855
FXUS65 KPSR 132018
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
118 PM MST TUE OCT 13 2026
KEY MESSAGES
- LINGERING RAIN CHANCES MAINLY ACROSS ARIZONA HIGH TERRAIN THIS
AFTERNOON BEFORE ENDING COMPLETELY THIS EVENING.
- BELOW NORMAL TEMPERATURES ARE FORECAST THROUGH WEDNESDAY BEFORE
CREEPING BACK INTO THE NORMAL RANGE LATE WEEK.
- BREEZY TO WINDY CONDITIONS WILL IMPACT THE WESTERN DESERTS
THROUGH THURSDAY BEFORE SPREADING ACROSS THE REST OF SOUTHERN
AND CENTRAL ARIZONA BY FRIDAY. ADVISORY LEVEL WINDS WILL BE
POSSIBLE BY FRIDAY, PARTICULARLY ACROSS SOUTHEAST ARIZONA.
SHORT TERM /TODAY THROUGH WEDNESDAY/
SCATTERED LIGHT TO MODERATE RAIN SHOWERS WERE CONTINUING TO FALL
THIS MORNING ACROSS SOUTH-CENTRAL AZ AND A LOT OF THE AREA WAS
LOCKED UNDER THICK LOW-LEVEL CLOUDS. SOUNDINGS FROM THE PHOENIX
AREA THIS MORNING SHOWED A NEARLY FULLY SATURATED LAYER FROM THE
SURFACE TO 700MB. ABOVE 700MB THERE IS A LOT OF DRY AIR. THIS
MOISTURE HAS BEEN TRAPPED BELOW 700MB FOR THE PAST COUPLE DAYS AND
THE PERSISTENT S-SW FLOW HAS CONTINUED TO SUPPORT MODEST UPSLOPE
ASCENT FOR SHOWERS TO CONTINUOUSLY DEVELOP. MOST HI-RES MODELS
HAVE SHOWERS SHIFTING EAST OF THE PHOENIX AREA FOR THE AFTERNOON
AND EVENING, FOCUSING OVER THE HIGHER TERRAIN AREAS, BUT AN
ISOLATED SHOWER STILL CANNOT BE RULED OUT ACROSS PHOENIX THROUGH
4-6 PM THIS EVENING. HEADING INTO THIS EVENING AND TONIGHT THE
LAYER BELOW 700MB WILL FINALLY DRY OUT AS A DRY COLD FRONT MOVES
THROUGH, ASSOCIATED WITH A LOW PRESSURE SYSTEM THAT WILL PASS
THROUGH NORTHERN AZ (CURRENTLY OVER SOUTHERN NV). THE RAIN AND
CLOUDS HAVE STUCK AROUND A BIT LONGER THAN INITIALLY THOUGHT AND
AS A RESULT TEMPERATURES ARE A BIT COOLER. TEMPERATURES IN THE
PHOENIX AREA AT NOON WERE STILL IN THE MID AND UPPER 60S ACROSS
EASTERN AREAS TO LOW 70S ACROSS WESTERN AREAS. MOST OF PHOENIX
WILL LIKELY FAIL TO REACH 80 DEGREES THIS AFTERNOON, ESPECIALLY
THE LONGER THE CLOUDS CAN STICK AROUND.
AS MENTIONED, A DRY FRONT WILL SWEEP THROUGH THE AREA THIS EVENING
AND TONIGHT, WHICH ELIMINATE SHOWER CHANCES ACROSS THE ENTIRE
LOCAL AREA BY MIDNIGHT. THIS FRONT AND THE PASSING LOW PRESSURE
SYSTEM WILL ALSO BRING SOME COOLER AIR THAT WILL BE MOST
NOTICEABLEWITH THE TEMPERATURES THE NEXT COUPLE MORNINGS. LOW
TEMPERATURES TOMORROW MORNING ARE FORECAST TO BE IN THE 50S ACROSS
MOST LOWER DESERT AREAS WITH SOME LOW-LYING EXPOSED AREAS AND
SOME RURAL AREAS DIPPING INTO THE 40S. SOME LOCALIZED VALLEY FOG
CANNOT BE FULLY RULED OUT TOMORROW MORNING FOLLOWING THE WET
PERIOD, BETTER POTENTIAL IN SHELTERED VALLEYS NE AND E OF PHOENIX,
BUT THERE WILL BE A LOT OF DRY AIR ENTRAINMENT ABOVE THE SURFACE.
SKIES WILL BE CLEAR WEDNESDAY AND TEMPERATURES WILL WARM INTO THE
70S ACROSS SOUTH-CENTRAL AZ AND REACH 78-83 DEGREES ACROSS SOME
WESTERN DESERT LOCATIONS. WITH STRENGTHENING SURFACE PRESSURE TO
THE NORTH BEHIND THE UPPER LEVEL LOW PRESSURE SYSTEM, BREEZY TO
LOCALLY WINDY NORTHERLIES (25-35 MPH WIND GUSTS) WILL DEVELOP
ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA FROM THIS
AFTERNOON THROUGH TOMORROW.
LONG TERM /THURSDAY THROUGH MONDAY/
FORECAST CONFIDENCE IS INCREASING FOR ADVISORY LEVEL WINDS
DEVELOPING LATER THIS WEEK ACROSS EASTERN AND SOUTHERN ARIZONA.
GUIDANCE CONTINUES TO SHOW A FAST MOVING DRY SHORTWAVE TROUGH
DIVING SOUTHWESTWARD INTO THE WESTERN PART OF THE LARGE SCALE
TROUGH LINGERING ACROSS THE SOUTHWESTERN U.S. WEDNESDAY NIGHT
INTO THURSDAY. THIS DISTURBANCE IS THEN EXPECTED TO FORM A CUT-
OFF LOW JUST TO OUR SOUTHWEST AT THE SAME TIME STRONG RIDGING
EDGES INTO CALIFORNIA AND THE GREAT BASIN.
THURSDAY LOOKS TO BE A TRANSITION DAY WITH A CONTINUATION OF
ENHANCED NORTHERLY WINDS DOWN THE LOWER CO RIVER VALLEY WHILE
TEMPERATURES WARM CLOSER TO NORMALS AS NORTHERLY DOWNSLOPE
WARMING SPREADS THROUGH MUCH OF ARIZONA. THESE NORTHERLY WINDS
SHOULD QUICKLY SHIFT OUT OF THE EAST LATE THURSDAY NIGHT/FRIDAY
MORNING AS THE CUT-OFF LOW FORMS AND DRIFTS SOUTHWESTWARD OFF THE
COAST OF BAJA. A STRONG PRESSURE GRADIENT WILL THEN DEVELOP ACROSS
ARIZONA IN RESPONSE TO STRONG SURFACE HIGH PRESSURE BUILDING OVER
THE SOUTHERN ROCKIES AND THE PLAINS TO THE EAST AND LOW PRESSURE
TO OUR WEST. THERE MAY EVEN BE A DISTINGUISHABLE BACKDOOR COLD
FRONT BOUNDARY THAT WILL MOVE THROUGH FRIDAY MORNING. GUIDANCE
SHOWS 30-45 KT H8 WINDS SETTING UP ACROSS SOUTHERN ARIZONA FRIDAY
MORNING WHICH SHOULD TRANSLATE TO WIDESPREAD 30-40 MPH EASTERLY GUSTS
AT TIMES TO AS HIGH AS 45 MPH ACROSS PORTIONS OF PINAL AND
SOUTHERN MARICOPA COUNTIES. A WIND ADVISORY IS EXPECTED TO BE
NEEDED FOR THESE AREAS ON FRIDAY AND POSSIBLY INTO SATURDAY
MORNING BEFORE THE GRADIENT BEGINS TO RELAX.
THE STRONG EASTERLY WINDS ON FRIDAY WILL ALSO USHER IN SOME COOLER
AIR FROM NEW MEXICO, KEEPING DAYTIME HIGHS IN THE LOW TO MID 80S
ACROSS THE PHOENIX AREA. THE WESTERN LOWER DESERTS WILL BE LESS
AFFECTED BY THIS BACK-DOOR FRONT WITH HIGHS CLOSER TO 90 DEGREES.
MODEL UNCERTAINTY INCREASES FOR THE WEEKEND AS THERE IS SOME
QUESTION OF HOW LONG THE CUT-OFF LOW WILL SIT JUST TO OUR SOUTH
BEFORE EJECTING BACK TO THE EAST AND WHETHER OR NOT THE REMNANTS
OF TC SIMON WILL PLAY ANY ROLE IN OUR WEATHER. AS OF RIGHT NOW,
GUIDANCE SHOWS THE CUT-OFF WEAKENING AND SHIFTING EAST NORTHEAST
ACROSS NORTHERN MEXICO LATER SATURDAY INTO SUNDAY WHILE THE
REMNANTS OF SIMON MOSTLY LIKELY BYPASSES OUR REGION TO THE
SOUTHEAST. BEFORE THIS OCCURS, THE POSITIONING OF THE CUT-OFF LOW
AND THE INCREASED EASTERLY FLOW IS EXPECTED TO BRING GOOD MID AND
UPPER LEVEL MOISTURE ADVECTION INTO ARIZONA AND SOUTHERN
CALIFORNIA ON FRIDAY, BUT LIKELY LITTLE IF ANY LOW LEVEL MOISTURE.
THE MOST LIKELY SCENARIO CALLS FOR INCREASED HIGHER LEVEL CLOUDS
ON SATURDAY AND A 10-20% CHANCE OF SHOWERS FOCUSED MORE TOWARD
SOUTHEAST ARIZONA. HOWEVER, THERE ARE SOME ENSEMBLE MEMBERS (MAYBE
20%) THAT TRY TO PULL BETTER LOW LEVEL MOISTURE (EVEN POTENTIALLY
FROM SIMON'S REMNANTS) INTO AT LEAST SOUTHEAST ARIZONA SATURDAY
INTO EARLY SUNDAY. IF THIS WERE TO OCCUR, IT WOULD BRING MUCH
BETTER RAIN CHANCES AS FAR NORTHWEST AS THE PHOENIX AREA.
ALTHOUGH STILL UNLIKELY, IT WILL BE SOMETHING TO WATCH OVER THE
NEXT FEW DAYS. BY EARLY NEXT WEEK, WE SHOULD HAVE ANOTHER RIDGE
WITH DRY AIR ADVECTION MOVING IN FROM THE WEST LEADING TO QUIETER
WEATHER CONDITIONS.
AVIATION
UPDATED AT 1815Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
THE PRIMARY AVIATION WEATHER CONCERN WILL CONTINUE TO BE LINGERING
SHOWERS WITH LOW CIGS THROUGH THIS AFTERNOON. SHOWERS WILL
CONTINUE INTO THIS AFTERNOON, RESULTING IN LOWERED CIGS DOWN TO
AROUND 1-3 KFT, ALONG WITH BRIEF MVFR VISIBILITIES, AT TIMES
PRIMARILY AT KIWA, KSDL, AND KDVT. EXPECT SOME IMPROVEMENT IN
CIGS WITH SCT-BKN BASES GENERALLY AOA 3-5 KFT THIS AFTERNOON
BEFORE CLEARING OUT THIS EVENING. WESTERLY WINDS WILL INCREASE
INTO THIS AFTERNOON WITH A FEW GUSTS AROUND 15-20 KTS. WINDS
WEAKEN THIS EVENING BEFORE BECOMING LIGHT AND VARIABLE TONIGHT
INTO THE OVERNIGHT PERIOD.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION WEATHER CONCERNS ARE ANTICIPATED THROUGH THE
NEXT 24 HOURS UNDER MOSTLY CLEAR SKIES. WINDS WILL FAVOR THE W TO
NW AT KIPL, WHILE FAVORING THE N TO NW AT KBLH. A FEW GUSTS TO
AROUND 20 KTS ARE EXPECTED AT KBLH, TAPERING OFF THIS EVENING.
FIRE WEATHER
ISOLATED SHOWERS WILL PERSIST ACROSS THE EASTERN DISTRICTS, MAINLY
HIGH TERRAIN AREAS, THROUGH THIS AFTERNOON BEFORE DRIER AIR
SWEEPS THROUGH THE AREA BEHIND A PASSING COLD FRONT THIS EVENING
AND TONIGHT. ELEVATED MOISTURE LEVELS WILL KEEP MINRHS TODAY
BETWEEN 25-35% FOR THE WESTERN DISTRICTS TO 40-70% FOR THE EASTERN
DISTRICTS BEFORE LOWERING DOWN TO 20-40% WEDNESDAY. NORTHERLY
BREEZY WINDS WILL DEVELOP ACROSS SOUTHEAST CA AND SOUTHWEST AZ
TODAY AND STRENGTHEN EACH DAY THROUGH THURSDAY BEFORE STRONG
EASTERLY WINDS SPREAD THROUGH THE REGION BY FRIDAY. BELOW NORMAL
TEMPERATURES THROUGH WEDNESDAY WILL EVENTUALLY RETURN TO NEAR
NORMAL TEMPERATURES LATE WEEK. SOME MOISTURE RETURN FRIDAY INTO
THE WEEKEND MAY BRING LOW- END RAIN CHANCES BY SATURDAY.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...BENEDICT
LONG TERM...KUHLMAN
AVIATION...SMITH
FIRE WEATHER...KUHLMAN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page