703
FXUS65 KPSR 131801
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1101 AM MST MON JUL 13 2026
UPDATE
18Z AVIATION DISCUSSION.
KEY MESSAGES
- A FAIRLY TYPICAL MONSOON PATTERN WILL CONTINUE THROUGH THE
FIRST HALF OF THE WEEK, WITH EARLY AFTERNOON SHOWERS AND
THUNDERSTORMS FORMING OVER THE ARIZONA HIGH TERRAIN DAILY
FOLLOWED BY CHANCES OVER THE LOWER DESERTS FOCUSED LATER IN THE
AFTERNOON INTO THE EVENING.
- A DISTURBANCE MAY APPROACH THE REGION FROM THE EAST DURING THE
LATTER HALF OF THE WEEK, BRINGING FAVORABLE CONDITIONS FOR MORE
WIDESPREAD SHOWERS AND THUNDERSTORMS.
- SEASONABLY HOT TEMPERATURES WILL PERSIST THROUGH THE MIDDLE OF
THE WEEK RESULTING IN WIDESPREAD MODERATE HEAT RISK AND LOCALLY
MAJOR HEAT RISK ON WEDNESDAY IN SOUTHEAST CALIFORNIA, FOLLOWED
BY COOLER TEMPERATURES LATE WEEK.
SHORT TERM /TODAY THROUGH TUESDAY/
UPPER LEVEL OBJECTIVE ANALYSIS DEPICTS AN ANTICYCLONICALLY CURVED
POLAR JET STRETCHING FROM THE PACIFIC NORTHWEST INTO SOUTH-CENTRAL
CANADA, ALLOWING A CENTER OF STRONGLY POSITIVE MIDLEVEL HEIGHT
ANOMALIES TO MIGRATE FROM THE INTERMOUNTAIN WEST TO AS FAR NORTHEAST
AS THE NORTHERN PLAINS EARLY THIS WEEK. AT THIS HOUR, THE FORECAST
AREA REMAINS UNDER WEAKENING SOUTHEASTERLY FLOW ALONG THE PERIPHERY
OF THE BROAD MIDLEVEL ANTICYCLONE, WHICH HAS AIDED TO IMPORT
ABUNDANT MOISTURE INTO THE REGION AND CARRY STORMS OFF EASTERN AZ
HIGH TERRAIN AND INTO THE LOWER ELEVATIONS DURING THE PAST COUPLE
AFTERNOONS/EVENINGS.
ABUNDANT MOISTURE WILL REMAIN IN PLACE ACROSS THE FORECAST AREA WITH
ENSEMBLE MEAN PWATS HOVERING BETWEEN 1.5-1.8" THROUGH THE FIRST HALF
OF THE WEEK AND CLOSE TO 2" AT TIMES NEAR THE GULF OF CALIFORNIA AND
NORTHWARD TOWARDS THE LOWER COLORADO RIVER VALLEY. THESE TYPICAL
MOISTURE VALUES FOR THE TIME OF YEAR ARE ALSO FAIRLY WELL
DISTRIBUTED THROUGHOUT THE COLUMN, WITH 10-12 G/KG NEAR SURFACE
MIXING RATIOS BEING MAINTAINED THROUGHOUT THE WEEK, SUPPORTIVE OF
DEEP MOIST CONVECTION EVEN OVER ARIZONA LOWER DESERTS. HOWEVER, THE
GRADUALLY WEAKENING SOUTHEASTERLY FLOW ALOFT WILL SOMEWHAT INHIBIT
THE POTENTIAL FOR STRONGER CLUSTERS OF THUNDERSTORMS TO DEVELOP THE
NEXT FEW DAYS. AS SUCH, ANTICIPATE A FAMILIAR CONVECTIVE PATTERN TO
TAKE SHAPE THE NEXT FEW DAYS, WITH EARLY AFTERNOON THUNDERSTORMS
FIRING OVER ARIZONA HIGHER TERRAIN AREAS, FOLLOWED BY CONDITIONAL
SLIGHT (10-35%) CHANCES FOR THUNDERSTORMS MOVING OVER OR FORMING IN
THE SOUTH-CENTRAL AZ LOWER DESERTS LATER IN THE AFTERNOON AND INTO
THE EVENINGS. THE COVERAGE OF STORMS WILL VARY DAY TO DAY BASED ON
SUBTLE DISTURBANCES IN THE FLOW, SUBTLE MOISTURE DIFFERENCES, AND
PRIOR CONVECTIVE ACTIVITY - EITHER FROM THE PRIOR DAY OR EARLIER
THAT SAME DAY.
THIS AFTERNOON/EVENING, INSTABILITY MEASURES SEEM SOMEWHAT
DIMINISHED FROM THAT OF SUNDAY, PERHAPS DUE TO LESS FAVORABLE
MIDLEVEL LAPSE RATES (GFS BUFR SOUNDINGS FOR PHX SHOWING 700-500 MB
LAPSE RATES AROUND 6 C/KM COMPARES TO THE ~7C/KM ON SUNDAY). HREF
MEAN MUCAPES ARE MOSTLY BETWEEN 500-1000 J/KG THIS AFTERNOON/EVENING
IN SOUTH-CENTRAL AZ, AND MODEL SOUNDINGS INDICATE MLCAPE VALUES
PEAKING AROUND 1100 J/KG IN THE EARLY EVENING FOR PHOENIX. WITH
THESE VALUES, IT IS NOT OUT OF THE QUESTION TO SEE STRONG STORMS AND
PERHAPS AN ISOLATED MARGINALLY SEVERE STORM OR TWO, ESPECIALLY WITH
INVERTED-V SOUNDINGS RESULTING IN DCAPES PEAKING AROUND 1000-1500
J/KG. AND STEERING FLOW STILL ELEVATED TO AROUND 15-20 KTS WILL
BE CAPABLE OF CARRYING CLUSTERS OF STORMS OFF HIGHER TERRAIN AND
INTO THE LOWER DESERTS DOWNSTREAM. HOWEVER, HREF MEMBERSHIP DOES
NOT SHOW A CONSENSUS ON AN ORGANIZED OUTFLOW FORMING AND
TRIGGERING NEW CONVECTION OVER THE LOWER DESERTS OR WHERE THE
GREATEST COVERAGE OF STORMS WILL BE. NEIGHBORHOOD PROBABILITIES
FOR 35+ MPH GUSTS NEAR STORMS ARE LOWER THAN THAT OF SUNDAY BUT
STILL AROUND 50-70%, FOCUSED ALONG A CORRIDOR FROM PHOENIX
SOUTH/SOUTHEASTWARD TO THE INTERNATIONAL BORDER. ACTIVITY WILL
THEN LIKELY TREND INTO SOUTHWEST AZ (LA PAZ COUNTY) HEADING INTO
THE MID-LATE EVENING, THOUGH AGAIN, THIS IS HIGHLY CONDITIONAL ON
UPSTREAM ACTIVITY AND IF OUTFLOWS FROM CENTRAL AZ HIGH TERRAIN
STORMS CAN TRIGGER ADDITIONAL CELLS.
TUESDAY, THERMODYNAMICS MAY BE SLIGHTLY MORE FAVORABLE FOR STRONG
STORMS, HOWEVER, FLOW ALOFT WEAKENS FURTHER AND DIRECTIONS BECOME
COMPLEX AS WEAK ANTICYCLONIC AND CYCLONIC CIRCULATIONS BEGIN TO
IMPINGE ON THE REGION, CREATING A DEFORMATION AREA. THE THREAT FOR
LOWER DESERT STORMS WILL BE EVEN MORE CONDITIONAL ON LIFTING
MECHANISMS FROM EARLIER STORMS OR SUBTLE LIFT FROM THE DEFORMATION
ZONES DRAPED ACROSS THE REGION.
IN TERMS OF TEMPERATURES, AFTERNOON HIGHS WILL INCREASE FROM A 102F-
107F RANGE TODAY INTO A 105F-110F RANGE. TUESDAY PLENTIFUL MOISTURE
(BY DESERT STANDARDS) WILL MAKE INSOLATION LESS EFFICIENT AT HEATING
US UP, BUT IN TURN, THE INCREASED HUMIDITY WILL MAKE IT FEEL HOTTER,
WITH HEAT INDICES CLIMBING TOWARD 110F-117F DEGREES, ESPECIALLY ON
TUESDAY. MODERATE HEATRISK WILL REMAIN WIDESPREAD THROUGH THE NEXT
FEW DAYS, SO IF PLANS TAKE YOU OUTSIDE, BE SURE TO EXERCISE HEAT
PRECAUTIONS.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
THERE IS STILL EXCELLENT AGREEMENT WITHIN THE EPS AND GEFS
MEMBERS REGARDING THE PLACEMENT OF THE UPPER HIGH OVER THE
NORTHERN PLAINS AND UPPER MIDWEST THROUGH MIDWEEK BEFORE
RETROGRADING OVER THE CENTRAL ROCKIES BY THE LATTER HALF OF THE
WEEK. THE OVERALL POSITION OF THE 500 MB HIGH WILL MAINTAIN DEEP
EASTERLY FLOW ACROSS THE DESERT SOUTHWEST, HELPING ENHANCE
MOISTURE TRANSPORT. LATEST EPS AND GEFS CONTINUE TO SHOW PWATS
HOVERING AROUND 1.5"-1.8" THROUGH THE ENTIRE WEEK WITH LOW-LEVEL
MIXING RATIOS REMAINING BETWEEN 10-12 G/KG. THEREFORE, CONDITIONS
WILL CONTINUE TO REMAIN CONDUCIVE FOR DAILY THUNDERSTORM ACTIVITY
WITH VARIATIONS IN THE OVERALL COVERAGE. BOTH THE MEAN OF THE EPS
AND GEFS SHOW AN UPTICK IN QPF ACROSS THE REGION BY THE END OF
THIS WEEK DUE TO AN EASTERLY WAVE/INVERTED TROUGH APPROACHING THE
AREA BY THURSDAY-FRIDAY. IF THIS OCCURS, THIS TROUGHING FEATURE
WILL LIKELY ENHANCE CONVECTIVE ACTIVITY POTENTIALLY INTRODUCE A
RISK FOR HEAVY RAINFALL ACROSS PORTIONS OF AZ. THIS WILL HAVE TO
BE MONITORED CLOSELY IN THE COMING DAYS.
TEMPERATURES ARE EXPECTED TO PEAK WEDNESDAY MOSTLY BETWEEN
105F-110F ACROSS THE ARIZONA LOWER DESERTS, BUT SOME AREAS OF
MAJOR HEATRISK ENTER THE PICTURE FOR PORTIONS OF SOUTHEAST CA AND
ALONG THE LOWER COLORADO RIVER VALLEY, WHERE LATEST NBM FORECAST
SHOWS HIGHS AS HIGH AS 113F AND LOWS IN THE MIDDLE TO UPPER 80S
THANKS TO THE INEFFICIENT OVERNIGHT RADIATIVE COOLING FROM HIGHER
HUMIDITY AND LIKELY SOME MID-HIGH CLOUD COVER. THE NBM CONTINUES
TO INDICATE TEMPERATURES COOLING TO WELL BELOW NORMAL BY THE END
OF THE WEEK WITH HIGHS FALLING INTO THE 90S TO AROUND 100 DEGREES
ACROSS THE LOWER DESERTS BY FRIDAY. THIS IS LIKELY DUE TO THE
INCREASED SIGNAL FOR THICKER CLOUD COVER AND THE POTENTIAL FOR
MORE WIDESPREAD RAINFALL.
AVIATION
UPDATED AT 1800Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
THE MAIN AVIATION CONCERNS DURING THE PERIOD WILL BE GUSTY OUTFLOW
WINDS AND THUNDERSTORMS IN THE VICINITY OF THE TERMINALS. CURRENT
PROJECTIONS HAVE VCTS SOMEWHERE IN THE WINDOW OF 22-04Z, THOUGH
DIRECT IMPACTS EACH SITE IS UNCERTAIN AT THIS TIME. CONVECTION IN
CLOSER PROXIMITY TO THE AIRPORTS, ALONG WITH MORE DISTANT
ACTIVITY, WILL PUSH OUT MULTIPLE OUTFLOWS, BUT WHEN, HOW STRONG
THEY ARE, AND OUT OF WHAT DIRECTION THEY SWITCH WINDS TO WILL BE
HIGHLY CONDITIONAL ON THE POSITION OF STORMS AND HOW THEY EVOLVE.
ONE THING THAT APPEARS MORE CERTAIN IS THAT POTENTIAL BOUNDARIES
WILL CONTAIN SOME DEGREE OF AN E'RLY COMPONENT. REGARDLESS,
AMENDMENTS ARE LIKELY TO BE NEEDED DURING THE AFTERNOON AND
EVENING. OTHERWISE, WINDS WILL FOLLOW TYPICAL DIRECTIONAL TRENDS,
BUT TIMING OF THE E'RLY SHIFT WILL DEPEND ON THE ABOVE MENTIONED
OUTFLOW(S). SCT-BKN SKIES WILL BE COMMON WITH THE LOWEST BASES
AROUND 8-10 KFT ASSOCIATED WITH AFTERNOON/EVENING CB'S.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION CONCERNS ARE EXPECTED OVER THE NEXT 24 HOURS.
WINDS WILL FOLLOW DIURNAL TRENDS AT EACH TERMINAL WITH PERIODS OF
VRB DURING THE OVERNIGHT AND MORNING HOURS TUESDAY. THERE ARE
INDICATIONS OF A WEAK OUTFLOW MOVING THROUGH KIPL THIS AFTERNOON,
BUT CHANCES OF THAT OCCURRING ARE TOO LOW TO INCLUDE IN THE TAF AT
THIS TIME. AT WORST, IT APPEARS IT WOULD INITIATE THE W'RLY SWITCH
AN HOUR OR TWO EARLY AND MAYBE PRODUCE SOME WEAK GUSTS. SCT CLOUDS
WILL BE COMMON DURING THE PERIOD WITH THE LOWEST BASES AROUND
10-12 KFT.
FIRE WEATHER
SEASONABLY HOT TEMPERATURES WILL PREVAIL THROUGH THE NEXT SEVERAL
DAYS AS READINGS WILL BE NEAR TO SLIGHTLY ABOVE NORMAL. DAILY
THUNDERSTORM ACTIVITY WILL BE POSSIBLE THROUGH THIS WEEK WITH THE
POTENTIAL FOR MORE WIDESPREAD WETTING RAINFALL INCREASING ACROSS
THE EASTERN DISTRICTS LATER IN THE WEEK. DUE TO INCREASING
BOUNDARY LAYER MOISTURE, AFTERNOON HUMIDITY LEVELS WILL REMAIN IN
A 20-30% RANGE WHICH WILL KEEP ANY FIRE WEATHER CONCERNS AT A
MINIMUM. OVERNIGHT RECOVERIES WILL BE FAIR TO GOOD, OR BETWEEN
40-70%. OUTSIDE OF ANY THUNDERSTORM DRIVEN OUTFLOW, WINDS SHOULD
FAVOR DIURNAL TRENDS WITH THE TYPICAL AFTERNOON BREEZINESS AROUND
20-25 MPH.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...WHITTOCK
LONG TERM...SALERNO/WHITTOCK
AVIATION...RW
FIRE WEATHER...WHITTOCK/SALERNO
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