNDARIES WHICH COULD GENERATE ADDITIONAL SHOWERS AND STORMS BY
THIS EVENING, HOWEVER COVERAGE STILL LOOKS TO REMAIN LIMITED. THE
MAIN THREATS WITH ANY STORM WILL BE STRONG, GUSTY WINDS WITH
AROUND A 30-50% CHANCE OF GUSTS EXCEEDING 35 MPH IN MARICOPA AND N
PINAL COUNTIES THIS AFTERNOON/EVENING. BY THURSDAY, ACTIVITY
SHOULD BECOME RELEGATED TO THE WHITE MOUNTAINS OF EASTERN ARIZONA,
ONLY POTENTIALLY CLIPPING FAR EASTERN GILA COUNTY AS DRY AIR
CONTINUES TO FILTER INTO THE STATE FROM W TO E.
OVERALL 500 MB HGHTS WILL CONTINUE A DOWNWARD TREND OVER THE NEXT
24 HOURS AS THE RIDGE AXIS SHIFTS EWD INTO NM AND THE WEAK AREA OF
LOW PRESSURE MOVES OVER CENTRAL AZ. THIS REDUCTION IN HEIGHTS/THICKNESS
WILL RESULT IN TEMPERATURES ACROSS THE LOWER DESERTS DECREASING
FROM 105-111F TODAY TO AROUND 102-107F ON THURSDAY. WITH DRIER AIR
OVERSPREADING THE FORECAST AREA, OVERNIGHT LOWS WILL NOT BE AS
WARM AS PREVIOUS NIGHTS, MAINLY IN THE UPPER 70S TO MID 80S ON
THURSDAY MORNING WITH FURTHER COOLING ANTICIPATED BY THE END OF
THIS WEEK.
LONG TERM /FRIDAY THROUGH TUESDAY/
THERE IS EXCELLENT AGREEMENT AMONG ENSEMBLE MEMBERSHIP THAT MORE
PRONOUNCED EAST PACIFIC TROUGHING WILL EJECT INTO THE GREAT BASIN
RESULTING IN STRONG ZONAL FLOW ACROSS THE FORECAST AREA. THIS FLOW
PATTERN WILL COMPLETELY SCOUR AWAY MOISTURE SUCH THAT MIXING RATIOS
FALL CLOSER TO 2-3 G/KG ELIMINATING ALL CHANCES FOR PRECIPITATION.
WHILE H5 HEIGHTS WILL NOT DROP MARKEDLY, SUBTLE COOLING ALONG WITH
THE INTRODUCTION OF THIS MUCH DRIER AIRMASS WILL RESULT IN
TEMPERATURES FALLING TO NEAR NORMAL LEVELS OVER THE WEEKEND. THE
INITIAL ROUND OF MODEST HEIGHT FALLS COMBINED WITH SEASONABLY DEEP
MIXING DEPTHS WILL PROMOTE REPEATED CHANCES OF GUSTY AFTERNOON WINDS
LATE IN THE WEEK. JUXTAPOSED WITH THE INCOMING DRY AIRMASS AND
RECEPTIVE, DESSICATED FUELS, FIRE DANGER WILL BECOME QUITE ELEVATED.
ENSEMBLE SPREADS GROWS SOMEWHAT TOWARDS THE MIDDLE OF NEXT WEEK,
HOWEVER THE MAJORITY OF MEMBERS INDICATE BUILDING SUBTROPICAL
RIDGING OVER THE CWA AFTER THE TROUGH PASSAGE. H5 HEIGHTS SHOULD
REBOUND OVER 594DM WITH THE ANTI-CYCLONE CENTER BECOMING POSITIONED
DIRECTLY OVER ARIZONA. SOME OF THE MORE AGGRESSIVE MODELING IN THE
UPPER QUARTILE OF THE MODEL DISTRIBUTION EVEN SUGGESTS HEIGHTS
BREACHING 597DM BY THE MIDDLE OF THE WEEK WHICH WOULD EQUATE TO
LOWER ELEVATION TEMPERATURES REACHING 115F YIELDING EXPANSIVE MAJOR
HEATRISK.
AVIATION
UPDATED AT 0525Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
NO MAJOR AVIATION WEATHER CONCERNS UNDER A FEW MID TO HIGH CLOUDS
CAN BE EXPECTED THROUGHOUT THE TAF PERIOD. THE OVERALL WIND
PATTERN WILL RESUME THE TYPICAL DIURNAL TENDENCIES WITH EASTERLY
WINDS OVERNIGHT THROUGH THURSDAY MORNING SHIFTING OUT OF THE WEST
BY THE EARLY AFTERNOON. THERE WILL BE A PERIOD OF SOUTHERLY WINDS
DURING THE LATE MORNING BEFORE THE WESTERLY SHIFT. AFTERNOON GUSTS
INTO THE UPPER TEENS WILL BE COMMON.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
GUSTY WINDS, ESPECIALLY AT KIPL, WILL CONTINUE TO BE THE MAIN
AVIATION WEATHER ISSUE UNDER CLEAR SKIES THROUGHOUT THE TAF
PERIOD. AT KIPL, GENERALLY WESTERLY WINDS WILL PREVAIL WHILE AT
KBLH, WINDS WILL GENERALLY FLUCTUATE BETWEEN THE SOUTH TO
SOUTHWEST. SOME ELEVATED GUSTS NEAR 25 KTS WILL CONTINUE FOR THE
NEXT COUPLE OF HOURS AT KIPL BEFORE SUBSIDING DURING THE OVERNIGHT
PERIOD. HEADING INTO THURSDAY, AFTERNOON GUSTS UPWARDS OF 20-25
KTS WILL BE COMMON AT KBLH AND NEAR 25 KTS, POTENTIALLY HIGHER,
DURING THE EARLY EVENING HOURS AT KIPL.
FIRE WEATHER
A PRONOUNCED DRYING TREND WILL TRANSPIRE ACROSS THE REGION THROUGH
THE REMAINDER OF THIS WEEK WITH TERRAIN INDUCED SHOWERS/STORMS
BECOMING COMPLETELY ELIMINATED FROM THE FORECAST BY FRIDAY.
ISOLATED TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE OVER HIGHER TERRAIN FEATURES THIS AFTERNOON, HOWEVER
CHANCES OF WETTING RAINFALL WILL BE REMOTE. THE MAIN IMPACTS WITH
ANY STORM WILL BE GUSTY AND ERRATIC WINDS AND DRY LIGHTNING.
DESPITE TEMPERATURES COOLING CLOSER TO NORMAL LATER THIS WEEK, A
MUCH DRIER AIRMASS WILL ALLOW MINIMUM HUMIDITY LEVELS PRIMARILY IN
A 10-20% RANGE TO DETERIORATE INTO WIDESPREAD SINGLE DIGITS OVER
THE WEEKEND AND EARLY NEXT WEEK. CORRESPONDINGLY, OVERNIGHT
RECOVERY WILL DETERIORATE INTO A POOR TO FAIR 15-40% RANGE. WINDS
WILL FREQUENTLY BECOME GUSTY THE REMAINDER OF THE WEEK YIELDING A
WIDESPREAD ELEVATED FIRE DANGER, HOWEVER AT THIS TIME, SPEEDS
APPEAR TO REMAIN BELOW CRITICAL THRESHOLDS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...WIND ADVISORY UNTIL MIDNIGHT PDT TONIGHT FOR CAZ562-566-567.
SHORT TERM...SALERNO
LONG TERM...18
AVIATION...LOJERO
FIRE WEATHER...SALERNO/18
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