413
FXUS65 KPSR 010805
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
105 AM MST MON JUN 1 2026
KEY MESSAGES
- TEMPERATURES WILL HOVER IN A SLIGHTLY ABOVE NORMAL RANGE MUCH OF
THE WEEK BEFORE RETREATING CLOSER TO NORMAL OVER THE WEEKEND.
- OTHER THAN A SLIGHT CHANCE OF A THUNDERSTORM IN EASTERN ARIZONA
DURING THE MIDDLE OF THE WEEK, DRY CONDITIONS UNDER MOSTLY SUNNY
SKIES WILL BE THE MAIN WEATHER THEME THIS WEEK.
SHORT TERM /TODAY THROUGH WEDNESDAY/
EARLY MORNING OBJECTIVE ANALYSIS DEPICTS A WELL DEFINED NORTHERN
STREAM OMEGA BLOCK DEFINED BY PRONOUNCED RIDGING ACROSS CENTRAL
CANADA AND BOUNDED BY NEGATIVE HEIGHT ANOMALIES ON EITHER SIDE.
MEANWHILE, AN ENHANCED SOUTHERN STREAM SUBTROPICAL JET CONTINUES TO
BE REINFORCED ACROSS THE EASTERN PACIFIC ALLOWING WEAK TROUGHING AND
PREDOMINANT WESTERLY FLOW TO BE MAINTAINED OVER THE SW CONUS. THERE
IS EXCELLENT ENSEMBLE AGREEMENT THAT THE NORTHERN STREAM BLOCK WILL
BE UNDERCUT THROUGH THE MIDDLE OF THE WEEK WITH NORTHERN STREAM
ENERGY HELPING PULL A WEAK VORTICITY CENTER IN THE SOUTHERN STREAM
INTO NORTHERN MEXICO.
DESPITE MEAN TROUGHING ENTERING THE REGION, THERE WILL BE AN OVERALL
WEAKENING PHASE WITH H5 HEIGHTS CURRENTLY IN A 582-585DM RANGE
ACTUALLY INCREASING CLOSE TO 586DM BY THE MIDDLE OF THE WEEK. AS A
RESULT, TEMPERATURES WILL STEADILY WARM WITH AFTERNOON HIGHS
REACHING AROUND 5F ABOVE NORMAL BY WEDNESDAY, AND NARROW ENSEMBLE
NUMERICAL SPREAD YIELDING EXCELLENT FORECAST CONFIDENCE. GIVEN THE
DRY AIRMASS IN PLACE, OVERNIGHT LOWS WILL REMAIN FAIRLY COMFORTABLE
AND NOT FAR FROM THE SEASONAL AVERAGE RESULTING IN ONLY PATCHY AREAS
OF MODERATE HEATRISK. THIS TROUGHING PATTERN WILL ALLOW A MORE
MERIDIONAL FLOW PATTERN BY THE MIDDLE OF THE WEEK WITH WAVE
STRUCTURE FAVORABLE FOR WEAK ASCENT. WHILE THE MAJORITY OF THE CWA
WILL REMAIN TOO DRY FOR PRECIPITATION, MOISTURE BACKED INTO NEW
MEXICO WILL SUPPORT DIURNAL MOUNTAIN THUNDERSTORMS WITH MOIST
OUTFLOW LEAKING INTO FAR EASTERN ARIZONA. THUS, IT WOULD NOT BE OUT
OF THE QUESTION FOR A FEW THUNDERSTORMS/LIGHTNING STRIKES SKIRTING
FAR EASTERN GILA COUNTY WEDNESDAY AFTERNOON.
LONG TERM /THURSDAY THROUGH SUNDAY/
DURING THE LATTER HALF OF THE WEEK, NAEFS MEMBERS ARE IN FAIR
AGREEMENT SHOWING WEAK SOUTHERN STREAM TROUGHING SLOWLY TRANSLATING
INTO THE SOUTHERN PLAINS AS DEEP NEGATIVE HEIGHT ANOMALIES APPROACH
THE WESTERN CONUS. THE PRIMARY UNCERTAINTY IS THE FORWARD SPEED AT
WHICH THIS OCCURS, AND HOW QUICKLY THE FORECAST AREA FALLS UNDER
ANTI-CYCLONIC SUBSIDENCE. THE PREPONDERANCE OF ENSEMBLE OUTPUT
SUGGESTS THE TROUGH AXIS NOT PASSING INTO THE SOUTHERN ROCKIES UNTIL
FRIDAY, THUS KEEPING MODEST ASCENT MECHANISMS INTO EASTERN ARIZONA
THURSDAY WITH A CONTINUED SLIGHT CHANCE OF STORMS OVER MOUNTAINOUS
AREAS. REGARDLESS, THE PATTERN EVOLUTION LATE IN THE WEEK WILL
PROMOTE HEIGHT FALLS AND DRY WESTERLY FLOW WITH H5 READINGS
RETREATING CLOSER TO 580-582DM BY THE WEEKEND (AND POSSIBLY MUCH
LOWER EARLY NEXT WEEK). WHILE NUMERICAL GUIDANCE SPREAD WIDENS
DURING THE EVOLUTION, AN INCREASING NUMBER OF ENSEMBLE MEMBERS
INDICATE DEEPER TROUGHING AND MORE ROBUST COOLING ARRIVING OVER THE
WEEKEND SUCH THAT TEMPERATURES SHOULD RETURN TO NEAR NORMAL, OR
EVEN INTO A SLIGHTLY BELOW NORMAL CATEGORY.
AVIATION
UPDATED AT 0530Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT; AND
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION WEATHER CONCERNS ARE ANTICIPATED UNDER GENERALLY CLEAR
SKIES THROUGHOUT THE TAF PERIOD. THE OVERALL WIND PATTERN WILL
EXHIBIT TYPICAL DIURNAL FLUCTUATIONS WITH SPEEDS GENERALLY REMAINING
AOB 10 KTS. THERE MAY ALSO BE PERIODS OF LIGHT AND VRB TO CALM
CONDITIONS AT TIMES, PARTICULARLY PRIOR TO THE ONSET OF ANY WIND
SHIFTS.
FIRE WEATHER
THE THREAT FOR A FEW LIGHTNING STRIKES WITH LITTLE RAINFALL IN FAR
EASTERN GILA COUNTY WEDNESDAY AND THURSDAY IS THE MAIN FIRE WEATHER
HAZARD THIS WEEK. WITH TEMPERATURES HOVERING SLIGHTLY ABOVE NORMAL,
WINDS WILL MAINTAIN A DIURNAL UPSLOPE/NOCTURNAL DRAINAGE PATTERN.
GUSTS WILL BE LIMITED THE FIRST HALF OF THE WEEK, THEN INCREASE
LATER IN THE WEEK, PARTICULARLY ACROSS THE LOWER COLORADO RIVER
VALLEY AND OVER MOUNTAINOUS LOCATIONS. MINIMUM AFTERNOON HUMIDITY
LEVELS WILL GENERALLY FALL IN A 5-15% RANGE FOLLOWING A WIDELY
RANGING POOR TO FAIR OVERNIGHT RECOVERY OF 15-45%.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...18
LONG TERM...18
AVIATION...SALERNO
FIRE WEATHER...18
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