231
FXUS65 KPSR 181117
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
417 AM MST FRI SEP 18 2026
UPDATE
UPDATED 12Z AVIATION DISCUSSION.
KEY MESSAGES
- DRY AND TRANQUIL CONDITIONS ARE EXPECTED THROUGH THIS WEEKEND
WITH NEAR ZERO RAIN CHANCES.
- NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES ARE EXPECTED THROUGH
AT LEAST THIS WEEKEND, WITH AFTERNOON TEMPERATURES NEAR 100
DEGREES ACROSS THE LOWER DESERTS.
- A LOW PRESSURE SYSTEM AND MOISTURE RETURN EARLY NEXT WEEK WILL
BRING A RETURN OF RAIN CHANCES TO AT LEAST THE HIGH TERRAIN OF
NORTHERN AND EASTERN ARIZONA.
SHORT TERM /TODAY THROUGH SUNDAY/
DRYING CONDITIONS WITH NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES
ARE EXPECTED TODAY THROUGH THIS WEEKEND. IT IS STILL MUGGY AT THE
SURFACE IN SOUTH-CENTRAL AZ, INCLUDING PHOENIX, WITH DEW POINT
TEMPERATURES IN THE 60S TO NEAR 70 DEGREES EARLY THIS MORNING, BUT
DRY AIR HAS MOVED IN ALOFT, WHICH IS PARTLY WHY THERE WERE NO
ADDITION SHOWERS AND STORMS THURSDAY AFTER THE VERY WET WEDNESDAY.
PWATS AT MIDNIGHT YESTERDAY WERE AROUND 1.7-1.9", BUT HAVE SINCE
DROPPED TO 1.0-1.2" AND WILL CONTINUE FALLING TODAY THROUGH
SATURDAY. SURFACE MOISTURE WILL ALSO STEADILY SCOUR OUT TODAY
THROUGH SATURDAY, FALLING INTO THE 50S BY THIS EVENING AND INTO
THE 40S BY SATURDAY EVENING IN SOUTH-CENTRAL AZ. IT WILL BE EVEN
DRIER WEST OF PHOENIX. THE ABUNDANT DRY AIR THAT WILL BE MOVING
THROUGH CAN BE SEEN UPSTREAM ON WATER VAPOR SATELLITE IMAGERY.
SATELLITE ALSO SHOWS A SHORTWAVE MOVING THROUGH SOUTHEAST AZ,
WHICH MAY PROVIDE JUST ENOUGH FORCING TO SPARK ISOLATED SHOWERS
AND STORMS IN THE WHITE MTNS THIS MORNING AND EARLY THIS
AFTERNOON, POSSIBLY CLIPPING PORTIONS OF SOUTHEASTERN GILA COUNTY.
THERE IS ALSO A BROAD UPPER LEVEL LOW SITUATED OVER THE NORTHWEST
CONUS. THIS LOW WILL GRADUALLY TRACK EASTWARD THROUGH THIS
WEEKEND AND HELP SUPPRESS H5 HEIGHTS OVER THE DESERT SOUTHWEST AND
THUS MODERATING THE TEMPERATURES. TEMPERATURES WILL BE NEARLY THE
SAME EACH DAY, WITH MORNING LOWS IN THE 70S AND AFTERNOON HIGHS
AROUND 97-103 DEGREES ACROSS THE LOWER DESERTS. NORMAL HIGHS ARE
RIGHT AROUND 100 DEGREES FOR MID-SEPTEMBER. THESE TEMPERATURES
WILL BE A NICE REPRIEVE, ESPECIALLY THE MORNINGS, BUT WILL STILL
RESULT IN MINOR HEATRISK.
LONG TERM /MONDAY THROUGH THURSDAY/
HEADING INTO EARLY NEXT WEEK, THERE IS GOOD CONFIDENCE THAT A
PACIFIC LOW WILL MOVE TO THE CENTRAL/SOUTHERN COAST OF CALIFORNIA
BY THE END OF THE DAY MONDAY. EXACTLY HOW THIS LOW EVOLVES ONCE
REACHING THE COAST IS STILL A LITTLE UNCERTAIN, BUT LATEST
MODEL CONSENSUS SUGGESTS THE LOW WILL TRACK ENE INLAND STAYING
MOSTLY NORTH OF THE LOCAL AREA AND DRIVING A CHANCE FOR SHOWERS
AND STORMS ACROSS NORTHERN AZ. CONCEPTUALLY THIS IS NOT A BAD
SETUP FOR A TRANSITIONAL SEVERE WEATHER EVENT, WITH POTENTIAL
FRONTOGENETICAL FORCING AND A MODERATELY STRONG UPPER LEVEL JET
WITH HIGHER SHEAR, BUT REBOUNDING QUICKLY FROM THE VERY DRY AIR
THIS WEEKEND AND GETTING SUFFICIENT MOISTURE IN HERE TO SUPPORT
ANY LOWER DESERT RAIN CHANCE WILL BE TOUGH. MODEL GUIDANCE DOES AT
LEAST SUPPORT A SLOW RETURN OF MOISTURE MONDAY THROUGH NEXT WEEK,
MORE SO COMING FROM THE SOUTHEAST LIKE TYPICAL EARLY STAGES OF
THE MONSOON. MODEL GUIDANCE IS ALSO POINTING TOWARD A STRONG RIDGE
DEVELOPING THROUGH THE MIDDLE OF THE U.S. WITH THE SUBTROPICAL
HIGH RESTRENGTHENING NEAR/OVER TEXAS BY MID TO LATE WEEK. THIS
WOULD KEEP THE DESERT SOUTHWEST UNDER PREDOMINANT SOUTHWEST FLOW
WHICH IS NOT THE MOST IDEAL SETUP FOR LOWER DESERT STORM CHANCES,
ESPECIALLY NOT FOR SOUTHEAST CA AND SOUTHWEST AZ. LATEST NBM
FORECAST HAS POPS FOCUSED PRIMARILY ACROSS NORTHERN AND EASTERN AZ
EACH DAY NEXT WEEK WITH ONLY MINOR (10-20%) POPS FOR SOUTH-
CENTRAL AZ LOWER DESERTS IN THE EVENINGS. THE ONE THING THIS
PATTERN DOES OPEN THE DOOR FOR, THE LONGER IT PERSISTS, IS
POTENTIAL EASTERN PACIFIC TROPICAL MOISTURE ADVECTING NORTH.
TEMPERATURES THROUGH NEXT WEEK WILL MOSTLY STAY THE SAME DAY-TO-
DAY, WITH HIGHS IN THE UPPER 90S TO LOWER 100S, WHICH WILL BE AROUND
2-5 DEGREES ABOVE NORMAL, AND LOWS REMAINING MOSTLY IN THE 70S.
THE TEMPERATURES WILL LEAD TO WIDESPREAD MINOR HEATRISK THROUGH
AT LEAST THE FIRST HALF OF THE WEEK WITH A TREND TOWARD AREAS OF
MODERATE HEATRISK BY THE SECOND HALF OF THE WEEK AS MORNING LOW
TEMPERATURES CREEP BACK UP.
AVIATION
UPDATED AT 1115Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
NO MAJOR AVIATION CONCERNS ARE EXPECTED DURING THE TAF PERIOD
UNDER MOSTLY CLEAR SKIES. WINDS WILL TEND TO FOLLOW LIGHT AND
DIURNAL TENDENCIES WITH A SLOW TURN TO WESTERLY WINDS THIS
AFTERNOON AND A BRIEF PERIOD OF SOUTHERLY WINDS EXPECTED. WIND
SPEEDS WILL GENERALLY AOB 10 KT.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION CONCERNS ARE EXPECTED DURING THE NEXT 24 HOURS UNDER
MOSTLY CLEAR SKIES. OUTSIDE OF EXTENDED PERIODS OF VRB CONDITIONS,
W/NW WINDS WILL BE FAVORED AT KIPL, WHILE KBLH WILL FAVOR WINDS
OUT OF THE S/SW. WIND SPEEDS WILL BE AOB 10 KT.
FIRE WEATHER
OVERALL THERE ARE NO FIRE WEATHER CONCERNS THROUGH THE NEXT WEEK.
A DRYING TREND WILL CONTINUE TODAY THROUGH THIS WEEKEND. WITH NO
RAIN EXPECTED THROUGH AT LEAST THE START OF NEXT WEEK. MINIMUM RH
VALUES THIS AFTERNOON WILL BE AROUND 20-35% ACROSS SOUTH-CENTRAL
AZ TO 10-20% ACROSS SOUTHEAST CA AND SOUTHWEST AZ. THE MINIMUM RHS
WILL THEN DIP TO 10-20% FOR NEARLY ALL AREAS THIS WEEKEND.
OVERNIGHT RECOVERIES ACROSS SOUTH-CENTRAL AZ WILL STILL BE GOOD
TONIGHT AT 45-75%, BUT THEN FALLS LOWER THIS WEEKEND. THERE WILL
BE A GRADUAL RETURN OF MOISTURE NEXT WEEK, BEST ACROSS EASTERN AZ
AND THERE WILL BE AN INCREASE IN RAIN CHANCES AGAIN, BUT AS OF NOW
RAIN CHANCES LOOK TO PRIMARILY FAVOR NORTHERN AND EASTERN AZ HIGH
TERRAIN. BESIDES A POTENTIAL INCREASE IN BREEZINESS EARLY NEXT
WEEK WITH A WEATHER SYSTEM, WINDS WILL MOSTLY FOLLOW TYPICAL
DIURNAL PATTERNS WITH MODEST AFTERNOON UPSLOPE/UPVALLEY GUSTINESS
(15-25 MPH).
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...BENEDICT
LONG TERM...BENEDICT
AVIATION...BERISLAVICH/RW
FIRE WEATHER...BENEDICT
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