Small Craft Advisory 70, NWS Fairbanks, AK

NORTHERN ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FAIRBANKS AK
243 AM AKDT THU AUG 11 2011

.DISCUSSION...
MODELS NOT IN GOOD AGREEMENT AT THE GET GO...ALTHOUGH SOME OF THE
CHARACTERISTICS ARE NOT TOO FAR OFF. THE BIG DISCREPANCY RIGHT OFF
OF THE BAT IS THE SURFACE LOW AND THE UPPER LEVEL LOW MOVING
TOWARD THE CHUKOTSK PENINSULA THAT MOVES NORTHEASTWARD THROUGH
FRI. THE SURFACE LOW POSITION IS HELD CLOSE UNTIL ABOUT 06Z FRI
WHEN THE MODELS BEGIN TO DIVERGE.

THE NAM HAS THE SURFACE LOW MUCH DEEPER THAN THE GFS AND FURTHER WEST.

THE GFS IS QUICKER WITH THE SURFACE LOW BUT HANGS THE UPPER LEVEL
LOW BACK WHILE THE ECMWF RUNS THE UPPER LEVEL LOW DOWN TO ABOUT
PAXSON WHILE THE GFS KEEPS THE UPPER LOW NEAR KOTZEBUE BY THE SAME
TIME FRAME. THE EXACT POSITION OF THE SURFACE LOW AND THE UPPER
LEVEL LOW WILL AFFECT THE STRENGTH OF THE SURFACE WIND FIELD.
EXPECT ADVISORY LEVEL WINDS IN ZONES 210...220...225...230 AND 235
THROUGH THU NIGHT.

RAINFALL OVER THE EASTERN INTERIOR WILL TAPER OFF TODAY AND BE
CONFINED MAINLY TO ZONE 224 AS THE UPPER LEVEL LOW CONTINUES TO
MOVE SOUTHEAST OUT OF THE AREA OF INFLUENCE.

THE OLD TROPICAL CYCLONE FROM THE SEA OF JAPAN HAS MOVED INTO THE
BERING SEA BRINGING WITH IT A PLETHORA OF WARM AIR AND MOISTURE.
THIS IS BEGINNING TO IMPACT THE WEST COAST THIS MORNING AND WILL
CONTINUE TO MOVE EAST TO NEAR THE THE CENTRAL PORTION OF THE STATE
BY EARLY SAT AND WILL CONTINUE THROUGH SUNDAY. THE AIR MASS WILL
LOSE ITS WARM PUNCH AS IT MOVES EAST THOUGH.

THE NCEP RMOPS CONTINUE TO PAINT LOW MEASURES OF PREDICTABILITY
ACROSS NORTHERN AK DURING THE MEDIUM RANGE.  THERE IS GOOD AGREEMENT
THAT AN UPPER RIDGE WILL EXTEND FROM NORTHEAST RUSSIA TO THE EAST
SIBERIAN ISLANDS.  DOWNSTREAM FROM THIS RIDGE AND ACROSS THE
FORECAST AREA IS WHERE THE GREATEST UNCERTAINTY LIES.  AT THE START
OF THE MEDIUM RANGE A COMPLEX UPPER TROUGH IS EXPECTED TO SLIDE OUT
OF FAR EAST RUSSIA AND THE CHUKCHI SEA AND DIVE SOUTHEAST ACROSS THE
MAINLAND...BUT THE DETAILS VARY FROM MODEL TO MODEL AND RUN TO RUN.
SIDED CLOSER TO THE ECMWF WHICH HAS BEEN A BIT MORE CONSISTENT THE
LAST FEW RUNS WITH THE PROGRESSIVE NATURE OF THIS COMPLEX TROUGH.
LATER IN THE MEDIUM RANGE THE OPERATIONAL ECMWF BECOMES A STRONG
OUTLIER WITH AN ANOMALOUSLY DEEP LOW DROPPING OUT OF THE HIGH ARCTIC
AND INTO NORTHERN AK.  THIS SOLUTION HAS NO SUPPORT FROM EITHER THE
ECMWF OR GFS ENSEMBLE MEANS AND WAS DISCARDED.

COASTAL HAZARD POTENTIAL DAYS 3 AND 4...NONE

&&

.FIRE WEATHER...

&&

.HYDROLOGY...

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY FOR PKZ210-PKZ220-PKZ225-PKZ230-PKZ235.

GALE WARNING FOR PKZ230.
&&

CF AUG 11