Small Craft Advisory 220, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT THU MAR 13 2014

.ANALYSIS AND UPPER LEVELS...
THE MAIN UPPER LOW IS SITUATED OVER THE NORTHERN BERING SEA. A
STRONG LOW IS SPINNING UP OVER THE SOUTHERN GULF OF ALASKA AND
MOVING NORTH. A COLD FRONT ASSOCIATED WITH THESE TWO LOWS IS
SITUATED NORTH-SOUTH ACROSS SOUTHWEST ALASKA AND THEN SOUTHEAST
ACROSS THE WESTERN GULF.

.MODEL DISCUSSION...
THE NUMERICAL MODELS ARE STRUGGLING WITH THE GULF LOW AND THIS IS
CREATING SOME DIFFICULTIES WITH THE FORECAST. THE ECMWF IS SLOWER
AND STRONGER WITH THE LOW THAN THE GFS AND NAM. THE UKMET IS VERY
CLOSE TO THE ECMWF...WHILE THE GEM GLOBAL AND GEM LOCAL ARE IN
BETWEEN...BUT CLOSER TO THE ECMWF THEN THE GFS. THE ECMWF IS THE
PREFERRED SOLUTION DUE TO ITS SUPERIOR PERFORMANCE AND BETTER MODEL
CONSENSUS. UNFORTUNATELY WE ONLY GET HIGH RESOLUTION MODEL DATA FOR
THE NAM AND GFS (ESPECIALLY THE NAM)...AND THIS CREATES CHALLENGES
FORECASTING SMALL SCALE (BUT IMPORTANT) DETAILS. THUS THE FORECAST
CONFIDENCE IS LOWER THAN NORMAL.

.SHORT TERM FORECAST...
FOR SOUTH CENTRAL ALASKA...THE LOW SPINNING UP OVER THE SOUTHERN
GULF WILL WORK ITS WAY ACROSS THE GULF TONIGHT AND THEN INLAND ON
FRIDAY. THERE IS A FAIRLY STRONG PUSH OF COLD AIR BEHIND THIS LOW.
THIS WILL CREATE BLIZZARD CONDITIONS ON KODIAK AS IT PASSES...AND
PROBABLY AROUND KACHEMAK BAY AS WELL. SNOW WILL MOVE NORTH WITH THE
LOW/COLD FRONT AND REACH ANCHORAGE SOMETIME FRIDAY AFTERNOON/EVENING
(TIMING IS A LITTLE UNCERTAIN DUE TO THE MODEL ISSUES MENTIONED
ABOVE).

ON SATURDAY AND SUNDAY THE PATTERN WILL TRANSITION FROM THE CURRENT
"BLOCKY/HIGH AMPLITUDE" INTO A MORE ZONAL FLOW. THE BERING UPPER LOW
WILL SLIDE INTO SOUTHWEST ALASKA ON SATURDAY...THEN BE "KICKED OUT"
TO THE NORTH BY THE NEXT LOW APPROACHING LOW FROM THE WEST. THIS
NEXT LOW WILL RACE ACROSS THE BERING SEA LATER SATURDAY THROUGH
SUNDAY. ON SUNDAY AFTERNOON THE LEADING FRONT WILL REACH SOUTH
CENTRAL ALASKA.

FOR SOUTHWEST ALASKA...THE COLD FRONT OVER THE AREA WILL SLIDE EAST
ACROSS THE AREA TONIGHT. AREAS OF PRECIPITATION WILL CONTINUE INTO
SATURDAY AS THE BERING LOW REMAINS TO THE WEST. CONDITIONS WILL DRY
AS IT MOVES ACROSS SOUTHWEST ALASKA DURING THE DAY SATURDAY...WITH
BRIEF RIDGING SATURDAY NIGHT. THE LEADING FRONT OF THE NEXT LOW WILL
REACH THE WEST COAST SUNDAY MORNING AND SPREAD ACROSS SOUTHWEST
ALASKA DURING THE DAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 171.
         BLIZZARD WATCH 125.
MARINE...STORM WARNING 119.
         GALE WARNING 120 130 131 132 136 137 138 139 141 150 155
                        160 176 177 178.
         HEAVY FREEZING SPRAY 130 131 136 137 138 139 140 141 150
                        155 160 165 179 180.
FIRE WEATHER...NONE.

LUDWIG MAR 14