FXAK69 PAFG 112023
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
1123 AM AKST FRI DEC 11 2009

.DISCUSSION...
THROUGH 12Z MON THERE ARE NO SIGNIFICANT DIFFERENCES BETWEEN 
THE CURRENT RUNS OF THE GFS/NAM/ECMWF OVER THE NORTHERN ALASKA
FORECAST AREA. THE UPPER RIDGE EXTENDING FROM THE SEWARD PENINSULA
SOUTHEASTWARD WILL WEAKEN AND MOVE WEST THROUGH TUE AS AN UPPER
LOW DEVELOPING NORTHWEST OF BANKS ISLAND DEEPENS AND MOVES SLOWLY
SOUTHWEST. THE MOVEMENT OF THESE TWO FEATURES WILL BRING COLDER
AIR OVER THE FORECAST AREA...WITH THE COLDEST AIR BEING OVER THE
CENTRAL/EASTERN PARTS OF THE BROOKS RANGE AND ARCTIC ZONES BY MON.
NO SIGNIFICANT SURFACE SYSTEMS ARE EXPECTED THROUGH MON...WITH
MARINE AREA WINDS REMAINING BELOW ADVISORY.

MEDIUM RANGE...
FOR WED...GGS/ECMWF PROGS REMAIN IN GOOD AGREEMENT OVER
THE FORECAST AREA...AND THERE ARE NO MAJOR DEVIATIONS FROM 
THE GFS ENSEMBLE MEAN 500 MB HEIGHTS/850 MB TEMPERATURES. 
THE DEEP UPPER LOW WILL LIKELY BE CENTERED OVER THE EASTERN
BROOKS RANGE...WITH COLD AIR OVER MOST OF THE FORECAST AREA.

BEYOND WED...LARGE DIFFERENCES DEVELOP BETWEEN THE 11/12Z GFS 
RUN AND THE 11/00Z ECMWF RUN. THE GFS RETREATS THE UPPER LOW
CENTER NORTHWARD INTO THE ARCTIC OCEAN WHILE THE ECMWF HOLDS 
THE COLD LOW CENTER OVER THE NORTHERN ALASKA INTERIOR. THE
11/12Z GFS RUN HAS LITTLE SUPPORT FROM ITS ENSEMBLE MEAN
WHICH HAS A SOLUTION MUCH CLOSER TO THE ECMWF RUN. TODAYS
HPC ALASKA DISCUSSION INDICATES THE 11/00Z ECMWF RUN IS QUITE
CONSISTENT WITH THE 00Z EUROPEAN/GFS AND NAEFS ENSEMBLE
MEANS FOR MUCH OF THE PERIOD...AND THUS A BLEND OF THE
ECMWF WITH ENSEMBLE MEANS LOOKS LIKE THE BEST PLAN.

WHAT THIS MEANS FOR NORTHERN ALASKA...VERY COLD AIR LIKELY
REMAINING OVER THE FORECAST AREA THROUGH NEXT FRI. SOME
MODERATION MAY OCCUR BY MON AS THE COLD UPPER LOW SLIDES 
EAST INTO CANADA.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

RF DEC 09