Wind Chill Advisory 46, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
454 AM AST FRI FEB 22 2008

.DISCUSSION...THE NAM AND GFS MODELS GIVE SIMILAR RESULTS WITH ONE
NOTABLE EXCEPTION...THE GFS BRINGS DOWN COLDER AIR ALOFT FROM THE
ARCTIC INTO THE NORTH INTERIOR STARTING SATURDAY NIGHT. THE
DIFFERENCE AT 850 MB IS A WHOPPING 10 DEGREES C. SO THE GFS MOS
HAVE GENERALLY BEEN FOLLOWED FOR THAT PART OF THE WORLD STARTING
SATURDAY NIGHT AND GOING FORWARD THROUGH THE FORECAST PERIODS.

THE GFS MODEL FORECASTS A TROUGH ALOFT TO MOVE EASTWARD OVER THE
ARCTIC OF ALASKA FROM SATURDAY ONWARD...AND REACHING THE YUKON
BORDER EARLY MONDAY. FROM SATURDAY ONWARD...THE GFS FORECASTS A
LARGE RIDGE OF HIGH PRESSURE ALOFT TO BUILD OVER THE BERING SEA
THROUGH MONDAY...AND EXITING INTO THE CHUKCHI SEA TUESDAY. THIS
FORECAST SEEMS OVERDONE...BUT THE ONSET OF NORTH/NORTHEAST FLOW
OVER MAINLAND ALASKA THAT COMES ARE PART OF THIS FORECAST LOOKS
REASONABLE...AS DO A FORECAST OF BELOW ZERO NIGHT TIME
TEMPERATURES AND CLEAR SKIES OVER NEARLY ALL THE REALM. THERE WILL
LIKELY BE SOME FRESH NORTHEAST BREEZES OVER MUCH OF THE INTERIOR
NEXT WEEK...ESPECIALLY OVER THE HIGHLANDS. OTHERWISE THE UPCOMING
WEEK APPEARS SET TO BRING SOME CLASSIC FINE EARLY SPRING WEATHER
TO MUCH OF NORTHERN ALASKA.

OVER THE KOTZEBUE SOUND REGION FRESH NORTHWEST WINDS CONTINUE TO
BLOW...ACCOMPANIED WITH BLOWING SNOW. THE SMALL SCALE BUT
PERSISTENT RIDGE OF HIGH PRESSURE FROM THE CHUKOTSK PENINSULA TO
THE NORTH SEWARD PENINSULA IS A TYPICAL PART OF THE MESOSCALE
STRUCTURE OF SUCH AN EVENT. THE NAM 20 MODEL...WHICH IS DESIGNED
TO PICK UP SUCH MESOSCALE FEATURES...HAS PREDICTED THIS WELL...AND
FORECASTS IT TO HOLD UNTIL LATE TONIGHT. UP ON THE EASTERN ARCTIC
COAST...THE NAM 20 SURE SEEMS TO UNDER FORECASTING THE WEST WINDS
THAT ARE NOW DEVELOPING. THE GFS...IN CONTRAST...IS HANDING THE
EASTERN ARCTIC WINDS PRETTY WELL. THIS IS NOT A TYPICAL MODEL
DIFFERENCE.

COOLING OVER THE AREA WILL LEAD TO A BIG LOWERING OF FREEZING
LEVELS...DOWN TO ZERO IN MOST OF NORTHERN ALASKA BY THE WEEKEND.
AS IS OFTEN THE CASE IN CHANGEABLE WEATHER...THERE IS A LARGE
MAGNITUDE IN THE FLUCTUATION. THIS CASE HOWEVER HAS MORE OF A
CHANGE THAN MOST. OFTEN IN LATE WINTER WARMINGS THERE IS NOT A
RETURN TO BELOW NORMAL TEMPERATURES TO THE EXTENT FORECAST HERE.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY FOR AKZ207.

BRISK WIND ADVISORY FOR PKZ210-PKZ215-PKZ220-PKZ245.
&&

TF FEB 08