381
FXUS65 KPSR 052015
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
115 PM MST SAT SEP 5 2026
KEY MESSAGES
- A PLUME OF MOISTURE WILL YIELD MINIMAL RAIN CHANCES ACROSS
PORTIONS OF SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA THROUGH
THE WEEKEND.
- MOSTLY DRY AND QUIET WEATHER CONDITIONS CAN BE EXPECTED EARLY
NEXT WEEK BEFORE THUNDERSTORM CHANCES INCREASE BY THE LATTER
HALF OF THE WEEK.
- TEMPERATURES WILL REMAIN NEAR TO SLIGHTLY BELOW NORMAL THROUGH
THIS WEEKEND BEFORE WARMING TO SLIGHTLY ABOVE NORMAL BY EARLY
NEXT WEEK.
SHORT TERM /TODAY THROUGH SUNDAY/
LATEST OBJECTIVE ANALYSIS REVEALS THE SUBTROPICAL RIDGE SITUATED
OVER THE SOUTHERN PLAINS WHILE A BROAD UPPER TROUGH ENCOMPASSES MUCH
OF THE WEST COAST WITH LOW PRESSURE PRESSURE CENTERED ACROSS THE
PACIFIC NORTHWEST. THIS OVERALL PATTERN CONFIGURATION IS CONTINUING
TO RESULT IN SOUTHWESTERLY FLOW ALOFT, WHICH HAS HELPED ADVECT A
PLUME OF MAINLY MID TO UPPER-LEVEL MOISTURE ORIGINATING FROM
HURRICANE MARIE, SPINNING WELL OF THE COAST OF THE BAJA PENINSULA,
INTO THE REGION. THE HIGHEST MOISTURE CONTENT IS EXPECTED TO BE
CONFINED ACROSS SOUTHWEST AZ AND SOUTHEAST CA WHERE PWATS ARE
EXPECTED TO CLIMB IN EXCESS OF 1.5" LATER TODAY. THIS INCREASE IN
MOISTURE COMBINED WITH SOME UPPER-LEVEL FORCING FROM THE
AFOREMENTIONED TROUGH WILL CAUSE ISOLATED TO SCATTERED LIGHT
SHOWERS TO BREAK OUT. HOWEVER, SINCE MUCH OF THE MOISTURE IS
MOSTLY IN THE MID TO UPPER-LEVELS WITH THE LOW-LEVELS RATHER DRY
AS SURFACE DEWPOINTS ARE IN THE 40S AND 50S, ANY RAIN THAT FALLS
WILL BE MOSTLY VIRGA/SPRINKLES WITH LITTLE TO NO MEASURABLE
ACCUMULATIONS. SOME BETTER LOW-LEVEL MOISTURE WILL BE IN PLACE ON
SUNDAY, HOWEVER, MOST OF THE UPPER-LEVEL FORCING WILL BE SHIFTING
NORTHWARD WITH THE MOHAVE DESERT REGION EXPECTED TO HAVE THE
BETTER RAINFALL POTENTIAL AS GUIDANCE SHOWS AN EXTENSIVE AREA OF
LIGHT TO LOCALLY MODERATE INTENSITY RAINFALL MATERIALIZING. ACROSS
SOUTH-CENTRAL AZ, GENERALLY DRY AND QUIET WEATHER CONDITIONS ARE
EXPECTED THROUGH THE REST OF THE WEEKEND AS THE COMBINATION OF THE
LACK OF INSTABILITY AND FORCING FOR ASCENT WILL HINDER STORM
ACTIVITY. WITH THE RAINFALL ACTIVITY OVER THE MOHAVE DESERT
REGION ON SUNDAY, OUTFLOW WINDS FROM THE NORTHWEST ARE EXPECTED TO
IMPACT MUCH OF THE LOWER DESERTS WITH AFTERNOON/EARLY EVENING
PEAK GUSTS OF 20-30 MPH LIKELY.
TEMPERATURES TODAY AND SUNDAY WILL CONTINUE TO RUN NEAR TO A FEW
DEGREES BELOW NORMAL, WITH TODAY BEING THE COOLER DAY GIVEN THE
PRESENCE OF MORE ABUNDANT MID TO HIGH CLOUDS. THE COOLER
TEMPERATURES FOR THIS AFTERNOON ARE EXPECTED ACROSS THE WESTERN
DESERTS WHERE THE THICKER CLOUD COVER WILL LIKELY CAUSE READINGS
TO FALL SHY OF THE TRIPLE DIGITS, WHEREAS FURTHER EAST INTO
SOUTH-CENTRAL AZ, SLIGHTLY WARMER READINGS INTO THE LOW 100S
UNDER MORE SUNSHINE CAN BE EXPECTED. TEMPERATURES WILL WARM A FEW
MORE DEGREES ON SUNDAY UNDER SLIGHTLY LESS CLOUD COVER.
LONG TERM /MONDAY THROUGH FRIDAY/
ENSEMBLE MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT ON THE
SYNOPTIC PATTERN FOR THE BEGINNING OF THE WORKWEEK. ENSEMBLE MEMBERS
SHOW THE LONGWAVE TROUGH OVER WESTERN CONUS LIFTING NORTHEASTWARD
AND PUSHING INTO THE NORTHERN ROCKIES, TC MARIE MOVING
NORTH/NORTHWESTWARD (STAYING WELL OFF THE COAST OF CALIFORNIA), AND
THE SUBTROPICAL RIDGE PUSHING BACK INTO THE DESERT SOUTHWEST. WITH
THE SUBTROPICAL RIDGE BUILDING BACK OVERHEAD, H5 HEIGHTS WILL RISE
TO AROUND 591-594 DM. THIS INCREASE IN HEIGHTS ALOFT WILL RESULT IN
A GRADUAL WARMING TREND. THE NBM SHOWS AFTERNOON HIGH TEMPERATURES
INCREASING TO 100-108 DEGREES ACROSS THE LOWER DESERTS AND 90-100
DEGREES ACROSS THE HIGHER TERRAIN. TEMPERATURES OF THIS MAGNITUDE
ARE SLIGHTLY ABOVE NORMAL, WHICH WILL RESULT IN WIDESPREAD
MODERATE HEATRISK ACROSS THE LOWER DESERTS. THE AFOREMENTIONED
SYNOPTIC PATTERN WILL ALSO RESULT IN THE CONTINUATION OF DRY
SOUTHWESTERLY FLOW ALOFT. PWATS ARE EXPECTED TO DROP TO AROUND
1.3-1.6", RESULTING IN MOSTLY DRY CONDITIONS ACROSS THE CWA.
HEADING INTO THE LATER HALF OF THE WORKWEEK, ENSEMBLE MODEL GUIDANCE
CONTINUE TO DISAGREE ON THE SYNOPTIC PATTERN. NOT ONLY DO THE MODELS
DIFFER ON THE STRENGTH AND POSITIONING OF THE SUBTROPICAL RIDGE,
THEY ALSO DIFFER ON THE STRENGTH AND POSITIONING OF THE LOW PRESSURE
SYSTEM OVER THE EASTERN PACIFIC. OVERALL THE EPS HAS A STRONGER
SOLUTION, IT IS SHOWING A STRONGER SUBTROPICAL RIDGE ALONG WITH A
STRONGER/DEEPER LOW PRESSURE SYSTEM IN THE PACIFIC (IN FACT IT IS
SHOWING A CLOSED LOW). ADDITIONALLY, THE EPS HAS BOTH OF THESE
FEATURES FURTHER WEST. THE EPS SHOWS THE HIGH MAXING OUT AROUND 597
DM DURING THE MIDDLE OF THE WEEK, WITH THE CENTER STRETCHED ACROSS
THE PLAINS, AND THEN THE HIGH WEAKENING SLIGHTLY, BUT MOVING
OVERHEAD BY THE END OF THE WORKWEEK. THEN THE GEFS IS SHOWING A
WEAKER RIDGE AND A WEAKER, OPEN WAVE TROUGH, WITH BOTH OF THESE
FEATURES FURTHER EAST. THESE DIFFERENCE CAN BE SEEN IN THE LARGE
TEMPERATURE SPREADS IN THE NBM INTERQUARTILE RANGE (WITH THE EPS
BEING A WARMER SOLUTION AND THE GEFS BEING A COOLER SOLUTION). THE
NBM CONTINUES TO LEAN MORE TOWARDS THE GEFS, WITH A GRADUAL COOLING
TREND BEGINNING WEDNESDAY. BOTH ENSEMBLE MODELS DO SHOW A RETURN OF
MOISTURE BY THE MIDDLE OF NEXT WEEK, WITH PWATS INCREASING TO AROUND
1.5-1.8" (EPS HAS SLIGHTLY HIGHER PWATS). THIS INCREASE IN
MOISTURE WILL RESULT IN RAIN CHANCES RETURNING TO THE REGION AS
EARLY AS WEDNESDAY. THE NBM SHOWS POPS OF 20-40% AREA WIDE BY THE
WEDNESDAY- THURSDAY TIMEFRAME. THE GFS ALSO SHOWS AN INVERTED
TROUGH MOVING THROUGH THE REGION DURING THE MIDDLE OF NEXT WEEK.
IF THIS WERE TO OCCUR IT WOULD SIGNIFICANTLY INCREASE RAIN
CHANCES FOR THE REGION. DESPITE THIS, BOTH THE GEFS AND EPS DO
SHOW MEASURABLE RAINFALL RETURNING TO AT LEAST SOME PORTIONS OF
THE REGION DURING THE LATTER HALF OF THE UPCOMING WORKWEEK.
HOWEVER, FORECAST CONFIDENCE REMAINS LOW AND WE'LL HAVE TO WAIT TO
SEE HOW THE MODELS EVOLVE OVER THE COMING DAYS.
AVIATION
UPDATED AT 1825Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
NO MAJOR WEATHER CONCERNS WILL EXIST THROUGH THROUGH THE FORECAST
PERIOD UNDER INCREASING MID/HIGH LEVEL CLOUD DECKS. MOSTLY DIURNAL
TRENDS WITH A SOUTHERLY CROSSWIND BEFORE WINDS SETTLE OUT OF THE
WEST FOR THE AFTERNOON. UNCERTAINTY EXISTS IF WINDS WILL GO
EASTERLY FOR THE OVERNIGHT PERIOD INTO TOMORROW MORNING, CURRENTLY
MODELS SUGGEST VRB CONDITIONS HOWEVER FAVORING A WESTERLY
DIRECTION. WIND SPEEDS WILL BE AOB 12KTS THROUGHOUT THE TAF PERIOD.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR WEATHER ISSUES WILL EXIST THROUGH THE FORECAST PERIOD
UNDER THICKENING MID/HIGH LEVEL CLOUDS. WINDS WILL FOLLOW GENERAL
DIURNAL PATTERNS, FLUCTUATING BETWEEN WESTERLY TO SOUTHEASTERLY AT
KIPL AND SOUTHERLY SLOWLY SHIFTING TO THE NW BY TOMORROW MORNING
(~16Z) AT KBLH. CONFIDENCE HAS LOWERED SINCE THE LAST PACKAGE FOR
VCSH AT EACH TERMINAL SO THEY HAVE BEEN REMOVED FROM THE TAFS AT
THIS TIME, BUT THE VERY SLIM CHANCE THEY DO MATERIALIZE NO
OPERATIONAL IMPACTS ARE EXPECTED.
FIRE WEATHER
NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES CONTINUE THROUGH THE
WEEKEND. A GRADUAL WARMING TREND BEGINS EARLY NEXT WEEK BEFORE
ANOTHER COOLING TREND IS EXPECTED FOR THE END OF THE WORKWEEK.
RAIN CHANCES TODAY WILL BE CONFINED TO THE WESTERN DISTRICTS, BUT
CHANCES FOR WETTING RAINFALL REMAIN VERY LOW. AFTERNOON MINRH'S
TODAY WILL BE 15-30%, INCREASING SLIGHTLY STARTING ON SUNDAY
WITH VALUES ABOVE 20% AREA WIDE THROUGH MUCH OF NEXT WEEK ALONG
WITH GOOD OVERNIGHT RECOVERIES. WINDS WILL GENERALLY REMAIN LIGHT
TODAY BEFORE SOME ELEVATED AFTERNOON/EARLY EVENING BREEZINESS OUT
OF THE NORTHWEST RETURN ON SUNDAY WITH PEAK GUSTS OF 20-30 MPH. A
MORE TYPICAL DIURNAL WIND PATTERN WITH SOME OCCASIONAL AFTERNOON
UPSLOPE BREEZINESS CAN BE EXPECTED THROUGH MUCH OF NEXT WEEK.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...LOJERO
LONG TERM...BERISLAVICH
AVIATION...RYAN
FIRE WEATHER...LOJERO/BERISLAVICH
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