Small Craft Advisory 67, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKST MON JAN 21 2013

.MODEL DISCUSSION...
.ANALYSIS AND UPPER LEVELS...
A BROAD TROUGH OVER THE NORTHERN PACIFIC IS PUSHING EAST ALONG INTO
AN AMPLIFIED RIDGE OVER THE EASTERN PACIFIC. A MOISTURE PLUME ALONG
THE BORDERING PRESSURE SYSTEMS IS STREAMING NORTH OVER SOUTH ALASKA
AND THE EASTERN BERING. THERE IS A BREAK IN THE CLOUDS BETWEEN THE
TWO SYSTEMS OVER SOUTHCENTRAL ALASKA AND PATCHY FOG HAS FORMED IN
AREAS WHERE SKIES HAVE CLEARED. TEMPERATURES HAVE WARMED ACROSS THE
EASTERN ALEUTIANS TO SOUTHEAST PRINCE WILLIAM SOUND IN THE WAKE OF
THE FRONT THAT MOVED THROUGH YESTERDAY. FURTHER WEST...A WEAK
SHORTWAVE IS MOVING IS BRINGING LIGHT RAIN SHOWERS ACROSS THE EASTERN
BERING THIS MORNING. COLD AIR ADVECTION ON THE BACKSIDE OF A SURFACE
LOW IN THE WESTERN BERING HAS COOLED TEMPERATURES SLIGHTLY ACROSS THE
WEST AND CENTRAL ALEUTIANS.

.MODEL DISCUSSION...
MODELS CONTINUE TO BE IN FAIR AGREEMENT THROUGH THE SHORT TERM
FORECAST. THE EXPANSIVE COMPLEX LOW OVER THE ALEUTIAN CHAIN WILL
PUSH EASTWARD THROUGH THE MIDDLE OF THE WEEK AND BREAK DOWN THE
RIDGE ALONG THE EASTERN PACIFIC. TWO LOW PRESSURE CENTERS WILL CLOSE
OFF FROM THE COMPLEX LOW BY MONDAY MORNING...ONE CENTER SOUTH OF
COLD BAY AND THE OTHER SOUTH OF SHEMYA. THESE CENTERS WILL TRACK
EASTWARD STAYING SOUTH OF THE ALEUTIANS. A RIDGE WILL AMPLIFY ON
WEDNESDAY ALONG THE WESTERN ALEUTIANS. THE NAM AND THE ECMWF WERE
THE MODELS OF CHOICE THROUGH THE SHORT TERM.

SOUTHCENTRAL ALASKA...
EASTERLY OFFSHORE FLOW WILL INCREASE INTO THE AFTERNOON TODAY AS A
SURFACE LOW MOVES INTO THE SOUTHERN GULF. WINDS WILL TAPER OFF
WEDNESDAY MORNING WHEN THE LOW CENTER DISSIPATES. THROUGH
MIDWEEK...MAINLY RAIN SHOWERS WILL FALL ACROSS THE GULF AND ALONG THE
COAST AS THE SURFACE LOW TRACKS FROM THE SOUTHERN TO NORTHERN GULF.
THE DYNAMICS ARE NOT STRONG WITH THIS SYSTEM THEREFORE ONLY ISOLATED
SNOW SHOWERS WILL MAKE IT INLAND.

SOUTHWEST ALASKA...
STRONG EASTERLY OFFSHORE FLOW WILL CONTINUE ACROSS BRISTOL AS THE
SURFACE LOW MOVES TOWARD THE SOUTHERN GULF AND THEN BEGIN TO TAPER
OFF THIS AFTERNOON. TODAY AND AND TUESDAY...SCATTERED RAIN AND SNOW
SHOWERS WILL MOVE ACROSS THE ALASKA PENINSULA AND THEN INTO BRISTOL
BAY AS THE SURFACE LOW SOUTH OF COLD BAY MOVES INTO THE SOUTHERN
GULF. ONLY ISOLATED RAIN AND SNOW SHOWERS NORTH. DRIER CONDITIONS ON
WEDNESDAY AND THURSDAY WITH THE BREAK IN BETWEEN LOW PRESSURE
CENTERS.

ALEUTIANS/BERING SEA...
CLOUDY AND COLDER CONDITIONS WILL CONTINUE THROUGH MID WEEK AS LOW
PRESSURE CENTERS MOVE SOUTH OF THE ALEUTIAN CHAIN. A RIDGE WILL MOVE
INTO THE WESTERN ALEUTIANS ON WEDNESDAY AND THEN CONTINUE AN
EASTWARD TRACK INTO THE EASTERN ALEUTIANS BY THURSDAY. THIS WILL
BRING DRIER CONDITIONS AS IT MOVES THROUGH.

.LONG TERM FORECAST...
COLDER TEMPERATURES RETURN TOWARD THE END OF THE WEEK AS ARCTIC AIR
PUSHES SLOWLY SOUTHWARD. LOW PRESSURE WILL CONTINUE TO BE THE
DOMINANT PATTERN OVER THE NORTH PACIFIC AND BERING. LOW PRESSURE
CENTERS WILL CONTINUE TO TRACK ACROSS THE ALEUTIANS AND SOUTH OF
ALASKA THROUGH THE EXTENDED FORECAST. THIS WILL KEEP CLOUDS AND
CHANCES OF RAIN OR ISOLATED SHOWERS ACROSS THE REGION THROUGH THE
NEXT WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALES 120 130 132 138 140 160 172
FIRE WEATHER...NONE.

KH JAN 13