Freezing Rain Advisory 2, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
600 AM AKST SAT JAN 8 2011

.DISCUSSION...
THE GFS AND NAM COMPUTER WEATHER FORECAST MODELS HAVE SIMILAR
PROJECTIONS THROUGH MONDAY AFTERNOON. AN ACTIVE AND STRENGTHENING
NORTH PACIFIC LOW PRESSURE SYSTEM CROSSED THE ALEUTIANS NEAR
AMCHITKA FRIDAY EVENING. THIS HAS BEEN AN UNUSUALLY FAST MOVING
SYSTEM...MOVING NORTH 40 KNOTS FOR THE PAST 12 HOURS. THE COMPUTER
WEATHER FORECAST MODELS PREDICT THAT THIS VERY RAPID MOVEMENT WILL
CONTINUE THROUGH THE WEEKEND. THE GEOSTATIONARY SATELLITE IMAGERY
CONFIRMS THE RAPID NORTHWARD MOVEMENT OF THIS SYSTEM. EXTENSIVE
THICK CLOUD COVER HAS SPREAD OVER ALL THE BERING SEA COAST OF
NORTHERN ALASKA. A MIXTURE OF SNOW...FREEZING RAIN...AND RAIN HAS
BEGUN FROM BERING STRAIT DOWN TO THE YUKON DELTA.

AN UNUSUAL ASPECT OF THE COMPUTER WEATHER FORECASTS THIS MORNING
IS THE LARGE EXTENT OF FREEZING RAIN IN THE MODEL OUTPUT
STATISTICS. INDEED...ITS HARD TO RECALL ANY EPISODE IN WHICH THESE
FORECASTS OF FREEZING RAIN HAVE BEEN SO EXTENSIVE. SO FAR THE
OBSERVED WEATHER IS HEADING IN THE PREDICTED DIRECTION. THIS IS
PARTICULARLY TRUE THIS MORNING ON THE YUKON DELTA. THE WINTER
STORM WATCH IN EFFECT YESTERDAY EVENING WAS UPGRADED TO A WINTER
STORM WARNING FOR THESE REASONS.

THE COMPUTER WEATHER FORECAST MODELS PREDICT THE WINDS ALOFT TO
CHANGE FROM SOUTH TO SOUTHWEST OVER NORTHWEST ALASKA TONIGHT. THIS
SHIFT IN THE CIRCULATION IS EXPECTED TO BRING PRECIPITATION INTO
THE UPPER KOBUK AND NOATAK VALLEYS THIS EVENING.

THE COMPUTER MODELS HAVE BEEN FORECASTING UNUSUALLY WARM
TEMPERATURES ALOFT TO DEVELOP OVER THE BERING SEA COAST
TODAY...AND OVER THE WEST ARCTIC AND THE WESTERN AND CENTRAL
INTERIOR BY SUNDAY AFTERNOON. INDEED...THE MODELS FORECAST
TEMPERATURES AT 850 MILLIBARS / ABOUT 5000 FEET / FROM ZERO TO
PLUS 3 DEGREES CELSIUS OVER THOSE AREAS ON SUNDAY AFTERNOON. WITH
WESTERLY FLOW OVER THE ARCTIC THERE IS A CHANCE OF FREEZING RAIN
AS FAR AFIELD AS THE ENTIRE ALASKAN ARCTIC AND BROOKS RANGE. THE
ONLY LIMITING FACTOR IN THIS REGARD IS THE LENGTHY PATH INCOMING
MOISTURE MUST TAKE TO REACH THE ARCTIC. ALONG THIS PATH...MOST OF
THE EXCESS MOISTURE AVAILABLE FOR PRECIPITATION CAN BE EXPECTED TO
FALL OUT BEFORE REACHING THE ARCTIC.

NONETHELESS...THE TEMPERATURES FORECAST ALOFT ARE REMARKABLY HIGH
FOR MID JANUARY IN THIS PART OF THE WORLD. THE GFS MODEL FORECASTS
A VERY UNUSUALLY STRONG HIGH PRESSURE SYSTEM TO BUILD OVER THE
WESTERN MAINLAND STARTING TONIGHT AND RUNNING THROUGH THE WEEKEND.
THE PREDICTED HEIGHT OF THE 500 MILLIBAR SURFACE / ROUGHLY 18000
FEET / IN THE CENTER OF THE HIGH PRESSURE AREA TO REACH AN
ASTOUNDING 5830 METERS IN THE CENTER OF THE HIGH...LOCATED OVER
NOATAK AT 3 AM AKST TUESDAY. THIS WOULD BE NOTABLE FOR MID
SUMMER. THE GFS MODEL IS ALMOST SURELY OVERDOING THE FORECAST
HERE...BUT THE OVERALL PATTERN LOOKS LIKE A REASONABLE PREDICTION.

FOLLOWING THE MOVEMENT OF THIS MORNINGS BERING SEA LOW UP INTO THE
GULF OF ANADYR THIS EVENING...AND INTO THE NORTH CHUKCHI SEA ON
SUNDAY...NO FURTHER ONSLAUGHT FROM THE NORTH PACIFIC IS IN SIGHT
FOR THE NEXT 8 DAYS OR MORE.

THE POLAR ORBITING SATELLITE IMAGERY THIS MORNING SHOWS THE
REMAINS OF A WEAK OCCLUDED FRONT THAT CAME IN FROM THE BERING SEA
YESTERDAY NOW EXTENDING FROM PRUDHOE BAY SOUTH TO FAIRBANKS. THE
EASTERN INTERIOR IS MOSTLY CLEAR.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FOR AKZ211-AKZ213-AKZ214.

WINTER STORM WATCH FOR AKZ207-AKZ208-AKZ209-AKZ210-AKZ212-AKZ217.

GALE WARNING FOR PKZ210-PKZ220.

BRISK WIND ADVISORY FOR PKZ200-PKZ215-PKZ225-PKZ230.
&&

TF JAN 11