264
FXUS65 KFGZ 191940
AFDFGZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1240 PM MST MON OCT 19 2026
SYNOPSIS
NORTHERN ARIZONA WILL REMAIN IN AN ACTIVE WEATHER
PATTERN THROUGH THE WEEK. SCATTERED SHOWERS AND A FEW
THUNDERSTORMS AND FORECAST FOR TODAY, WITH ACTIVITY BECOMING MORE
ISOLATED ON TUESDAY. HIGH CHANCES FOR SHOWERS AND THUNDERSTORMS
ARE FORECAST BEGIN WEDNESDAY MORNING, CONTINUING THURSDAY AS A
STRONG WEATHER SYSTEM APPROACHES. THE MAIN CONCERNS ARE FLOODING
AND FLASH FLOODING, ESPECIALLY ACROSS EASTERN ARIZONA.
ADDITIONALLY, WIND SPEEDS WILL INCREASE, WITH WELL BELOW NORMAL
TEMPERATURES FORECAST BY THURSDAY OR FRIDAY.
DISCUSSION
CURRENT SATELLITE AND UPPER-AIR ANALYSIS SHOW A
SHORTWAVE TROUGH OVER NORTHERN ARIZONA. THIS FEATURE IS
INTERACTING WITH MODEST LOW-LEVEL MOISTURE (SURFACE DEW POINTS
BETWEEN 45 AND 55 DEGREES F) TO PRODUCE SCATTERED SHOWERS,
ALTHOUGH A FEW ISOLATED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON
AS WELL. ATMOSPHERIC INSTABILITY IS LIMITED (CAPE OF 100-500
J/KG), BUT 0-6KM BULK SHEAR IS ELEVATED (25-35 KTS) DUE TO THE
PASSING SHORTWAVE TROUGH. THE BEST COMBINATION OF INSTABILITY AND
SHEAR IS EXPECTED ALONG AND EAST OF THE I-17, RESULTING IN THE
HIGHEST POTENTIAL FOR SHOWERS AND STORMS THERE. TODAY'S STORMS
WILL BE CAPABLE OF PRODUCING OUTFLOW WINDS BETWEEN 25-35 MPH WITH
ISOLATED POCKETS OF RAINFALL BETWEEN 0.5-1.0 INCHES. WHILE THE
PROBABILITY IS LOW, A SEVERE STORM OR TWO CAPABLE OF PRODUCING 1
INCH HAIL CANNOT BE RULED OUT.
ON TUESDAY, A LOW PRESSURE SYSTEM IS FORECAST TO DIVE SOUTHWARD
ALONG THE WEST COAST. THIS WILL SANDWICH NORTHERN ARIZONA BETWEEN
THE DEEPENING WEST COAST TROUGH AND BROAD HIGH PRESSURE OVER THE
CENTRAL UNITED STATES. AS THIS HAPPENS, ONLY MINOR CHANGES TO THE
SENSIBLE WEATHER ARE EXPECTED. HIGH TEMPERATURES ARE FORECAST TO
INCREASE BY A COUPLE OF DEGREES WITH AFTERNOON WINDS BECOMING
MORE BREEZY. HIGH-RESOLUTION MODEL GUIDANCE DOES INDICATES A LOW
POTENTIAL FOR SOME ISOLATED SHOWER, OR THUNDERSTORM ACTIVITY, BUT
STABLE CONDITIONS DUE TO THE PRESENCE OF AN INVERSION ABOVE THE
BOUNDARY LAYER SHOULD KEEP ACTIVITY SUBDUED.
ON WEDNESDAY AND THURSDAY, THE WEST COAST LOW SHIFTS EASTWARD
TOWARD NORTHERN ARIZONA ALLOWING DEEP SUBTROPICAL MOISTURE TO PUSH
INTO THE AREA FROM THE SOUTH. SOME OF THIS INCOMING MOISTURE WILL
BE ASSOCAITED WITH WHAT IS CURRENTLY TROPICAL STORM TRUDY
CENTERED SOUTH OF THE BAJA PENINSULA. MODEL FORECASTS SHOWS
PRECIPITABLE WATER (A MEASURE OF ATMOSPHERIC MOISTURE) RANGING
FROM 0.70 TO 1.0 INCHES. THIS LEVEL OF MOISTURE IS EXCEEDINGLY
RARE FOR MID-OCTOBER, WITH VALUES ABOVE THE 98TH PERCENTILE. DUE
TO THIS, FLOODING/FLASH FLOODING WILL BE THE PRIMARY HAZARDS. AT
THIS POINT, THE HEAVIEST RAINFALL IS EXPECTED ALONG AND SOUTH OF
THE MOGOLLON RIM, WHERE THE FORECAST CALLS FOR A BROAD AREA OF
STORM TOTAL RAINFALL OF 1.0-3.0 INCHES. FURTHER NORTH OVER THE
NAVAJO NATION, STORM TOTAL RAINFALL OF 1.0-2.0 INCHES IS FORECAST.
THE SEVERE WEATHER POTENTIAL IS MORE DIFFICULT TO ASSESS, AS
THICK CLOUD COVER MAY LIMIT INSTABILITY. THAT SAID, FORCING FROM
THE PASSING LOW AND STRONG WIND SHEAR (50+ KTS) SUGGEST AT LEAST A
LOW POTENTIAL FOR SEVERE, ROTATING STORMS. OTHERWISE, SOUTHERLY
WIND SPEEDS WILL INCREASE DURING THIS TIME, STRONGEST ON THURSDAY.
HOWEVER, THE PROBABILITY OF WIND SPEEDS EXCEEDING WIND ADVISORY
THRESHOLDS (>40 MPH) IS LOW.
ON FRIDAY, THE FORECAST CALLS FOR DECREASING CHANCES FOR SHOWERS
AND THUNDERSTORMS THROUGH THE DAY, AND WELL BELOW NORMAL
TEMPERATURES. FORECAST CONFIDENCE IN THE EVOLUTION OF THE OVERALL
WEATHER PATTERN HEADING INTO THE WEEKEND REMAINS LOW.
AVIATION...MONDAY 19/18Z THROUGH TUESDAY 20/18Z
MAINLY VFR
CONDITIONS WITH LOCALIZED MVFR IN SCT -SHRA/-TSRA THROUGH 02Z.
ISO -SHRA EAST OF A KPAN-KOV7 LINE OVERNIGHT. SOME SHOWERS MAY BE
HEAVY ALONG WITH GUSTY/ERRATIC WINDS. OUTSIDE OF SHOWERS/STORMS,
EXPECT S-SW WINDS 5-15 KTS, BECOMING LIGHT AND VRB OR TERRAIN
DRIVEN OVERNIGHT.
OUTLOOK...TUESDAY 20/18Z THROUGH THURSDAY 22/18Z...MAINLY VFR
CONDITIONS WITH ISO -SHRA/-TSRA THROUGH 12Z/WEDS, THEN PERIODS OF
MVFR/IFR IN WDSPRD SHRA/TSRA THROUGH THURSDAY. GUSTY/ERRATIC
WINDS NEAR STORMS. OUTSIDE OF STORMS, EXPECT S WINDS 10-20 KTS
WITH GUSTS TO 30 KTS EACH DAY, BECOMING LIGHT AND VRB DURING THE
OVERNIGHT PERIODS.
FIRE WEATHER...THIS AFTERNOON THROUGH WEDNESDAY
COOL CONDITIONS
CONTINUE. SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH
THIS EVENING, THEN BECOME ISOLATED ON TUESDAY. ACTIVITY WILL
INCREASE IN COVERAGE LATE TUESDAY AND BECOME WIDESPREAD ON
WEDNESDAY. SOME STORMS MAY PRODUCE VERY HEAVY RAINFALL LEADING TO
FLOODING OR FLASH FLOODING ON WEDNESDAY. SOUTH WINDS 5-15 MPH
THROUGH THIS EVENING, INCREASING TO 10-20 MPH ON TUESDAY, THEN 15-25
MPH WITH GUSTS 30-40 MPH ON WEDNESDAY.
THURSDAY THROUGH SATURDAY...COOL TEMPERATURES CONTINUE. WIDESPREAD
SHOWERS AND THUNDERSTORMS LIKELY ON THURSDAY, THEN BECOMING ISOLATED
FOR FRIDAY AND SATURDAY. SOME STORMS MAY PRODUCE VERY HEAVY RAINFALL
LEADING TO FLOODING OR FLASH FLOODING ON THURSDAY. SOUTH WINDS 15-25
MPH WITH GUSTS 30-40 MPH ON THURSDAY, BECOMING SOUTH THROUGH
SOUTHWEST 10-20 MPH WITH GUSTS 25-30 MPH ON FRIDAY, THEN LIGHT
NORTHERLY WINDS 5-15 MPH ON SATURDAY.
FGZ WATCHES/WARNINGS/ADVISORIES
NONE.
PUBLIC...RR
AVIATION...MEOLA
FIRE WEATHER...MEOLA
FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF
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