Small Craft Advisory 63, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
430 PM AKST SAT JAN 19 2013

.ANALYSIS AND UPPER LEVELS...
AN AMPLIFIED UPPER LEVEL RIDGE REMAINS OVER THE FAR EASTERN PACIFIC
WITH AN AXIS EXTENDING NORTHWESTWARD THROUGH SOUTHCENTRAL ALASKA TO
NEAR SAINT LAWRENCE ISLAND. MEANWHILE...A COMPLEX UPPER LEVEL TROUGH
WITH SEVERAL EMBEDDED LOW PRESSURE CENTERS EXTENDS THROUGH THE BERING
SEA AND INTO THE NORTHERN PACIFIC. THE MOST PROMINENT OF THESE
EMBEDDED FEATURES IS A STRENGTHENING UPPER LOW WHICH IS FAST
APPROACHING THE AKPEN FROM THE SOUTH...WITH ANOTHER UPPER LOW WELL
SOUTH OF THE CENTRAL ALEUTIANS AND AN ELONGATED AREA OF LOW PRESSURE
ALSO LOCATED OVER THE CENTRAL AND WESTERN PART OF THE CHAIN. AT THE
SURFACE...A SUB 980 MB LOW IS CURRENTLY MOVING INTO THE EASTERN
BERING BETWEEN DUTCH HARBOR AND THE TIP OF THE AKPEN WITH AN
ASSOCIATED FRONT EXTENDING ACROSS THE AKPEN INTO THE NORTHERN GULF OF
ALASKA. THIS FEATURE CONTINUES TO BRING WIDESPREAD PRECIPITATION TO
SOUTHERN ALASKA...WITH RAIN FALLING FROM THE EASTERN ALEUTIANS AND
AKPEN TO KODIAK ISLAND AND SNOW SHOWERS OCCASIONALLY MIXING WITH RAIN
FURTHER NORTH OVER THE MAINLAND. GUSTY NORTHEASTERLY WINDS AHEAD OF
THE FRONT ARE SUPPORTING BLIZZARD CONDITIONS ACROSS THE PRIBILOFS AND
OVER COASTAL PORTIONS OF THE KUSKOKWIM DELTA.

.MODEL DISCUSSION...
MODELS REMAIN IN GOOD AGREEMENT THROUGH THE SHORT TERM WITH RESPECT
TO THE OVERALL SYNOPTIC PATTERN. THE AKPEN LOW WILL MOVE WESTWARD
THROUGH THE BERING DURING THE EARLY PART OF THE WEEK WHILE THE LOW
CURRENTLY SOUTH OF THE CENTRAL ALEUTIANS CONTINUES EASTWARD AND
REACHES THE CENTRAL GULF OF ALASKA BY LATE TUESDAY. YET ANOTHER NORTH
PACIFIC LOW WILL FOLLOW BEHIND THAT SYSTEM...TRACKING SOUTH OF THE
ALEUTIANS DURING THE MIDDLE OF THE WEEK.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
PRECIPITATION WILL CONTINUE THROUGH SUNDAY AS THE LOW PUSHES INTO THE
BERING AND AN ASSOCIATED FRONT MOVES OVER SOUTHCENTRAL AK.
PRECIPITATION WILL BE MOST WIDESPREAD ALONG THE GULF COAST AND WILL
BE LIMITED TO SCATTERED SNOW SHOWERS FURTHER INLAND. ALONG THE
COAST...PRECIPITATION TYPE WILL STAY PREDOMINANTLY SNOW THROUGH
TONIGHT AND THEN BEGIN TO MIX WITH RAIN DURING THE DAY ON SUNDAY AS
WARMER AIR CONTINUES TO ADVECT INTO THE AREA FROM THE SOUTH. KODIAK
ISLAND WILL CONTINUE TO SEE ALL RAIN. SOUTHEASTERLY WINDS WILL
INCREASE THROUGH THE EVENING HOURS AS THE FRONT BEGINS TO MOVE
THROUGH...POTENTIALLY LEADING TO AREAS OF BLOWING SNOW TONIGHT
THROUGH THE PORTAGE VALLEY AND ALONG THE TURNAGAIN ARM.

SOUTHWEST ALASKA...
WIDESPREAD PRECIPITATION WILL CONTINUE INTO TONIGHT ACROSS THE
SOUTHWEST MAINLAND AND AKPEN AS THE LOW AND ASSOCIATED FRONT MOVE
INTO THE EASTERN BERING. STRONG NORTHEASTERLY WINDS WILL CONTINUE TO
SUPPORT BLIZZARD CONDITIONS THROUGH THE EVENING HOURS ALONG THE COAST
OF THE KUSKOKWIM DELTA. PRECIPITATION TYPE WILL REMAIN PREDOMINANTLY
SNOW NORTH AND WEST OF DILLINGHAM WHERE TEMPERATURES WILL BE SLOWER
TO WARM...POSSIBLY MIXING WITH RAIN OR FREEZING RAIN ALONG THE COAST.
AREAS EAST OF DILLINGHAM AND ALONG THE AKPEN WILL CONTINUE TO SEE A
RAIN/SNOW MIX. PRECIPITATION WILL START TO TAPER OFF ACROSS THE
SOUTHWEST MAINLAND ON SUNDAY AS THE LOW MOVES INTO THE CENTRAL
BERING...BUT WILL CONTINUE ALONG THE AKPEN AS THE NEXT FRONT BEGINS
TO IMPACT THE AREA.

ALEUTIANS/BERING SEA...
BLIZZARD CONDITIONS WILL PERSIST OVER THE PRIBILOFS INTO THE EVENING
HOURS BEFORE IMPROVING TONIGHT AS STRONG WINDS BEGIN TO SUBSIDE AS
THE FRONT MOVES THROUGH AND THE LOW MOVES INTO THE CENTRAL BERING.
RAIN AND SNOW SHOWERS WILL CONTINUE ACROSS THE PRIBILOFS AND EASTERN
ALEUTIANS THROUGH SUNDAY AS THE NEXT FRONT APPROACHES THE AREA FROM
THE SOUTH. RAIN AND SNOW SHOWERS WILL ALSO REMAIN POSSIBLE OVER THE
WESTERN AND CENTRAL PARTS OF THE CHAIN AS LOW PRESSURE REMAINS OVER
THE BERING.

.LONG TERM FORECAST...
THE EASTERN PACIFIC RIDGE WILL MOVE EASTWARD BY MID WEEK...ALLOWING
BROAD UPPER LEVEL TROUGHING TO BECOME ESTABLISHED OVER MAINLAND
ALASKA WITH EMBEDDED DISTURBANCES KEEPING A CHANCE OF PRECIPITATION
IN THE FORECAST INTO THE EXTENDED TERM.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 155 195
         WINTER WEATHER ADVISORY 125 161
MARINE...STORM WARNING 130 185
         GALE WARNING 120 138 140 150 155 160 165 172 175 179 180
         HEAVY FREEZING SPRAY WARNING 140 185
FIRE WEATHER...NONE

CB JAN 13