761
FXUS65 KPSR 081111
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
411 AM MST THU OCT 8 2026
UPDATE
UPDATED 12Z AVIATION DISCUSSION.
KEY MESSAGES
- DRY CONDITIONS ALONG WITH TEMPERATURES RUNNING ABOUT 10 DEGREES
ABOVE NORMAL WILL PERSIST THROUGH FRIDAY.
- AN EXTREME HEAT WARNING REMAINS IN EFFECT FOR PORTIONS OF
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA THROUGH FRIDAY AS
TEMPERATURES WARM TO NEAR RECORD LEVELS, RESULTING IN AREAS OF
MAJOR HEATRISK.
- A MUCH MORE UNSETTLED WEATHER PATTERN IS EXPECTED THIS WEEKEND
THROUGH EARLY NEXT WEEK AS A SERIES OF WEATHER SYSTEMS AFFECT
THE REGION RESULTING IN MUCH COOLER TEMPERATURES, INCREASING
WINDS, AND ELEVATED RAIN CHANCES.
SHORT TERM /TODAY THROUGH FRIDAY/
LATEST OBJECTIVE ANALYSIS SHOWS A BROAD RIDGE OF HIGH PRESSURE IN
PLACE ACROSS THE REGION WHILE A VERY WEAK SHORTWAVE IS SITUATED NEAR
THE FOUR CORNERS. THIS SHORTWAVE IN COMBINATION WITH ENOUGH MID-
LEVEL MOISTURE WILL LIKELY PRODUCE ANOTHER ROUND OF ISOLATED TO
WIDELY SCATTERED SHOWERS ACROSS THE WHITE MOUNTAINS ONCE AGAIN
FOR THIS AFTERNOON. OTHERWISE, WITH HIGH PRESSURE CONTINUING TO
REMAIN THE DOMINANT FEATURE OVER MUCH OF THE REGION, DRY
CONDITIONS WILL PERSIST THROUGH FRIDAY.
WITH 500 MB HEIGHTS RANGING BETWEEN 586-589 DAM, AFTERNOON HIGH
TEMPERATURES WILL ONCE AGAIN BE RUNNING ABOUT 10 DEGREES ABOVE
NORMAL ACROSS THE REGION AS LOWER DESERT HIGHS WILL RANGE BETWEEN
100-103 DEGREES ACROSS SOUTH-CENTRAL AZ AND 102-109 DEGREES ACROSS
THE WESTERN DESERTS. WITH TEMPERATURES NEARING DAILY RECORDS AT BOTH
YUMA AND EL CENTRO, AREAS OF MAJOR HEATRISK WILL CONTINUE AND THUS
EXTREME HEAT WARNINGS ARE IN EFFECT FOR THE IMPERIAL, LOWER COLORADO
RIVER, AND GILA RIVER VALLEYS AS WELL AS FOR YUMA. EVEN THOUGH
THE RIDGE WILL BE ON A WEAKENING PHASE HEADING INTO FRIDAY, LOW-
LEVEL THERMAL PROFILES WILL NOT CHANGE THAT MUCH AND THUS ANOTHER
DAY OF WIDESPREAD TRIPLE DIGITS WILL CONTINUE, ALTHOUGH LIKELY A
DEGREE OR TWO COOLER FROM TODAY. AREAS OF MAJOR HEATRISK WILL
CONTINUE TO BE PROMINENT ACROSS THE IMPERIAL VALLEY AND YUMA AREA
AND THUS EXTREME HEAT WARNINGS REMAIN IN EFFECT FOR THESE AREAS.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
A MAJOR PATTERN SHIFT IS STILL ON SCHEDULE FOR THE WEEKEND
THROUGH EARLY NEXT WEEK AS A TROUGHING PATTERN WILL SET UP ACROSS
MUCH OF THE WESTERN THIRD OF THE CONUS. A LARGE NORTHERN STREAM
TROUGH IS EXPECTED TO DIVE INTO THE PACIFIC NORTHWEST ON SATURDAY
BEFORE DIVING INTO CA BY SUNDAY. IN THE MEANTIME, A SHORTWAVE
TROUGH SWEEPING ACROSS THE EASTERN PACIFIC WILL PICK UP TROPICAL
STORM RACHEL WITH BOTH SYSTEMS TO BE STEERED NORTHEASTWARD OUT
AHEAD OF THE LARGE WEST COAST TROUGH. THE LATEST TRACK FORECAST
FROM THE NATIONAL HURRICANE CENTER CONTINUES TO SHOW RACHEL
TRACKING INTO THE FAR NORTHERN PART OF THE BAJA PENINSULA LATE
SATURDAY NIGHT BEFORE ACCELERATING NORTH-NORTHEASTWARD THROUGH
THE COLORADO RIVER VALLEY DURING THE DAY SUNDAY AS A POST-
TROPICAL STORM. SOUTH TO SOUTHWEST FLOW ALOFT OUT AHEAD OF THE
PACIFIC TROUGH AND TROPICAL STORM RACHEL WILL ADVECT SIGNIFICANT
MOISTURE INTO THE DESERT SOUTHWEST DURING THE DAY ON SATURDAY WITH
BOTH THE EPS AND GEFS SHOWING PWATS EXCEEDING 200-250% OF NORMAL
BY SATURDAY EVENING. THE INCREASING MOISTURE COMBINED WITH AN
UPPER- LEVEL JET STREAK MOVING THROUGH THE GREAT BASIN, INCREASING
THE UPPER-LEVEL FORCING FOR ASCENT, WILL CAUSE AREAS OF SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS TO BREAK OUT, MAINLY OVER
CENTRAL AND SOUTHERN AZ SATURDAY AFTERNOON/EVENING.
AS BOTH THE PACIFIC SHORTWAVE AND THE REMNANTS OF RACHEL MOVE
THROUGH LATE SATURDAY NIGHT THROUGH SUNDAY, EVEN DEEPER MOISTURE
WILL BE PULLED INTO THE REGION AND THIS WILL LIKELY BE THE
TIMEFRAME FOR THE BEST RAIN CHANCES ACROSS THE REGION WITH NBM
POPS AT GREATER THAN 50-60% AREA WIDE. THERE CONTINUES TO BE
QUITE A BIT UNCERTAINTY WITH THE RAINFALL AMOUNTS AS IT WILL BE
DEPENDENT ON THE EVENTUAL TRACK OF THE REMNANTS OF RACHEL AND WILL
LIKELY HAVE TO WAIT FOR THE HI-RES GUIDANCE DATA TO HAVE BETTER
CONFIDENCE ON AMOUNTS. IN ADDITION TO THE RAINFALL ACTIVITY, WINDS
WILL LIKELY BE ANOTHER HAZARD TO DEAL WITH, ESPECIALLY FOR AREAS
EAST OF THE TRACK OF RACHEL AS THE GUIDANCE IS DEPICTING 850 MB
WINDS TO EXCEED 40-50 KTS, WHICH WILL LIKELY TRANSLATE TO SURFACE
WIND GUSTS IN EXCESS OF 40 MPH. AS BOTH THE PACIFIC SHORTWAVE AND
THE REMNANTS OF RACHEL LIFT TO THE NORTH LATE SUNDAY THROUGH
MONDAY, SUBSIDENCE LEFT BEHIND WILL RESULT IN DECREASING RAIN
CHANCES DURING THIS PERIOD BEFORE CHANCES INCREASE ONCE AGAIN,
MAINLY FOR SOUTH-CENTRAL AND EASTERN AZ, ON TUESDAY AS THE LARGER
WEST COAST TROUGH PROGRESSES EASTWARD.
WITH THE TROUGHING PATTERN EXPECTED TO TAKE PLACE THIS WEEKEND
THROUGH EARLY NEXT WEEK ALONG WITH THE INCREASING CLOUD COVER AND
MOISTURE, TEMPERATURES ARE EXPECTED TO TAKE A NOSE DIVE. AFTERNOON
HIGHS ACROSS THE LOWER DESERTS WILL GO FROM THE LOW TO MID 90S ON
SATURDAY TO LOW 80S ON MONDAY, WITH MANY AREAS TUESDAY AND WEDNESDAY
LIKELY TOPPING OUT IN THE 70S.
AVIATION
UPDATED AT 1110Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
NO WEATHER CONCERNS WILL EXIST THROUGH THE TAF PERIOD UNDER
OCCASIONAL MIDLEVEL CLOUD DECKS. CONFIDENCE IS VERY GOOD THAT
LIGHT EAST WINDS WILL PREVAIL THROUGH MID/LATE AFTERNOON BEFORE
ATTEMPTING TO BECOME W/SW. HOWEVER, THIS SWITCH MAY NOT COMPLETED,
AND A VARIABLE COMPONENT MAY OCCUR FOR SEVERAL HOURS BEFORE
REVERTING BACK TO EASTERLY LATE THIS EVENING.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO WEATHER CONCERNS WILL EXIST THROUGH THE TAF PERIOD UNDER CLEAR
SKIES. EXTENDED PERIODS OF LIGHT AND VARIABLE WINDS WILL PERSIST
WITH A GENERAL TREND FOR DIRECTIONS TO VARY BETWEEN NORTHWESTERLY
(MAINLY AT KBLH) AND WESTERLY (MAINLY AT KIPL).
FIRE WEATHER
DRY CONDITIONS ALONG WELL-ABOVE NORMAL TEMPERATURES WILL CONTINUE
THROUGH FRIDAY AS LOWER DESERT HIGHS REACH INTO THE TRIPLE
DIGITS. WINDS TODAY GENERALLY BE LIGHT AND DIURNALLY DRIVEN
BEFORE INCREASING FRIDAY AND INTO THE WEEKEND. AFTERNOON MINRHS
THROUGH FRIDAY WILL RANGE BETWEEN 15-25% WITH FAIR TO GOOD
OVERNIGHT RECOVERIES (35-60%). A MUCH MORE UNSETTLED WEATHER
PATTERN IS EXPECTED THIS WEEKEND THROUGH EARLY NEXT WEEK AS A
SERIES OF WEATHER SYSTEMS AFFECT THE AREA WITH MUCH COOLER
TEMPERATURES ALONG WITH INCREASING MOISTURE AND CHANCES FOR
WETTING RAINFALL.
CLIMATE
RECORD HIGHS:
DATE YUMA EL CENTRO
---- ---- ---------
OCT 8 107 IN 1996 106 IN 1996
OCT 9 106 IN 2024104 IN 1996
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST FRIDAY FOR AZZ532.
EXTREME HEAT WARNING FROM 10 AM THIS MORNING TO 8 PM MST THIS
EVENING FOR AZZ530-536.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT FRIDAY FOR CAZ566-567.
EXTREME HEAT WARNING FROM 10 AM THIS MORNING TO 8 PM PDT THIS
EVENING FOR CAZ569-570.
SHORT TERM...LOJERO
LONG TERM...LOJERO
AVIATION...BERISLAVICH/18
FIRE WEATHER...LOJERO
CLIMATE...RW
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