Small Craft Advisory 217, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
402 PM AKDT TUE MAR 10 2015

.ANALYSIS AND UPPER LEVELS...
GENERALLY FAIR SKIES WERE EVIDENT ACROSS MUCH OF THE SOUTHERN
MAINLAND AND NORTHERN GULF WITH BROAD OFFSHORE FLOW. CLOUDY
CONDITIONS WITH SNOW SHOWERS UNDER A BROAD NORTHEASTERLY FLOW
WERE EVIDENT ACROSS MUCH OF THE BERING SEA AND ALEUTIANS. OUTFLOW
WINDS AS SEEN BY LOW CLOUD BANDS ON SAT IMAGERY...ARE PRESENT
OVER SOUTHERN COOK INLET...WESTERN GULF...SHELIKOF STRAIT...AND
THE NORTH GULF COAST. GUSTY GAP/OUTFLOW WINDS DOMINATE THE
NORTHERN GULF FROM THE EASTERN KENAI PEN TO THE NORTHERN GULF
COAST.

&&

.MODEL DISCUSSION(THROUGH THU)...
MODELS INITIALIZED WELL. THE ECMWF AND GFS WERE IN FAIR AGREEMENT
AND REASONABLE THROUGH THU. THE AFTERNOON PACKAGES WILL BE BASED
GENERALLY ON THE GFS/ECMWF...THOUGH THE NAM/GEM REG WILL BE USED
FOR MESOSCALE WINDS IN THE EAST.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE UPPER LEVELS CONTINUE WITH WESTERLY FLOW WITH CONDITIONS
REMAINING DRY AND COLD WITH SUNNY SKIES HEADING INTO MIDWEEK.
THERE IS A ZONAL 80 KNOT JET STREAK OVER SOUTHCENTRAL ALASKA THAT
WILL TRANSITION TO A SOUTHERLY MERIDIONAL JET STREAK BY THURSDAY.
THE PRESSURE GRADIENT WILL CONTINUE TO WEAKEN RESULTING IN
DIMINISHING GAP WINDS ALONG THE GULF COAST. HOWEVER...GAP WINDS
WILL RAMP RIGHT BACK UP AGAIN LATE THURSDAY THROUGH THURSDAY NIGHT
AS A DEEP LOW MOVES INTO THE EASTERN GULF CAUSING AN INCREASE IN
PRESSURE GRADIENTS OVER SOUTHCENTRAL.

THE SATELLITE IMAGERY CONTINUES TO REFLECT OCEAN-EFFECT SNOW SHOWERS
FROM SOUTHERN COOK INLET DOWN TO NORTHERN KODIAK ISLAND. THE MODELS
ARE NOT DOING A GREAT JOB PICKING UP ON THESE SHOWERS. THE
MAJORITY OF THE SNOWFALL WILL LIKELY BE OVER AFOGNAK ISLAND AND
PORTIONS OF THE NORTHEASTERN SIDE OF KODIAK ISLAND...WITH AT LEAST
A FEW OF THESE SHOWERS MAKING IT INTO KODIAK CITY.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
A BROAD UPPER LEVEL TROUGH WILL PERSIST OVER THE MAINLAND WITH A
WEAK JET OVER THE BRISTOL BAY COAST. THE UPPER TROUGH WILL DIG TO
THE ALASKA PENINSULA THROUGH WEDNESDAY MORNING THEN SWING TO THE
SOUTHEAST ACROSS KODIAK ISLAND BY THURSDAY AFTERNOON. SOME MID TO
HIGH LEVEL MOISTURE WILL MOVE OVER SOUTHWEST ALASKA WITH THIS
TROUGH...BRINGING SOME CLOUD COVER THAT WILL HELP TO MODERATE THE
OVERNIGHT LOWS IN THIS COLD AIRMASS. A SNOW SHOWER OR TWO ARE
POSSIBLE MAINLY ALONG THE IMMEDIATE COAST AS THIS TROUGH SWINGS
THROUGH WEDNESDAY NIGHT AND THURSDAY. THE ONSHORE FLOW AND COLD
ADVECTION ALONG THE NORTH SIDE OF THE ALASKA PENINSULA WILL RESULT
IN SNOW SHOWERS ON THE BERING SIDE FOR THE NEXT FEW DAYS.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAY 1 AND DAY 2)...
THE LOW SOUTH OF THE CENTRAL ALEUTIANS WILL DROP TO THE SOUTH
RELAXING THE PRESSURE GRADIENT ALONG THE ALEUTIANS AND ALLOWING
THE WINDS TO SLOWLY DIMINISH. WEAK HIGH PRESSURE WILL MOVE IN
OVER THE WESTERN ALEUTIANS THROUGH WEDNESDAY MORNING. THE NEXT
FRONTAL SYSTEM WILL BE MOVING INTO THE WESTERN ALEUTIANS WED NIGHT
AND WILL SWING ACROSS TO THE CENTRAL ALEUTIANS BY THURSDAY
AFTERNOON. THIS WILL BRING WARMER AIR ACROSS THE ALEUTIANS THAT
WILL RESULT IN MIXED RAIN AND SNOW AS THE FRONT MOVES THROUGH
ALONG WITH GALE FORCE WINDS.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
COLD AND DRY CONDITIONS ARE EXPECTED TO REMAIN FOR MUCH OF
MAINLAND ALASKA THROUGH SATURDAY. AT THAT POINT A LOW THAT WILL
BE JUST SOUTH OF THE ALEUTIANS THROUGH THE END OF THE WEEK WILL
MAKE ITS WAY TOWARDS THE GULF. THIS LOW WILL BRING A STRONG PUSH
OF SOUTHERLY AIR WHICH WILL HELP TO WARM TEMPS BACK UP AND BRING
MORE WIDESPREAD PRECIP TO THE REGION.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING...130 131 178.
         HEAVY FREEZING SPRAY WARNING...121 126 127 128 129 130
                                        131 138 139 150 160 165
                                        179 180 185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...BC
SOUTHCENTRAL ALASKA...PD
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...SA
LONG TERM...DK