Small Craft Advisory 18, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AST THU JAN 5 2006

.DISCUSSION...

12Z GFS AND 18Z ETA IN RELATIVELY GOOD AGREEMENT FOR THIS FORECAST
PACKAGE. ONLY DIFFERENCES ARE WEAK CIRCULATIONS ESTABLISHED OVER THE
GULF OF ALASKA MAINLY DUE TO TERRAIN RESOLUTION DIFFERENCES.

UPPER LEVELS...RIDGE OVER THE ROCKIES EXTENDING INTO EASTERN ALASKA
WITH A CLOSED LOW OVER THE SOUTHERN GULF. HIGH PRESSURE OVER EASTERN
RUSSIA WITH A LOW OVER THE KAMCHATKA PENINSULA AND NEAR GAMBELL
ISLAND. JET STREAM ORIENTED ALONG 40N FROM NEPAL TO 160W CURRENTLY.
JET TO REMAIN ALONG 40N BUT SHIFT EAST OVER TIME LEAVING A ZONAL
PATTERN OVER THE FORECAST AREA. HOWEVER...THE MAIN STORM TRACK WILL
REMAIN SOUTH OF THE ALEUTIAN CHAIN AND THE MAINLAND AND THEN
DISSIPATE AS THEY ROLL IN THE GULF OF ALASKA. SOME OF THE STORMS WILL
APPROACH THE ALEUTIAN CHAIN AND BRING STRONG SURFACE WINDS.

SOUTH CENTRAL SURFACE...LOW IN THE SOUTHERN GULF WEAKENING AND MOVING
TOWARD THE NORTHERN GULF COAST OVER THE NEXT 24 HOURS THEN
DISSIPATING BY SATURDAY. IN THE MEANTIME...GOOD PRESSURE GRADIENT
ALONG THE NORTHERN GULF COAST. IN ADDITION...COLD AIR IN THE COPPER
RIVER BASIN. THEREFORE...MODERATE TO STRONG NORTHERLY GAP WINDS TO BE
MAINTAINED THROUGH TOMORROW. WOULD ALSO EXPECT MODERATE EASTERLY
WINDS IN THE COASTAL WATERS AS LONG AS THE LOW AND TROUGH ARE
PRESENT. PRECIPITATION TO BE ON THE INCREASE AS WELL LATER TONIGHT
AND FRIDAY AS THE LOW WORKS NORTH IN THE GULF. MOST PRECIPITATION
WILL BE ALONG COASTAL LOCATIONS WITH THE LOW. SOME PRECIPITATION TO
WORK INTO THE LOWER SUSITNA VALLEY AS WELL. MAY SEE A FEW FLURRIES
SQUEAK OVER THE WESTERN KENAI AND ANCHORAGE BOWL. THE LOW DISSIPATES
AS A RESULT OF IT WRAPPING NORTHWEST TO THE COAST AND FILLING. IT IS
ALSO BEING PUSHED BY ANOTHER LOW CURRENTLY NEAR ADAK WHICH ROUNDS THE
UPPER LEVEL LOW IN THE GULF SATURDAY AND HEADS TOWARD THE NORTHERN
GULF COAST. THIS WILL MAINTAIN SHOWERS ALONG THE COAST THROUGH
SATURDAY. THE LOW CURRENTLY WEST OF SHEMYA TO SLOWLY MOVE EAST ALONG
THE ALEUTIAN CHAIN TO THE WESTERN GULF LATE SATURDAY. THE LOW WRAPS
UP IN THE GULF AND WEAKENS SUNDAY AS IT RUNS TO THE ROCKIES RIDGE OF
HIGH PRESSURE.

SURFACE WEST...WEAKENING FRONT OVER THE WESTERN AND CENTRAL ALEUTIAN
CHAIN AND BERING SEA. THEREFORE...WINDS ARE DIMINISHING ALONG THIS
FRONT. BUT...PRECIPITATION WILL NOT WANE OVER THE BERING SEA AND
ALEUTIAN CHAIN. LOW DEVELOPING ALONG THE FRONT NEAR ADAK WHICH WILL
TRAVEL LOW INTO THE SOUTHERN GULF FRIDAY. THE ANCHOR LOW FOR THIS
FRONT IS NEAR THE KAMCHATKA PENINSULA AND WILL WEAKEN OVER THE NEXT
COUPLE DAYS AS IT GETS DRAGGED ALONG BY A DEVELOPING LOW IN THE NORTH
PACIFIC. THIS DEVELOPING LOW IS ALONG THE JET STREAM AND WILL DEEPEN
TO NEAR 965 MB BY FRIDAY AFTERNOON SOUTH OF ADAK. EXPECT GALE TO
STORM FORCE WINDS WITH THIS LOW NEAR THE CENTRAL ALEUTIAN CHAIN. THE
LOW WILL MAINTAIN ITS STRENGTH ALONG THE CHAIN INTO SATURDAY
AFTERNOON BEFORE LOSING JET SUPPORT SUNDAY OVER THE GULF OF ALASKA.
MOST OF SOUTHWEST ALASKA WILL REMAIN DRY DURING THIS TIME FRAME
OUTSIDE OF A FEW MOUNTAIN SHOWERS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE WARNING 138 176
FIRE WEATHER...NONE

JN JAN 06