Gale Warning 50, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
239 PM AKDT SUN JUL 27 2008

.DISCUSSION...THE NAM AND GFS MODELS ARE NICELY AGREEABLE ON THE
FORECAST OF A BIG OUTBREAK OF COLD AIR OVER NORTHWEST ALASKA
STARTING TUESDAY. THE GFS IS A LITTLE FASTER ON THIS, AND IT
BRINGS IN A STRONG WESTERLY JET OVER NORTHWEST ALASKA ON TUESDAY.
THE NAM LOOKS ABOUT 12 HOURS SLOWER ON THIS EVENT. IT MAY NOT LOOK
LIKE IT IS LATE JULY, BUT ALL OF THIS IS REAL, JUST LIKE LAST
WEEKS SNOW OVER THE WEST ARCTIC. ALTHOUGH THIS MONTH HAS BEEN
COOL AND GLOOMY OVER MUCH OF THE REALM, PAST EXPERIENCE SUGGESTS
THAT A CHILLY AND CLOUDY JULY CAN EASILY BE FOLLOWED BY A FINE
AUGUST WITH LOTS OF SUNSHINE. WELL SEE ON THIS ONE.

A LOW ALOFT IN THE NORTHEAST GULF OF ALASKA IS EXPECTED TO
CONTINUE TO BRING A SERIES OF INVERTED TROUGHS ALOFT TO THE EAST
INTERIOR THROUGH MONDAY NIGHT. THE INCOMING ENERGY IS EXPECTED TO
BE ESPECIALLY STRONG ON MONDAY. THIS MAY BRING SUBSTANTIAL
RAINFALL TO THE EAST INTERIOR AND THE NORTH SLOPES OF THE ALASKA
RANGE ON MONDAY. FOLLOWING MONDAY NIGHT, CIRCULATION AROUND THE
ARCTIC LOW WILL COVER ALL OF NORTHERN ALASKA.

THE INCOMING CHUKCHI SEA SURFACE LOW IS EXPECTED TO BE ABOUT 250
MILES NORTHWEST OF POINT LAY MONDAY AFTERNOON. AS OF THE 18Z
SURFACE ANALYSIS THIS LOW IS MOVING EAST ABOUT 35 KNOTS, WHICH
PUTS IT ON SCHEDULE. AFTER MONDAY AFTERNOON, THE LOW WILL MOVE
RAPIDLY TO THE NORTH NORTHEAST. THE COLD FRONT WITH THIS SURFACE
LOW WILL BE STRONG, AND SWEEP OVER THE NORTHWEST WATERS OF ALASKA
ON MONDAY EVENING AND EXIT TO THE EAST BEAUFORT SEA TUESDAY. THIS
FRONT IS EXPECTED TO BRING A BRIEF SOUTHWEST GALE TO THE WATERS
FROM BERING STRAIT TO POINT HOPE ON MONDAY AND FROM POINT HOPE TO
POINT FRANKLIN ON MONDAY EVENING.

CONSIDERABLY COLDER AIR ALOFT WILL FOLLOW IT OVER ALL OF NORTHERN
ALASKA NORTH OF BERING STRAIT AND THE ARCTIC CIRCLE IN THE
INTERIOR. AS A RESULT OF ALL OF THIS, SNOW IS LIKELY OVER THE WEST
ARCTIC TUESDAY, AND WILL SPREAD OVER THE REMAINDER OF THE ARCTIC
NORTH OF THE BROOKS RANGE TUESDAY NIGHT AND WEDNESDAY.

PRIOR TO THE PASSAGE OF THE COLD FRONT, THE EASTERN ARCTIC OF
ALASKA LOOKS LIKE IT WILL BE QUITE WARM ON TUESDAY, DUE TO
SOUTHWESTERLY OFFSHORE FLOW. THIS WILL CHANGE IN A HURRY TUESDAY
NIGHT. SOME PLACES WILL SEE A 30 DEGREE DROP, FROM THE 60S TO THE
30S, AS THIS TRANSPIRES. STARTING WEDNESDAY NIGHT, SUBSTANTIAL
WARMING IN THE WEST ARCTIC WILL BEGIN. THIS WEEK IS NO OCCASION
FOR PERSISTENCE FORECASTS.

THE COLD OUTBREAK WILL BE EXITING INTO THE YUKON THURSDAY,
FOLLOWED IN SHORT OVER BY STRONG WEST NORTHWEST FLOW ALOFT. THIS
WILL RESULT IN A CONTINUATION OF CLOUDY AND RAINY WEATHER OVER
NORTHERN ALASKA FROM THE ALASKA RANGE AND SEWARD PENINSULA UP OVER
THE ARCTIC. HIGH PRESSURE ALOFT WILL BE BUILDING OVER THE
SOUTHEAST BERING SEA THURSDAY AND ON TO SOUTHWEST ALASKA THURSDAY
NIGHT. SOME CLEARING AND WARMING SHOULD ACCOMPANY THIS.

THE MEDIUM RANGE FORECASTS ARE STRUGGLING BY THIS WEDNESDAY. THIS
IS COMMON IN FAST-MOVING WEATHER SUCH AS THIS. THE GFS FORECAST OF
CONTINUED BUILDING OVER THE RIDGE ALOFT OVER SOUTHWEST ALASKA
LOOKS MORE REASONABLE THAN THE EUROPEAN MODEL WHICH HOLDS A COLD
TROUGH ALOFT OVER THE ALASKA MAINLAND THROUGH TUESDAY AUGUST 5.
THE GFS MODEL PROBABLY FORECASTS TOO STRONG HIGH PRESSURE ALOFT
OVER THE MAINLAND IN THE WEEK FOLLOWING THE PRESENT WEEK, BUT IT
APPEARS TO BE CORRECTLY SEIZING ON AN OMEGA BLOCKING PATTERN WHICH
IS FORECAST TO DEVELOP OVER THE GULF OF ALASKA AT THE END OF THIS
PRESENT WEEK. THIS ASPECT OF THE GFS FORECAST, AS WELL AS ITS
AVOIDANCE OF PERSISTENCE OF THE COLD TROUGH OVER THE MAINLAND, ARE
THE REASONS THE GFS MID RANGE FORECASTS SEEM TO BE THE BETTER
CHOICE FOR NOW.

THE ONLY PART OF NORTHERN ALASKA THAT WILL HAVE RELATIVELY SETTLED
WEATHER FOR THE NEXT 5 DAYS WILL BE THE SOUTHWEST MAINLAND.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4 (WEDNESDAY, JULY 30 AND
THURSDAY, JULY 31)...NONE ON JULY 30. BRIEF GALE POSSIBLE FROM
BERING STRAIT TO CAPE LISBURNE JULY 31.

&&

.FIRE WEATHER...SOME LIGHTNING IS EXPECTED OVER THE EAST INTERIOR.
HOWEVER, EXTENSIVE CLOUD COVER AND RECENT RAINS WILL KEEP THE
SCENE CALM.

&&

.HYDROLOGY...AS HAS BEEN THE CASE FOR WEEKS, RIVER STAGES HAVE
BEEN SURPRISINGLY LOW AND CONTINUE TO BE SO. IN SPITE OF
CONTINUING BOUTS OF RAIN, RIVER STAGES ARE EXPECTED TO REMAIN
BELOW ACTION LEVELS.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY FOR PKZ210-PKZ220-PKZ225-PKZ230-PKZ245.

GALE WARNING FOR PKZ225.
&&

TF JUL 08