419
FXUS65 KFGZ 262023
AFDFGZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
123 PM MST SAT SEP 26 2026
SYNOPSIS
A BIG PATTERN CHANGE WILL OCCUR STARTING SUNDAY
AFTERNOON. AN INCOMING TROUGH FROM THE WEST COAST WILL INTERACT
WITH TROPICAL MOISTURE AND POTENTIALLY BRING HEAVY RAIN, STRONG
THUNDERSTORMS AND POSSIBLE FLASH FLOODING. A FLASH FLOOD WATCH HAS
BEEN ISSUED FOR MONDAY AND TUESDAY WHICH IS THE TIME PERIOD WHEN
THE HEAVIEST RAIN IS LIKELY TO OCCUR. WEDNESDAY AFTERNOON ONWARD
THINGS DRY OUT AND THE REGION WILL SEE DRY AND WARM CONDITIONS TO
START OFF OCTOBER.
DISCUSSION
AFTER A PLEASANT DAY TODAY AND A QUIET NIGHT TONIGHT
THINGS WILL START TO SHIFT TO AN ACTIVE PATTERN STARTING SUNDAY
AFTERNOON. MOISTURE FROM TROPICAL CYCLONES ODALYS AND POLO WILL
BEGIN OVERSPREADING THE AREA, MOST LIKELY IN THE HIGH AND
MID LEVELS AT FIRST WHICH WILL BRING IN THE CLOUDS AND SOME LIGHT
RAIN STARTING SUNDAY EVENING AND SUNDAY NIGHT. THE LOWER LEVELS
WILL BE DRY AT FIRST BUT START MOISTENING UP FROM THESE INITIAL
RAIN SHOWERS.
BY MONDAY A DEEP WEST COAST TROUGH APPROACHES WITH A CLOSED UPPER
LEVEL LOW AT ITS BASE. THIS WILL ACT UPON THE TROPICAL MOISTURE
ALREADY IN PLACE AND THIS IS WHEN THE BEST RAIN CHANCES WILL
START. BY THE AFTERNOON LIFT FROM THE APPROACHING TROUGH WILL
GENERATE SOME EMBEDDED THUNDERSTORMS THAT COULD BECOME STRONG TO
SEVERE AT TIMES WITH HEAVY RAIN, STRONG WINDS AND SOME LARGE HAIL.
WPC HAS UPGRADED OUR AREA INTO THE MODERATE CATEGORY FOR EXCESSIVE
RAINFALL SO TO GET A JUMP ON MESSAGING TO OUR PARTNERS WE'VE
ALREADY ISSUED A FLOOD WATCH FOR MONDAY AND TUESDAY. THIS TROUGH
LOOKS TO TAKE ITS TIME MOVING ACROSS THE AREA SO TUESDAY WILL BE
ANOTHER ACTIVE DAY FOR THE REGION WITH MUCH OF THE SAME RISKS AS
MONDAY ALTHOUGH THE FOCUS MAY BE MORE TOWARDS THE EASTERN PART OF
THE STATE. TEMPERATURES ACROSS THE REGION MONDAY AND TUESDAY WILL
BE QUITE COOL DUE TO THE CLOUD COVER AND RAINFALL, ABOUT 10
DEGREES BELOW AVERAGE. BY WEDNESDAY AFTERNOON PRECIPITATION
CHANCES SHOULD START WINDING DOWN IN THE FAR EASTERN PARTS OF THE
STATE AS THE TROUGH SWEEPS EAST AND TAKES THE MOISTURE PLUME WITH
IT.
ONE THING TO NOTE: DESPITE THE FACT THE TROPICAL MOISTURE IS
COMING FROM TWO TROPICAL CYCLONES TO THE SOUTH, NEITHER ONE OF
THESE CIRCULATIONS WILL ACTUALLY MAKE IT UP INTO ARIZONA. ODALYS
IS LOOPING SOUTH AND WILL LIKELY DIE IN THE OPEN OCEAN, POLOS IS
EXPECTED TO MAKE LANDFALL IN BAJA CALIFORNIA, CROSS THE GULF OF
CALIFORNIA AND BREAK APART TO OUR SOUTH WHEN IT MAKES LANDFALL
AGAIN IN MAINLAND MEXICO. THE STRONG TROUGH AND UPPER LEVEL LOW
MOVING IN FROM THE WEST ACTING ON THAT TROPICAL MOISTURE DRAWN
NORTH WILL BE MORE THAN ENOUGH TO KEEP US BUSY.
BY THURSDAY ONWARD DRY AIR FROM THE WEST AND NORTH WILL TAKE OVER
AND PRECIPITATION WILL BE A DISTANT MEMORY FOR QUITE AWHILE AS
LONG TERM MODELS AT THIS TIME AREN'T SHOWING ANYTHING ELSE COMING
IN. THIS WILL BE THE END OF MONSOON 2026, BOTH METEORLOGICALLY AND
CALENDER WISE. WITH SOME RIDGING MOVING IN TOWARDS THE END OF THE
WEEK LOOK FOR A PLEASANT START TO OCTOBER AS HIGH TEMPERATURES
RECOVER TO A FEW DEGREES ABOVE AVERAGE.
AVIATION...SATURDAY 26/18Z THROUGH SUNDAY 27/18Z
VFR
CONDITIONS. WINDS SW-SE 5-15 KTS THROUGH 02Z, LIGHT AND VRB
OTHERWISE.
OUTLOOK...SUNDAY 27/18Z THROUGH TUESDAY 29/18Z....VFR CONDITIONS
THROUGH SUNDAY EVENING, WITH PERIODS OF MVFR EXPECTED IN SCT-NMRS
SHRA/TSRA THEREAFTER. DAYTIME WINDS ARE S/SW 10-15 KTS GUSTING TO
25 KTS ON SUNDAY, BECOMING S 10-20 KTS ON MONDAY. OVERNIGHT WINDS
LIGHT AND VARIABLE. GUSTY AND ERRATIC WINDS NEAR STORMS.
FIRE WEATHER...TODAY THROUGH MONDAY
DRY CONDITIONS ARE EXPECTED
UNTIL SLIGHT CHANCES FOR SHOWERS AND THUNDERSTORMS RETURN SUNDAY
AFTERNOON. PRECIPITATION CHANCES CONTINUE TO RAMP UP OVERNIGHT
SUNDAY WITH WIDESPREAD WETTING RAIN AND EMBEDDED THUNDERSTORMS ON
MONDAY, PRESENTING A MODERATE FLOOD RISK. S-SW WINDS ARE 10-20 MPH
GUSTING TO 30 MPH ON SUNDAY, 5-15 MPH ON MONDAY.
TUESDAY THROUGH THURSDAY...PROLONGED WIDESPREAD PRECIPITATION
CHANCES CONTINUE INTO TUESDAY NIGHT AS AN APPROACHING WEATHER SYSTEM
COMBINES WITH TROPICAL MOISTURE. PRECIPITATION CHANCES DECLINE FROM
WEST TO EAST OVERNIGHT TUESDAY INTO WEDNESDAY MORNING. THERE IS A
THREAT OF HEAVY RAINFALL AND FLASH FLOODING ON TUESDAY FOR ALL OF
NORTHERN AZ. WINDS N-NE 10-20 MPH ON TUESDAY, THEN NW-N 5-15 MPH ON
WEDNESDAY AND THURSDAY.
FGZ WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH FROM SUNDAY EVENING THROUGH TUESDAY EVENING FOR
AZZ004>018-037>040.
PUBLIC...BERNHART
AVIATION...ZANKER
FIRE WEATHER...ZANKER
FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF
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