102
FXUS65 KPSR 151833
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1034 AM MST MON SEP 15 2025
UPDATE
18Z AVIATION DISCUSSION.
KEY MESSAGES
- HOTTER CONDITIONS WILL BE SEEN OVER THE NEXT FEW DAYS WITH LOWER
DESERT HIGH TEMPERATURES TOPPING OUT BETWEEN 101 AND 105
DEGREES.
- RAIN CHANCES WILL ENTER THE PICTURE AGAIN BY WEDNESDAY WITH THE
BEST CHANCES FOCUSED ACROSS SOUTHEAST CALIFORNIA ON THURSDAY AND
ACROSS SOUTHERN AND CENTRAL ARIZONA ON FRIDAY.
- TEMPERATURES ARE LIKELY TO RETURN TO NORMAL LATER THIS WEEK INTO
NEXT WEEKEND.
SHORT TERM /TODAY THROUGH TUESDAY/
THE DRY CONDITIONS WE HAVE SEEN OVER THE PAST COUPLE OF DAYS ARE
ABOUT TO END AS SUBTROPICAL MOISTURE IS FORECAST TO SURGE
NORTHWARD INTO OUR REGION OVER THE NEXT FEW DAYS. WESTERLY ZONAL
FLOW STILL REMAINS DOMINANT OVER THE DESERT SOUTHWEST, BUT A WEAK
UPPER LOW HAS RECENTLY FORMED OFF THE COAST OF NORTHERN BAJA AND
TC MARIO (SOUTHWEST OF THE TIP OF SOUTHERN BAJA) IS ABOUT TO SEND
SOME GOOD MOISTURE NORTHWARD. FOR TODAY, NOT MUCH WILL CHANGE BUT
THE WARM UP WILL CONTINUE WITH HIGHS REACHING BETWEEN 101-104
DEGREES ACROSS THE LOWER DESERTS. MOISTURE WILL ALSO GRADUALLY
BEGIN TO SEEP INTO OUR AREA LATER TODAY, BUT MORE SO TONIGHT INTO
TUESDAY AS SURFACE DEW POINTS RISE FROM THE CURRENT 30S AND 40S TO
THE 50S ON TUESDAY.
TUESDAY IS LOOKING LIKE A FAIRLY HOT DAY FOR MID SEPTEMBER WITH
TEMPERATURES LIKELY REACHING THEIR PEAK OF THE WEEK WITH HIGHS
BETWEEN 102-105 DEGREES. THIS WILL RESULT IN SOME AREAS OF
MODERATE HEATRISK FOCUSED ACROSS THE PHOENIX METRO AND ACROSS
IMPERIAL CO. WE ALSO CAN'T RULE OUT SOME ISOLATED SHOWERS AND
MAYBE A FEW WEAK THUNDERSTORMS FOCUSED OVER GILA CO., THE KOFAS,
AND MOSTLY OVER HIGHER TERRAIN AREAS IN SOUTHEAST CALIFORNIA.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
MODEL UNCERTAINTY REMAINS QUITE HIGH FOR THE LATTER HALF OF THE
WEEK AS GUIDANCE IS HAVING DIFFICULTY RESOLVING THE EVOLUTION OF
TC MARIO. AS OF NOW, THE MOST LIKELY SCENARIO CALLS FOR MARIO TO
GRADUALLY DISSIPATE AS IT SLOWLY MOVES NORTHWESTWARD OFF THE COAST
OF SOUTHERN BAJA. THERE IS STILL A SLIGHT POSSIBILITY OF ITS
REMNANTS REACHING AS FAR NORTH AS SOUTHERN CALIFORNIA, BUT OF MUCH
HIGHER LIKELIHOOD IS ITS MOISTURE WILL GET ABSORBED INTO THE
LARGER SCALE UPPER LEVEL LOW JUST TO ITS NORTH.
FOR OUR AREA, THE MAIN UNCERTAINTIES ARE HOW MUCH MOISTURE WILL
REACH SOUTHERN CALIFORNIA AND ARIZONA AND WHEN EXACTLY WILL BE THE
BEST RAIN CHANCES. THE LATEST NBM MODEL RUN HAS BACKED OFF ON THE
RAIN CHANCES FOR MUCH OF OUR AREA AS THE BEST AREA OF MOISTURE
AND RAIN LOOKS TO HAVE SHIFTED TO MORE ALONG THE COAST OF
SOUTHERN CALIFORNIA AND NORTHWARD. THIS SHIFT IS MORE SEEN WITHIN
THE EPS AS THE GEFS IS STILL HOLDING ONTO BETTER MOISTURE AND RAIN
CHANCES FARTHER TO THE EAST INTO OUR AREA. HAVE MOSTLY MAINTAINED
THE NBM POPS, BUT HAVE ADJUSTED UPWARDS SLIGHTLY FOR WEDNESDAY
AND THURSDAY AS THEY SEEMED TOO PESSIMISTIC. MOISTURE LEVELS ARE
AT LEAST LIKELY TO RISE TO NEAR 200% OF NORMAL ACROSS SOUTHEAST
CALIFORNIA AND TO AROUND 150% OF NORMAL FOR SOUTHERN AND CENTRAL
ARIZONA BY THURSDAY.
MOISTURE IS NOT LIKELY GOING TO BE AN ISSUE DURING THE LATTER HALF
OF THIS WEEK, BUT THERE SHOULD BE AN OVERALL LACK OF FORCING FOR
WIDESPREAD PRECIPITATION. AS OF NOW, SHOWERS AND THE POTENTIAL FOR
THUNDERSTORMS MAY END UP BEING FOCUSED ALONG A TROUGH AXIS MOVING
FROM SOUTH TO NORTH LATER ON WEDNESDAY AND THEN FROM OVERALL
LARGE SCALE UPPER LEVEL JET FORCING FOR THURSDAY AND FRIDAY.
CHANCES LATER WEDNESDAY AND THURSDAY ARE LIKELY TO BE FOCUSED
MORE ACROSS SOUTHEAST CALIFORNIA AND FAR SOUTHWEST ARIZONA BEFORE
SHIFTING MORE ACROSS CENTRAL ARIZONA ON FRIDAY. THE HIGHER LEVELS
OF UNCERTAINTY MEANS POPS ARE MOSTLY BETWEEN 20-40% AS OF NOW, BUT
CHANCES MAY RISE (AT LEAST FOR A SMALL WINDOW) ONCE UNCERTAINTY
DECREASES. QPF AMOUNTS HAVE ALSO BEEN DIALED BACK A GOOD DEAL WITH
THE MOISTURE SHIFT TO THE WEST WITH AMOUNTS MOSTLY FROM 0.2-0.5"
ACROSS SOUTHEAST CALIFORNIA TO AS LITTLE AS TRACE AMOUNTS FROM
PHOENIX AND AREAS TO THE EAST OF PHOENIX. AS A REMINDER, THERE IS
STILL A SMALL MINORITY OF MEMBERS THAT SHOW MUCH BETTER RAINFALL
TOTALS FOR SOUTHERN AND CENTRAL ARIZONA, SO BIG CHANGES TO THE
FORECAST MAY STILL HAPPEN.
GOING INTO THE WEEKEND, GUIDANCE MOSTLY AGREES THE BEST MOISTURE
WILL PUSH TO THE NORTH OF OUR AREA AS THE SUBTROPICAL RIDGE
CENTERED JUST TO OUR SOUTH BEGINS TO SHIFT NORTHWARD. WE MAY HAVE
SOME RESIDUAL SLIGHT RAIN CHANCES OVER THE WEEKEND, BUT OVERALL
CHANCES LOOK TO BE AT MOST 10-15%.
TEMPERATURES FOR THE LATTER HALF OF THE WEEK WILL TREND SLIGHTLY
LOWER WITH THE INCREASED MOISTURE AND CLOUDS, BUT HIGHS ARE NOT
EXPECTED TO FALL MUCH BELOW 100 DEGREES. ASSUMING THE SUBTROPICAL
RIDGE DOES MOVE MORE OVERHEAD FOR THE UPCOMING WEEKEND,
TEMPERATURES MAY BEGIN TO DRIFT BACK ABOVE 100 DEGREES AGAIN.
AVIATION
UPDATED AT 1730Z.
SOUTH CENTRAL ARIZONA AND SOUTHEAST CA INCLUDING KPHX, KIWA,
KSDL, KDVT, KBLH AND KIPL:
NO AVIATION WEATHER CONCERNS ARE EXPECTED THROUGH THE FORECAST
PERIOD UNDER MOSTLY CLEAR SKIES OVER THE REGION. WINDS WILL
FOLLOW TYPICAL DIURNAL PATTERNS WITH SPEEDS REMAINING AOB 7 KTS.
PERIODS OF CALM AND VRB WINDS WILL ALSO BE LIKELY, ESPECIALLY AT
THE SE CALIFORNIA TERMINALS AND PRIOR TO DIURNAL WIND SHIFTS.
FIRE WEATHER
HOTTER TEMPERATURES AND INCREASING MOISTURE WILL BE SEEN INTO MID
WEEK. AFTER ANOTHER DRY DAY TODAY, RAIN CHANCES WILL ALSO
GRADUALLY INCREASE BY MID WEEK, PARTICULARLY ACROSS THE WESTERN
DISTRICTS. MINIMUM RH VALUES SHOULD AVERAGE 15% TODAY, AROUND 20%
TUESDAY AND 25% FOR WEDNESDAY, WITH IMPROVED OVERNIGHT RECOVERIES
STARTING TONIGHT. WINDS WILL REMAIN LIGHT OVER THE NEXT FEW DAYS
WITH DIRECTIONS MOSTLY FOLLOWING DIURNAL TRENDS. DAILY RAIN
CHANCES OF 20-30% ARE EXPECTED FOR LATER THIS WEEK WITH
HUMIDITIES STAYING ELEVATED AND TEMPERATURES RETURNING INTO THE
NORMAL RANGE.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...SALERNO
FIRE WEATHER...KUHLMAN
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