Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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000
FXUS65 KFGZ 281640
AFDFGZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
930 PM MST SAT SEP 27 2014

.SYNOPSIS...SHOWERS AND OCCASIONAL THUNDERSTORMS WILL CONTINUE
THROUGH THE NIGHT AND INTO MUCH OF SUNDAY FOR PORTIONS OF EASTERN
ARIZONA. EXPECT ISOLATED TO SCATTERED ACTIVITY OVER THE CENTRAL
PORTIONS OF THE AREA...WITH MOSTLY CLEAR SKIES OVER PORTIONS OF
WESTERN COCONINO AND YAVAPAI COUNTIES. ACTIVITY WILL CONTINUE TO
DECREASE FROM WEST TO EAST LATER SUNDAY...WITH DRY AND COOLER
CONDITIONS MOVING OVER ALL OF THE AREA ON MONDAY.

&&

.DISCUSSION...A LARGE AND COLD CLOSED LOW CURRENTLY COVERS MUCH OF
THE WESTERN UNITED STATES AND IS CENTERED JUST NORTHWEST OF LAS
VEGAS. THIS LOW DROVE A COLD FRONT THROUGH ARIZONA TODAY AND THE
FRONT IS NOW APPROACHING THE FOUR CORNERS...EXTENDING SOUTHWEST
TOWARD THE PHOENIX AREA. SHOWERS AND EMBEDDED THUNDERSTORMS ARE
STILL FAIRLY ACTIVE ALONG THIS FRONT...ALTHOUGH RAINFALL RATES HAVE
DECREASED AND THE THREAT FOR SEVERE HAS NEARLY ENDED.

WATER VAPOR IMAGERY CURRENTLY SHOWING A SIGNIFICANT S/WV AND
REINFORCING POOL OF COLD AIR MOVING DOWN THE WESTERN SIDE OF THIS
LOW. THIS WILL KEEP THE LOW FROM MOVING ANY FARTHER EAST TONIGHT AND
MAY EVEN CAUSE SOME SLIGHT RETROGRESSION AND DEEPENING. THIS MEANS
THE EASTERN ZONES WILL STAY FAIRLY ACTIVE THROUGH THE NIGHT BEFORE
SLOWLY DRYING OUT ON SUNDAY. OUR FAR WESTERN ZONES HAVE HAD MUCH
DRIER AIR MOVE IN...EVEN AT THE SURFACE...EFFECTIVELY ENDING ANY
THREAT FOR RAINFALL. THE CENTRAL ZONES ARE A BIT TRICKIER.

FOR NOW...MUCH DRIER MID-LEVEL AIR HAS ENTERED THE CENTRAL
ZONES...BUT THE BOUNDARY LAYER REMAINS QUITE MOIST. NAM12 MODEL
SOUNDING SHOW A SATURATED AND VERY UNSTABLE BOUNDARY LAYER THROUGH
SUNDAY...EVEN RE-GENERATING SOME UPSLOPE CONVECTION LATE TONIGHT AND
SUNDAY. THE GFS DOES NOT INDICATE THIS FEATURE...AND THE NAM12
MODELS SOUNDING SEEM A BIT UNREALISTIC. HOWEVER...THE UPSLOPE FLOW
WILL CONTINUE AND SOME SHALLOW SHOWERS REMAIN POSSIBLE IN THIS
AIRMASS...JUST PROBABLY NOT THE DEEPER CONVECTION SHOWERS AS SHOWN
BY THE NAM12.

FINALLY...BY LATE SUNDAY NIGHT AND MONDAY...THE FINAL WAVE MOVES
AROUND THE BOTTOM OF THE LOW AND EJECTS THE LOW EASTWARD INTO
MONDAY. THE REGION WILL BE IN A VERY DRY AND COOL AIRMASS AT THIS
POINT...AND THE THREAT FOR RAINFALL WILL END.

WE HAVE ALREADY UPDATED SEVERAL TIMES TONIGHT FOR CURRENT TRENDS AND
NO FURTHER UPDATES ARE EXPECTED.

&&

.AVIATION...FOR THE 06Z PACKAGE...EXPECT WDSPRD CU/TCU/CB EAST OF A
LINE FROM KPHX TO KPAN TO THE FOUR CORNERS THROUGH 18Z-20Z SUNDAY.
SCT TO NMRS SHRA/TSRA WILL CONTINUE IN THIS AREA...WITH AREAS OF
MVFR AND ISOLATED IFR/LIFR IN THE HEAVIER SHOWERS.

SOME LIFR/VLIFR CIGS AND VIS ALONG THE SOUTH FACING SECTIONS OF THE
MOGOLLON RIM ARE ALSO POSSIBLE TONIGHT AS SHALLOW MOISTURE MOVES
UPSLOPE IN THE SW FLOW.

ALONG A CORRIDOR FROM KPRC TO KSEZ TO KFLG...ISOLD TO SCT -SHRA WILL
CONTINUE THROUGH 16Z...WITH ISOLD -TSRA AFT 16Z.

WEST OF A LINE FROM KPRC TO KGCN TO KPGA...EXPECT VFR CONDITIONS
THROUGH THE PERIOD.

ALL AREAS WILL BECOME VFR BY 02Z-04Z MONDAY AS DRIER AIR MOVES INTO
THE REGION. AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS.

&&

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

&&

$$

PUBLIC.........PETERSON
AVIATION.......PETERSON

FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF




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