Small Craft Advisory 85, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
415 PM AKST SAT JAN 26 2013

.ANALYSIS AND UPPER LEVELS...
A CLOSED UPPER LEVEL LOW CENTERED OVER THE NORTHERN YUKON TERRITORY
CONTINUES TO SINK SLOWLY SOUTHWARD ALONG THE ALCAN BORDER...WITH
ASSOCIATED COLD AIR ADVECTION BRINGING MUCH COLDER TEMPERATURES TO
THE SOUTHERN MAINLAND AND STRONG GAP WINDS THROUGH FAVORED AREAS
ALONG THE NORTHERN GULF COAST. A 995 MB SURFACE LOW IS SLOWLY
WEAKENING OVER THE NORTHEASTERN GULF. FURTHER WEST...AN UPPER LOW
REMAINS NEARLY STATIONARY OVER THE FAR WESTERN ALEUTIANS BUT WILL
BEGIN TO MOVE WESTWARD THIS EVENING AS THE NEXT NORTH PACIFIC LOW
ADVANCES NORTHWARD TOWARDS THE EASTERN PART OF THE CHAIN.

.MODEL DISCUSSION...
MODELS HAVE BEEN CONSISTENT IN THE HANDLING OF THE NEXT SYSTEM
APPROACHING THE EASTERN ALEUTIANS AND AKPEN IN THE MONDAY
NIGHT/TUESDAY MORNING TIME FRAME. THE EC AND GFS REMAIN IN GOOD
OVERALL AGREEMENT IN BRINGING A SUB 980 MB SURFACE LOW TO THE
VICINITY OF DUTCH HARBOR BY TUESDAY MORNING. HOWEVER...THE GFS
SOLUTION CONTINUES TO BE SLIGHTLY FASTER IN BRINGING THE LOW INTO THE
BERING AND THUS THE EC WAS UTILIZED FOR THE FORECAST. THE NAM REMAINS
THE OUTLIER IN DEPICTING A MUCH FASTER AND FURTHER EASTWARD TRACK OF
THE LOW. FURTHER EAST...MODELS ARE IN GOOD AGREEMENT WITH RESPECT TO
THE EVOLUTION OF THE SYNOPTIC PATTERN OVER THE MAINLAND THROUGH THE
SHORT TERM. THE UPPER LOW WILL CONTINUE SLOWLY SOUTHWARD ALONG THE
ALCAN BORDER THROUGH SUNDAY AFTERNOON AND THEN BE FORCED EASTWARD
INTO NORTHERN CANADA AS AN UPPER RIDGE BUILDS OVER THE EASTERN
PACIFIC AND SOUTHCENTRAL AK THROUGH THE EARLY PART OF THE WEEK.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
COLD AIR ADVECTION WILL CONTINUE ACROSS SOUTHCENTRAL AK THROUGH
SUNDAY AFTERNOON AS THE UPPER LOW MOVES SOUTHWARD INTO THE INTERIOR.
THIS COLD ADVECTION COUPLED WITH STRONG UPPER LEVEL SUPPORT IN THE
FORM OF A 140 KT JET STREAK MOVING OVERHEAD WILL CONTINUE TO SUPPORT
STRONG WINDS THROUGH FAVORED AREAS ALONG THE GULF COAST SUCH AS
WHITTIER...SEWARD...VALDEZ...AND THE COPPER RIVER DELTA. BLIZZARD
CONDITIONS WILL REMAIN POSSIBLE THROUGH SUNDAY MORNING IN THOMPSON
PASS AS STRONG WINDS CREATE AREAS OF BLOWING SNOW. COLD TEMPERATURES
AND GUSTY WINDS WILL ALSO LEAD TO WIND CHILL VALUES APPROACHING
ADVISORY CRITERIA THROUGH THE PASS AS WELL AS THE COPPER RIVER BASIN
AND THE NORTHERN SUSITNA VALLEY. WINDS WILL SUBSIDE THROUGH THE DAY
ON SUNDAY AS THE UPPER LOW BEGINS TO RETREAT INTO CANADA.

SOUTHWEST ALASKA...
COLD AND DRY CONDITIONS WILL CONTINUE THROUGH THE WEEKEND OVER THE
SOUTHWEST MAINLAND AS THE PREVIOUSLY DISCUSSED UPPER LOW MOVES OVER
THE EASTERN INTERIOR. SNOW SHOWERS WILL THEN BEGIN TO SPREAD OVER THE
AREA FROM SOUTH TO NORTH ON MONDAY AND TUESDAY AS A FRONT ASSOCIATED
WITH THE APPROACHING LOW REACHES THE COAST.

ALEUTIANS/BERING SEA...
SNOW SHOWERS WILL CONTINUE OVER THE EASTERN ALEUTIANS AND AKPEN
THROUGH THE BEGINNING OF THE WEEK AS THE LOW APPROACHES FROM THE
SOUTH. WINDS WILL BEGIN TO INCREASE TONIGHT AS THE FRONT REACHES THE
AREA...LEADING TO THE POTENTIAL FOR WIDESPREAD AREAS OF BLOWING SNOW.
A BLIZZARD WATCH HAS BEEN ISSUED TO ACCOUNT FOR THIS POSSIBILITY.
RAIN WILL BEGIN TO MIX IN WITH THE SNOW ON MONDAY AS TEMPERATURES
CONTINUE TO WARM WITH THE ADVANCE OF THE LOW.

.LONG TERM FORECAST...
MODELS SUGGEST A WARMING TREND FOR THE SOUTHERN MAINLAND BY MIDWEEK
AS THE AFOREMENTIONED UPPER LEVEL RIDGE MOVES OVER THE EASTERN
PACIFIC AND SOUTHERLY FLOW BECOMES ESTABLISHED OVER THE REGION. A
CHANCE OF SNOW WILL RETURN TO SOUTHCENTRAL AK MONDAY NIGHT INTO
TUESDAY AS A FRONT ASSOCIATED WITH THE EASTERN BERING LOW MOVES
NORTHWARD OVER THE GULF.

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

CB JAN 13