550
FXUS65 KPSR 221734
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1034 AM MST TUE SEP 22 2026
UPDATE
UPDATED 18Z AVIATION DISCUSSION.
KEY MESSAGES
- RAIN CHANCES RETURN TO PORTIONS OF EASTERN ARIZONA STARTING
TODAY, WITH MOST ACTIVITY FOCUSED OVER FOOTHILL AND HIGH TERRAIN
AREAS.
- BEST CHANCES TO SEE LOWER DESERT RAINFALL WILL OCCUR ON
WEDNESDAY, BUT OTHERWISE, MOST OF THE ACTIVITY SHOULD REMAIN TO
THE NORTH AND EAST OF THE PHOENIX METRO THROUGH THE END OF THE
WORK WEEK.
- NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES WILL PERSIST OVER
THE NEXT SEVERAL DAYS.
SHORT TERM /TODAY THROUGH WEDNESDAY/
CURRENT RAP ANALYSIS REVEALS SHORTWAVE RIDGING OVER THE ROCKIES AS
FLANKING WAVES SPIN NEAR THE GREAT LAKES AND GREAT BASIN. THE LATTER
OF THESE DISTURBANCES WILL BE THE MAIN WEATHER FOCUS OVER THE DESERT
SOUTHWEST THROUGH AT LEAST THE MIDDLE PORTION OF THE WEEK, HELPING
TO RENEW RAIN CHANCES DURING THE WANING DAYS OF MONSOON SEASON.
EVEN THOUGH SOUTHWESTERLY FLOW WILL PERSIST, WHICH TYPICALLY
TRANSLATE TO RATHER BENIGN CONDITIONS ACROSS THE REGION, THE
PACIFIC LOW WILL BE STRONG/DEEP ENOUGH TO HELP PULL SUB-TROPICAL
MOISTURE UPWARDS INTO EASTERN ARIZONA TODAY, WITH PWATS INCREASING
TOWARD 150- 175% OF NORMAL. COMBINE THIS MOISTURE WITH POSITIVE
VORTICITY ADVECTION AND A DEVELOPING UPPER-LEVEL JET STREAK, AND
YOU GET AN ENVIRONMENT FAVORABLE FOR SHOWER AND ISOLATED
THUNDERSTORM DEVELOPMENT. HOWEVER, WITH A SHARP EAST-WEST CUTOFF
OF SUFFICIENT MOISTURE EXPECTED, MOST, IF NOT ALL, RAINFALL
ACTIVITY WILL BE CONFINED TO THE EASTERNMOST THIRD OF ARIZONA, AND
THEREFORE, COVERAGE OVER OUR AREA WILL BE FOCUSED PRIMARILY OVER
GILA COUNTY. WITH THIS SETUP AND BETTER SYNOPTIC SUPPORT, ROUNDS
OF SHOWERS AND ISOLATED OF STORMS WILL BE POSSIBLE FROM MID-
MORNING INTO THE EARLY NIGHTTIME HOURS AS THE ENVIRONMENT WILL NOT
BE SOLELY RELIANT ON SURFACE HEATING AND OROGRAPHIC INFLUENCES,
WHICH TYPICALLY LIMIT WARM SEASON ACTIVITY TO THE AFTERNOON AND
EVENING HOURS. DUE TO THE POTENTIAL TO SEE MULTIPLE INSTANCES OF
RAIN OVER THE SAME AREAS, MINOR FLOODING WILL BE THE MAIN CONCERN,
ESPECIALLY IF A SPECIFIC LOCATIONS EXPERIENCES SEVERAL HEAVIER
CELLS.
ONE FORECAST ASPECT THAT WILL NEED TO MONITORED LATER THIS EVENING
WILL BE THE POTENTIAL FOR AREAS OF BLOWING DUST IN LOWER DESERTS OF
PINAL AND MARICOPA COUNTIES DUE TO GUSTY SOUTHEASTERLY OUTFLOW WINDS
FROM DISTANT SHOWERS AND STORMS. HI-RES DATA IS HIGHLIGHTING THIS
POTENTIAL AND WITH A DRY BOUNDARY LAYER IN PLACE, DCAPE VALUES WILL
NEAR OR EXCEED 1000 J/KG, MAKING THIS OUTCOME NOT SO FAR-FETCHED,
EVEN THOUGH THIS IS NOT YOUR TYPICAL BLOWING DUST SIGNAL.
HOWEVER, DUST GENERATION WILL BE HEAVILY DEPENDENT ON IF STRONG
ENOUGH CONVECTION CAN BECOME ESTABLISHED. AT THE VERY MINIMUM, THE
SOUTHEASTERLY FLOW WILL HELP INCREASE BOUNDARY LAYER MOISTURE
TUESDAY NIGHT, WHICH COULD SET THE STAGE FOR FURTHER ACTIVITY ON
WEDNESDAY.
SPEAKING OF WEDNESDAY, THE SOUTHWESTERN WAVE IS SHOWN SPLITTING
IN TWO SEPARATE AREAS OF ENERGY, WITH ONE AREA BEING EJECTED
TOWARD THE NORTHERN PLAINS, WHILE ANOTHER AREA LINGERS OFF THE
BAJA COAST. THE LATTER AREA WILL TILT REGIONAL FLOW MORE OUT OF
THE SOUTH AND PERHAPS EVEN SLIGHTLY SOUTHEASTERLY, HELPING TO
NUDGE MOISTURE FURTHER WEST OVER THE LOWER DESERTS. THIS, ALONG
WITH THE PREVIOUSLY MENTIONED LOW-LEVEL MOISTURE INCREASE, HAS
CAUSED A SHIFT IN THE FORECAST COMPARED TO 24 HOURS AGO, WITH THE
NBM NOW INDICATING THE BETTER POTENTIAL FOR RAINFALL OVER SOUTH-
CENTRAL ARIZONA WILL NOW BE ON WEDNESDAY AS OPPOSED TO THURSDAY.
THOUGH THE MOISTURE MAY STILL BE IN PLACE, WITH THE LOW NOW
SIGNIFICANTLY WEAKER, AND THE AFOREMENTIONED JET STREAK MIGRATING
FURTHER NORTH, THE SYNOPTIC SETUP BECOMES MUCH LESS FAVORABLE TO
SEE RAINFALL OUTSIDE OF THE TYPICAL ENHANCED TERRAIN AREAS. ONE
WILDCARD THOUGH IS THE PROJECTED PRESENCE OF A 700MB WAVE MOVING
UP OUT OF NORTHERN MEXICO WEDNESDAY MORNING. CURRENT FORECAST
TRACKS HAVE THIS KINK PROGRESSING NEAR THE ARIZONA/NEW MEXICO
BORDER, WHICH WOULD LIKELY PROVIDE BETTER SUPPORT FOR RAINFALL
ONCE AGAIN FOR AREAS FURTHER EAST OF HERE. WITH THAT BEING SAID,
ANY SUBTLE CHANGES TO TROUGH EVOLUTION COULD YIELD SHOWER AND
THUNDERSTORMS FOR LOWER DESERT AREAS, WHICH IS LIKELY WHY 20-30%
POPS ARE INDICATED FOR PHOENIX AS THE RAINFALL POTENTIAL CANNOT BE
COMPLETELY IGNORED.
EVEN WILL THAT, TEMPERATURES HAVE NOT BEEN MENTIONED. HIGHS ACROSS
THE REGION WILL NOT VARY TOO MUCH COMPARED TO WHAT WE HAVE SEEN THE
PAST FEW DAYS WITH READINGS RUNNING NEAR TO SLIGHTLY ABOVE NORMAL.
LOWER DESERTS CAN EXPECTED MAXTS AROUND 93-102 DEGREES WHILE HIGHER
ELEVATION LOCATIONS WILL EXPERIENCE TEMPS CLOSER TO THE LOWER 80S TO
LOWER 90S.
LONG TERM /THURSDAY THROUGH MONDAY/
HEADING INTO THE BACK HALF OF THE WEEK, THE INFLUENCE FROM THE
PREVIOUSLY-MENTIONED LOW WILL CONTINUE TO DIMINISH, BUT SUFFICIENT-
ENOUGH MOISTURE FOR FURTHER RAIN CHANCES WILL REMAIN IN PLACE, AT
LEAST THROUGH THURSDAY. NBM/WPC CONTINUE TO PAINT EASTERN AN
NORTHERN ARIZONA IN DECENT POPS (30-60%), INCLUDING OUR PORTION OF
GILA COUNTY, THANKS TO OROGRAPHIC INFLUENCES, BUT SYNOPTIC SUPPORT
WILL BE ALL BUT GONE BY THIS POINT, SO DESERT CHANCES DROP BACK TO
GENERALLY BELOW 20%, BUT NOT ALL THE WAY ZERO. PWATS 100-150% OF
NORMAL ARE LIKELY WHY NON-ZERO POPS ARE SHOWN FOR THE LOWER
ELEVATIONS, BUT UNLESS YOU FIND YOURSELF AROUND ENHANCED TERRAIN
FEATURES SUCH AS THE KOFAS OR TABLE TOP WILDERNESS, ANOTHER RAINFALL
SHOULD NOT BE COUNTED ON AT THIS POINT. GRADUAL DRYING BEGIN ON
SATURDAY, BUT IT MAY NOT REMAIN THAT WAY FOR TOO LONG AS WE MAY
START TO SEE FRINGE MOISTURE ASSOCIATED WITH HURRICANE POLO BY AS
EARLY AS THE WEEKEND. FORECAST CONFIDENCE REGARDING WHERE THIS
TROPICAL CYCLONE WILL PROGRESS IN THE LONGER TERM IS LOW, AND
THERE WILL LIKELY BE MANY FORECAST CHANGES REGARDING IT IN THE
COMING DAY, BUT ITS POTENTIAL INFLUENCE WILL BE MONITORED
REGARDLESS OVER THROUGH THE REMAINDER OF THE WEEK.
IN TERM OF TEMPERATURES, MUCH LIKE DURING THE SHORT TERM, NOT MUCH
FLUCTUATION IN DAY-TO-DAY READINGS IS EXPECTED TO OCCUR. DAILY
VALUES WILL HOVER RIGHT AROUND TO JUST ABOVE NORMAL, WHICH
TRANSLATES TO LOWER DESERT READINGS RANGING BETWEEN 94-105 DEGREES
THROUGH THE WEEKEND. OVERNIGHT LOWS WILL BE SLIGHTLY MORE ELEVATED
COMPARED TO WHERE THEY TYPICALLY ARE FOR LATE SEPTEMBER, LIKELY AN
EFFECT OF LINGERING MOISTURE AND CLOUD COVER (AT LEAST FOR SOME
SPOTS), WITH READINGS BETWEEN 70-82 DEGREES. MEANWHILE HIGHER
ELEVATION CONDITIONS WILL BE QUITE COMFORTABLE AS MOST LOCATIONS
SHOULD BE IN THE 80S, WITH PERHAPS A FEW SPOTS TOUCHING THE LOWER
90S. LOWS FOR THESE SPOTS IN THE UPPER 50S TO LOWER 70S WILL BE
COMMON.
AVIATION
UPDATED AT 1733Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
PRIMARY AVIATION IMPACT WILL BE THE POTENTIAL FOR VCSH/VCTS THIS
AFTERNOON/EVENING, AND GUSTY OUTFLOWS. A WESTERLY SHIFT THIS
AFTERNOON LOOKS UNLIKELY WITH A BRIEF PERIOD OF S-SSW CROSS WINDS
BEFORE SHIFTING BACK OUT OUT THE SE FOR THE REMAINDER OF THE TAF
PERIOD. UNDER 10% CHANCES REMAINS FOR SHRA/TSRA ACTIVITY TO
DEVELOP IN THE METRO, WITH ACTIVITY EXPECTED TO REMAIN THE THE
SOUTH AND EAST OF THE TERMINALS. THE THE MAIN SE'RELY OUTFLOW
FROM THE PREVIOUS PACKAGE HAS BEEN SHIFTED BACK A FEW HOURS NOW
EXPECTED JUST PAST MIDNIGHT TONIGHT, HOWEVER A FEW GUSTY PERIODS
MAY STILL DEVELOP THIS EVENING AHEAD OF THE MAIN OUTFLOW. GUSTS
WILL LIKELY BE NEAR 20KTS WITH LOW CONFIDENCE OF BLDU OR REDUCED
VIS. FEW-SCT CLOUDS WILL BE COMMON THROUGH THE AFTERNOON WITH
LOWEST BASES AROUND 8-10 KFT AGL. THERE WILL ALSO BE INCREASING
HIGH CLOUDS (AROUND 25 KFT) THROUGH THE PERIOD AND SHOULD BECOME
BKN BY THIS EVENING.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION IMPACTS ARE ANTICIPATED THROUGH THE NEXT 24
HOURS WITH MOSTLY CLEAR SKIES. WINDS WILL FAVOR W/NW AT BOTH KIPL
AND KBLH, WITH WIND SPEEDS MOSTLY STAYING BELOW 10 KTS AND PERIODS
OF LIGHT AND VARIABLE WINDS.
FIRE WEATHER
NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES WILL PREVAIL OVER THE
NEXT SEVERAL DAYS, WITH MINIMAL DAY-TO-DAY FLUCTUATIONS. DAILY
RAIN CHANCES RETURN FOR THE HIGH TERRAIN THROUGH THE END OF THE
WORKWEEK WITH LOWER DESERT CHANCES FOCUSED ON WEDNESDAY. MINRHS
BETWEEN 15-30% WILL BE COMMON ACROSS THE REGION THROUGH THE START
OF THE WEEKEND, WITH EVEN HIGHER READINGS (35-50%) FOR THE FAR
EASTERN DISTRICTS. MAXRHS WILL RANGE FROM FAIR TO GOOD OVER THE
WESTERN AND CENTRAL DISTRICTS, TO GOOD AND EXCELLENT FOR THE
EASTERN DISTRICTS INTO THE WEEKEND. DRIER AIR BY THE WEEKEND WILL
LOWER RHS SLIGHTLY, BUT THEY SHOULD REMAIN ABOVE CRITICAL FIRE
WEATHER THRESHOLDS. OUTSIDE OF ANY THUNDERSTORM RELATED OUTFLOWS,
WINDS WILL FOLLOW FAMILIAR DIURNAL TRENDS WITH TYPICAL TERRAIN
INDUCED AFTERNOON GUSTS AROUND 15-25 MPH.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...RW
LONG TERM...RW
AVIATION...RYAN/BERISLAVICH
FIRE WEATHER...RW
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page