Small Craft Advisory 307, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT SUN APR 7 2013

.MODEL DISCUSSION...
NUMERICAL MODELS IN DECENT AGREEMENT TODAY. THERE ARE SOME
DISAGREEMENTS ON HOW THEY HANDLE THE SURFACE LOW(S) WITH THE NEXT
SYSTEM THAT MOVES INTO SOUTH CENTRAL ALASKA ON MONDAY. THE GFS AND
ECMWF ARE SIMILAR IN BRINGING THE MAIN LOW INTO PRINCE WILLIAM SOUND
MONDAY NIGHT WITH A SECONDARY LOW SPINNING UP TO THE SOUTHEAST AND
MAKING LANDFALL NEAR YAKUTAT TUESDAY MORNING. THE ECMWF IS A LITTLE
FURTHER EAST WITH THE MAIN LOW AND A LITTLE FASTER WITH THE
SECONDARY LOW COMPARED TO THE GFS. THE NAM SPLITS THE LOWS EVEN
FURTHER...WITH THE MAIN LOW FURTHER WEST AND THE SECONDARY FURTHER
EAST AND SLOWER THAN EITHER THE GFS OR ECMWF. THE GFS WAS A GOOD
COMPROMISE AND WAS GENERALLY FOLLOWED FOR THE AFTERNOON FORECAST
PACKAGE.

.ANALYSIS AND UPPER LEVELS...
THERE IS A LARGE UPPER LEVEL LOW CENTERED OVER CENTRAL ALASKA THAT
COVERS THE ENTIRE STATE AND THE EASTERN BERING SEA. STRONG
SOUTHWESTERLY FLOW ALOFT IS CURRENTLY OVER SOUTH CENTRAL ALASKA. A
LOW OVER SOUTH CENTRAL ALASKA IS SLOWLY WORKING ITS WAY NORTHEAST
TOWARD THE YUKON TERRITORY. AN UPPER LEVEL TROUGH SOUTH OF THE
ALASKA PENINSULA IS WORKING ITS WAY NORTHEAST AND BEGINNING TO ENTER
THE SOUTHWEST FLOW. A RIDGE IS OVER THE WESTERN BERING SEA AND
ANOTHER IS ALONG THE WEST COAST OF CANADA AND WASHINGTON THAT
STRETCHES INTO THE NORTHWEST TERRITORIES OF CANADA.

.SHORT TERM FORECAST...
FOR SOUTH CENTRAL ALASKA...THE LOW OVER THE AREA WILL EXIT TO THE
NORTHEAST TONIGHT. THE LOW SOUTH OF THE ALASKA PENINSULA WILL MOVE
INTO THE EASTERN PORTION OF SOUTH CENTRAL ALASKA TONIGHT THEN INTO
ANCHORAGE AND THE WESTERN PORTION OF THE AREA MONDAY. THIS WILL
BRING ANOTHER ROUND OF SNOW WHICH SHOULD LAST INTO TUESDAY. ON
TUESDAY NIGHT AND THURSDAY THE UPPER LOW WILL MOVE SOUTHEAST AND BY
WEDNESDAY AFTERNOON WILL BE CENTERED ALMOST DIRECTLY OVER ANCHORAGE.
THIS WILL KEEP SHOWERS AND COOLER THAN NORMAL WEATHER OVER THE AREA.

FOR SOUTHWEST ALASKA...GENERALLY DRY CONDITIONS EXPECTED THROUGH
MONDAY NIGHT EXCEPT SOME SNOW SHOWERS POSSIBLE ALONG THE COAST FROM
CAPE NEWENHAM NORTH. FOR TUESDAY THROUGH WEDNESDAY THERE WILL BE A
CHANCE OF SOME SNOW SHOWERS OVER THE KUSKOKWIM VALLEY AND ALONG THE
ALASKA/ALEUTIAN RANGES AS THE UPPER LEVEL LOW CROSSES THE AREA.

FOR THE ALEUTIAN ISLANDS AND BERING SEA...LITTLE WILL CHANGE IN THE
OVER-ALL PATTERN THROUGH WEDNESDAY. THE UPPER LEVEL RIDGE WILL
REMAIN OVER THE WESTERN BERING SEA WITH THE UPPER LOW OVER ALASKA.
WINDS WILL REMAIN NORTHERLY...THOUGH A GRADUAL SHIFT FROM
NORTHEASTERLY TO NORTHWESTERLY WILL OCCUR THROUGH THE PERIOD.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING 120 130 132 155 170 172.
         HEAVY FREEZING SPRAY 130 150 155 160 165 170 179.
FIRE WEATHER...NONE.

LUDWIG APR 13