664
FXUS65 KFGZ 271927
AFDFGZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1227 PM MST SUN SEP 27 2026
SYNOPSIS
SHOWER AND THUNDERSTORM CHANCES WILL INCREASE THROUGH
TONIGHT, WITH WIDESPREAD SHOWERS AND EMBEDDED THUNDERSTORMS
MONDAY. THIS IS ASSOCIATED WITH AN INCOMING TROUGH FROM THE WEST
COAST THAT WILL INTERACT WITH TROPICAL MOISTURE AND POTENTIALLY
BRING HEAVY RAIN, STRONG THUNDERSTORMS AND FLASH FLOODING. A
FLOOD WATCH HAS BEEN ISSUED FOR MONDAY AND TUESDAY WHICH IS THE
TIME PERIOD WHEN THE HEAVIEST RAIN IS LIKELY TO OCCUR. SHOWER AND
THUNDERSTORM CHANCES WILL THEN DECREASE WEDNESDAY AND WEDNESDAY
NIGHT, WITH MILD AND DRY CONDITIONS TO START OFF OCTOBER.
DISCUSSION
MOISTURE FROM TROPICAL CYCLONES ODALYS AND POLO IS
BEGINNING TO OVERSPREAD THE AREA, STARTING IN THE HIGH AND MID
LEVELS AT FIRST WHICH HAS INCREASED CLOUD COVER TODAY, WITH SOME
LIGHT RAIN TRYING TO REACH THE SURFACE LATE THIS AFTERNOON. THE
POTENTIAL FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE TO INCREASE
OVERNIGHT AS MOISTURE SURGES ACROSS AZ.
BY MONDAY, A DEEP WEST COAST TROUGH APPROACHES WITH A CLOSED
UPPER-LEVEL LOW EXPECTED TO DEVELOP AT ITS BASE, THEN SLOWLY MOVE
ACROSS THE REGION TUESDAY. THIS TROUGH WILL ACT UPON THE TROPICAL
MOISTURE ALREADY IN PLACE AND 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 CONTINUES TO MESSAGE A MODERATE RISK FOR EXCESSIVE
RAINFALL FOR MOST OF THE REGION FOR MONDAY AND THEN SHIFTING FOCUS
FOR THE EASTERN PART OF THE STATE TUESDAY AS THE TROUGH AND
CLOSED UPPER-LEVEL LOW MOVE EASTWARD. A FLOOD WATCH REMAINS IN
EFFECT FOR MONDAY AND TUESDAY. WIDESPREAD RAINFALL AMOUNTS OF 1 TO
2 INCHES FORECAST ACROSS THE HIGH DESERTS OF NORTHEAST ARIZONA
HAVE AN AVERAGE RETURN INTERVAL OF 5 TO 10 YEARS, MAKING THIS AT
LEAST AN UNCOMMON EVENT THERE. HIGH TEMPERATURES ACROSS THE REGION
MONDAY AND TUESDAY WILL BE QUITE COOL DUE TO THE CLOUD COVER AND
RAINFALL, 10 TO 20 DEGREES BELOW AVERAGE. BY WEDNESDAY NIGHT,
PRECIPITATION CHANCES 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, POLO 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 AND ACTING ON THAT TROPICAL MOISTURE DRAWN
NORTH WILL BE THE SOURCE OF THE ACTIVE WEATHER MONDAY AND
TUESDAY.
BY THURSDAY ONWARD DRY AIR FROM THE WEST AND NORTH WILL TAKE OVER
AND LIMIT THE POTENTIAL FOR PRECIPITATION THROUGH THE REST OF THE
WEEK. SOME RIDGING WILL 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...SUNDAY 27/18Z THROUGH MONDAY 28/18Z
VFR CONDITIONS
TO START THE PERIOD, LOWERING TO MVFR BETWEEN 09Z-12Z. CLOUD DECKS
WILL PROGRESSIVELY LOWER THROUGH THE TAF PERIOD WITH SCATTERED SHOWERS
AND THUNDERSTORMS DEVELOPING AROUND 00Z. SHOWERS AND THUNDERSTORMS
WILL BECOME MORE NUMEROUS AS THE NIGHT PROGRESSES AREA WIDE.
WINDS SW 10-20KTS DAYTIME, LIGHT AND VARIABLE OVERNIGHT. GUSTY AND
ERRATIC WINDS NEAR STORMS.
OUTLOOK...MONDAY 28/18Z THROUGH WEDNESDAY 30/18Z...VFR-MVFR WITH
BRIEF IFR POSSIBLE IN HEAVIEST SHOWERS AND THUNDERSTORMS. EXPECT
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS AREA WIDE MONDAY
INTO TUESDAY WITH THE FOCUS OF PRECIPITATION MOVING TOWARDS
EASTERN ARIZONA TUESDAY AFTERNOON AND NIGHT. DAYTIME WINDS
S 5-15KTS MONDAY, N-E 5-15KTS TUESDAY. LIGHT AND VARIABLE OR
TERRAIN DRIVEN OVERNIGHT.
FIRE WEATHER...TONIGHT THROUGH TUESDAY
PRECIPITATION CHANCES WILL
RAMP UP OVERNIGHT TONIGHT WITH WIDESPREAD WETTING RAIN AND EMBEDDED
THUNDERSTORMS ON MONDAY, PRESENTING A MODERATE FLOOD AND FLASH FLOOD
RISK. WIDESPREAD PRECIPITATION EXPECTED TUESDAY WITH FLASH FLOOD
CHANCES CONTINUING. PRECIPITATION WILL BEGIN TO FOCUS MORE OVER
EASTERN ARIZONA TUESDAY EVENING. WINDS S 5-15 MPH ON MONDAY, N-NE 10-
20 MPH ON TUESDAY.
WEDNESDAY THROUGH FRIDAY...SOME LINGERING PRECIPITATION CHANCES IN
FAR EASTERN ARIZONA WEDNESDAY, DRYING OUT ELSEWHERE. DRY WITH NO
PRECIPITATION ACROSS THE STATE THURSDAY AND FRIDAY. WINDS NW-N 5-15
MPH ON WEDNESDAY, LIGHT AND VARIABLE 5-10 MPH THURSDAY, LIGHT AND
VARIABLE MOST AREAS FRIDAY WITH THE EXCEPTION OF SOME WINDS E 5-15
MPH ALONG THE RIM.
FGZ WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH FROM THIS EVENING THROUGH TUESDAY EVENING FOR
AZZ004>018-037>040.
PUBLIC...ZANKER
AVIATION...BERNHART
FIRE WEATHER...BERNHART
FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF
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