Small Craft Advisory 906, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
110 PM AKST SAT NOV 16 2013

.ANALYSIS AND UPPER LEVELS...
THE FLAT NORTH PACIFIC RIDGE THAT HAS FEATURED A ZONAL JET BRINGING
WARM AIR AND MOISTURE INTO THE MAINLAND HAS NOW BEGUN THE TRANSITION
TO A MORE AMPLIFIED PATTERN. THE NEW PATTERN SETTING UP FEATURES A
HIGH AMPLITUDE RIDGE OVER THE FAR WESTERN BERING/KAMCHATKA PENINSULA
RESULTING IN NORTHERLY FLOW ACROSS MOST OF THE MAINLAND AND PANHANDLE
AND EVEN NOW SPREADING INTO THE BERING SEA. THIS IS ALLOWING THE
FLOOD GATES OF COLD ARCTIC AIR TO OPEN AS THE FIRST SIGNIFICANT COLD
SNAP OF THE SEASON TAKES HOLD AND LOOKS TO REMAIN IN PLACE FOR THE
NEXT WEEK. WEAK EMBEDDED SHORTWAVES BROUGHT SOME CLOUD-COVER TO
INLAND AREAS OF SOUTHCENTRAL THIS MORNING...BUT ARE NOW GIVING WAY TO
WIDESPREAD CLEAR AND COLD CONDITIONS. WINDS ARE BLOWING THROUGH THE
USUAL TERRAIN GAPS ASSOCIATED WITH COLD OUTFLOW WINDS OFF THE ALASKAN
LANDMASS AND ARE FAIRLY STEADY IN THE 40-60 MPH RANGE. THE ONLY REAL
LOW PRESSURE CENTER TO SPEAK OF IS LOCATED WEST OF THE WESTERN
ALEUTIANS...AND IS BRINGING GUSTY WINDS AND RAIN TO THE WESTERN HALF
OF THE ALEUTIAN ISLANDS.

.MODEL DISCUSSION...
THE MODELS ARE IN DECENT OVERALL AGREEMENT...BUT ARE STRUGGLING WITH
THE TIMING AND PLACEMENT OF TWO KEY FEATURES OVER THE NEXT SEVERAL
DAYS. FIRST IS THE LOW CURRENTLY AFFECTING THE WESTERN ALEUTIANS.
THIS LOW IS IN THE PROCESS OF BEING CUTOFF FROM STRONG STEERING
FLOW...AND WILL BEGIN MEANDERING AROUND THE NORTH PACIFIC THROUGH
MUCH OF THE UPCOMING WEEK. THE MODELS HAVE UNDERSTANDABLY STRUGGLED
WITH THE PATH OF THIS FEATURE...AND ARE ONLY GRADUALLY COMING INTO
BETTER AGREEMENT ON A GENERAL EASTWARD DRIFT FOLLOWING BY A TURN TO
THE SOUTH AND AWAY FROM THE ALASKAN DOMAIN. THANKFULLY IMPACTS TO THE
STATE WILL BE FAIRLY MINOR AS THE LOW WILL ONLY SKIRT THE BOUNDARIES
OF THE AOR. THE SECOND FEATURE IS AN UPPER LOW SET TO DROP DOWN
THROUGH THE INTERIOR OF THE STATE AND INTO THE GULF SOMETIME TUESDAY.
THE EC AND GFS HAVE BOTH SPED UP THE SOUTHWARD PROGRESS OF THE LOW
AND ARE NOW IN BETTER AGREEMENT THAN RECENT DAYS...THOUGH STILL
SLOWER THAN THE NAM SOLUTION. THIS INCREASES CONFIDENCE THAT CLOUDS
AND PERHAPS SOME LIGHT SNOW WILL MOVE THROUGH PARTS OF SOUTHERN
ALASKA TUESDAY AFTERNOON/EVENING BEFORE DROPPING INTO THE GULF

.SHORT TERM FORECAST...
MAINLAND...THE SHORTWAVE BRINGING MID-LEVEL CLOUDINESS THIS MORNING
FROM ANCHORAGE NORTHWARD CONTINUES TO GRADUALLY AMPLIFY AS IT MOVES
INTO THE NORTHERN GULF. ENHANCED DOWNWARD MOTION BEHIND THIS
FEATURE...COUPLED WITH DECENT LINGERING SUPPORT FROM THE DEPARTING
JET STREAM...WILL MAINTAIN MANY OF THE COASTAL GAP WINDS IN THE
STRONG WIND CATEGORY THROUGH TONIGHT BEFORE THE PRESSURE GRADIENT
RELAXES A BIT TOMORROW. TEMPERATURES ACROSS THE REGION HAVE DROPPED
DOWN NEAR-NORMAL...AND BY TOMORROW AT THIS TIME WILL BE ABOUT 10
DEGREES BELOW NORMAL FOR BOTH DAYTIME AND OVERNIGHT TEMPERATURES. AS
MENTIONED IN THE MODEL DISCUSSION...CLEAR AND COLD CONDITIONS WILL
CONTINUE UNTIL CLOUDS AND POSSIBLY SOME LIGHT SNOW MOVE IN FROM THE
NORTH ON TUESDAY...PROVIDING SOME SMALL MODERATION OF TEMPERATURES.

BERING SEA AND ALEUTIANS...THE MOST ACTIVE WEATHER IS CURRENTLY
CONFINED TO THE WESTERN HALF OF THE ALEUTIANS...A SCENARIO THAT WILL
GRADUALLY DIMINISH THROUGH THE START OF THE WEEK AS THE
AFOREMENTIONED LOW WEAKENS AND DROPS AWAY FROM THE AREA AND INTO THE
NORTH PACIFIC. COLD AIR AND NORTHERLY WINDS WILL GRADUALLY SPREAD
ACROSS THE REST OF THE REGION THROUGH THE START OF NEXT WEEK...WITH
COLD AIR TRIGGERING INSTABILITY SHOWERS ACROSS MUCH OF THE EASTERN
BERING AND ALEUTIANS BY MONDAY.

.LONG TERM FORECAST...
THE LONG-RANGE MODELS CONTINUE TO STRUGGLE WITH A POSSIBLE BREAKDOWN
LATE NEXT WEEK OF THE BERING RIDGE AND RESULTANT CLEAR AND COLD
CONDITIONS OVER THE MAINLAND. WHILE IT LOOKS LIKELY THAT CLOUD-COVER
WILL INCREASE AND TEMPERATURES MODERATE A BIT 7 DAYS FROM NOW...NO
RESUMPTION OF UNUSUALLY WARM SOUTHERLY FLOW IS ON THE HORIZON. WINTER
HAS ARRIVED IN ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 119 121 127 128 131 173 174 175 176 177 178
         HEAVY FREEZING SPRAY 140
FIRE WEATHER...NONE

AMD NOV 13