Blizzard in Alaska, January 15, 2008

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
148 PM AST TUE JAN 15 2008

.DISCUSSION...

ALOFT...
PROGRESSIVE SOUTHWESTERLY FLOW PATTERN WILL BE MAINTAINED
OVER THE ALASKA MAINLAND AS SEVERAL RIDGES AND TROUGHS
MOVE THROUGH. 850 MB TEMPERATURES OVER THE THE CENTRAL
AND SOUTHERN PARTS OF THE FORECAST AREA WILL BE NEAR NORMAL TO
ABOVE NORMAL FOR MOST OF THE TIME DURING THE UPCOMING WEEK.

SURFACE...
FOR TODAYS 12Z MODEL RUN CYCLE...GFS AND ECMWF HAD THE
BEST INITIALIZATIONS ON THE CENTRAL PRESSURE OF THE LOW
WEST OF THE PRIBILOFS...ABOUT 970 MB. SHIP JUST SOUTHEAST
OF THE CENTER REPORTED 976 MB WITH A 35 KT WIND...AND
CENTRAL PRESSURE OF THE LOW AT THIS TIME WAS PROBABLY
AROUND 968-970 MB.

ALL MODELS AND GFS ENSEMBLE MEAN ARE CLUSTERING CLOSE
ON THE LOW POSITION AND CENTRAL PRESSURE FOR 12Z WED...
LOW CENTERED OVER OUTER NORTON SOUND WITH CENTRAL
PRESSURE AROUND 990 MB. PRESSURE GRADIENTS OVER THE
WEST COAST AND WESTERN ARCTIC ARE QUITE SIMILAR AT THIS
VERIFYING TIME.

AT 00Z TUE...MODEL LOW CENTER POSITIONS ARE A LITTLE MORE
DISPERSED BUT STILL TELLING THE SAME BASIC STORY. GFS/ENSEMBLE/ECMWF
POSITION IS NEAR KOTZEBUE...ALL RUNS SHOWING 1000-1005 MB CENTRAL
PRESSURE AND GENERALLY SIMILAR PRESSURE GRADIENTS ALONG AND NORTH
OF THE ARCTIC COAST.

BLIZZARD WARNINGS HAVE BEEN CANCELLED FOR ALL ZONES EXCEPT ZONE
213...CURRENT AND EXPECTED WINDS WILL BE BELOW BLIZZARD CRITERIA
AND PRECIPITATION WITH THE LOW CENTER HAS DEGENERATED TO SNOW
SHOWERS. VISIBILITIES AT TIN CITY AND GAMBELL HAVE BEEN MAINLY
IN THE 1 TO 2 MILE RANGE...BUT WILL RETAIN THE BLIZZARD FOR 213
TO COVER ANY DIPS TO NEAR ZERO IN HEAVIER SNOW SHOWERS AND
BLOWING SNOW.

ALONG THE ARCTIC COAST AND OVER THE INTERIOR ARCTIC PLAIN...
EAST WINDS ARE EXPECTED TO INCREASE TO AROUND 15 MPH TONIGHT...
CONTINUING THROUGH WEDNESDAY. WE WILL CONTINUE THE WIND CHANNEL
WARNINGS FOR ZONES 201-202-203-205 AND WIND CHILL ADVISORIES FOR
ZONES 204-206. TIMING WILL BE CRITICAL SINCE WHILE THE WINDS
ARE EXPECTED TO INCREASE OVERNIGHT...TEMPERATURES WILL ALSO
RISE AS CLOUD COVER EXPANDING NORTHWARD. COMPLICATING THE
FORECAST PROBLEM IS VERY SHALLOW EXTENT OF THE VERY COLD AIR...THE
BARROW 12Z RAOB SHOWED THE COLD AIR LAYER TO BE ONLY ABOUT 10 MB
THICK...WITH A TEMPERATURE OF AROUND -25F AT THE TOP OF THE
INVERSION. THERE IS A POSSIBILITY THAN ANY REAL INCREASE IN WIND
SPEED COULD POP THE INVERSION...BRINGING A FAST RISE IN
TEMPERATURE...BRINGING WIND CHILL VALUES FROM WARNING LEVELS TO
THE ADVISORY CATEGORY.

ISOLATED GUSTS AT OR NEAR ADVISORY LEVELS ARE STILL OCCURRING
IN OR NEAR WINDY AND ISABEL PASSES...BUT ARE EXPECTED TO
END THIS EVENING. SUPPORT FROM WINDS ALOFT IS RATHER MINIMAL.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FOR AKZ225-AKZ226.

WIND CHILL ADVISORY FOR AKZ204-AKZ206-AKZ207-AKZ208-AKZ209-
AKZ210-AKZ217.

WINTER STORM WARNING FOR AKZ216.

BLIZZARD WARNING FOR AKZ213.

WIND CHILL WARNING FOR AKZ201-AKZ202-AKZ203-AKZ205.

GALE WARNING FOR PKZ210.

BRISK WIND ADVISORY FOR PKZ200-PKZ210-PKZ215-PKZ225.
&&

RF JAN 08