Small Craft Advisory 629, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT FRI SEP 2 2011

.ANALYSIS AND UPPER LEVELS...

LARGE UPPER LEVEL TROUGH EXTENDS FROM NEAR THE BERING STRAIT TO THE
SOUTHERN YUKON THIS AFTERNOON WITH A CUT-OFF UPPER LEVEL LOW JUST
EAST OF KODIAK ISLAND. ANOTHER UPPER TROUGH OF LOW PRESSURE IS OVER
THE CENTRAL BERING. UPPER RIDGES ARE OVER THE SOUTHEAST PANHANDLE AND
THE CENTRAL BERING. A STRONG JET IS PUSHING WIDESPREAD HIGH LEVEL
CLOUDS ACROSS THE BERING. AT THE SURFACE....A TIGHTLY WOUND OCCLUDED
FRONT IS MAKING LANDFALL ALONG THE NORTH GULF COAST. A COASTAL
BARRIER JET BRINGING GALE AND STORM FORCE WINDS AND ABUNDANT COASTAL
RAINFALL TO THIS REGION IS BEGINNING TO DISSIPATE AS THE FRONT MOVES
INLAND. MEANWHILE A SURFACE LOW ASSOCIATED WITH THE NORTHERN FLANK OF
THE BERING JET IS MAKING ITS WAY ACROSS EASTERN RUSSIA AND WILL BE
PART OF A SIGNIFICANT LOW IN THE EASTERN BERING LATER THIS WEEKEND.

.MODEL DISCUSSION...

MODELS ARE IN EXCELLENT AGREEMENT WITH THE WEAKENING GULF LOW
DRIFTING UNTIL IT DISSIPATES SAT NIGHT EAST OF KODIAK. THE ASSOCIATED
FRONT MOVES INLAND TONIGHT...WITH GALE FORCE SOUTH FLOW BEHIND THE
FRONT SLOWLY WEAKENING THROUGH SAT. WHILE THIS IS OCCURRING...THE
TROUGH IN THE BERING IS ABSORBED BY THE EASTERN RUSSIA LOW WITH THE
ASSOCIATED TRIPLE POINT LOW THEN MOVING TO BRISTOL BAY SUN MORNING.
UP TO THIS POINT THE FORECAST REPRESENTS A BLEND OF NAM AND GFS. THE
MODELS THEN DIVERGE. ALTHOUGH ALL MODELS TAKE THE BRISTOL BAY LOW
SOUTH OF THE AKPEN ON SUN...THE EC SHOWS A STRONGER JET AND GREATER
DEEPENING OF THE LOW SOUTH OF KODIAK THAN DOES THE GFS. BECAUSE OF
GREATER RUN TO RUN CONSISTENCY OF THE EC SOLUTION THE FORECAST IS A
BLEND OF EC AND HPC GUIDANCE...WHICH DEEPENS THE LOW INTO THE MID 960
MB RANGE...RATHER THAN THE EC MID 950 MB SOLUTION. THE LOW IS BROUGHT
WELL SOUTH OF KODIAK ISLAND ON TUE...AND INTO THE WESTERN GULF WED
BEFORE RETROGRADING OVER THE ISLAND THU.

.SHORT TERM FORECAST...

IN THE WEST...SHOWERS AND FOG WILL PERSIST THROUGH THE WEEKEND.
SHOWERS WILL THEN BE LIMITED TO THE EASTERN HALF OF THE BERING AND
ALEUTIANS THROUGH MON BEHIND THE LOW CROSSING THE AKPEN.

FOR SOUTHWEST AK...RAIN AND SHOWERS WILL PERSIST INTO NEXT WEEK
BENEATH THE UPPER TROUGH. PRECIPITATION WILL BE ENHANCED AT TIMES AS
THE LOW MOVES TO BRISTOL BAY AND THEN ACROSS THE AKPEN SUN THROUGH
MON.

SOUTH AND EAST OF THE AK RANGE...RAIN AND SHOWERS WILL PERSIST
TONIGHT AND SLOWLY DIMINISH DURING THE WEEKEND. GALE FORCE WINDS
ACROSS THE NORTHERN GULF AND COASTAL ZONES WILL DIMINISH LATER
TONIGHT. PRECIPITATION ALONG THE COAST WILL INCREASE EARLY NEXT WEEK
AS ONSHORE FLOW INCREASES TO THE EAST OF THE LOW NEAR KODIAK.

.LONG TERM FORECAST...

SHOWERS PERSIST OVER THE EASTERN BERING AND SOUTHWEST AK UNTIL HIGH
PRESSURE BUILDS ACROSS THE AREA BY MIDWEEK. PRECIPITATION SOUTHEAST
OF THE AK RANGE WILL DIMINISH BY MIDWEEK ALTHOUGH ONSHORE FLOW WILL
KEEP MOST COASTAL AREAS WET UNTIL THE END OF THE WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALES 120 125 130 140
FIRE WEATHER... NONE

DS SEP 11