Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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000
FXUS65 KFGZ 211021
AFDFGZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
230 AM MST SUN SEP 21 2014

.SYNOPSIS...
LOW PRESSURE WILL MOVE FROM SOUTHERN CALIFORNIA INTO NEVADA TODAY.
THIS SYSTEM WILL BRING SCATTERED SHOWERS AND THUNDERSTORMS TO
NORTHERN ARIZONA...THOUGH CLEARING SKIES SHOULD MOVE INTO WESTERN
ARIZONA BY THIS AFTERNOON. HIGH PRESSURE OVER THE REGION FROM MONDAY
THROUGH THURSDAY WILL DELIVER MAINLY DRY WEATHER AND WARMER DAYTIME
TEMPERATURES.

&&

.DISCUSSION...

LOW PRESSURE WAS CENTERED OVER CENTRAL CALIFORNIA EARLY THIS
MORNING...ACCELERATING NORTHEASTWARD TOWARD NEVADA. AN AREA OF WEAK
UPWARD MOTION WILL REMAIN OVER NORTHERN ARIZONA RESULTING IN THE
BEST CONCENTRATION OF STORMS MAINLY NORTH OF INTERSTATE-40.
HOWEVER...STORM CONCENTRATION WILL ALSO BE HIGHER OVER THE WHITE
MOUNTAINS AREA OF FAR EAST CENTRAL ARIZONA WHERE DEEPER MOISTURE
WILL LEND ITSELF TO DECENT INSTABILITY WITH DAYTIME HEATING. THE
FLOW WILL SHIFT TO A MORE SOUTHWESTERLY DIRECTION THROUGH THE DAY
WITH GRADUAL DRYING...ESPECIALLY OVER WESTERN TO CENTRAL PORTIONS OF
ARIZONA. WE WILL UPDATE THE FORECAST AS NEEDED FOR ANY OBSERVED
DRYING.

MONDAY THROUGH THURSDAY...WARM HIGH PRESSURE BUILDS INTO THE DESERT
SOUTHWEST WITH A DRIER WESTERLY FLOW. A VERY STABLE AIR MASS
OVERHEAD WILL SHARPLY LIMIT DAYTIME CONVECTION WITH FAIR NIGHTS
EXPECTED.

FRIDAY AND SATURDAY...MODELS SHOW THAT A STORM SYSTEM FROM THE WEST
WILL LIKELY INTERACT WITH LINGERING MOISTURE OVER ARIZONA FOR A
CHANCE OF SHOWERS AND THUNDERSTORMS. AT THIS TIME...TIMING IS THE
MAIN DIFFERENCE BETWEEN THE ENSEMBLE OF MODELS. WE`LL KEEP YOU
POSTED.

&&

.AVIATION...

FOR THE 12Z PACKAGE...ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS WILL DEVELOP ACROSS NORTHERN ARIZONA THROUGH DAY.
DRIER AIR WILL MOVE INTO WESTERN AND CENTRAL PORTIONS OF ARIZONA
DURING THE MORNING HOURS REDUCING CHANCES FOR THUNDERSTORM
DEVELOPMENT. EXPECT MOSTLY VFR CONDITIONS...WITH WIDELY SCATTERED
IFR/MVFR AND ERRATIC SURFACE WIND GUSTS 30 TO 40 KTS NEAR THE
STRONGER STORMS. AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS.

&&

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

&&

$$

PUBLIC.........MCCOLLUM
AVIATION.......BOHLIN

FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF





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