427
FXUS65 KPSR 201015
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
315 AM MST MON JUL 20 2026
KEY MESSAGES
- SHOWER AND THUNDERSTORM CHANCES WILL INCREASE TODAY AND TUESDAY,
ESPECIALLY OVER THE ARIZONA HIGH TERRAIN. ISOLATED STORMS CAN
ALSO BE EXPECTED INTO THE SOUTH-CENTRAL ARIZONA LOWER DESERTS.
- DRIER CONDITIONS DURING THE LATTER HALF OF THE WEEK WILL GREATLY
CURTAIL MONSOON STORM CHANCES WITH AT MOST SLIGHT CHANCES BY
THURSDAY.
- TEMPERATURES WILL REMAIN NEAR NORMAL EARLY THIS WEEK BEFORE
HEATING UP DURING THE LATTER HALF OF THE WEEK.
- AREAS OF MAJOR HEAT RISK ARE EXPECTED BEGINNING THURSDAY WITH A
HIGH LIKELIHOOD OF FAIRLY WIDESPREAD MAJOR TO EXTREME HEAT RISK
BY THE WEEKEND.
SHORT TERM /TODAY THROUGH TUESDAY/
THE SUBTROPICAL RIDGE REMAINS QUITE EXPANSIVE ACROSS THE CENTER
PART OF THE CONUS, BUT MULTIPLE INVERTED TROUGHS CONTINUE TO
TRACK WESTWARD UNDER THE HIGH. ONE MESOSCALE CIRCULATION IS
CURRENTLY TRACKING ACROSS SOUTHWEST ARIZONA INTO SOUTHEAST
CALIFORNIA, BUT MOST OF THE SHOWER ACTIVITY IS SOUTH OF THE
BORDER. A LARGER CIRCULATION IS SLOWLY MAKING WESTWARD PROGRESS
ACROSS WESTERN TEXAS AND NEW MEXICO WITH THIS FEATURE EXPECTED TO
HELP PROVIDE BROAD UPPER LEVEL ASCENT LATER TODAY FOR CONVECTION
OVER EASTERN AND POSSIBLY CENTRAL ARIZONA.
MOISTURE LEVELS REMAIN PLENTY ADEQUATE ACROSS THE AREA WITH PWATS
BETWEEN 1.5-1.8" AND LOW LEVEL MIXING RATIOS OF 11-13 G/KG, BUT
SOME DRYING IS ONGOING. CURRENT ANALYSIS SHOWS VERY LITTLE MUCAPE
ACROSS THE LOWER DESERTS AT THE MOMENT WITH FORECAST MUCAPE OVER
THE SOUTH-CENTRAL ARIZONA LOWER DESERTS AT MOST REACHING 500 J/KG
THIS AFTERNOON. HIGHER MOISTURE CONTENT AND BETTER INSTABILITY
WILL EXIST ACROSS THE AZ HIGH TERRAIN WITH MUCAPES THIS AFTERNOON
OF 500-1000 J/KG. HI-RES CAMS MOSTLY AGREE ON GOOD COVERAGE OF
SHOWERS AND STORMS OVER THE HIGH TERRAIN THIS AFTERNOON, BUT
DIFFER ON WHETHER ANY ADDITIONAL STORMS WILL BE ABLE TO DEVELOP
INTO THE LOWER DESERTS AS OUTFLOWS PUSH THROUGH. THE LATEST HRRR
IS MORE OPTIMISTIC FOR LOWER DESERT REDEVELOPMENT, WHILE OTHER
HREF MEMBERS SHOW MUCH MORE LIMITED POTENTIAL. A WILDCARD THAT
COULD PLAY A ROLE IN CONVECTIVE POTENTIAL THIS EVENING IS A GULF
MOISTURE SURGE MOVING NORTHEASTWARD THROUGH SOUTHWEST ARIZONA LATE
THIS AFTERNOON/EARLY EVENING PUSHING INTO MARICOPA/WESTERN PINAL
COUNTIES AT SOME POINT EARLY TO MID EVENING. IF THE HIGH TERRAIN
STORMS AND/OR OUTFLOWS ARE LATE ENOUGH, THEY MAY INTERACT WITH THE
GULF SURGE CAUSING BETTER POTENTIAL FOR STORMS TO REDEVELOP OVER
OR NEAR THE PHOENIX METRO. AS OF RIGHT NOW, WE HAVE 20-30 POPS IN
PHOENIX THIS EVENING. GUSTY WINDS UP TO AROUND 40 MPH AND
LOCALIZED HEAVY RAINFALL WILL BE THE MAIN FORECAST CONCERNS FOR
THE AZ HIGHER TERRAIN TODAY, WHEREAS GUSTY WINDS AND PATCHY
BLOWING DUST WILL BE THE MAIN CONCERNS OVER THE LOWER DESERTS.
SCATTERED SHOWERS AND A FEW STORMS WILL REMAIN POSSIBLE ACROSS
SOUTH-CENTRAL AND EASTERN ARIZONA TONIGHT INTO TUESDAY MORNING AS
THE INVERTED TROUGH MOVES INTO WESTERN NEW MEXICO. THE REST OF
TUESDAY IS OF LOWER FORECAST CONFIDENCE AS MODELS DISAGREE ON HOW
FAST THE INVERTED TROUGH MOVES NORTHWESTWARD INTO CENTRAL AND
NORTHERN ARIZONA. DECENT MOISTURE AND INSTABILITY SHOULD STILL
EXIST ACROSS EASTERN ARIZONA LATER TUESDAY PROMOTING SIMILAR
SHOWER AND THUNDERSTORM CHANCES, BUT SOUTHERLY DRYING FLOW INTO
THE LOWER DESERTS IS LIKELY TO FURTHER INHIBIT CHANCES IN THE
PHOENIX AREA. SIMILAR TO TODAY, TUESDAY SHOULD BRING A LOCALIZED
HEAVY RAINFALL THREAT, WHILE THE GUSTY WIND THREAT SHIFTS MORE TO
THE NORTH INTO NORTHERN ARIZONA. SHOWER AND STORM CHANCES TUESDAY
AFTERNOON/EVENING OVER THE SOUTH-CENTRAL ARIZONA LOWER DESERTS ARE
LIKELY TO BE MORE LIMITED COMPARED TO TODAY WITH THE THREAT FOR
ANY IMPACTS DIMINISHING EVEN FURTHER.
HEAT IMPACTS EARLY THIS WEEK SHOULD BE FAIRLY LIMITED WITH MINOR
TO MODERATE HEATRISK THROUGH TUESDAY. FORECAST HIGHS ARE STILL
BELOW NORMAL ACROSS CENTRAL AND EASTERN ARIZONA, BUT FOR SOUTHWEST
ARIZONA AND SOUTHEAST CALIFORNIA HIGHS WILL BEGIN TO PUSH TO
ABOVE NORMAL AS EARLY AS TUESDAY. OVERNIGHT TEMPERATURES ARE
EXPECTED TO FALL WITHIN THE NORMAL RANGE WITH LOWS IN THE LOW TO
MID 80S ACROSS THE LOWER DESERTS.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
MODEL GUIDANCE IS NOW TRENDING TOWARD A NOTICEABLY LESS ACTIVE
MONSOON PERIOD DURING THE LATTER HALF OF THE WEEK, LARGELY IN PART
DUE TO THE SUBTROPICAL HIGH STRENGTHENING AND SETTING UP OVER
WEST TEXAS THROUGH OUR REGION. THE MAIN FORECAST CONCERN WILL
QUICKLY SHIFT FROM MONSOON STORMS TO EXTREME HEAT BY THURSDAY.
ENSEMBLES SHOW THE HIGH SHIFTING SOUTHWARD STARTING WEDNESDAY AND
THEN EXPANDING INTO OUR REGION THURSDAY INTO FRIDAY AS H5 HEIGHTS
OVER OUR REGION QUICKLY RISE FROM 591-593DM WEDNESDAY TO
596-598DM BY FRIDAY. SOUTHERLY DRY FLOW WILL PICK UP ACROSS OUR
AREA ON WEDNESDAY, DECREASING RAIN CHANCES FURTHER BEFORE CHANCES
LIKELY DROP BELOW 10-15% STARTING THURSDAY AS STRONG SUBSIDENCE
SPREADS OVER THE REGION.
TEMPERATURES SHOULD QUICKLY RESPOND TO THE INCREASING HEIGHTS AND
THE DECREASING MONSOON ACTIVITY LATER THIS WEEK. NBM FORECAST
HIGHS SHOW READINGS TOPPING 110 DEGREES AS EARLY AS WEDNESDAY
ACROSS SOUTHEAST CALIFORNIA AND AS EARLY AS THURSDAY ACROSS THE
ARIZONA LOWER DESERTS. AREAS OF MAJOR HEATRISK ARE EXPECTED BY
THURSDAY, LIKELY EXPANDING IN COVERAGE FRIDAY INTO THE WEEKEND AS
THE HEAT REACHES ITS PEAK. OVERNIGHT LOWS WILL ALSO BECOME AN
ISSUE AS SURFACE MOISTURE REMAINS ELEVATED ENOUGH TO CAUSE LOWS
TO ONLY DIP INTO THE UPPER 80S TO LOWER 90S BY THURSDAY. DAYTIME
HIGHS OF 113-116 DEGREES ACROSS THE WESTERN DESERTS TO 110-113
DEGREES IN THE PHOENIX AREA ARE SHOWN FOR THIS WEEKEND, WHILE HEAT
INDICES OF 115 DEGREES ARE LIKELY TO APPEAR AS EARLY AS THURSDAY
FOR THE WESTERN DESERTS. AN EXTREME HEAT WATCH IS LIKELY TO BE
ISSUED OVER THE NEXT DAY OR SO.
AVIATION
UPDATED AT 0900Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
AVIATION CONCERNS WILL REMAIN RELATIVELY LOW THROUGH AT LEAST THE
FIRST HALF OF THE TAF PERIOD BEFORE A POTENTIAL OUTFLOW BOUNDARY BRINGS
AN ABRUPT EASTERLY WIND SHIFT LATER THIS EVENING. UNTIL THEN, A FAIRLY
TYPICAL DIURNAL WIND PATTERN WILL EXIST THROUGH THIS AFTERNOON WITH
WINDS VEERING BACK AROUND TO THE W/SW BY THE LATE MORNING HOURS. GUSTS
UP TO 18-20 KTS WILL BE POSSIBLE THROUGH THIS AFTERNOON. AFTER 00Z,
CONVECTION OVER THE HIGHER TERRAIN SURROUNDING PHOENIX WILL LIKELY
SEND AN OUTFLOW INTO THE LOWER DESERTS. CONFIDENCE IN TIMING OF THIS
OUTFLOW IS STILL LOW WITH GUIDANCE SHOWING IT ARRIVING BY 02Z AT THE
EARLIEST AND AROUND 05Z AT THE LATEST. WHEN THE BOUNDARY ARRIVES,
EXPECT GUSTY EASTERLY WINDS AROUND 25-30 KTS. THERE WILL BE A LOW
CHANCE (30%) FOR ISOLATED SHOWERS AND STORMS TO DEVELOP INVOF THE
AREA TERMINALS THIS EVENING AND THUS VCTS/VCSH HAS BEEN
INTRODUCED TO THIS PACKAGE. SCT TO AT TIMES BKN MID-TO-HIGH CLOUDS
WILL BE COMMON THROUGH THE TAF PERIOD WITH LOWEST BASES AROUND
8-10 KFT AGL.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION WEATHER IMPACTS ARE EXPECTED THROUGH TONIGHT AT
THE SE CALIFORNIA TERMINALS. WINDS WILL REMAIN PREDOMINATELY SOUTHERLY
AT KBLH WITH SPEEDS REMAINING ELEVATED AROUND 10-11 KTS AND GUSTS UP
TO 20 KTS MATERIALIZING THIS AFTERNOON. AT KIPL, WINDS WILL FOLLOW
TYPICAL DIURNAL TRENDS WITH A RETURN TO S-SE WINDS BY THIS AFTERNOON
FOLLOWED BY A WESTERLY SHIFT EARLY THIS EVENING. SPOTTY VCSH MAY DEVELOP
INVOF KBLH THIS MORNING, MAINLY BETWEEN 12-18Z, BUT NO IMPACTS ARE
ANTICIPATED. FEW TO SCT CLOUDS AOA 10K FT AGL WILL BE COMMON
THROUGHOUT THE PERIOD.
FIRE WEATHER
AMPLE MOISTURE WILL BE AVAILABLE FOR ADDITIONAL ROUNDS OF SHOWERS
AND STORMS THROUGH AT LEAST TUESDAY FOR THE ARIZONA HIGHER
TERRAIN. MUCH MORE LIMITED CHANCES ARE EXPECTED OVER THE ARIZONA
LOWER DESERTS. HUMIDITIES WILL REMAIN ELEVATED WITH MINRHS MOSTLY
RANGING FROM 20-25% ACROSS THE WESTERN DISTRICTS TO 25-40% ACROSS
THE EASTERN DISTRICTS, WHILE OVERNIGHT RECOVERIES REMAIN GOOD.
OUTSIDE ANY INFLUENCES FROM SHOWERS AND THUNDERSTORMS, WINDS EARLY
THIS WEEK WILL TEND TO FAVOR THE SOUTHWEST WITH ONLY SHORT
PERIODS OF DOWNSLOPE EASTERLIES LATE AT NIGHT FOR THE EASTERN
DISTRICTS. HOTTER TEMPERATURES WITH SOME SLIGHT DRYING IS
EXPECTED DURING THE LATTER HALF OF THE WEEK AS A STRONGER HIGH
PRESSURE SYSTEM SETS UP OVER THE REGION. RAIN CHANCES WILL BE
GREATLY DIMINISHED BY THURSDAY, LIKELY LASTING THROUGH THE
UPCOMING WEEKEND.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...SALERNO
FIRE WEATHER...KUHLMAN
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