Small Craft Advisory 10, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
1215 PM AKST WED JAN 2 2013

.ANALYSIS AND UPPER LEVELS...
A LARGE UPPER LOW REMAINS OVER THE EASTERN BERING SEA...RESULTING IN
SOUTHERLY FLOW ACROSS THE SOUTHERN MAINLAND AND NORTHERLY FLOW ACROSS
THE WESTERN BERING. A 969 MB LOW SOUTH OF THE ALASKA PENINSULA IS THE
LATEST IN A STRING OF LOWS TO DEVELOP ON THE SOUTHEAST FLANK OF THE
BROAD UPPER LEVEL TROUGH. SATELLITE IMAGERY SHOWS AN ASSOCIATED FRONT
APPROACHING KODIAK ISLAND FROM THE SOUTHWEST. AHEAD OF THE
FRONT...FLOW IS SOUTHERLY ACROSS THE NORTHERN GULF WITH WIDESPREAD
RAIN AND SNOW SHOWER ACTIVITY BRINGING PRECIPITATION TO COASTAL
LOCATIONS. LOW CLOUDS AND FOG IN THE WAKE OF THE PREVIOUS STORM
ACROSS THE SOUTHWEST MAINLAND ARE IMPROVING AS FLOW BECOMES
NORTHEASTERLY AHEAD OF THE NEXT LOW. FURTHER WEST...A VERY ELONGATED
TROUGH IS LOCATED OVER THE WESTERN HALF OF THE ALEUTIAN
CHAIN...BRINGING LIGHT NORTHERLY WINDS AND SCATTERED SNOW SHOWERS TO
THE AREA.

.MODEL DISCUSSION...
MODESL REMAIN IN GOOD SYNOPTIC AGREEMENT. ALL SOLUTIONS SHOW THE LOW
NEAR THE AKPEN CROSSING INTO THE EASTERN BERING TONIGHT BEFORE
WEAKENING RAPIDLY AND RETREATING WESTWARD THURSDAY MORNING. THE
ASSOCIATED FRONT IS WEAKER THAN PREVIOUS STORMS...WITH GALE-FORE
WINDS LOCATED ALONG THE FRONT. THE FRONT WILL FALL APART AS IT
REACHES THE NORTH GULF COAST LATE TONIGHT. THERE REMAINS SOME MODEL
UNCERTAINTY REGARDING THE DEVELOPMENT OF A LOW IN THE FAR SOUTHEAST
GULF FRIDAY NIGHT. THE ECMWF IS CURRENTLY THE ODD-SOLUTION OUT WITH A
MUCH FURTHER NORTH TRACK...AND WILL BE IGNORED WITH THE AFTERNOON
FORECAST PACKAGE. MEANWHILE...A COMPLEX LOW WITH MULTIPLE CENTERS
WILL PERSIST OVER THE BERING SEA...THE EXACT DETAILS OF WHICH ARE
VERY DIFFICULT TO PINPOINT MORE THAN 48 HOURS IN ADVANCE.

.SHORT TERM FORECAST...
SOUTHCENTRAL...IMPRESSIVE SHOWER ACTIVITY ACROSS THE GULF IS BEING
ENHANCED BY SEVERAL WEAK MIDLEVEL SHORTWAVES. FLOW WILL GRADUALLY
BECOME MORE EASTERLY TONIGHT AS THE FRONT NEAR KODIAK PROGRESSES
NORTHWARD. SINCE THIS FRONT WILL BE MUCH WEAKER THAN THE PREVIOUS
SEVERAL...DO NOT EXPECT WARNING-LEVEL WINDS THROUGH THE FAVORED
TERRAIN GAPS LIKE TURNAGAIN ARM. HOWEVER...WINDS WILL STILL INCREASE
SIGNIFICANTLY TONIGHT AND PERSIST THROUGH THURSDAY AFTERNOON. CLASSIC
DOWNSLOPING EFFECT WILL BE ON DISPLAY AS THE FRONT MOVES
THROUGH...WITH THE VAST MAJORITY OF PRECIP FALLING ALONG THE COASTAL
MOUNTAINS. PRECIPITATION EXPECTED TO FALL AS A RAIN/SNOW MIX AT LOWER
ELEVATIONS...WITH SIGNIFICANT SNOWFALL ACCUMULATIONS ONCE AGAIN
EXPECTED THROUGH TURNAGAIN PASS AND THOMPSON PASS.

SOUTHWEST MAINLAND...SOUTHEASTERLY WINDS WILL CONTINUE TO INCREASE
THROUGH GAPS IN THE ALEUTIAN RANGE AHEAD OF THE FRONT. AS WITH THE
PREVIOUS STORMS...MINIMAL PRECIP EXPECTED UNTIL FLOW BECOMES MORE
SOUTHERLY AS THE LOW BEGINS TO RETREAT BACK OUT TO THE BERING SEA
THURSDAY MORNING. THERMALLY...THE ATMOSPHERE REMAINS IN A SIMILAR
CONDITION AS THE LAST SEVERAL STORMS. AS SUCH...CANNOT RULE OUT A
BRIEF PERIOD OF FREEZING DRIZZLE MIXING IN WITH THE SNOW SHOWERS.
HOWEVER NOT EXPECTING ANY SIGNIFICANT ICE ACCUMULATIONS. BY SATURDAY
MORNING...A MORE SIGNIFICANT WEATHER FRONT MOVES IN FROM THE
BERING...BRINGING MORE WIDESPREAD CHANCES OF SNOW THAN HAS BEEN SEEN
IN RECENT STORMS.

BERING SEA AND ALEUTIANS...LARGE BUT FAIRLY WEAK COMPLEX LOW WILL
PERSIST OVER THE CENTRAL BERING THROUGH THURSDAY NIGHT. THIS WILL
KEEP SHOWERS BUT FAIRLY LIGHT WINDS ACROSS MUCH OF THE REGION. BY
FRIDAY MORNING...A MORE SUBSTANTIAL LOW WILL MOVE INTO THE WESTERN
BERING...BRINGING STRONGER WINDS THAN RECENT STORMS AS IT TRACKS INTO
THE NORTHERN BERING ON SATURDAY.

.LONG TERM FORECAST...
A GRADUAL AMPLIFICATION OF THE JET STREAM WILL ALLOW SOME STRONGER
AND MORE PERSISTENT STORMS TO MOVE INTO THE ALASKA DOMAIN BY THIS
WEEKEND. GENERALLY...THE BERING SEA WILL BE THE FOCUS OF THESE
STRONGER LOWS. THIS WILL SET THE STAGE FOR MAINLAND ALASKA TO REMAIN
UNDER GENERAL SOUTHERLY FLOW...WHICH WILL KEEP TEMPERATURES COOLER
THAN RECENT DAYS BUT STILL SLIGHTLY ABOVE NORMAL.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 120 125 130 132 150 155 160 175 185
         HEAVY FREEZING SPRAY 185
FIRE WEATHER...NONE

AMD JAN 13