FXUS65 KFGZ 022158
AFDFGZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
300 PM MST WED DEC 2 2009

.SYNOPSIS...A DRY COLD FRONT WILL BRING SHARPLY COLDER TEMPERATURES 
AND GUSTY NORTH TO NORTHEAST WINDS THURSDAY THROUGH FRIDAY...BUT 
MOSTLY CLEAR SKIES WILL CONTINUE. OVER THE WEEKEND...EXPECT 
INCREASING CLOUD COVER...NEAR NORMAL TEMPERATURES...AND BREEZY 
SOUTHWEST WINDS AS A WEAK WEATHER DISTURBANCE AFFECTS NORTHERN 
ARIZONA. A WEATHER PATTERN CHANGE APPEARS LIKELY NEXT WEEK...WITH 
INCREASING CHANCES FOR RAIN ALONG WITH HIGHER ELEVATION SNOW. 

&&

.DISCUSSION...A DRY COLD FRONT CONTINUES TO MOVE TOWARD NORTHERN AZ 
TODAY...AND IS EXPECTED TO MOVE INTO NORTHERN AZ THURSDAY MORNING. 
BY THURSDAY AFTERNOON...MOST AREAS ALONG THE MOGOLLON RIM AND 
NORTHWARD WILL SEE SHARPLY COLDER TEMPERATURES AND GUSTY 
NORTH-NORTHEASTERLY WINDS. THE COLD AIRMASS AND NORTHEAST-SOUTHWEST 
ORIENTED PRESSURE GRADIENT WILL REMAIN THROUGH FRIDAY. AS IS TYPICAL 
IN THESE NORTHEAST WIND EVENTS...GUSTY WINDS WILL CONTINUE THROUGH 
THE NIGHTTIME HOURS THURSDAY NIGHT ALONG AND SOUTH OF THE MOGOLLON 
RIM AND IN FAVORED AREAS OF YAVAPAI AND GILA COUNTIES.

OVER THE WEEKEND...WESTERLY FLOW ALOFT WILL DEVELOP AS A TROUGH 
MOVES SOUTHWARD THROUGH THE GREAT BASIN. THIS WILL BRING A MILDER 
AIRMASS INTO NORTHERN AZ..ALONG WITH A SLIGHT CHANCE OF SHOWERS ON 
SUNDAY.

A MAJOR PATTERN CHANGE IS LIKELY BEGINNING EARLY NEXT WEEK AS A HIGH 
AMPLITUDE RIDGE OVER THE PACIFIC BEGINS TO BE UNDERCUT BY A 
STRENGTHENING SOUTHERN JET STREAM. MODELS STILL DISAGREE WITH EXACT 
SOLUTIONS IN THIS PATTERN...HOWEVER THE GENERAL PATTERN OF 
DISTURBANCES DROPPING SOUTHWARD ALONG THE WEST COAST COMBINING WITH 
SIGNIFICANT SUBTROPICAL MOISTURE IS IN AGREEMENT. MOIST WARM 
ADVECTION FEATURING ISENTROPIC UPGLIDE IS A PREVALENT FEATURE IN 
BOTH THE GFS AND ECMWF AND COULD RESULT IN PROLONGED PERIODS OF 
PRECIPITATION. SNOW LEVELS ARE SOMEWHAT UNCERTAIN AT THIS POINT DUE 
TO THE UNCERTAIN AMOUNT OF COLD LOW LEVEL AIR WHICH MAY BE TRAPPED 
BELOW RELATIVELY WARM MOIST AIR STREAMING IN ALOFT. AT THIS 
POINT...FORECAST SNOW LEVELS OF 5000-7000 FEET ARE ESTIMATED FOR THE 
FIRST HALF OF NEXT WEEK.

&&

.AVIATION...FOR THE 00Z PACKAGE...EXPECT VFR CONDITIONS AND LIGHT 
WINDS THROUGH 12Z THURSDAY. A STRONG BUT DRY COLD FRONT WILL PUSH 
SOUTH ACROSS NORTHERN ARIZONA ON THURSDAY. THIS WILL INCREASE THE 
NORTHERLY WINDS THROUGH THE DAY. AVIATION DISCUSSION NOT UPDATED 
FOR AMENDMENTS.

&&

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

&&
$$

PUBLIC..................DJO
AVIATION/FIRE WEATHER...MAS

VISIT WEATHER.GOV/FLAGSTAFF FOR NORTHERN ARIZONA WEATHER INFORMATION.