Small Craft Advisory 345, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
151 PM AKDT FRI APR 25 2014

.ANALYSIS AND UPPER LEVELS...
A JET STREAM IN EXCESS OF 165 KT AT 250 MB IS RUNNING FROM WEST TO
EAST SOUTH OF THE ALEUTIAN ISLANDS AND GULF OF ALASKA. THIS JET
HAS BEEN LOCATED IN A GOOD POSITION OT STRENGTHEN TO MID 970S MB
LOW THAT IS NEAR SAND POINT. AS THIS JET EDGES SOUTHWARD IT WILL
CUT OFF ENERGY FEEDING INTO THIS LOW AND THE LOW WILL END UP
SOUTH OF KODIAK ISLAND TOMORROW WHERE IT WILL REMAIN NEARLY
STATIONARY THROUGH SUNDAY. THERE IS A FRONT AHEAD OF THIS LOW
MOVING THROUGH THE GULF OF ALASKA AND BRINGING RAIN TO KODIAK
ISLAND AND WIDESPREAD SHOWER ACTIVITY ALONG THE GULF COAST. &&

.MODEL DISCUSSION...
MODELS REMAIN IN GOOD AGREEMENT THROUGH THE WEEKEND. ALL SOLUTIONS
POINT TO THE LOW SOUTH OF THE ALASKA PENINSULA MOVING EASTWARD AND
THEN BECOMING STATIONARY SOUTH OF KODIAK ISLAND ON SATURDAY. IT
WILL REMAIN THERE AS IT SLOWLY WEAKENS THROUGH SUNDAY NIGHT.
THE MODEL UNCERTAINTY INCREASES BY THE MIDDLE OF THE WEEK IN THE
BERING SEA REGION AS THE ECMWF AND GFS DIVERGE IN THE STRUCTURE
AND MOVEMENT OF THE COMPLEX LOW IN THAT AREA. THIS IS EXACERBATED
BY THE SAME ISSUE IN THE SOUTHERN GULF AND FARTHER SOUTH WITH A
LOW THAT WILL BE ON THE EAST SIDE OF AN UPPER LEVEL RIDGE THAT
WILL EXTEND OVER THE ALASKA PENINSULA INTO THE INTERIOR OF THE
STATE.
&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
THE FRONT ON THE GULF IDS BRINGING WIDESPREAD RAIN SHOWERS TO THE
GULF COAST REGION WITH SOME GUSTY WINDS ALONG IT. MOST OF THE
PRECIPITATION IS DOWNSLOPING ON THE LEE SIDE OF THE KENAI AND
CHUGACH MOUNTAINS AND THIS IS LIKELY TO PERSIST THROUGH TOMORROW.
BY SUNDAY THE LOW IN THE GULF AND THE ASSOCIATED FRONT WILL HAVE
BOTH WEAKENED ENOUGH TO END ANY PRECIPITATION INLAND AND REDUCE IT
TO JUST A FEW SHOWERS ALONG THE COAST.
WINDS ARE GUSTY AHEAD OF THE FRONT IN AREAS SUCH AS TURNAGAIN ARM
AND THE KNIK RIVER VALLEY.

SOUTHWEST ALASKA...THE UPPER TROUGH CURRENTLY NEAR SAND POINT WILL
CONTINUE TO BRING GUSTY SOUTH WINDS TO THE AKPEN AND SOUTHERN
BRISTOL BAY THROUGH THIS EVENING. DOWNSLOPING WILL BE LIMIT
RAINFALL ON THE LEE SIDE OF THE ALEUTIAN RANGE AND AKPEN TO JUST
PASSING SHOWERS. FURTHER TO THE WEST...THERE WILL BE SOME AFTERNOON
CONVECTION OVER WESTERN BRISTOL BAY AND KUSKOKWIM VALLEY THIS
AFTERNOON...WHICH WILL BRING A FEW MORE SHOWERS TO THE AREA THIS
EVENING THAN WAS SEEN YESTERDAY. ONCE THIS LOW MOVES INTO THE
SOUTHWEST GULF LATE FRIDAY/EARLY SATURDAY...PRECIPITATION WILL BE
LIMITED MOSTLY TO COLD AIR ADVECTION RAIN/SNOW SHOWERS ALONG THE
BERING SEA COAST AS THE WINDS SWING AROUND TO NORTHWESTERLY. THE
AREA WILL THEN BEGIN TO CLEAR ON SUNDAY AS MID LEVEL RIDGING ONCE
AGAIN BUILDS INTO THE AREA.

BERING SEA/ALEUTIANS...
CONDITIONS ALONG THE WESTERN ALEUTIANS
WILL BEGIN TO IMPROVE STARTING AS RIDGING STARTS TO SLOWLY BUILD
IN. THE EASTERN ALEUTIANS AND AKPEN WILL REMAIN UNDER A RISK FOR
RAIN/SNOW SHOWERS AND GUSTY NORTHEASTERLY TO NORTHWESTERLY WINDS
UNTIL THE RIDGE WORKS ITS WAY THROUGH THE BERING ON SUNDAY. THE
WEATHER WILL REMAIN RELATIVELY QUIET UNTIL THE FRONT FROM A LOW
CENTERED OVER EASTERN RUSSIA WILL MOVE TO THE WESTERN ALEUTIANS
LATE SUNDAY NIGHT.

&&
LONG TERM FORECAST...
THE MODELS ARE IN GOOD AGREEMENT THAT THE UPPER LOW THAT WILL FORM
OVER EASTERN RUSSIA ON SUNDAY WILL BECOME A SEMI PERMANENT TROUGH
OVER THE CENTRAL BERING SEA BY THE MIDDLE OF NEXT WEEK. THIS WILL
SETUP SOUTHWESTERLY FLOW ALOFT OVER THE WESTERN MAINLAND WITH WEAK
RIDGING OVER THE EAST MAINLAND. THE BEST CHANCE OF PRECIPITATION
CURRENTLY APPEARS TO OVER THE WESTERN MAINLAND...BUT A FEW CLOUDY
AND RAINY PERIODS TO THE EAST CANNOT BE RULED OUT DUE TO THE WEAK
NATURE OF THE MAINLAND RIDGE.

AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 119 120 130-139 174.
FIRE WEATHER...NONE.
&&

APR 14