628
FXUS65 KPSR 090929
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
229 AM MST MON FEB 9 2026
KEY MESSAGES
- WELL ABOVE NORMAL TEMPERATURES WILL PERSIST THROUGH TUESDAY,
RESULTING IN AREAS OF MINOR HEATRISK ACROSS THE LOWER ELEVATIONS.
- A PATTERN CHANGE MID TO LATE WEEK WILL LEAD TO COOLER TEMPERATURES
AND INCREASING RAIN CHANCES, PARTICULARLY ACROSS THE EASTERN HALF OF
ARIZONA.
- WEATHER CONDITIONS WILL BRIEFLY TURN MORE TRANQUIL OVER THE
UPCOMING WEEKEND BEFORE BECOMING MORE UNSETTLED ONCE AGAIN EARLY
NEXT WEEK AS ANOTHER STORM SYSTEM POTENTIALLY IMPACTS THE REGION.
SHORT TERM /TODAY THROUGH WEDNESDAY/
EARLY MORNING WATER VAPOR SATELLITE IMAGERY SHOWS A CUTOFF LOW WELL
TO THE SOUTH NEAR THE CENTRAL/SOUTHERN BAJA PENINSULA WHILE ACROSS
THE REGION, RIDGING CONTINUES TO HOLD WITH 500 MB HEIGHT FIELDS NEAR
580DM. THE OVERALL UPPER-AIR PATTERN FOR TODAY WILL REMAIN UNCHANGED
WITH RIDGING PREVAILING OVER THE REGION AS THE CUTOFF REMAINS NEARLY
STATIONARY OVER THE CENTRAL/SOUTHERN BAJA PENINSULA. WITH 850 MB
TEMPERATURES EXPECTED TO REMAIN AROUND 15-16C ACROSS THE REGION,
AFTERNOON HIGH TEMPERATURES WILL ONCE AGAIN REACH THE MIDDLE 80S
ACROSS MOST OF THE LOWER DESERT COMMUNITIES, WITH A 40% CHANCE OF
PHOENIX SKY HARBOR ONCE AGAIN POTENTIALLY TYING A DAILY HIGH, WHICH
IS 86 DEGREES LAST SET IN 2016. ON TUESDAY, THE PATTERN BEGINS TO
SHIFT AS AN UPPER TROUGH BEGINS TO ENCROACH THE WEST COAST, WHICH
WILL ALLOW THE CUTOFF LOW OVER THE BAJA PENINSULA TO FINALLY EJECT
MORE QUICKLY TO THE EAST-NORTHEAST THROUGH NORTHERN MEXICO AND INTO
WESTERN TEXAS. THE APPROACHING UPPER TROUGH WILL ALSO BEGIN TO LOWER
HEIGHTS ALOFT AND INCREASE MID TO UPPER-LEVEL CLOUDS, WHICH WILL
LOWER AFTERNOON HIGHS BY ABOUT 5 DEGREES FROM TODAY WITH READINGS
NEAR 80 DEGREES ACROSS THE LOWER DESERTS. WITH THE WELL-ABOVE
NORMAL AFTERNOON HIGH TEMPERATURES CONTINUING THROUGH TUESDAY,
MINOR HEATRISK WILL BE COMMON ACROSS THE LOWER DESERTS. AS A
RESULT, IF SPENDING TIME OUTDOORS FOR A PROLONGED STRETCH, MAKE
SURE TO FREQUENTLY HYDRATE AND TAKE BREAKS IN THE SHADE.
THE UPPER TROUGH WILL MOVE ONSHORE INTO CENTRAL CA LATE TUESDAY
NIGHT THROUGH WEDNESDAY WHILE ON A WEAKENING PHASE WITH MOST OF
THE ASSOCIATED PVA MOVING THROUGH THE GREAT BASIN. WHILE MOST OF
THE FORCING ASSOCIATED WITH THE TROUGH IS EXPECTED TO REMAIN TO
THE NORTH OF THE REGION, MOISTURE LEVELS ARE EXPECTED TO INCREASE
IN THE MID TO UPPER-LEVELS AND THUS A FEW SHOWERS WITH THE
UPSLOPE FLOW MAY BE SQUEEZED OUT LATE TUESDAY NIGHT INTO EARLY
WEDNESDAY ACROSS THE HIGHER TERRAIN AREAS NORTH AND EAST OF
PHOENIX. THIS SCENARIO IS SUPPORTED BY SOME OF THE HI-RES MODELS,
WITH NBM POPS AROUND 20%. NEVERTHELESS, ANY SHOWERS THAT DO
DEVELOP SHOULD BE SHORT-LIVED WITH LITTLE TO NO ACCUMULATIONS.
AFTERNOON HIGH TEMPERATURES ON WEDNESDAY WILL LOWER A BIT MORE BUT
STILL REMAIN ABOVE NORMAL WITH READINGS IN THE MIDDLE TO UPPER
70S ACROSS THE LOWER DESERTS.
LONG TERM /THURSDAY THROUGH SUNDAY/
WEATHER CONDITIONS WILL REMAIN UNSETTLED HEADING TOWARDS THE END OF
THE WEEK AS ANOTHER TROUGHING FEATURE AFFECTS THE REGION. THE LATEST
MODEL GUIDANCE SHOWS THE TROUGH MOVING THROUGH LATE THURSDAY INTO
FRIDAY. THERE IS STILL SOME UNCERTAINTY IN TERMS OF THE OVERALL
STRENGTH OF THE TROUGH AS IT PASSES BY, HOWEVER, THE LATEST TRENDS
FROM THE GUIDANCE DOES SHOW THE TROUGH RATHER PROGRESSIVE AND
POSITIVELY TILTED, WHICH IS NOT AN IDEAL SETUP FOR GOOD MOISTURE
ADVECTION AND THUS WIDESPREAD RAIN POTENTIAL. THEREFORE, ANY
PRECIPITATION POTENTIAL WILL BE MAINLY CONFINED ACROSS THE EASTERN
AZ HIGHER TERRAIN AREAS, WHERE NBM POPS ARE BETWEEN 30-60% DURING
THE DAY FRIDAY. WITH THE TROUGH PASSAGE, AFTERNOON HIGH
TEMPERATURES ON FRIDAY WILL COOL DOWN TO AROUND 70 DEGREES ACROSS
THE SOUTH-CENTRAL AZ LOWER DESERTS (WHICH IS RIGHT AROUND SEASONAL
NORMS) TO THE MIDDLE 70S ACROSS THE WESTERN DESERTS.
AFTER THE TROUGH EXITS TO THE EAST, MORE TRANQUIL WEATHER SETTLES IN
OVER THE WEEKEND AS A TRANSIENT RIDGE MOVES OVERHEAD WITH DRY
CONDITIONS AND TEMPERATURES SLIGHTLY WARMING UP. THE TRANQUIL
WEATHER WILL LIKELY BE SHORT-LIVED AS BOTH THE DETERMINISTIC AND
ENSEMBLE MODEL SUITE CONTINUE TO BE CONSISTENT IN INDICATING A
MORE POTENT TROUGHING FEATURE SETTING UP EARLY NEXT WEEK ACROSS
THE WESTERN CONUS, WHICH IF THE OVERALL TRAJECTORY IS IDEAL, COULD
LEAD TO MORE WIDESPREAD PRECIPITATION CHANCES ACROSS THE DESERT
SOUTHWEST. GIVEN THAT THIS POTENTIAL STORM SYSTEM IS STILL ABOUT A
WEEK OUT, THERE IS A GOOD DEAL OF UNCERTAINTY ON HOW THINGS WILL
PLAY OUT WITH THE PRECIPITATION POTENTIAL AND IS SOMETHING THAT
WILL HAVE TO BE MONITORED THROUGHOUT THE WEEK.
AVIATION
UPDATED AT 0500Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT; AND
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION WEATHER CONCERNS UNDER MOSTLY CLEAR SKIES CAN BE
EXPECTED THROUGHOUT THE TAF PERIOD. THE OVERALL WIND PATTERN WILL
EXHIBIT LIGHT AND DIURNAL TENDENCIES WITH EXTENDED PERIODS OF
VARIABLE TO CALM CONDITIONS. WINDS SPEEDS AT ALL TERMINALS WILL
GENERALLY BE AOB 8 KT.
FIRE WEATHER
WELL-ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS WILL PERSIST
EARLY THIS WEEK. MINRH VALUES WILL RANGE BETWEEN 10-20% TODAY
BEFORE INCREASING TO 20-35% ON TUESDAY. BY MID TO LATE WEEK, A
PATTERN CHANGE IS EXPECTED THAT WILL COOL TEMPERATURES SEVERAL
DEGREES (ALTHOUGH REMAINING ABOVE NORMAL) AND MAINTAIN MINRHS
ABOVE 20%. WINDS WILL REMAIN VERY LIGHT TODAY, WITH OCCASIONAL
BREEZINESS EXPECTED THE REST OF THE WEEK. A WEATHER SYSTEM LATE IN
THE WEEK WILL BRING A 20-50% CHANCE OF WETTING RAINS OVER THE
HIGHER TERRAIN AREAS OF THE EASTERN DISTRICTS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...LOJERO
LONG TERM...LOJERO
AVIATION...BERISLAVICH/RW
FIRE WEATHER...LOJERO
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