Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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000
FXUS65 KFGZ 250443
AFDFGZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
940 PM MST SUN AUG 24 2014

.SYNOPSIS...SUBTROPICAL MOISTURE WILL MOVE NORTHWARD OVER NORTHERN
ARIZONA ON MONDAY AHEAD OF AN ADVANCING LOW PRESSURE TROUGH WITH
INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS.  FROM LATE MONDAY
THROUGH TUESDAY...THE PASSING TROUGH WILL BRING NUMEROUS SHOWERS AND
THUNDERSTORMS TO THE STATE. SOME STRONG THUNDERSTORMS WILL BE
POSSIBLE...ALONG WITH THE THREAT OF HEAVY RAIN. THURSDAY ONWARD...A
DRYING NORTHWEST FLOW WILL DECREASE THUNDERSTORM CHANCES.

&&
.DISCUSSION...HIGH CLOUDS FROM FORMER HURRICANE MARIE ARE STARTING TO
MOVE OVER NORTHERN ARIZONA TONIGHT AHEAD OF A TROUGH OF LOW PRESSURE
MOVING ACROSS THE PACIFIC NORTHWEST AND INTO THE GREAT BASIN. THE
CURRENT FORECAST IS IN GOOD SHAPE WITH INCREASING CHANCES OF
PRECIPITATION MONDAY THROUGH TUESDAY. MONDAY NIGHT COULD BE AN
ACTIVE NIGHT OVER NORTHERN ARIZONA.

&&

.PREV DISCUSSION /334 PM MST/...FAIR WEATHER CONTINUES TODAY ACROSS
NORTHERN ARIZONA AS RELATIVELY DRY AND STABLE AIR HAS LEAD TO ONLY
THE DEVELOPMENT OF FLAT CUMULUS CLOUDS. OUR FOCUS IS QUICKLY TURNING
TO THE NEXT PRECIPITATION EVENT COMING TOGETHER FOR THE EARLY PART
OF THIS WEEK.

A TROUGH OF LOW PRESSURE CURRENTLY OVER THE PACIFIC NORTHWEST IS FORECAST
TO MOVE SOUTH INTO THE GREAT BASIN ON MONDAY AND THEN EAST ACROSS
UTAH TUESDAY AND TUESDAY NIGHT. AHEAD OF THE TROUGH...A MODERATE
SOUTHERLY FLOW DEVELOPS...PARTLY ENHANCED BY HURRICANE MARIE...THAT
PUSHES MOISTURE NORTH BACK INTO NORTHERN PORTIONS OF THE STATE.
MOISTURE BEGINS TO STREAM NORTH ON MONDAY WHILE COOLING ALOFT ALSO
BEGINS AHEAD OF THE APPROACHING TROUGH. FOR THESE REASONS...HAVE
BUMPED PRECIPITATION CHANCES SLIGHTLY UPWARD MONDAY AFTERNOON AND
EVENING. THE UPWARD MOTION ASSOCIATED WITH THE TROUGH BEGINS IN
EARNEST LATE MONDAY NIGHT AND CONTINUES THROUGH TUESDAY. THIS IS
WHEN WE EXPECT NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP WITH
THE THREAT OF HEAVY RAIN AND LOCALIZED FLOODING.

EXPECT THE BEST POTENTIAL FOR HEAVY RAIN WILL BE FROM THE GRAND
CANYON REGION...ALONG THE MOGOLLON RIM AND WHITE MOUNTAINS...SOUTH
INTO YAVAPAI AND GILA COUNTIES WHERE THE MOISTURE IS RICHEST AND
UP-SLOPE FLOW MAY ENHANCE LIFT. THE UNSEASONABLY
STRONG TROUGH IS ASSOCIATED WITH ENOUGH WIND SHEAR TO POSSIBLY
RESULT IN SOME STRONG STORMS.

SOME FORECAST MODEL RUNS THIS MORNING ARE HINTING AT A SLOWER
MOVEMENT OF THE TROUGH WHICH COULD EXTEND RAINFALL INTO TUESDAY
NIGHT AND WEDNESDAY MORNING...BUT AM NOT CONFIDENT ON THE LONGER
DURATION AT THIS POINT. BY LATE WEDNESDAY NIGHT OR THURSDAY...THE TROUGH
MOVES EAST INTO COLORADO DECREASING SHOWER AND STORM ACTIVITY. A
DRIER PATTERN IS IN STORE FROM THURSDAY INTO NEXT WEEKEND AS HIGH
PRESSURE BUILDS OVER THE CALIFORNIA COAST AND LEAVES A NORTHWESTERLY
FLOW OVER NORTHERN ARIZONA.

&&

.AVIATION...FOR THE 06Z PACKAGE...INCREASING MID AND HIGH CLOUDS
OVERNIGHT. ON MONDAY...ISOLATED SHOWERS AND THUNDERSTORMS AFTER
18Z...WITH SCATTERED STORM COVERAGE FROM KSOW SOUTHEASTWARD. ISOLD
IFR CONDITIONS ARE POSSIBLE. AVIATION DISCUSSION NOT UPDATED FOR
AMENDMENTS.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

PUBLIC.........MAS/MCS
AVIATION.......MAS

FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF






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