Small Craft Advisory 345, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT FRI APR 19 2013

.ANALYSIS AND UPPER LEVELS...
THERE IS AN UPPER LEVEL LOW CLOSING OFF OVER KODIAK ISLAND. AN UPPER
LEVEL HIGH OVER THE EASTERN BERING SEA AND WEST COAST OF ALASKA IS
BUILDING INTO CENTRAL ALASKA. A SHORT-WAVE TROUGH IN THE CHUKCHI SEA
IS MOVING SOUTH. A RIDGE IS BUILDING INTO THE WESTERN BERING SEA.

.MODEL DISCUSSION...
NUMERICAL GUIDANCE IN FAIRLY GOOD AGREEMENT THROUGH 84 HOURS. THE
MAIN DIFFERENCES INVOLVE THE KODIAK LOW. THERE SEEM TO BE TWO
CLUSTERS OF SOLUTIONS WITH THE ECMWF/NAM SHOWING A FASTER AND
SLIGHTLY FURTHER SOUTH TRACK ACROSS THE NORTH GULF COAST AND THE
GFS/GEM/UKMET SLOWER AND FURTHER NORTH. THIS WILL IMPACT HOW FAR
INLAND PRECIPITATION REACHES INTO SOUTHERN ALASKA. GENERALLY PREFER
THE ECMWF/NAM SOLUTION...BUT WITH LOWER THAN NORMAL CONFIDENCE.

.SHORT TERM FORECAST...
FOR SOUTH CENTRAL AND SOUTHWEST ALASKA...THE LOW CLOSING OFF NEAR
KODIAK ISLAND WILL CUT OFF FROM THE FLOW TONIGHT AND REMAIN FAIRLY
STATIONARY THROUGH SATURDAY AFTERNOON. AS IT SITS AND SPINS MOISTURE
WILL BE PULLED IN FROM THE SOUTH. PRECIPITATION SHOULD REACH KODIAK
BY EARLY SATURDAY AFTERNOON. THE LOW WILL THEN BEGIN TO MIGRATE TO
THE NORTHEAST BEGINNING SATURDAY NIGHT AND THEN EASTWARD ALONG THE
NORTH GULF COAST SUNDAY INTO MONDAY...AND THEN EXIT THE AREA LATE
MONDAY. PRECIPITATION WILL SPREAD TO THE KENAI PENINSULA ON SATURDAY
NIGHT AND TO THE REST OF THE GULF COAST ON SUNDAY. EXACTLY HOW FAR
INLAND PRECIPITATION WILL REACH IS STILL NOT REAL CLEAR. BY LATE
MONDAY THE LOW WILL HAVE EXITED SOUTH CENTRAL ALASKA AND THE RIDGE
OVER CENTRAL ALASKA WILL PUSH OVER THE AREA.

FOR THE BERING SEA AND ALEUTIANS...THE CHUKCHI LOW SHORT-WAVE WILL
DIVE RAPIDLY SOUTH TONIGHT AND CLOSE OFF NEAR THE PRIBILOFS SATURDAY
AFTERNOON. THIS SYSTEM WILL RAPIDLY DRIVE SOUTH OF THE ALEUTIANS BY
LATE SUNDAY MORNING. PRECIPITATION AND WINDS WITH THIS SYSTEM SHOULD
NOT BE VERY SIGNIFICANT DUE TO ITS RAPID MOVEMENT AND DRY SOURCE
REGION. THE WESTERN BERING SEA RIDGE WILL BUILD THROUGH TONIGHT AND
MOVE EASTWARD INTO THE EASTERN BERING SEA BY SUNDAY EVENING. A
WEATHER FRONT FURTHER WEST WILL PUSH ACROSS THE WESTERN BERING SEA
ON SUNDAY FOLLOWING THE HIGH. THE FRONT WILL RAPIDLY WEAKEN SUNDAY
NIGHT AND DISSIPATE MONDAY AS HIGH PRESSURE RE-ASSERTS ITSELF OVER
THE WESTERN BERING SEA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING 130 138.
FIRE WEATHER...NONE.

LUDWIG APR 13