818
FXUS65 KFGZ 180509
AFDFGZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1009 PM MST SAT OCT 17 2026
SYNOPSIS
DRY CONDITIONS AND LIGHTER EAST WINDS ARE EXPECTED
THROUGH THIS AFTERNOON, THEN A WEATHER SYSTEM BRINGS CHANCES FOR
SHOWERS AND THUNDERSTORMS THIS EVENING THROUGH SUNDAY. THIS ACTIVE
PATTERN CONTINUES THROUGH MOST OF NEXT WEEK WITH CONTINUED DAILY
SHOWER CHANCES, OCCASIONAL GUSTY WINDS, AND BELOW NORMAL DAYTIME
TEMPERATURES. THE HIGHEST CHANCE OF RAIN NEXT WEEK IS ON WEDNESDAY
AND THURSDAY.
DISCUSSION...FOR TODAY AND SUNDAY
A LOW PRESSURE SYSTEM WAS
SEEN SPINNING JUST OFF THE BAJA CALIFORNIA COAST SATURDAY
MORNING. OVER THE NEXT 24- TO 36-HOURS THE LOW CENTER WILL TRACK
TOWARD THEN ACROSS ARIZONA, WEAKENING AND FILLING AS IT GOES. THE
LOW WILL BRING WITH IT UPWARD MOTION AND INCREASING MOISTURE.
BY SATURDAY NIGHT SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL DEVELOP FROM SOUTH TO NORTH ACROSS ARIZONA STARTING, THEN
LAST THROUGH SUNDAY. A FEW LIMITING FACTORS WITH THIS LOW. FIRST,
THE AIR MASS ACROSS ARIZONA IS VERY DRY AND IT WILL TAKE A BIT
FOR THE DEPTH OF THE ATMOSPHERE TO MOISTEN. IN ADDITION, THE FLOW
ASSOCIATED WITH THIS LOW IS WEAK SO VERY LITTLE IF ANY OROGRAPHIC
LIFT. ANOTHER FACTOR, IT WILL REMAIN MOSTLY CLOUDY AS THE LOW
MOVES ACROSS THE AREA WITH LITTLE IMPACT DUE TO DAYTIME HEATING.
AS A RESULT, LOOKING AT GENERALLY LIGHT PRECIPITATION TOTALS OF
0.10 INCHES OR LESS THROUGH EARLY MONDAY (HIGHER AMOUNTS OVER THE
HIGHEST MOUNTAIN PEAKS PERHAPS AS MUCH AS 0.50 INCHES). IN ANY
CASE, THIS IS A WARM SYSTEM SO SNOW LEVELS ARE EXPECTED TO REMAIN
PRIMARILY ABOVE 11,000 FEET BUT CAN'T RULE OUT SNOW LEVELS BRIEFLY
DIPPING A BIT LOWER AT THE ONSET OF PRECIPITATION DUE TO
EVAPORATIONAL COOLING. EASTERLY WINDS SATURDAY AFTERNOON WILL
BECOME LIGHT AND VARIABLE ON SUNDAY AS PRESSURE GRADIENTS BECOME
INDETERMINATE. THERE WILL BE A COOLING INFLUENCE FROM THE LIGHT
PRECIPITATION AND CLOUDS WITH HIGH TEMPERATURES DROPPING BY AROUND
5 DEGREES ON SUNDAY COMPARED TO SATURDAY.
FOR MONDAY AND TUESDAY...A STRONG LOW PRESSURE SYSTEM DROPPING
SOUTHWARD FROM THE GULF OF ALASKA WILL BEGIN TO APPROACH ARIZONA.
MOISTURE WILL CONTINUE TO LINGER IN ADVANCE OF THIS LOW WITH
CHANCES FOR SHOWERS OR A STRAY THUNDERSTORM CONTINUING MOSTLY IN
THE AFTERNOON DUE TO DAYTIME HEATING. WINDS WILL TURN MORE
SOUTHERLY AT 5-15 MPH ON MONDAY IN RESPONSE TO THE APPROACHING
THEN STRENGTHEN SOME ON TUESDAY AS THE LOW DRAWS CLOSER TO
ARIZONA. HIGH TEMPERATURES WILL WARM A BIT AS SOUTHERLY FLOW
PUSHES A MILD AIR MASS ACROSS ARIZONA.
FROM WEDNESDAY ONWARD...MODELS REMAIN CONSISTENT ON PUSHING THE
PACIFIC LOW ACROSS ARIZONA TAPPING INTO MOISTURE OF SUBTROPICAL
ORIGINS. THE RESULT, WIDESPREAD SHOWERS AND LIKELY A FEW
THUNDERSTORMS, ESPECIALLY ON WEDNESDAY AND THURSDAY. THE MOST
SUBSTANTIAL MOISTURE, WITH ORIGINS FROM OVER THE GULF OF
CALIFORNIA AND NORTHWEST MEXICO, WILL LIKELY MOVE ACROSS ARIZONA
FROM ABOUT FLAGSTAFF EASTWARD WHERE LOCAL RAINFALL TOTALS OF 1 TO
2 INCHES WILL BE POSSIBLE. THE AREA OF THE HIGHEST RAINFALL
TOTALS INCLUDES THE WHITE MOUNTAINS, EASTERN MOGOLLON RIM AND
NAVAJO NATION. FURTHER WEST LOOKING AT AMOUNTS OF 0.25-0.75
INCHES. ONCE AGAIN THE SNOW LEVEL WILL REMAIN ELEVATED FOR MUCH OF
THE STORM DUE TO THE SUBTROPICAL NATURE OF THE MOISTURE, PERHAPS
DROPPING AS LOW AS 8500 FEET AS THE LOW IS EXITING ARIZONA NEXT
SATURDAY. PRESSURE GRADIENTS WILL STRENGTHEN WITH BREEZY SOUTH TO
SOUTHWEST WINDS DEVELOPING. HIGH TEMPERATURES WILL BE ON THE
DECREASE UNDER THE INFLUENCE OF PERCEPTION, CLOUDS AND COOLER AIR
ASSOCIATED WITH THE LOW.
AVIATION...SUNDAY 18/06Z THROUGH MONDAY 19/06Z
MAINLY VFR BUT
MVFR MAY BE POSSIBLE AT HIGHER ELEVATIONS AFTER 18Z DUE TO LOWER
CEILINGS. EXPECTED SCATTERED SHOWERS OVERNIGHT AND MOST OF
TOMORROW BEFORE TAPERING OFF AFTER 00Z. THE BEST CHANCES FOR
SHOWERS WILL BE ALONG THE HIGHER ELEVATIONS. WINDS VARIABLE
5-10KTS.
OUTLOOK...MONDAY 19/06Z THROUGH WEDNESDAY 21/06Z...MAINLY VFR, BUT
BRIEF MVFR POSSIBLE NEAR HEAVIER SHOWERS. ISOLATED TO SCATTERED SHOWERS
AND POSSIBLY THUNDERSTORMS EXPECTED MONDAY AFTERNOON ALONG THE HIGHER
TERRAIN. ISOLATED SHOWERS ARE POSSIBLE OVER THE KAIBAB PLATEAU
AND WHITE MOUNTAINS TUESDAY AFTERNOON. WINDS S-SW 5-15KTS MONDAY
AND TUESDAY.
FIRE WEATHER...SUNDAY THROUGH MONDAY
COOL TEMPERATURES WITH LIGHT
AND VARIABLE WINDS ON SUNDAY, BECOMING SOUTH 5-15 MPH ON MONDAY.
SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS THROUGH SUNDAY
AFTERNOON, THEN ISOLATED TO SCATTERED SHOWERS ARE EXPECTED ON
MONDAY. MINIMUM RH BETWEEN 40-70% BOTH DAYS.
TUESDAY THROUGH THURSDAY...COOL TEMPERATURES CONTINUE THROUGH THE
WEEK. SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS ON TUESDAY,
BECOMING LIKELY SHOWERS AND THUNDERSTORMS ON WEDNESDAY AND THURSDAY.
SOUTH WINDS 10-20 MPH WITH GUSTS TO 30 MPH ON TUESDAY, INCREASING TO
15-25 MPH WITH GUSTS 30-40 MPH ON WEDNESDAY AND THURSDAY.
FGZ WATCHES/WARNINGS/ADVISORIES
NONE.
PUBLIC...MCCOLLUM
AVIATION...BERNHART
FIRE WEATHER...MEOLA
FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF
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