684
FXUS65 KFGZ 181727
AFDFGZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1027 AM MST SUN OCT 18 2026
SYNOPSIS
SHOWER AND THUNDERSTORM CHANCES CONTINUE THROUGH
SUNDAY EVENING AS A WEATHER SYSTEM APPROACHES. THIS ACTIVE
PATTERN CONTINUES THROUGH MOST OF THE WEEK WITH CONTINUED DAILY
SHOWER CHANCES, OCCASIONAL GUSTY WINDS, AND BELOW NORMAL DAYTIME
TEMPERATURES. THE HIGHEST CHANCE OF RAIN IS ON WEDNESDAY AND
THURSDAY.
DISCUSSION...TODAY
A LOW PRESSURE SYSTEM CURRENTLY SPINNING
OFF THE COAST OF NORTHERN BAJA CALIFORNIA IS VISIBLE IN MID-
LEVEL WATER VAPOR SATELLITE IMAGERY. THIS IS EXPECTED TO SLOWLY
DRIFT NORTHEASTWARD WHILE WEAKENING THROUGH SUNDAY-MONDAY. A
SOUTHERLY MOISTURE SURGE IS CURRENTLY UNDERWAY, SOMEWHAT ENHANCED
BY CONTINUED ACTIVE TROPICAL CYCLONE ACTIVITY IN THE EASTERN
PACIFIC. COMBINED WITH SYNOPTIC LIFT FROM THE APPROACHING WEATHER
SYSTEM, WE ARE SEEING BANDS OF LIGHT SHOWERS ACROSS NORTHERN
ARIZONA EARLY THIS MORNING. OBSERVED RAINFALL HAS REMAINED VERY
LIGHT THUS FAR DUE TO LINGERING DRY SURFACE CONDITIONS, THOUGH
SURFACE DEWPOINTS ARE QUICKLY RISING. MOISTURE WILL CONTINUE TO
STREAM INTO ARIZONA THROUGH THE DAY TODAY, WITH PWAT RISING WELL
ABOVE NORMAL FOR MID OCTOBER. HOWEVER CLOUD COVER WILL LIMIT
DAYTIME HEATING, AND WEAK FLOW WILL LIMIT OROGRAPHIC INFLUENCES.
AS A RESULT, TOTAL RAINFALL ACCUMULATIONS THROUGH SUNDAY EVENING
ARE EXPECTED TO REMAIN LIGHT, UP TO AROUND 0.2-0.4 INCHES. BESIDES
SHOWERS, EXPECT CONTINUED COOL DAYTIME TEMPERATURES AND LIGHT
WINDS.
MONDAY AND TUESDAY...A STRONG LOW PRESSURE SYSTEM WILL RAPIDLY DIVE
ALONG THE WEST COAST AND APPROACH ARIZONA. THIS WILL REINFORCE A
PRESSURE GRADIENT BRINGING SOUTH-SOUTHWESTERLY FLOW TO OUR REGION.
WE WILL SEE GRADUALLY STRENGTHENING SOUTHERLY SURFACE WINDS
THROUGH THE PERIOD. LINGERING MOISTURE WILL ALSO LEAD TO CONTINUED
CHANCES FOR DAYTIME SHOWERS AND THUNDERSTORMS, ESPECIALLY MONDAY
AFTERNOON. DAYTIME TEMPERATURES WILL CLIMB A FEW DEGREES, BUT
STILL STAY NEAR TO BELOW OCTOBER NORMALS.
WEDNESDAY THROUGH FRIDAY...THE STRONG LOW PRESSURE SYSTEM WILL
BEGIN TO PUSH INLAND AND CARRY A DEEPER SURGE OF MOISTURE TO
NORTHERN AZ. WIDESPREAD SHOWERS AND THUNDERSTORMS, SOME STRONG,
ARE EXPECTED ON WEDNESDAY AND THURSDAY. THE CURRENT OUTLOOK BRINGS
THE BEST MOISTURE AND RAINFALL ACCUMULATIONS ACROSS EASTERN AZ.
STRONGER LOW-LEVEL FLOW WITH OROGRAPHIC INFLUENCES IS ALSO
EXPECTED. MOST AREAS WILL SEE AT LEAST 0.25-0.75 INCHES OF RAIN,
WITH PREFERRED UPSLOPE REGIONS ACROSS EASTERN AZ SEEING AS MUCH AS
1.5-2.5 INCHES. ENSEMBLE GUIDANCE STILL DOES HAVE SOME SPREAD IN
THE TRAJECTORY AND HOW PROGRESSIVE THE TROUGH WILL BE, SO THERE IS
ROOM FOR CHANGE IN TOTAL ACCUMULATIONS AND WHERE THE DEEPEST
MOISTURE WILL LAND. ACTIVITY IS EXPECTED TO TREND DOWNWARD BY
FRIDAY INTO THE WEEKEND. ALSO EXPECT EVEN COOLER TEMPERATURES WITH
GUSTY SOUTH TO SOUTHWEST WINDS EACH DAY, STRONGEST ON THURSDAY.
AVIATION...SUNDAY 18/18Z THROUGH MONDAY 19/18Z
MAINLY VFR WITH
LOCALIZED MVFR POSSIBLE IN HEAVIER SHOWERS. SCT -SHRA WITH ISO TS
DIMINISHING AFTER 02Z. VARIABLE WINDS 5-10 KTS, BECOMING LIGHT
OVERNIGHT.
OUTLOOK...MONDAY 19/18Z THROUGH WEDNESDAY 21/18Z...MAINLY VFR WITH
BRIEF MVFR IN HEAVIER SHOWERS. SCT -SHRA/-TSRA ALONG THE HIGHER
TERRAIN ON MONDAY AFTERNOON, BECOMING ISO ON TUESDAY. DAYTIME
WINDS S-SW 5-15 KTS ON MONDAY, INCREASING TO 10-20 KTS ON TUESDAY.
EXPECT LIGHT AND VARIABLE WINDS DURING THE OVERNIGHT PERIOD.
FIRE WEATHER...TODAY THROUGH MONDAY
COOL CONDITIONS THROUGH THE
PERIOD. LIGHT AND VARIABLE WINDS ON SUNDAY, BECOMING SOUTH 5-15 MPH
ON MONDAY. SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS CONTINUE
THROUGH SUNDAY EVENING, THEN SCATTERED SHOWERS AND THUNDERSTORMS
AGAIN ON MONDAY.
TUESDAY THROUGH THURSDAY...SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS ON TUESDAY, BECOMING LIKELY SHOWERS AND THUNDERSTORMS
ON WEDNESDAY AND THURSDAY. WETTING RAINS ARE EXPECTED FOR MOST.
SOUTH WINDS 10-20 MPH ON TUESDAY, INCREASING TO 15-25 MPH WITH GUSTS
30-40 MPH ON WEDNESDAY AND THURSDAY. BELOW NORMAL TEMPERATURES
CONTINUE THROUGH THE WEEK.
FGZ WATCHES/WARNINGS/ADVISORIES
NONE.
PUBLIC...LEWANDOWSKI
AVIATION...MEOLA
FIRE WEATHER...LEWANDOWSKI
FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF
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