627
FXUS65 KPSR 280500
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1000 PM MST SUN JUL 27 2025
UPDATE
UPDATED AVIATION
KEY MESSAGES
- TEMPERATURES WILL CONTINUE TO WARM EARLY THIS WEEK PUSHING DAILY
HIGHS ACROSS THE LOWER DESERTS TO AROUND 110 DEGREES RESULTING IN
WIDESPREAD MODERATE HEATRISK.
- A RETURN TO A MORE TYPICAL MONSOON PATTERN WILL ALLOW SHOWER AND
THUNDERSTORM ACTIVITY TO INCREASE FOR EASTERN PORTIONS OF ARIZONA
MONDAY INTO TUESDAY AND THEN INTO SOUTH-CENTRAL ARIZONA WEDNESDAY
INTO THURSDAY.
SHORT TERM /TODAY THROUGH TUESDAY/
THOUGH SOME MEASURE OF BROAD CYCLONIC FLOW WILL BE MAINTAINED TO THE
NORTHWEST OF THE REGION, GUIDANCE SHOWS MIDLEVEL NEGATIVE HEIGHT
ANOMALIES RETREATING WESTWARD AND OFFSHORE THROUGH THE NEXT FEW
DAYS, ALLOWING THE INFLUENCE OF THE HIGH PRESSURE (CURRENTLY SPREAD
OVER THE SOUTHEAST US AND SOUTHERN PLAINS) TO ENCROACH ON EASTERN
AZ. THIS WILL TURN FLOW ALOFT FROM ITS CURRENT DRY, SOUTHWESTERLY
CONFIGURATION TO SOUTHEASTERLY, AT LEAST OVER THE EASTERN HALF OF
THE STATE, BY MONDAY. AS LONG AS THIS MORE TYPICAL MONSOON PATTERN
IS MAINTAINED, A FAMILIAR EVOLUTION WILL BEGIN TO TAKE PLACE, WITH
MOSTLY ISOLATED CONVECTIVE ACTIVITY ACROSS THE EASTERN AZ HIGH
TERRAIN MONDAY BECOMING SOMEWHAT MORE WIDESPREAD AND DRAWING CLOSER
TO SOUTH-CENTRAL AZ TUESDAY AS BETTER QUALITY MOISTURE CONTINUES TO
BE IMPORTED. THE MAIN CONCERN WITH CONVECTIVE ACTIVITY AT FIRST WILL
BE STRONG, GUSTY WINDS OVER THE EASTERN AZ HIGH TERRAIN MONDAY, WITH
HIGH CLOUD BASES AND INVERTED-V MODEL SOUNDINGS. BY TUESDAY, THE
VALLEY STANDS A BETTER CHANCE AT SEEING GUSTY OUTFLOW WINDS FROM
NEARBY CONVECTIVE ACTIVITY TO THE EAST/SOUTHEAST, THOUGH T-STORM
DEVELOPMENT SHOULD STILL OVERALL BE CONFINED TO HIGHER TERRAIN
FEATURES.
AS HIGH PRESSURE SHIFTS WESTWARD OVER THE DESERT SOUTHWEST, ENSEMBLE
MEAN H5 HEIGHTS INCREASE TO A 591-595 DAM RANGE BY MONDAY. THIS WILL
LEAD TO WARMING TEMPERATURES INTO THE BEGINNING OF THE WORKWEEK,
THOUGH INCREASING MOISTURE OVER THE EASTERN CWA SHOULD THEN TEMPER
DAILY HIGHS AS THE WEEK GOES ON. LATEST NBM SHOWS MONDAY AS THE
WARMEST DAY OF THE UPCOMING WEEK, WITH MANY LOWER DESERT LOCATIONS
NEARING 110F AND A FEW LIKELY EXCEEDING 110F (90% CHANCE
FOR 110+F AT PHOENIX SKY HARBOR AIRPORT.)
LONG TERM /WEDNESDAY THROUGH SATURDAY/
MODEL UNCERTAINTY COMES MORE INTO PLAY FOR WEDNESDAY AND THURSDAY AS
GUIDANCE SHOWS A BIG DISPARITY AMONG MEMBERS FOR HOW MUCH AND HOW
FAR WEST THE MOISTURE WILL REACH INTO ARIZONA. THE GEFS IS MUCH MORE
OPTIMISTIC WITH HOW MUCH MOISTURE WILL MAKE ITS WAY INTO SOUTH-
CENTRAL ARIZONA STARTING WEDNESDAY AND THIS IS LARGELY IN PART
BECAUSE THE GFS SHOWS AN INVERTED TROUGH MOVING INTO FAR SOUTHERN
ARIZONA WHEREAS THE EURO MOSTLY KEEPS IT OVER SONORA MEXICO. GIVEN
THE DIFFERENCES, FORECAST CONFIDENCE REMAINS FAIRLY LOW FOR THE
POTENTIAL FOR MONSOON ACTIVITY INTO THE LOWER DESERTS DURING THE
MIDDLE PART OF THE WEEK. FOR NOW, NBM POPS SEEM FAIRLY REASONABLE
FOR WEDNESDAY AND THURSDAY WITH 15-25% CHANCES OVER THE LOWER
DESERTS OF MARICOPA COUNTY TO AS HIGH AS 50% WITHIN GILA COUNTY.
OTHER THAN THE POTENTIAL MOISTURE, THE SYNOPTIC SET-UP DOES NOT LOOK
VERY FAVORABLE AS WE ARE LIKELY TO BE NEAR OR WITHIN THE RIGHT EXIT
SUBSIDENT REGION OF A WEST TO EAST UPPER LEVEL JET STREAMING OFF THE
PACIFIC THROUGH CENTRAL CALIFORNIA. WE WILL HOPEFULLY HAVE A BETTER
IDEA ON THIS STORM POTENTIAL WITHIN THE NEXT COUPLE DAYS.
THE SOUTHEASTERLY MOIST FLOW IS NOT LIKELY TO LAST LONG AS GUIDANCE
SHOWS THE CENTER OF THE SUBTROPICAL RIDGE SHIFTING OVER SOUTHERN NEW
MEXICO ON THURSDAY BEFORE POTENTIALLY SETTING UP OVER FAR SOUTHERN
ARIZONA AND NORTHERN MEXICO FRIDAY INTO NEXT WEEKEND. THIS SHIFT
WOULD LIKELY BRING IN DRIER WESTERLY FLOW AS EARLY AS LATE THURSDAY
OR EARLY FRIDAY, MOSTLY ENDING ANY RAIN CHANCES FOR THE LOWER
DESERTS ON FRIDAY. HIGHER TERRAIN AREAS OF EASTERN ARIZONA WILL
LIKELY STILL CONTINUE TO SEE DAILY CHANCES INTO NEXT WEEKEND, BUT
THE COVERAGE IS LIKELY TO BE SCALED BACK QUITE A BIT.
TEMPERATURES FOR THE LATTER HALF OF THIS WEEK ARE NOT LIKELY TO
CHANGE ALL THAT MUCH WITH DAILY HIGHS MOSTLY RUNNING A COUPLE
DEGREES ABOVE NORMAL. HOWEVER, NBM GUIDANCE DOES SHOW A BIT OF AN
UPTICK IN TEMPERATURES BY NEXT WEEKEND AND THIS MAKES SENSE GIVEN
THE LIKELIHOOD OF DECREASING MOISTURE AND THE RIDGE CENTER MOVING
CLOSER TO OUR AREA. THE UPPER END OF GUIDANCE ALSO SHOWS SOME
POTENTIAL FOR HIGHS NEAR 115 DEGREES AND LOCALIZED MAJOR HEATRISK
FOR NEXT WEEKEND.
AVIATION
UPDATED AT 0500Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
SOME MINOR UNCERTAINTY IN TIMING OF WIND SHIFTS WILL BE THE MAIN
WEATHER CHALLENGE THROUGH MONDAY NIGHT UNDER PERIODS OF OCCASIONAL
MID/HIGH CLOUD DECKS. CONFIDENCE IS GOOD THAT WINDS WILL SHIFT TO
AN EASTERLY COMPONENT OVERNIGHT, THOUGH EXACT TIMING IS SOMEWHAT
UNCERTAIN. WINDS SHOULD HAVE LIMITED GUSTINESS MONDAY AFTERNOON
AFTER THE W/SW WIND SHIFT WHILE THUNDERSTORMS REMAIN RELEGATED TO
FAR EASTERN ARIZONA. HOWEVER, CONFIDENCE IS MODERATE THAT DISTANT
OUTFLOWS WILL BE MAINTAINED INTO THE PHOENIX AIRSPACE SUCH THAT AN
EARLIER THAN USUAL, AND POSSIBLY ABRUPT WIND SHIFT WILL SWEEP ACROSS
AERODROMES MONDAY MID-EVENING.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO WEATHER CONCERNS WILL EXIST THROUGH MONDAY NIGHT UNDER CLEAR
SKIES. CONFIDENCE IS VERY GOOD THAT WIND BEHAVIOR WILL BE SIMILAR
TO THE PAST 24 HOURS INCLUDING A PREFERENCE TOWARDS DIRECTIONS
OSCILLATING BETWEEN WEST AND NORTH AT KIPL AND SOUTH TO SOUTHWEST
AT KBLH. ANY GUSTINESS SHOULD BE MINIMAL WITH NEARLY CALM
OR WEAK DRAINAGE CONDITIONS LIKELY DURING THE POST-SUNRISE MORNING
HOURS.
FIRE WEATHER
TODAY WILL BRING ANOTHER DRY AND QUIET DAY BEFORE MOISTURE FINALLY
BEGINS TO CREEP BACK INTO EASTERN PORTIONS OF ARIZONA TONIGHT INTO
MONDAY. THIS SHOULD BRING SOME SCATTERED SHOWERS AND A FEW
THUNDERSTORMS MONDAY AFTERNOON ACROSS THE FAR EASTERN ARIZONA HIGHER
TERRAIN. EXPECT SLIGHTLY ABOVE NORMAL TEMPERATURES OVER THE NEXT
SEVERAL DAYS. WINDS WILL GENERALLY FOLLOW TYPICAL DIURNAL TENDENCIES
WITH SOME AFTERNOON UPSLOPE GUSTINESS. MINRHS WILL CONTINUE TO RANGE
FROM 5-10% AREAWIDE THROUGH MONDAY, WITH POOR OVERNIGHT RECOVERIES
OF 15-35%. MOISTURE AND RAIN CHANCES ARE THEN LIKELY TO SPREAD
WESTWARD INTO SOUTH-CENTRAL ARIZONA BY THE MIDDLE OF NEXT WEEK WITH
A MODEST INCREASE IN HUMIDITIES.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...WHITTOCK
LONG TERM...KUHLMAN
AVIATION...18
FIRE WEATHER...KUHLMAN
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