Small Craft Advisory 158, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
254 AM AKDT SUN OCT 28 2012

.DISCUSSION...
A LARGE SCALE SYNOPTIC PATTERN CHANGE OVER ALASKA IS UNDERWAY. THE
PERSISTENT HIGH ALOFT WHICH HAS BEEN ANCHORED OVER THE BERING SEA
FOR MORE THAN A WEEK IS BEGINNING TO BE SQUASHED BY A VIGOROUS
UPPER LEVEL LOW DIVING DOWN FROM THE HIGH ARCTIC. THIS UPPER LOW
WILL DIG SOUTHWARD TO THE NORTHERN GULF OF ALASKA BY WEDNESDAY AND
REMAIN AS A CLOSED LOW OVER THE GULF THROUGH AT LEAST NEXT
WEEKEND. SOME RIDGING ALOFT FROM THE YUKON TERRITORY WILL NUDGE
INTO THE SOUTHERN INTERIOR BY MID-WEEK BUT A SECOND UPPER LOW WILL
DROP DOWN FROM THE ARCTIC LATE NEXT WEEK. SO A GENERAL LONG WAVE
TROUGH PATTERN WILL PERSIST OVER NORTHERN ALASKA FOR THE
FORESEEABLE FUTURE.

THE ARRIVAL OF THE ARCTIC LOW WILL QUICKLY USHER IN MUCH COLDER
AIR ALOFT ACROSS THE FORECAST AREA ALONG WITH INCREASING MOISTURE
AND BOUTS OF SNOW. THIS WILL BRING THE FIRST MEASURABLE SNOW IN
MANY AREAS SOUTH OF THE BROOKS RANGE IN ABOUT 10 DAYS. VARIABLE
CLOUD COVER UNDER THIS PATTERN WILL RESULT IN A WIDE RANGE IN
TEMPERATURES...AS CLEAR AREAS MAY SEE TEMPERATURE FALL WELL BELOW
ZERO.

AT THE SURFACE...A 1007 MB LOW 300 MILES NORTH OF BARROW WILL
DRIFT SOUTHEAST TO THE MACKENZIE DELTA BY TUESDAY. STRONG NORTH TO
NORTHWEST WINDS WILL PERSIST ON THE BACK SIDE OF THIS LOW AND
CONTINUE TO BRING HIGH SEAS AND HEAVY SURF THE WESTERN ARCTIC
COAST. THE RECENT LIGHT WIND REGIME OVER THE BERING SEA WILL BE
REPLACED WITH WITH A TIGHTENING PRESSURE GRADIENT AND AN INCREASE
IN NORTHERLY WINDS SUNDAY NIGHT AND MONDAY.

NORTH SLOPE...FLURRIES OR SNOW SHOWERS AND PATCHY FOG WILL
CONTINUE WITH COOLER ONSHORE FLOW. WEST WINDS 25-35 KTS IN THE
EASTERN ARCTIC DIMINISHING ON MONDAY...WHILE NORTHWEST WINDS IN
THE WESTERN ARCTIC WILL LIGHTEN UP SOME TODAY BUT THEN BECOME MORE
NORTHERLY AND INCREASE AGAIN TONIGHT.

WEST COAST....AN INCREASE IN NORTHERLY WINDS WILL DEVELOP TONIGHT
NORTH OF THE SEWARD PENINSULA AND AREAS TO THE SOUTH ON MONDAY.
LARGE AREAS OF MARINE STRATUS AND FOG WILL DIMINISH AS NORTHERLY
WINDS PICK UP. NORTH WINDS GUSTING OVER 40 MPH ARE LIKELY NEAR
POINT HOPE AND THROUGH THE BERING STRAIT TONIGHT. SOME LIGHT SNOW
AND FLURRIES WILL ALSO DEVELOP THROUGH MONDAY AND SOME LOCAL AREAS
OF BLOWING SNOW.

INTERIOR...EXTENSIVE AREAS OF LOW CLOUDS AND PATCHY FOG UNDER THE
CURRENT LIGHT WIND REGIME WILL LINGER TODAY AND ARE NOT EXPECTED
TO COMPLETELY DISSIPATE UNTIL POSSIBLY TONIGHT. THE ARRIVAL OF
COLDER AIR ALOFT AND INCREASING DYNAMICS WILL ALLOW SNOW TO
DEVELOP OVER MUCH OF THE INTERIOR TONIGHT AND MONDAY. SEVERAL
INCHES ARE LIKELY IN THE EASTERN INTERIOR WITH LIGHTER AMOUNTS IN
THE WEST.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NORTH WINDS 20-30 KNOTS
EXPECTED TO PERSIST ALONG THE WESTERN COASTAL WATERS.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY FOR AKZ202-AKZ204.

HEAVY FREEZING SPRAY WARNING FOR PKZ230-PKZ235.

SMALL CRAFT ADVISORY FOR PKZ210-PKZ220-PKZ225-PKZ230-PKZ230-
PKZ235-PKZ240.

GALE WARNING FOR PKZ245.
&&

OCT 12