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FXAK69 PAFG 121119
AFDAFG

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
319 AM AKDT SUN OCT 12 2008

.DISCUSSION...

PROGRESSIVE PATTERN CONTINUES OVER NORTHERN ALASKA...THO THE TREND
WILL BE FOR WEAKENING FLOW ALOFT OVER MOST OF THE REGION BY LATE
IN THE WEEK.

LONG WAVE TROF IS PRETTY MUCH LOCKED IN OVER THE FORECAST AREA
WITH MOST OF THE ENERGY REMAINING SOUTH OF 60N. PRESENTLY...963 MB
LOW WEST OF THE KAMCHATKA PENINSULA HAS OCCLUSION STRUNG OUT INTO
THE WESTERN BERING SEA. TRIPLE POINT LOW EXPECTED TO DEVELOP NEAR
OR EAST OF ATKA BY THIS EVENING. SFC LOW NEAR NEAR CIRCLE CITY
WITH WELL DEFINED ARCTIC FRONT SOUTH FROM LOW TO JUST WEST OF DOT
LAKE. 1019 MB HIGH OVER CHUKCHI SEA BETWEEN WRANGEL ISLAND AND
BARROW. A WORM IN THE APPLE IS TIGHT LITTLE LOW ALOFT THAT HAS
BEEN SOUTH OF WRANGEL ISLAND IS NOW BEING PUSHED SE AS RIDGE
BUILDS AHEAD OF DEEP LOW IN THE SEA OF OKHOSTK. THIS FEATURE WILL
LIKELY ENHANCE SNOW SHOWER ACTIVITY VCNTY BERING STRAIT BEFORE
DROPPING INTO LONGWAVE TROUGH OVER WESTERN INTERIOR ON MON.

MODELS IN QUITE GOOD AGREEMENT THRU MONDAY WITH HANDLING FEATURES.
BY MONDAY AFTERNOON...SFC HIGH WILL MOVE EASTWARD TO BE ABOUT OVER
BARROW. LOW AND OLD OCCLUSION STRUNG OUT S OF 60N FROM CENTRAL
BERING SEA TO NEAR KODIAK ISLAND. WEAK PRES GRAD OVER INTERIOR
UNDER REMAINS OF THE UPPER LOW.

MEDIUM RANGE...MODELS OVERALL ARE IN DECENT AGREEMENT...HOWEVER...
THE GFS HAS HAD SOME WILD SWINGS FROM RUN TO RUN. THE MAIN STORM
TRACK REMAINS ACROSS THE ALEUTIANS AND INTO THE NORTHERN GULF. THE
12Z GFS WAS DISCOUNTED LATE IN THE WEEK AS IT TOOK A MODERATE AREA
OF LOW PRESSURE MUCH FURTHER NORTH ACROSS THE BERING SEA TOWARD
THE BERING STRAIT FRI. THE 18Z AND 00Z RUNS CAME IN MORE IN LINE
WITH THE ECMWF/CANADIAN AND ENSEMBLE MEAN WHICH MAINTAIN A MORE
SOUTHERLY TRACK WITH THE LOW. THE MODELS ARE IN BETTER AGREEMENT
ON AN UPPER LOW THAT IS CURRENTLY NEAR 80N/100E WILL SWING DUE
EAST TO NEAR THE DATELINE BY 00Z WED AND INTO THE WESTERN CANADIAN
ISLANDS LATE IN THE WEEK. THIS WILL BRING INCREASINGLY WESTERLY
FLOW TO THE NORTH SLOPE LATE IN THE WEEK. GIVEN THAT THERE IS A
MODERATE AMOUNT OF UNCERTAINTY LATE IN THE WEEK INTO NEXT WEEKEND
ELECTED TO USE A BLEND OF THE ONGOING FORECAST AND THE LATEST HPC
GRIDS/ECMWF WHICH WAS CLOSE TO THE ENSEMBLE MEAN.

NORTH SLOPE...WE WILL CONTINUE WINTER STORM WARNING FOR ZONE 206
AS MOST MODELS HAVE MORE THAN QUARTER INCH LIQUID OVER MUCH OF THE
ZONE FOR THE 12 HOURS ENDING AT 00Z MON.

WEST COAST...DEEP STORM IN THE SEA OF OKHOSTK AND ASSOCIATED
OCCLUSION INTO THE WESTERN BERING SEA WILL MOSTLY BE A WIND MAKER
FOR WEST COAST ZONES..WITH ONLY SAINT LAWRENCE ISLAND AND SOUTHERN
ZONE 214 EVEN HAVING A CHANCE OF ANY SNOW.

INTERIOR...WE WILL CANCEL ALASKA RANGE ADVISORIES AS SNOW
AMOUNTS NOT EXPECTED TO REACH CRITERIA. WE WILL LET THE ADVISORIES
FOR 221 AND 219 AND WINTER STORM WARNING FOR 218 RIDE. WELL
DEFINED COLD FRONT WORKING EWD.  SNOW IS ONLY SLOWLY BREAKING OUT
BEHIND THE FRONT AND IT SEEMS QUITE LIKELY THAT ALL THE
OPERATIONAL MODELS ARE OVERDOING PRECIP ON THE LEADING EDGE OF
FRONT. COOLEST AIRMASS OF THE SEASON THUS FAR WILL OVERSPREAD
EARLY IN THE WEEK. CLOSED ALOW ALOFT WILL ALLOW FOR AT LEAST SOME
SNOW SHOWERS...ESPECIALLY EAST OF THE CENTER.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...THERE IS SOME RISK
THURSDAY OF MODERATE TO STRONG WESTERLY WINDS AND ASSOCIATED
COASTAL EROSION OR FLOODING ISSUES FOR ZONES 201 AND 202 IF..AND
THIS IS A BIG IF...SURFACE LOW WINDS ASSOCIATED WITH DEEP LOW
ALOFT WELL NORTH OF BARROW IS FAR ENOUGH SOUTH. IF SO...THE LARGE
FETCH COULD PRODUCE PROBLEMS.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FOR AKZ206-AKZ218.

WINTER WEATHER ADVISORY FOR AKZ219-AKZ221.

GALE WARNING FOR PKZ210.
&&

$$

RT/CB OCT 08