Small Craft Advisory 66, NWS Anchorage, AK

AREA FORECAST DISCUSSION SOUTHWEST ALASKA
1130 AM AST TUE JAN 18 2005

.DISCUSSION...A LARGE LOW COMPLEX CONTINUES TO ROTATE OVER THE NORTH
PACIFIC WITH ITS CENTER NEAR 50N 160W. HIGH PRESSURE REMAINS OVER THE
INTERIOR WITH A ARCTIC BOUNDARY ALONG THE NORTHERN GULF COAST. THE
SURFACE PRESSURE GRADIENT IS RATHER STRONG WITH MODERATE TO STRONG
NORTHERLY FLOWS WORKING THROUGH GAPS IN THE TERRAIN. A HIGH WIND
WARNING REMAINS IN EFFECT FOR THE COPPER RIVER DELTA AND MATANUSKA
VALLEY. ALTHOUGH UPPER LEVEL SUPPORT IS WANING FOR THESE EVENTS...THE
COLD AIR DOME IN THE COPPER RIVER BASIN COMBINED WITH THE STRONG
PRESSURE GRADIENTS HAS ALLOWED FOR THESE EVENTS TO CONTINUE.

AN UPPER LEVEL LOW IS CURRENTLY STACKED OVER THE SURFACE LOW IN THE
NORTH PACIFIC WITH UPPER LEVEL HIGH OVER WESTERN ALASKA. IN
ADDITION...A TROUGH EXTENDS OVER SOUTH CENTRAL ALASKA FROM A LOW IN
THE YUKON. A SHORT WAVE TROUGH ROTATING AROUND THE NORTH PACIFIC LOW
WILL BRING A WARM FRONT THROUGH THE GULF TODAY AND INTO THE NORTHERN
GULF COAST BY THURSDAY. THIS WILL PUSH THE TROUGH OUT OF SOUTH
CENTRAL ALASKA TONIGHT. THE HIGH PRESSURE WILL MOVE OVER THE ENTIRE
INTERIOR AT THIS POINT. PRECIP IS EXPECTED TO SPREAD NORTH TO THE
COAST WITH THIS WARM FRONT. NOT MUCH PRECIP IS EXPECTED TO REACH
INLAND UNTIL THE MAIN LOW ROTATES NORTH FRIDAY. THE FLOW ALOFT WILL
ALSO TURN AND STRENGTHEN FROM THE SOUTH TONIGHT INTO WEDNESDAY. THIS
WILL ERASE ANY MINIMAL UPPER LEVEL SUPPORT FOR THE STRONG WIND EVENTS
CURRENTLY HAPPENING. HOWEVER...THE SURFACE PRESSURE GRADIENT WILL
REMAIN STRONG. SO EXPECT WIND WARNINGS TO DROP TONIGHT AS THE FLOW
BECOMES UNFAVORABLE ALOFT.

IN THE MEANTIME...A WEAK TROUGH OVER THE WESTERN ALEUTIAN CHAIN TO BE
REINFORCED BY A SHORT WAVE TROUGH MOVING OUT OF THE POLAR LOW NORTH
OF SIBERIA WEDNESDAY INTO THURSDAY. PRECIP AND WINDS WITH THE TROUGH
WILL REMAIN LIGHT THROUGH WEDNESDAY. WINDS WILL PICK UP IN THE
EXTREME WESTERN ALEUTIANS THURSDAY WITH THE ADVECTION OF COLD AIR.
THE LOW IN THE NORTH PACIFIC TO BE PUSHED ALONG WEDNESDAY AND
THURSDAY INTO THE WESTERN GULF AS A SHORT WAVE MOVES ACROSS THE NORTH
PACIFIC ALONG 45N EVENTUALLY BECOMING A CLOSED LOW NEAR 45N 155W
THURSDAY AFTERNOON. IN ADDITION...THE POLAR LOW SLIPS INTO SIBERIA
DEVELOPING A TROUGH OVER THE BERING SEA INTO THE NORTH PACIFIC. BY
THIS TIME...THE PREVIOUS LOW OVER THE WESTERN GULF WEAKENS AND WORKS
BACK TO THE BERING SEA TROUGH AXIS. THE TROUGH ALONG WITH THE NORTH
PACIFIC LOW WILL SWING EAST NORTHEAST FRIDAY. A SURFACE LOW
ASSOCIATED WITH THE NORTH PACIFIC LOW WILL WORK NORTH INTO THE GULF
FRIDAY WITH A TROUGH/FRONT BACK TO POLAR LOW IN SIBERIA. PLENTY OF
PRECIP AND MODERATE TO STRONG WINDS TO MOVE INTO THE GULF AT THIS
TIME AS WELL AND SPREAD INLAND SATURDAY. A SHORT WAVE RIDGE WILL
FOLLOW THE FRONT ACROSS THE BERING SEA FRIDAY AHEAD OF ANOTHER LOW
WORKING INTO THE WESTERN ALEUTIANS FRIDAY NIGHT. THE LOW OVER THE
GULF WILL WEAKEN OVER THE WEEKEND WHILE THE LOW OVER THE WESTERN
ALEUTIAN CHAIN INTENSIFIES. STRONG WINDS AND MODERATE TO HEAVY PRECIP
WILL ACCOMPANY THIS LOW. THE INTENSIFICATION IS DUE TO THE FACT THIS
LOW TAPS INTO THE COLD AIR FROM THE SIBERIAN LOW. THE RIDGE BY THIS
TIME IS OVER THE EASTERN BERING SEA WITH A WEAK TROUGH OVER THE
INTERIOR EXTENDING INTO THE GULF.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING ZONE 111 135
MARINE...HEAVY FREEZING SPRAY 2B1 2C 3A 4 4A 6A 8 14
         GALE 3A 3B 3C 4 5A 5B 13B
FIRE WEATHER...NONE

JN JAN 05