454
FXAK69 PAFG 261300
AFDAFG
NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
400 AM AKST THU NOV 26 2009
DISCUSSION
A FAIRLY ACTIVE LOW HEIGHT SOUTHERLY FLOW PATTERN TO CONTINUE
INTO NEXT WEEK. THERE WILL BE A COUPLE OF MODERATE OR BETTER
CHINOOKS AND THE POTENTIAL FOR A STRONG STORM SYSTEM THAT COULD
IMPACT PARTS OF THE FORECAST AREA BY EARLY NEXT WEEK.
SURFACE...A 976 MB LOW IS MIDWAY BETWEEN THE PRIBILOF ISLANDS AND
NIKOLSKI EARLY THIS MORNING. THE LOW WILL CONTINUE TO MOVE OFF
TOWARD THE AK PENINSULA THIS AFTERNOON WITH A TRIPLE POINT LOW
DEVELOPING NEAR OR A LITTLE EAST OF KODIAK ISLAND LATE TODAY. THIS
WILL BECOME THE MAIN LOW CENTER AND WILL TRACK INTO THE SUSITNA
VALLEY TONIGHT...AND THEN RAPIDLY LIFT NORTH-NORTHWEST TO BETWEEN
AMBLER AND ALLAKAKET BY FRIDAY AFTERNOON.
INTERIOR...EVERYTHING STILL LOOKS TO BE ON TRACK FOR A MODERATE
CHINOOK EVENT TODAY INTO FRIDAY. THE TALKEETNA WIND PROFILER HAS
BEEN SHOWING A STEADY INCREASE IN THE S'LY FLOW ALOFT OVERNIGHT.
EXPECT THE WIND TO RAPIDLY PICK UP IN THE FAVORED WINDY PASSES OF
THE AK RANGE TODAY. THERE IS GOOD SUPPORT ALOFT WITH THE GFS AND
NAM INDICATING 40 TO 55 KT WINDS AT 700 MB FROM THIS AFTERNOON
THROUGH FRIDAY MORNING BEFORE BEGINNING TO DIMINISH. WILL ISSUE WIND
ADVISORIES FOR THE AK PASSES TODAY AS WELL AS ZONE 227 NEAR THE
AK RANGE. IT IS ALSO POSSIBLE THAT THE WIND COULD COME CLOSE TO
ADVISORY LEVELS IN THE DELTA JUNCTION AREA AT SOME POINT LATER
TODAY OR TONIGHT. THERE HAVE ALREADY BEEN SOME GUSTS TO 40 MPH
EARLY THIS MORNING. FOR NOW WILL COVER THIS WITH WIND GUSTS TO 45
MPH...BUT LATER SHIFTS MAY NEED TO ISSUE AN ADVISORY AT SOME
POINT. STRONG WARM ADVECTION ACROSS THE UPPER KOYUKUK VALLEY WILL
LIKELY PRODUCE A SHOT OF OVERRUNNING SNOW THIS AFTERNOON AND
EVENING WITH A FEW INCHES OF SNOW. AS THE MAIN LOW CENTER LIFTS
NORTH ON FRIDAY ANOTHER SHOT OF SNOW IS EXPECTED WITH ANOTHER FEW
TO SEVERAL INCHES OF SNOW. WILL ISSUE A WINTER WEATHER ADVISORY
FOR ZONE 219 FOR THIS AFTERNOON THROUGH FRIDAY AND MAKE MENTION
THAT THERE WILL BE A BREAK IN THE SNOW TONIGHT. THE CHINOOK WILL
KEEP TEMPS QUITE WARM ON THE HILLS AND IN THE PASSES THE NEXT
COUPLE OF DAYS WITH TEMPS MUCH COOLER IN THE VALLEYS UNDER STRONG
INVERSIONS. POSSIBLE ON FRIDAY THAT SOME OF THE VALLEY SPOTS COULD
BRIEFLY MIX OUT AND SEE A RAPID RISE IN TEMPS INTO THE 20S.
NORTH SLOPE...ABOVE AVERAGE TEMPERATURES ARE EXPECTED FOR THE NEXT
SEVERAL DAYS. SOME OVERRUNNING SNOW IS EXPECTED TONIGHT AND FRIDAY
MORNING ALONG THE WESTERN AND NORTHERN ARCTIC COAST. ANOTHER SHOT
OF SNOW IS POSSIBLE FRIDAY NIGHT AND SATURDAY ASSOCIATED WITH THE
LOW THAT RAPIDLY LIFTS NORTH AND SHOULD END UP IN THE VCNTY OF
BARROW BY SAT MORNING.
WEST COAST...THE BEST CHANCE OF SNOW THE NEXT FEW DAYS WILL BE
ACROSS ZONES 216 AND 217 ASSOCIATED WITH THE LOW THAT LIFTS NORTH
ACROSS THE INTERIOR. A BAND OF OVERRUNNING SNOW WILL LIFT NORTH
THIS AFTERNOON AND SHOULD END THIS EVENING IN THE NOATAK VALLEY.
SNOW SHOULD RE-DEVELOP FRIDAY MORNING AND SPREAD NORTH IN
ASSOCIATION WITH THE MAIN LOW CENTER. THE RAPID MOVEMENT OF THE
LOW SHOULD HELP TO LIMIT ACCUMULATIONS...BUT 2 TO 4 INCHES IS
CERTAINLY POSSIBLE.
MID-RANGE...POTENTIAL FOR A MAJOR STORM SYSTEM THAT COULD HAVE
VARIOUS IMPACTS ACROSS NORTHERN AK BY SUNDAY NIGHT AND CONTINUING
INTO EARLY NEXT WEEK. THE GFS AND ECMWF ARE REASONABLY CONSISTENT
THAT A DEEP LOW (SUB 950 MB) MOVES INTO THE SOUTHERN BERING SEA
SUNDAY AND ENDS UP IN THE VCNTY OF THE PRIBILOF ISLANDS MONDAY. THE
LOW IS THEN EXPECTED TO GRADUALLY WEAKEN AND TRACK NORTH AS A
STRONG RIDGE REMAINS IN PLACE ACROSS THE EASTERN PACIFIC AND
WESTERN CANADA. THIS STORM HAS THE POTENTIAL FOR PRODUCING
BLIZZARD CONDITIONS...ESPECIALLY ON SAINT LAWRENCE ISLAND AND
ALONG THE YUKON DELTA. ANOTHER MODERATE TO STRONG CHINOOK IS
POSSIBLE EARLY-MID NEXT WEEK ACROSS THE INTERIOR.
COASTAL HAZARD POTENTIAL DAYS 3 AND 4...GALE TO STORM FORCE WINDS
ARE POSSIBLE LATE SUNDAY NIGHT AND MONDAY ALONG THE WEST COAST.
WILL NEED TO CONTINUE TO CLOSELY MONITOR THE PROGRESS OF THE STORM
DURING THE NEXT FEW DAYS. AT LEAST MOST OF THE WEST COAST NOW HAS
DECENT ICE COVERAGE WHICH SHOULD SIGNIFICANTLY MITIGATE COASTAL
FLOODING CONCERNS.
AFG WATCHES/WARNINGS/ADVISORIES
WIND ADVISORY FOR AKZ225-AKZ226-AKZ227.
WINTER WEATHER ADVISORY FOR AKZ219.
HEAVY FREEZING SPRAY WARNING FOR PKZ210.
SMALL CRAFT ADVISORY FOR PKZ210.
BRISK WIND ADVISORY FOR PKZ220-PKZ225.
CB NOV 09
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