FXUS65 KFGZ 281018
AFDFGZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
320 AM MST SAT NOV 28 2009

.SYNOPSIS...A STRONG LOW PRESSURE SYSTEM WILL IMPACT NORTHERN 
ARIZONA LATER TODAY THROUGH MONDAY WITH COLDER TEMPERATURES...BREEZY 
CONDITIONS...AND AREAS OF MOUNTAIN SNOW AND VALLEY RAIN. THIS STORM 
WILL MOVE SOUTHEAST OF ARIZONA BY TUESDAY...WITH DRY AND SEASONAL 
TEMPERATURES EXPECTED FOR THE REST OF THE WEEK. 

&&

.DISCUSSION...A DEVELOPING AND DEEPENING LOW PRESSURE SYSTEM OVER 
CENTRAL CALIFORNIA WILL SLOW TO A CRAWL...AND CUT-OFF NEAR YUMA BY 
LATE TODAY. FROM THERE...THE STORM WILL MEANDER ALONG THE SOUTHERN 
ARIZONA STATE LINE SUNDAY...BEFORE EJECTING EAST INTO TEXAS BY LATE 
MONDAY.

THIS TYPE OF TRAJECTORY HAS THE POTENTIAL TO BRING AREAS OF 
SIGNIFICANT PRECIPITATION TO PORTIONS OF ARIZONA...ESPECIALLY ALONG 
THE EASTERN BORDER REGIONS BY SUNDAY.

AHEAD OF THE MAIN LOW...WE EXPECT FRONTOGENESIS TO DEVELOP OVER 
CENTRAL ARIZONA BY THIS AFTERNOON. THIS IS IN ADDITION TO A PERIOD 
OF MODERATE TO STRONG QG FORCING...AS THE LOW STILL HAS SOME 
CYCLOGENESIS TO COMPLETE FOR THE NEXT 12 HOURS. AN AREA OF MODERATE 
PRECIPITATION SHOULD DEVELOP ALONG I-17 AND INTO THE RIM ZONES LATER 
TODAY A A RESULT. THIS FEATURE WILL THEN ROTATE NORTHWARD AROUND THE 
LOW...AFFECTING TO NORTHERN ZONES TONIGHT. SNOW LEVELS WILL FALL TO 
AROUND 6500 FEET IN THE PRECIPITATION...BRINGING SOME SNOW 
ACCUMULATIONS OVERNIGHT FROM THE RIM NORTHWARD. SNOWFALL SHOULD STAY 
IN THE 2 TO 4 INCH FOR MOST AREAS THROUGH EARLY SUNDAY...WE WILL NOT 
ISSUE ANDY HEADLINES AT THIS TIME.

AFTER A QUIETER PERIOD SUNDAY...QPF WILL RE-DEVELOP AROUND THE LOW IN 
EASTERN ARIZONA SUNDAY NIGHT AND MONDAY. THIS WILL BE LESS 
DYNAMICALLY DRIVEN...AND SHOULD RESULT IN LESSER AMOUNTS. 

COLD EASTERLY FLOW AROUND THE LOW WILL NOT ABATE UNTIL TUESDAY OR 
WEDNESDAY...RESULTING IN COOLER HIGH TEMPERATURES THAN THE HGHT 
FIELDS WOULD OTHERWISE INDICATE. THE REMAINDER OF THE WEEK WILL 
FEATURE A SEASONABLE PATTERN...WITH ONLY A SLIGHT CHANCE OF A 
WEAKENING S/WV ON THURSDAY.

&&

.AVIATION...FOR THE 12Z PACKAGE...EXPECT VFR CONDITIONS WITH BKN-OVC 
CLOUD BASES AT OR ABOVE 15 KFT MSL THROUGH 17Z. AFT 17Z... BKN-OVC 
CIGS FROM 3K-5K FT AGL WITH SCATTERED SHOWERS WILL DEVELOP ALONG THE 
MOGOLLON RIM AND INCREASE IN COVERAGE THROUGH THIS AFTERNOON. RAIN 
AND SNOW IS LIKELY ABOVE 6000 FEET BY LATE THIS AFTERNOON AND 
EVENING. MVFR AND IFR CONDITIONS WILL ACCOMPANY THE PRECIPITATION. 
AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS.

&&

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

&&

$$

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

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