326
FXUS65 KFGZ 191721
AFDFGZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1021 AM MST MON OCT 19 2026
SYNOPSIS
WE REMAIN IN AN ACTIVE PATTERN THROUGH THE WEEK. ISOLATED
TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED MONDAY AND TUESDAY
AFTERNOON/EVENING. HIGH CHANCES FOR SHOWERS AND THUNDERSTORMS BEGINNING
WEDNESDAY MORNING AND CONTINUING THROUGH THURSDAY AS A STRONG WEATHER
SYSTEM APPROACHES. THERE WILL BE RISK OF FLOODING AND FLASH FLOODING,
ESPECIALLY ACROSS EASTERN ARIZONA. ALSO EXPECT INCREASING WINDS
AND BELOW NORMAL TEMPERATURES THROUGH THE WEEK.
DISCUSSION...TODAY
A LOW PRESSURE SYSTEM CURRENTLY LOCATED
OVER WESTERN ARIZONA CONTINUES TO DRIFT NORTHEASTWARD WHILE
WEAKENING. ENHANCED MOISTURE AND LARGE-SCALE LIFT STILL ACCOMPANY
THIS SYSTEM, AND WEAK SHOWERS CONTINUE TO FIRE THROUGH THE EARLY
MORNING AS A RESULT. SOME PATCHY FOG HAS ALSO BEEN OBSERVED AS
MID-UPPER LEVEL CLOUDS BEGIN TO CLEAR, AND AREAS OF FOG WILL BE
POSSIBLE THROUGH THE REMAINDER OF THE MORNING. LOW LEVEL MOISTURE
LINGERS INTO THE DAYTIME TODAY, AND PARTLY CLEARING SKIES WILL
ALLOW FOR MODEST DESTABILIZATION AND DIURNAL SCATTERED SHOWER AND
THUNDERSTORM ACTIVITY. A FEW STRONGER THUNDERSTORMS MAY BE
POSSIBLE ESPECIALLY TOWARDS EASTERN ARIZONA WHERE HIGHER SHEAR
WILL BE FOUND. BESIDES THE POTENTIAL FOR STORMS, EXPECT STEADY
WINDS WITH SLIGHTLY BELOW NORMAL TEMPERATURES.
TUESDAY...ANOTHER LOW PRESSURE SYSTEM IS VISIBLE IN MID-LEVEL WATER
VAPOR SATELLITE IMAGERY, CURRENTLY LOCATED OFF THE THE COAST OF
THE NORTHWEST CONUS. THIS SYSTEM IS FORECAST TO RAPIDLY DIVE
SOUTHWARD ALONG THE WEST COAST ON TUESDAY. THIS WILL ASSIST IN
LIFTING THE LINGERING DISTURBANCE NORTHEASTWARD OUT OF ARIZONA,
AND WILL PHASE WITH A STRENGTHENING RIDGE OVER THE CENTRAL CONUS
TO REINFORCE A PRESSURE GRADIENT BRINGING SOUTH-SOUTHWESTERLY FLOW
TO OUR REGION. THERE WILL BE CONTINUED DIURNAL SHOWER ACTIVITY,
THOUGH A SLIGHT DOWNTICK IS ANTICIPATED FROM MONDAY DUE TO THE
DEPARTURE OF THE WEAK DISTURBANCE. ALSO EXPECT BREEZIER SOUTH-
SOUTHWEST WINDS AND NEAR-NORMAL TEMPERATURES, LIKELY THE WARMEST
OF THE WEEK.
WEDNESDAY AND THURSDAY...THE STRONG LOW PRESSURE SYSTEM WILL BEGIN
TO PUSH INLAND AND CARRY A DEEPER SURGE OF MOISTURE. PWAT VALUES (A
MEASURE OF ATMOSPHERIC MOISTURE) ARE FORECAST TO RANGE FROM 0.7-1.0
INCHES ON WEDNESDAY. THIS IS VERY ANOMALOUS FOR THIS TIME OF
YEAR. HIGH CHANCES FOR SHOWERS AND THUNDERSTORMS ARE EXPECTED AS A
RESULT, BEGINNING WEDNESDAY MORNING AND CONTINUING THROUGH
THURSDAY. MOST AREAS ARE FORECAST TO RECEIVE AT LEAST 0.5 INCHES
OF RAIN, BUT LOCAL REGIONS ACROSS EASTERN AZ MAY SEE 1-3 INCHES OR
LOCALLY HIGHER, INCLUDING THE EASTERN MOGOLLON RIM, WHITE
MOUNTAINS, AND THE NAVAJO NATION. 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. WPC
HAS INTRODUCED A SLIGHT RISK OF EXCESSIVE RAINFALL FOR ALL OF
NORTHERN AND CENTRAL ARIZONA ON WEDNESDAY AND THURSDAY. A RISK OF
BOTH FLOODING AND FLASH FLOODING WILL BE IN PLAY THROUGH THE
PERIOD. ALSO OF NOTE IS A POTENTIAL DEVELOPING SEVERE THREAT. SPC
HAS INTRODUCED A MARGINAL (CATEGORY 1 OUT OF 5) RISK OF SEVERE
WEATHER ON WEDNESDAY. HIGH SHEAR IS LIKELY AS A STRONG 500MB JET
STREAK MOVES OVERHEAD, BUT THERE IS CONSIDERABLE UNCERTAINTY IN
AVAILABLE INSTABILITY. FOR NOW THERE IS AT LEAST A MENTIONABLE
THREAT OF SEVERE WEATHER THROUGH THE PERIOD. BESIDES THE RAIN AND
THUNDERSTORM THREATS, EXPECT GUSTY DAYTIME WINDS UP TO 30-40 MPH
EACH DAY.
FRIDAY AND ONWARD...ACTIVITY IS EXPECTED TO TREND DOWNWARD BY FRIDAY
INTO THE WEEKEND AFTER THE MAIN TROUGH AXIS PUSHES PAST NORTHERN AZ.
SOME SLIGHT CHANCES FOR SHOWERS MAY LINGER DEPENDING ON A POTENTIAL
REMNANT CUT-OFF LOW, BUT THERE IS CONSIDERABLE UNCERTAINTY. EXPECT
LIGHTER WINDS AND TEMPERATURES REMAINING BELOW NORMAL OTHERWISE.
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...TODAY THROUGH TUESDAY
COOL CONDITIONS EXPECTED
TO CONTINUE THROUGH THE PERIOD. SOUTH WINDS 5-15 MPH ON MONDAY,
INCREASING TO 10-20 MPH ON TUESDAY. SCATTERED SHOWERS AND
THUNDERSTORMS AGAIN ON MONDAY, WITH A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS ON TUESDAY.
WEDNESDAY THROUGH FRIDAY...COOL TEMPERATURES CONTINUE. SHOWERS AND
THUNDERSTORMS LIKELY ON WEDNESDAY AND THURSDAY WITH MOST AREAS
SEEING WETTING RAINS, THEN SCATTERED ACTIVITY EXPECTED ON FRIDAY.
SOUTH WINDS 15-25 MPH WITH GUSTS 30-40 MPH ON WEDNESDAY AND
THURSDAY, BECOMING SOUTH THROUGH SOUTHWEST 10-20 MPH WITH GUSTS 25-
30 MPH ON FRIDAY.
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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