Small Craft Advisory 295, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
126 PM AKDT TUE APR 8 2014

.ANALYSIS AND UPPER LEVELS...A HIGH AMPLITUDE TROUGH EXTENDS FROM
THE ARCTIC SOUTHWARD ACROSS MAINLAND ALASKA TO COOK INLET AND THE
WESTERN GULF. A VORTICITY-MAXIMUM MOVING THROUGH THE BASE OF THE
TROUGH THIS MORNING HAS SLOWED THE PROGRESSION OF THE MAIN TROUGH
AXIS...WHICH IN TURN HAS SLOWED THE ARRIVAL OF COLDER AIR INTO
SOUTHCENTRAL. THE END RESULT IS THAT THE BULK OF SNOWFALL HAS BEEN
FALLING OVER WESTERN PRINCE WILLIAM SOUND AND THE KENAI AND
CHUGACH MOUNTAINS WHILE AREAS JUST TO THE WEST OF THE MOUNTAINS
(INCLUDING THE ANCHORAGE BOWL) HAVE REMAINED MOSTLY DRY. AS THE
VORT-MAX LIFTS NORTHWARD UP THE EAST SIDE OF THE TROUGH SOME OF
THE SNOW IS BEGINNING TO ROTATE A LITTLE FURTHER WEST. STILL
EXPECT AT LEAST A BRIEF PERIOD OF LIGHT SNOW IN ANCHORAGE AS THE
TROUGH AXIS GETS CLOSER THIS AFTERNOON.

MEANWHILE COLD ADVECTION BEHIND THEE VORT-MAX IS PRODUCING STRONG
GUSTY WINDS ACROSS PORTIONS OF SOUTHWEST ALASKA...THE ALASKA
PENINSULA AND THE KODIAK ISLAND WATERS.

OUT WEST A LARGE CLOSED LOW OVER THE NORTHWEST PACIFIC IS TRACKING
SLOWLY EASTWARD WITH A LEADING TROUGH OVER THE CENTRAL BERING
WEAKENING AS IT LIFTS NORTHWARD. AT THE SURFACE AN OCCLUDED FRONT
ACROSS THE BERING SEA AND EASTERN ALEUTIANS IS ELONGATING AND
DISSIPATING AS THE TRIPLE POINT TO THE SOUTH RACES RAPIDLY
EASTWARD.

&&

.MODEL DISCUSSION...MODELS ARE IN GOOD AGREEMENT THROUGH THE
SHORT-TERM. FORECAST CONFIDENCE IS ABOVE AVERAGE.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...THE UPPER TROUGH WILL SLOWLY EXIT
SOUTHCENTRAL TONIGHT THROUGH WEDNESDAY WITH DRY AND COLD AIR
SETTLING IN BEHIND IT. A SERIES OF UPPER LEVEL RIDGES WILL
PROVIDE DRY CONDITIONS THROUGH THE END OF THE WEEK WITH SLOWLY
MODERATING TEMPERATURES. FOR AREAS RECEIVING SNOW TODAY THERE IS
THE POSSIBILITY OF FOG OR STRATUS DEVELOPING AS SKIES CLEAR
BEHIND THE TROUGH. HOWEVER THE HIGHER PROBABILITY OF FOG WILL BE
WITH THE UPPER RIDGE MOVING OVERHEAD WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. CONDITIONS WILL BE FAVORABLE FOR RADIATIONAL
COOLING AT NIGHT WHICH WILL SET UP SOME STEEP SURFACE BASED
INVERSIONS.

SOUTHWEST ALASKA...WINDS WILL DIE DOWN QUICKLY TONIGHT AS HIGH
PRESSURE BUILDS IN FROM THE WEST AND RADIATIONAL COOLING QUICKLY
LEADS TO DECOUPLING OF THE BOUNDARY LAYER. WITH A COLD AND DRY
AIRMASS IN PLACE DON'T EXPECT MUCH IN THE DEVELOPMENT OF FOG
TONIGHT. AS THE UPPER RIDGE MOVES OVERHEAD MAY SEE SOME FOG
DEVELOPMENT...BUT IT SHOULDN'T BE WIDESPREAD DUE TO THE DRYNESS
OF THE AIRMASS. THE LARGE LOW MOVING INTO THE BERING WILL BEGIN
TO IMPACT SOUTHWEST ALASKA WITH CLOUDS AND PRECIP FRIDAY NIGHT
INTO SATURDAY.

BERING SEA/ALEUTIANS...THE LARGE UPPER LOW OVER THE NORTHWEST
PACIFIC WILL SET UP SHOP OVER THE BERING SEA AND ALEUTIANS BY MID
WEEK AND SLOWLY WOBBLE ITS WAY EASTWARD AS EMBEDDED WAVES ROTATE
AROUND THE PERIPHERY.

&&

.LONG TERM FORECAST...THERE ARE SOME MODEL DIFFERENCES IN
EASTWARD PROGRESSION OF THE ALEUTIAN LOW TOWARD THE MAINLAND WITH
LARGE DISAGREEMENT BETWEEN THE ECMWF AND GFS IN AMPLITUDE OF THE
DOWNSTREAM RIDGE. FOR NOW WILL TREND TOWARD INCREASING CLOUDS AND
CHANCE OF PRECIPITATION ALONG WITH MODERATING TEMPERATURES ACROSS
MAINLAND ALASKA AS WE HEAD INTO NEXT WEEK. THE WEST WILL REMAIN
UNSETTLED...BUT WITH GENERALLY WEAK FEATURES DON'T EXPECT ANY
MAJOR IMPACTS.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING...130.
         HEAVY FREEZING SPRAY WARNING...160 180.
FIRE WEATHER...NONE.

&&

SEB APR 14