863
FXUS65 KPSR 240847
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
147 AM MST THU SEP 24 2026
KEY MESSAGES
- SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE AGAIN THIS
AFTERNOON AND EVENING, WITH ACTIVITY MAINLY FOCUSED OVER THE
FOOTHILLS AND HIGH TERRAIN FEATURES.
- AFTER DRYING OUT TEMPORARILY THIS WEEKEND, RAIN CHANCES WILL RETURN
TO THE REGION LATE SUNDAY INTO MONDAY AS TROPICAL MOISTURE GETS
PULLED NORTHWARD INTO THE DESERT SOUTHWEST.
- NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES WILL PERSIST THROUGH
THE WEEKEND BEFORE NOTICEABLY COOLING EARLY NEXT WEEK.
SHORT TERM /TODAY THROUGH FRIDAY/
STORM COVERAGE WAS MUCH LOWER THAN HIGH-RES MODELS INDICATED LAST
NIGHT WHICH WAS MAINLY DUE TO LOWER INSTABILITY AND A STRONGER
CAP IN PLACE FROM EXTENSIVE CLOUD COVER OVER SOUTHCENTRAL AZ.
LATEST WV SATELLITE IMAGERY AND AREA RADARS STILL SHOW ABUNDANT
HIGH CLOUDS STREAMING INTO AZ WITH SHOWERS AND THUNDERSTORMS
PERCOLATING OVER SOUTHERN PORTIONS OF THE STATE. ALL OF THIS
ACTIVITY IS DEVELOPING AHEAD OF A COASTAL LOW PRESSURE SYSTEM
LOCATED WEST OF THE BAJA CALIFORNIA (NOT RELATED TO THE HURRICANES
MUCH FARTHER SOUTH). AS WE HEAD THROUGH THIS MORNING, SEVERAL
LOBES OF VORTICITY WILL PROGRESS NORTHWARD OUT OF MX AND PROVIDE A
FOCUS OF LIFT FOR ADDITIONAL SHOWERS AND STORMS THIS AFTERNOON
INTO THIS EVENING.
IT IS DIFFICULT TO PINPOINT EXACTLY WHERE THESE VORTMAXES WILL END
UP MOVING AS SOME MODELS FOCUS CONVECTIVE ACTIVITY OVER THE WESTERN
DESERTS THIS AFTERNOON WHILE OTHERS BRING STORMS INTO CENTRAL AZ.
EITHER WAY, THERE WILL LIKELY BE ANOTHER ROUND OF WIDELY SCATTERED
CONVECTION THIS AFTERNOON, ESPECIALLY OVER THE TERRAIN FEATURES OF
SOUTHWEST AZ AND THE FOOTHILLS AND HIGHER TERRAIN AREAS NE OF
PHOENIX. THERE IS STILL AROUND A 20-30% CHANCE THAT STORMS FORM OVER
THE LOWER DESERTS, BUT THIS WILL BE HIGHLY DEPENDENT ON IF ACTIVITY
ACROSS THE HIGHER TERRAIN CAN CONGEAL ENOUGH TO PRODUCE STRONG
OUTFLOWS WHICH COULD GENERATE ADDITIONAL CONVECTION. INSTABILITY
WILL NOT BE AS HIGH AS YESTERDAY (SBCAPE < 1000 J/KG) BUT THERE
STILL COULD BE A STRONG STORM OR TWO WHICH COULD PRODUCE LOCALLY
GUSTY WINDS AND PATCHY BLOWING DUST. THE COASTAL LOW WILL WEAKEN
AND LIFT NORTHWARD ON FRIDAY WHICH WILL CAUSE UPPER-LVL WINDS TO
SHIFT OUT OF THE WEST AND BRING MUCH DRIER AIR INTO OUR REGION.
COINCIDENTALLY, POPS WILL DECREASE BELOW 10% ACROSS THE ENTIRE
REGION ON FRIDAY.
THE PRESENCE OF THE UPPER-LOW OVER THE NEXT COUPLE OF DAYS PROMOTING
NEAR SEASONAL 500 MB HGHTS, COUPLED WITH PERIODS OF EXTENSIVE HIGH
CLOUDS WILL HELP KEEP TEMPERATURES NEAR NORMAL ACROSS SOUTHCENTRAL
AZ. HIGHS ACROSS THE LOWER DESERTS OF CENTRAL AZ WILL LIKELY
REMAIN IN THE MID TO UPPER 90S BOTH TODAY AND FRIDAY. TEMPERATURES
ALONG AND WEST OF THE COLORADO RIVER VALLEY WILL BE SLIGHTLY
WARMER WITH HIGHS REACHING THE LOWER 100S. OVERALL, THE HEATRISK
SHOULD REMAIN IN THE MINOR CATEGORY WITH ONLY VERY SMALL POCKETS
OF MODERATE.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
DRY WESTERLY FLOW IS EXPECTED TO PERSIST THROUGH AT LEAST
SATURDAY WITH LARGE SCALE TROUGHING REMAINING OVER THE PAC NW
WHILE THE SUBTROPICAL RIDGE SLOWLY SHIFTS SOUTHWESTWARD FROM EAST
TX INTO THE INTERIOR OF MX. DUE TO THE PRESENCE OF THE RIDGE TO
OUR EAST, 500 MB HGHTS ARE EXPECTED TO PEAK AROUND 586-588 DAM
SATURDAY AFTERNOON. THIS WILL RESULT IN HIGHS TOPPING OUT BETWEEN
100-105 DEGREES ACROSS THE LOWER DESERTS (4-6 DEGREES ABOVE
NORMAL) UNDER MOSTLY SUNNY SKIES AND ZERO CHANCE OF RAIN. FROM
SUNDAY INTO EARLY NEXT WEEK, THERE DOES LOOK TO BE A SIGNIFICANT
DEGREE OF COOLING AS TROPICAL MOISTURE ARRIVES AND RAIN CHANCES
INCREASE. HIGHS WILL LIKELY FALL BELOW 100 DEGREES ACROSS THE
LOWER DESERTS ON SUNDAY AND CONTINUE TO COOL TO THE UPPER 80S AND
LOWER 90S MONDAY THROUGH WEDNESDAY.
OUR ATTENTION THEN TURNS TO THE TROPICAL PACIFIC SUNDAY INTO EARLY
NEXT WEEK WHERE POTENTIAL MOISTURE FROM TWO WEAKENING HURRICANES
(POLO AND ODALYS) WILL COME INTO PLAY. THERE IS STILL A HIGH DEGREE
OF UNCERTAINTY AS TO A) HOW FAR NORTH THE RESIDUAL MOISTURE WILL BE
SHED OUT AHEAD OF THESE DECAYING STORMS, AND B) WHERE THE PLUME(S)
OF MOISTURE WILL SET UP. ANOTHER MAJOR QUESTION MARK WILL BE JUST
HOW DEEP AND PROGRESSIVE A DEVELOPING TROUGH OF LOW PRESSURE WILL BE
OVER THE INTERMOUNTAIN WEST. ALL OF THESE FACTORS WILL HAVE TO LINE
UP PERFECTLY FOR OUR FORECAST AREA TO GET SIGNIFICANT RAINFALL.
BOTH THE GEFS AND EPS ARE TELLING A DIFFERENT STORY WITH VARYING
DEGREES OF MOISTURE AND TIMING AND INTENSITY OF SAID TROUGH WHICH
IS REALLY COMPLICATING THINGS. THE LATEST NHC TRACK FOR HURRICANE
POLO SHOWS THE STORM MAKING LANDFALL ALONG THE COAST OF THE BAJA
CALIFORNIA BY MONDAY WHICH IF ALIGNED WITH THE PASSAGE OF THE
AFOREMENTIONED TROUGH WOULD DRAW A LARGE PLUME OF MOISTURE INTO
INTERIOR MX AND AND MUCH OF AZ. NBM POPS HAVE ALREADY INCREASED TO
AROUND 20-30% WITH AN INITIAL BAND OF MOISTURE ON SUNDAY, BUT
WITH THE MAIN LIFT ARRIVING ON MONDAY, POPS ARE NOW WIDESPREAD
30-60% ACROSS OUR FORECAST AREA. THE REMNANT TROPICAL MOISTURE MAY
LINGER INTO TUESDAY BEFORE FULLY EXITING THE REGION ON WEDNESDAY.
IT IS ALSO WORTH POINTING OUT THAT SOME ENSEMBLE MEMBERS ARE
SHOWING SIGNIFICANT RAINFALL TOTALS IN EXCESS OF 1-2" ACROSS
SOUTHCENTRAL AZ MONDAY-TUESDAY BUT THERE IS STILL SIGNIFICANT
SPREAD BETWEEN MEMBERS. THEREFORE, WE WILL LIKELY HAVE TO WAIT
UNTIL THIS WEEKEND FOR THINGS TO BECOME MORE CLEAR.
AVIATION
UPDATED AT 0534Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
THERE WILL BE POTENTIAL FOR SHRA/TSRA AND VARIABLE WINDS THURSDAY,
BUT OVERALL FORECAST CONFIDENCE IN THIS POTENTIAL AND TIMING
THINGS OUT IS LOW. ISOLATED TO SCATTERED SHOWERS MAY DEVELOP
IN/MOVE INTO THE METRO FROM THE SOUTH LATER THURSDAY
MORNING/MIDDAY. THIS IS REFLECTED WITH VCSH IN THE TAFS IN THE
MORNING. SHRA/TSRA MAY THEN DEVELOP IN THE METRO LATER IN THE
AFTERNOON-EVENING TIMEFRAME, BUT CHANCES WILL BE HIGHER OUTSIDE
THE METRO AREA. ACTIVITY AROUND THE REGION WILL BE CAPABLE OF
PRODUCING SEVERAL OUTFLOW BOUNDARIES WHICH MAY CAUSE ERRATIC WIND
BEHAVIOR AND OUTFLOW COLLISIONS COULD LEAD TO NEW DEVELOPMENT.
WINDS TONIGHT THROUGH THURSDAY MORNING WILL CONTINUE TO FAVOR AN
E/SE COMPONENT WITH LIGHT SPEEDS. CONFIDENCE IN WINDS THEN
DEGRADES FROM THERE WITH WINDS POTENTIALLY INFLUENCED BY SHOWERS
AND/OR CLOUD COVER THROUGH THE AFTERNOON AND EVENING. THICK HIGH
CIRRUS CIGS AND BRIEF PERIODS OF CIGS AS LOW AS 8-10K FT AGL WILL
CONTINUE THROUGH THE TAF PERIOD.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
THERE IS A LOW CHANCE (10%) FOR VCTS/TS AT KBLH THURSDAY
AFTERNOON. OTHERWISE, NO WEATHER ISSUES ARE EXPECTED THROUGH
THURSDAY EVENING UNDER INCREASING HIGH CIRRUS DECKS. CONFIDENCE
IN A SPECIFIC WIND DIRECTION AT ANY GIVEN TIME IS LOW GIVEN THE
WEAK PRESSURE GRADIENT. EXTENDED PERIODS OF LIGHT AND VARIABLE
WINDS WILL BE COMMON.
FIRE WEATHER
WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE AGAIN
THIS AFTERNOON AND EARLY EVENING, MAINLY FOCUSED OVER THE HIGHER
TERRAIN OF THE EASTERN DISTRICTS. LOCALIZED GUSTY AND ERRATIC
WINDS WILL BE POSSIBLE IN THE VICINITY OF ANY STORM THAT DEVELOPS.
RAIN CHANCES WILL DECREASE FRIDAY INTO THIS WEEKEND BEFORE MUCH
BETTER CHANCES FOR WETTING RAINFALL ARRIVES EARLY NEXT WEEK.
MINRHS WILL RANGE FROM 25-35% TODAY WITH A GRADUAL DECREASE TO
AROUND 15-25% ON REGION-WIDE SATURDAY. SIGNIFICANT MOISTURE RETURN
IS EXPECTED ACROSS THE EASTERN DISTRICTS BY MONDAY WHICH WILL
KEEP RH VALUES ABOVE 40% WITH EXCELLENT OVERNIGHT RECOVERY. WINDS
WILL GENERALLY FOLLOW DIURNAL PATTERNS WITH SPEEDS AROUND 10-15
MPH WITH TYPICAL AFTERNOON GUSTS IN THE UPPER TEENS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...SALERNO
LONG TERM...SALERNO
AVIATION...BENEDICT/18
FIRE WEATHER...SALERNO
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