599
FXUS65 KPSR 210810
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
110 AM MST THU MAY 21 2026
KEY MESSAGES
- TEMPERATURES WILL GRADUALLY WARM THROUGH THE WEEKEND WITH LOWER
DESERT HIGHS REACHING THE UPPER 90S TO NEAR 100 DEGREES FOLLOWING
COMFORTABLE MORNING READINGS.
- DRY CONDITIONS WILL PREVAIL THROUGH EARLY NEXT WEEK WITH TYPICAL
AFTERNOON BREEZINESS.
- A SLIGHT CHANCE OF THUNDERSTORMS WITH A FEW LIGHTNING STRIKES WILL
EXIST OVER EASTERN ARIZONA HIGH TERRAIN EARLY NEXT WEEK, ALBEIT WITH
LIMITED RAINFALL POTENTIAL.
SHORT TERM /TODAY THROUGH FRIDAY/
WHILE BROAD TROUGHING COVERS THE WESTERN CONUS EARLY THIS MORNING,
NORTHERN STREAM ENERGY CONTINUES TO PROPAGATE EASTWARD WITH
LINGERING CYCLONIC FLOW AND LOWERED MIDLEVEL HEIGHTS HANGING OVER
THE SOUTHWEST. THERE WILL BE LITTLE IMPETUS TO EJECT THIS SOUTHERN
STREAM TROUGHING FROM THE FORECAST AREA OVER THE NEXT 60 HOURS, AND
H5 HEIGHTS SHOULD BE MAINTAINED RIGHT AROUND 576DM UNDER VERY
TRANQUIL WEATHER CONDITIONS. DESPITE THE NEAR PERSISTENCE IN MID AND
UPPER TROPOSPHERIC MEASURES, BOUNDARY LAYER THERMAL PROFILES WILL
WARM SOMEWHAT IN RESPONSE TO SEASONALLY INTENSE SURFACE INSOLATION.
ENSEMBLE NUMERICAL SPREAD REMAINS EXTREMELY NARROW WITH INTER
QUARTILE RANGES ONLY A FEW DEGREES, YIELDING EXCELLENT FORECAST
CONFIDENCE OF TEMPERATURES WITHIN A FEW DEGREES OF CLIMATOLOGY THE
NEXT COUPLE DAYS.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
OVER THE WEEKEND, LOW AMPLITUDE SHORTWAVE RIDGING WILL TEMPORARILY
BUILD INTO THE SW CONUS IN RESPONSE TO DEEPENING TROUGHING ENTERING
THE EASTERN PACIFIC. THE FULL NAEFS SUITE CONTINUES TO EXHIBIT
MINIMAL SPREAD IN THE H5 HEIGHT PATTERN WITH A 582-585DM LEVELS
SETTLING OVER THE CWA. AS SUCH, CONFIDENCE IS VERY GOOD THAT
TEMPERATURES WILL WARM SEVERAL MORE DEGREES INTO A SLIGHTLY ABOVE
NORMAL RANGE, BUT CERTAINLY NOTHING PARTICULARLY UNUSUAL FOR THIS
TIME OF YEAR. EARLY NEXT WEEK, THE RIDGE AXIS SHIFTS EAST INTO NEW
MEXICO WITH A STRONG SUBTROPICAL JET PUNCHING INTO NORTHERN MEXICO.
THE RESULTING FLOW PATTERN WILL BECOME DEEPLY MERIDIONAL ALLOWING
THE IMPORT OF MARGINALLY BETTER MOISTURE PROFILES, ALTHOUGH LIKELY
NO MORE THAN 5 G/KG WITHIN THE BOUNDARY LAYER.
THIS TYPE OF TRANSITION SEASON PATTERN IS NOT UNCOMMON FOR THE SW
CONUS (ESPECIALLY DURING DEVELOPING EL NINO EPISODES - E.G. 2023 AND
2015), HOWEVER THE INTENSITY OF THIS SHORTWAVE AND ASSOCIATED
SUBTROPICAL JET ARE UNUSUALLY STRONG. GENERAL PATTERN RECOGNITION
CONTINUES TO SUGGEST ROBUST JET FORCED ASCENT AND COOLING ALOFT
SURGING INTO SOUTH-CENTRAL ARIZONA EARLY NEXT WEEK. ENSEMBLE
MEMBERSHIP INDICATES SOME MINOR UNCERTAINTY IN TIMING, INTENSITY,
AND MOISTURE AVAILABILITY, THOUGH THE OVERWHELMING PREPONDERANCE OF
MODEL OUTPUT HIGHLIGHTS MONDAY AFTERNOON AND EVENING AS THE MOST
OPPORTUNE TIME FRAME WHERE DEEP MOUNTAIN CONVECTION OVER THE EASTERN
CWA WOULD BE SUPPORTED. GIVEN THE LIKELY THERMODYNAMIC PROFILES,
MINIMAL ACTUAL RAINFALL MAY BE COMMON WITH THIS CONVECTION, BUT
RATHER NUMEROUS DRY LIGHTNING STRIKES AND GUSTY OUTFLOW WINDS WOULD
BE THE MORE LIKELY OUTCOME. SHOULD THIS EVOLUTION COME TO FRUITION,
THE GREATEST CONCERN WOULD BE WILDFIRE STARTS IN REMOTE HIGH TERRAIN
AREAS. THE PASSAGE OF STRONGER TROUGHING NORTH OF THE FORECAST AREA
MIDWEEK COULD HELP INCREASE WINDS WHICH COULD EXACERBATE FIRE
WEATHER ISSUES, THOUGH LARGER ENSEMBLE SPREAD YIELDS LOWER FORECAST
CONFIDENCE DURING THIS TIME FRAME AT THE END OF THE FORECAST PERIOD.
AVIATION
UPDATED AT 0455Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
NO AVIATION CONCERNS ARE EXPECTED DURING THE TAF PERIOD. WINDS WILL
FOLLOW LIGHT AND DIURNAL TRENDS WITH PERIODS OF VARIABILITY DURING
DIRECTIONAL SHIFTS. SKIES WILL BE MOSTLY CLEAR WITH FEW HIGH CLOUDS
TOMORROW AFTERNOON.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION CONCERNS ARE EXPECTED DURING THE NEXT 24 HOURS. WINDS
WILL FAVOR LIGHT AND DIURNAL TRENDS WITH SOME PERIODS OF VRB
CONDITIONS DURING DIRECTIONAL SHIFTS. SKIES WILL BE MOSTLY CLEAR
WITH FEW-SCT HIGH CLOUDS TOMORROW MORNING.
FIRE WEATHER
TEMPERATURES WILL REMAIN IN A SLIGHTLY ABOVE NORMAL CATEGORY THROUGH
EARLY NEXT WEEK WITH DRY CONDITIONS OVER THE MAJORITY OF THE
DISTRICTS. MINIMUM AFTERNOON HUMIDITY LEVELS WILL FALL INTO A 5-15%
RANGE THIS WEEK WITH A MODEST INCREASE IN MOISTURE RESULTING IN
LEVELS INCREASING CLOSER TO 10-20% OVER THE WEEKEND. THIS MOISTURE
INCREASE ALONG WITH AN INCOMING WEATHER DISTURBANCE MAY LEAD TO A
SLIGHT CHANCE FOR AFTERNOON/EVENING STORMS AND LIGHTNING STRIKES
OVER HIGH TERRAIN OF EASTERN DISTRICTS. LITTLE TO NO RAINFALL WOULD
BE EXPECTED WITH THIS ACTIVITY RESULTING IN A HEIGHTENED THREAT FOR
NEW WILDFIRE STARTS, PARTICULARLY MONDAY AFTERNOON. POOR TO FAIR
OVERNIGHT RECOVERY OF 20-40% WILL ONLY IMPROVE SLIGHTLY OVER THE
WEEKEND. TYPICAL AFTERNOON SPRING UPSLOPE GUSTINESS OF 15-25 MPH
WILL BE COMMON THROUGH THE PERIOD WITH THE MOST PRONOUNCED GUSTS
OVER EASTERN DISTRICT HIGH TERRAIN AND THROUGH THE LOWER COLORADO
RIVER VALLEY.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...18
LONG TERM...18
AVIATION...BERISLAVICH/RW
FIRE WEATHER...18
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