Small Craft Advisory 87, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKST SUN JAN 27 2013

.ANALYSIS AND UPPER LEVELS...
THE UPPER LEVEL PATTERN LOOKS SIMILAR TO YESTERDAY...WITH AN
ELONGATED AREA OF LOW PRESSURE EXTENDING SOUTHWESTWARD FROM THE
CANADIAN ARCTIC INTO THE EASTERN INTERIOR. COLD AIR ADVECTION
PERSISTS OVER THE SOUTHERN MAINLAND AS THIS FEATURE CONTINUES TO SINK
SLOWLY SOUTHWARD...SUPPORTING STRONG WINDS THROUGH FAVORED GAPS IN
TERRAIN ALONG THE NORTHERN GULF COAST. FURTHER WEST...A VERTICALLY
STACKED NORTH PACIFIC LOW IS PROGRESSING NORTHWARD ALONG ROUGHLY 170W
TOWARDS THE EASTERN ALEUTIANS. AN EAST TO WEST ORIENTED SURFACE FRONT
EXTENDS NORTHWARD FROM THE LOW...BRINGING SNOW SHOWERS TO THE EASTERN
ALEUTIANS AND AKPEN.

.MODEL DISCUSSION...
MODELS CONTINUE TO DISPLAY GOOD RUN TO RUN CONSISTENCY...WITH THE EC
AND GFS BRINGING A SUB 975 MB SURFACE LOW TO THE VICINITY OF DUTCH
HARBOR BY TUESDAY MORNING AS THE ASSOCIATED SURFACE FRONT MOVES
NORTHWARD OVER THE SOUTHERN MAINLAND. THE GFS SOLUTION REMAINS
SLIGHTLY FASTER BRINGING THE LOW INTO THE BERING...THEREFORE THE EC
WAS MORE HEAVILY UTILIZED FOR THE FORECAST. AS THE LOW MOVES TOWARD
THE BERING AN UPPER LEVEL RIDGE WILL BUILD OVER THE EASTERN PACIFIC
AND INTO SOUTHCENTRAL AK FOR THE EARLY PART OF THE WEEK...ALLOWING
THE LOW ENTRENCHED OVER THE INTERIOR TO BEGIN TO SLIDE EASTWARD
TONIGHT. THIS WILL BRING AN END TO THE COLD AIR ADVECTION AND
ASSOCIATED GAP WINDS DURING THE DAY ON MONDAY.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
COLD ADVECTION AND ASSOCIATED GAP WINDS WILL PERSIST OVER
SOUTHCENTRAL AK THROUGH MONDAY MORNING BEFORE THE UPPER LOW OVER THE
INTERIOR DEPARTS TO THE EAST. GUSTY WINDS AND COLD TEMPERATURES WILL
CONTINUE TO SUPPORT THE POSSIBILITY OF ADVISORY LEVEL WIND CHILL
VALUES THROUGH THOMPSON PASS AS WELL AS THE NORTHERN SUSITNA VALLEY
AND COPPER RIVER BASIN BEFORE WINDS BEGIN TO SUBSIDE MONDAY MORNING.
THE NEXT FORECAST CONCERN WILL BE THE POTENTIAL FOR BLIZZARD
CONDITIONS FOR KODIAK ISLAND AS THE FRONT ASSOCIATED WITH THE BERING
LOW MOVES INTO THE GULF ON MONDAY. THE FRONT WILL BRING SNOW AMOUNTS
IN EXCESS OF 6 INCHES TO KODIAK ISLAND ON MONDAY...WHICH COUPLED WITH
INCREASING NORTHEASTERLY WINDS WILL CREATE THE POTENTIAL FOR POOR
VISIBILITIES INTO MONDAY EVENING. TEMPERATURES SHOULD RISE ABOVE
FREEZING BY MONDAY NIGHT...PUTTING AN END TO THE BLIZZARD THREAT.
SNOW WILL THEN SPREAD OVER THE REST OF SOUTHCENTRAL AK MONDAY NIGHT
INTO TUESDAY AS THE FRONT REACHES THE NORTHERN GULF COAST.

SOUTHWEST ALASKA...
THE SYSTEM APPROACHING FROM THE SOUTH WILL BRING BLIZZARD CONDITIONS
TO THE AKPEN THIS EVENING THROUGH MONDAY MORNING AS SNOW CONTINUES
AND WINDS BEGIN TO INCREASE AHEAD OF THE LOW. BLIZZARD CONDITIONS
SHOULD COME TO AN END MONDAY MORNING AS TEMPERATURES WARM ABOVE
FREEZING AND RAIN BEGINS TO MIX IN WITH THE SNOW. SNOW WILL THEN
SPREAD NORTHWARD TOWARD BRISTOL BAY ON MONDAY WITH BLIZZARD
CONDITIONS POSSIBLE INTO THE EVENING HOURS AS WINDS BEGIN TO INCREASE
WITH THE APPROACH OF THE LOW. SCATTERED SNOW SHOWERS WILL SPREAD TO
THE REST OF THE SOUTHWEST MAINLAND BY TUESDAY. THE COLD AIR ALREADY
IN PLACE COMBINED WITH INCREASING WINDS AS THE LOW MOVES NORTHWARD
WILL LEAD TO WIND CHILL VALUES APPROACHING OR EXCEEDING 40 BELOW ZERO
FROM THIS EVENING THROUGH EARLY MONDAY AFTERNOON.

ALEUTIANS/BERING SEA...
THE APPROACHING FRONT WILL CONTINUE TO SPREAD SNOW OVER THE EASTERN
ALEUTIANS WITH BLIZZARD CONDITIONS DEVELOPING THIS EVENING AND
PERSISTING THROUGH THE NIGHT AS WINDS PICK UP IN ADVANCE OF THE LOW.
CONDITIONS WILL IMPROVE DURING THE MORNING HOURS AS WARMER AIR MOVES
IN AND PRECIPITATION CHANGES OVER TO A RAIN/SNOW MIX. THE POTENTIAL
FOR BLIZZARD CONDITIONS WILL THEN SPREAD NORTH TO THE PRIBILOFS
MONDAY MORNING INTO TUESDAY MORNING AS THE LOW APPROACHES THE EASTERN
BERING. ELSEWHERE...THE CENTRAL AND WESTERN PARTS OF THE CHAIN WILL
SEE STRONG WINDS THROUGH MONDAY AFTERNOON AS WELL AS A FEW SNOW
SHOWERS THROUGH THE EARLY PART OF THE WEEK.

.LONG TERM FORECAST...
TEMPERATURES OVER SOUTHERN ALASKA WILL BEGIN TO MODERATE BY MIDWEEK
AS A RIDGE MOVES OVER THE EASTERN PACIFIC AND SOUTHERLY FLOW BECOMES
ESTABLISHED OVER THE REGION. OCCASIONAL DISTURBANCES PROPAGATING
THROUGH THE FLOW WILL KEEP A CHANCE OF PRECIPITATION IN THE FORECAST
INTO THE EXTENDED TERM.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 181 185
         BLIZZARD WATCH 161 171 195
         WIND CHILL ADVISORY 131 141 145 155 161
MARINE...GALE WARNING...120 127 128 130 132 136 137 138 140 150 155
                        160 165 170 172 175 176 179 180 185
         HEAVY FREEZING SPRAY...120 121 125 126 127 128 129 130 136
                                137 138 140 141 160 165 179 185
FIRE WEATHER...NONE

CB JAN 13