FXAK69 PAFG 251320
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
420 AM AKST WED NOV 25 2009

.DISCUSSION...
A MILD PATTERN WILL CONTINUE FOR NORTHERN AK FOR THE NEXT SEVERAL 
DAYS WITH THE MEAN LONG-WAVE TROUGH POSITION TO THE WEST OF THE 
MAINLAND AND A FEW BOUTS OF SOUTHERLY FLOW ALOFT INTO NEXT WEEK. 
A CHINOOK OF AT LEAST MODERATE INTENSITY IS EXPECTED TO DEVELOP ON
THURSDAY AND CONTINUE INTO FRIDAY.

SURFACE...A 975 MB LOW IN THE SOUTHERN BERING SEA WILL CONTINUE TO 
MOVE EAST THROUGH WEDNESDAY AND IS EXPECTED TO PASS NEAR OR JUST 
SOUTH OF THE PRIBILOF'S WEDNESDAY NIGHT. AS ENERGY ROUNDS THE
BASE OF IT'S ASSOCIATED UPPER LEVEL TROUGH THE LOW DEEPENS AND
MOVES TO NEAR KODIAK ISLAND THURS AFTERNOON. WHAT HAPPENS TO THE
LOW AS IT LIFTS INTO NORTHERN AK REMAINS A POINT OF CONTENTION.
4 OUT OF THE LAST 6 RUNS OF THE GFS CARRIED THE LOW TO THE
NORTHWEST TO THE NORTON SOUND ON FRIDAY. THE MOST RECENT RUN IS
MORE IN LINE WITH THE NAM/ECMWF IN TAKING THE LOW TO NEAR LAKE
MINCHUMINA FRIDAY MORNING AND NORTH TO BETWEEN ALLAKAKET AND AMBLER
FRIDAY AFTERNOON. ENDED UP SIDING WITH THE SOLUTION THAT WAS IN
LINE WITH PREVIOUS GFS RUNS AS THE MODEL HAD BEEN VERY CONSISTENT
FOR SEVERAL RUNS. IF THE 12Z AND 18Z RUNS OF THE MODELS COME MORE
IN LINE WITH THE LATEST RUN WILL PROBABLY HAVE TO GIVE THIS
FURTHER EAST TRACK MORE WEIGHT IN THE FORECASTS.

INTERIOR...THE MAIN WEATHER CONCERN IN THE SHORT TERM WILL BE FOR
A PERIOD OF STRONG WIND IN THE AK RANGE PASSES AND AT DELTA
JUNCTION AS ANOTHER CHINOOK DEVELOPS. THE PRESSURE GRADIENT BEGINS
TO TIGHTEN UP GRADUALLY DURING THE DAY THURSDAY AND THE UPPER
LEVEL SUPPORT INCREASES WITH 850-700 MB WINDS PROGGED AT 40-55 KT
BY THURSDAY NIGHT. THIS SHOULD EASILY GENERATE ADVISORY LEVEL
WINDS IN THE AK PASSES AND POSSIBLY IN THE DELTA JUNCTION AREA
TOO. IT LOOKS LIKE A MODERATE TO BORDERLINE STRONG CHINOOK AND
THERE IS THE POTENTIAL FOR WARNING LEVEL WINDS. AS THE STRONGEST
WINDS LOOK TO BE 4TH INTO 5TH PERIOD (THURS NIGHT AND FRI) WILL
HOLD OFF ON A HIGH WIND WATCH. THE CHINOOK WILL ALSO BRING STRONG
DOWN SLOPE AND WARMING AND WILL LIKELY CAUSE TEMPS ACROSS THE
HILLS/HIGHER TERRAIN TO CLIMB ABOVE FREEZING FOR A TIME. POTENTIAL
FOR TEMPS TO CLIMB INTO THE UPPER 30S TO MID 40S IN THE AK RANGE
PASSES. THE CHINOOK SHOULD BEGIN TO WIND DOWN BY FRIDAY NIGHT
ALLOWING SOME MODEST COOLING INTO THE WEEKEND. LITTLE PROSPECT OF
ANY SNOW IN THE CENTRAL AND EASTERN INTERIOR WITH THE CHANCE OF A
LITTLE SNOW INTO PARTS OF THE WESTERN INTERIOR BY FRIDAY IN AREAS
NOT SUBJECTED TO THE STRONG DOWN SLOPE. IF THE LATEST GFS WHICH IS
MUCH FURTHER EAST WITH THE SURFACE LOW ON FRIDAY THERE COULD BE
ACCUMULATING SNOW IN PARTS OF THE WESTERN INTERIOR. THIS WILL NEED
TO BE WATCHED TODAY AS SOME MAJOR REVISIONS MAYBE
REQUIRED...ESPECIALLY TO THE WEST OF TANANA AND BETTLES. A
SOMEWHAT COOLER PATTERN EXPECTED BY THE WEEKEND AS THE FLOW
WEAKENS AND THIS MAY PRODUCE SOME AREAS OF LIGHT SNOW AND FLURRIES
TO MUCH OF THE INTERIOR.

NORTH SLOPE...ABOVE AVERAGE TEMPERATURES EXPECTED FOR THE NEXT 
SEVERAL DAYS.  A FRONTAL BOUNDARY WILL PRODUCE SOME WEAK OVERRUNNING 
ALONG PARTS OF THE WESTERN AND NORTHERN ARCTIC COAST TODAY AND 
TONIGHT WITH AREAS OF SNOW.  ACCUMULATIONS ARE NOT EXPECTED TO 
EXCEED AN INCH OR TWO IN ANY 12 HOUR PERIOD. ANOTHER CHANCE OF SNOW 
BY LATE FRIDAY AND FRI NIGHT ASSOCIATED WITH THE LOW THAT LIFTS 
NORTH/NORTHWEST ALONG THE WEST COAST. 

WEST COAST...THERE ARE SOME AREAS OF LIGHT SNOW AND FLURRIES...BUT 
NOTHING SIGNIFICANT EXPECTED THROUGH THURSDAY.  AS THE LOW NEAR 
KODIAK ISLAND THURS AFTERNOON BEGINS TO LIFT NORTH IT WILL SPREAD 
AREAS OF SNOW ALONG MUCH OF THE WEST COAST THURS NIGHT AND FRIDAY.
AGAIN IF THE TRACK TURNS OUT TO BE FURTHER EAST MOST OF THE
SNOWFALL WOULD LIKELY BE FURTHER INLAND.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HEAVY FREEZING SPRAY WARNING FOR PKZ210-PKZ220-PKZ225.

SMALL CRAFT ADVISORY FOR PKZ210-PKZ220-PKZ225.

SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FOR PKZ210.
&&

$$

CB NOV 09