Small Craft Advisory 852, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT TUE OCT 29 2013

.ANALYSIS AND UPPER LEVELS...
THE MAIN UPPER LEVEL LOW IS OVER THE BERING SEA. SEVERAL STORM
SYSTEMS ARE BEING STEERED BY THIS LOW. ONE OF THESE IS CURRENTLY
CENTERED JUST SOUTHWEST OF KODIAK ISLAND WITH ANOTHER CENTERED ON
THE TIP OF THE KAMCHATKA PENINSULA. ANOTHER STORM THAT IS CURRENTLY
OVER JAPAN WILL BECOME A FACTOR IN THE WEATHER FOR THE ALEUTIANS
THURSDAY NIGHT AND FRIDAY.

.MODEL DISCUSSION...
GUIDANCE CONTINUES TO BE IN FAIR AGREEMENT THROUGH 36 HOURS...WITH
THE GFS BEING A SLIGHT OUTLIER REGARDING THE TRACK OF THE
STRENGTHENING SURFACE LOW CURRENTLY 200 MILES SOUTHWEST OF KODIAK
ISLAND. BOTH THE NAM AND ECMWF ARE PREDICTING THIS SYSTEM TO
INTENSIFY FROM A 975 MB LOW INTO A 968 MB LOW JUST SOUTH OF KODIAK
CITY BY EARLY WEDNESDAY MORNING. CONFIDENCE IS HIGH THAT
INTENSIFICATION WILL OCCUR GIVEN THE PLACEMENT OF THE LOW ON THE
LEFT EXIT REGION OF A 300 MB JET WITH A 140 KT CORE...AS WELL AS A
DECENT INFLUX OF WARM MOIST SUBTROPICAL AIR AT LOWER AND MIDDLE
LEVELS. THE LOW WILL THEN TRACK INTO THE NORTHEASTERN GULF COAST
THURSDAY MORNING AND DISSIPATE THURSDAY EVENING. GUIDANCE IS ALSO
KEYING IN ON A NORTH PACIFIC LOW INTENSIFYING SOUTH OF SHEMYA
THURSDAY AFTERNOON AND PUSHING INTO THE WESTERN AND CENTRAL
ALEUTIANS AT 974 MB BY EARLY FRIDAY MORNING...THEN MOVING EASTWARD
INTO THE EASTERN BERING BY SATURDAY MORNING.

.SHORT TERM FORECAST...
FOR SOUTH CENTRAL ALASKA...THE KODIAK LOW WILL WORK TOWARDS THE
NORTHEAST INTO WEDNESDAY NIGHT. DECENT RAINS AND WINDS ARE EXPECTED
WITH THIS LOW...WITH MOST OF THE ACTION CONFINED TO THE COASTAL
AREAS. LITTLE PRECIPITATION IS EXPECTED FOR ANCHORAGE AND THE
MATANUSKA/SUSITNA VALLEYS WITH THIS SYSTEM. THIS IS DUE TO THE
UNFAVORABLE UPPER LEVEL WINDS FROM THE SOUTHEAST...EAST...AND EVEN
NORTHEAST KEEPING THOSE AREAS ON THE DOWN-SLOPE SIDE OF THE
MOUNTAINS. THE LOW WILL THEN SETTLE IN NEAR PRINCE WILLIAM SOUND ON
THURSDAY THEN WEAKEN INTO FRIDAY. WITH THE AIR ALOFT SLOWLY COOLING
THURSDAY AND FRIDAY...SOME SNOW MAY MIX IN AT LOWER ELEVATIONS...BUT
LITTLE OR NO ACCUMULATIONS ARE EXPECTED AT THIS TIME.

FOR SOUTHWEST ALASKA...LOW PRESSURE OVER THE INTERIOR ALONG WITH THE
APPROACHING SURFACE LOW TO THE SOUTH OF KODIAK WILL CONTINUE TO
BRING SCATTERED SHOWERS TO THE AREA...AS WELL AS GUSTY WINDS THROUGH
CHANNELED TERRAIN. THESE SHOWERS ARE BEING GENERATED BY MOIST
ONSHORE FLOW AND SYNOPTIC SCALE ASCENT ON THE BACK END OF THE
LOW...WHICH WILL TAPER OFF WEDNESDAY MORNING AS THE LOW TRACKS INTO
THE NORTHERN GULF.

FOR THE BERING SEA AND ALEUTIAN ISLANDS...A RELATIVELY BENIGN
WEATHER PATTEN IS IN STORE FOR THE AREA. NORTHERLY FLOW ALOFT WILL
CONTINUE TO ADVECT COLDER AIR OVER THE BERING SEA THROUGH THE END OF
THE WEEK BEFORE A NORTH PACIFIC LOW APPROACHES FROM THE SOUTHWEST ON
THURSDAY AFTERNOON. THE COLD NORTHERLY FLOW AND WARM SEA SURFACE
TEMPERATURES WILL ALLOW INSTABILITY SHOWERS TO DEVELOP EACH DAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING 130 131 138.
         GALE WARNING 119 120 132 136 137 139 150.
FIRE WEATHER...NONE.

LUDWIG/TP OCT 13