Small Craft Advisory 187, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AST SAT MAR 1 2008

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT THROUGH MONDAY AFTERNOON BEFORE SMALL
DIFFERENCES SHOW UP.

.ANALYSIS AND UPPER LEVELS...
THE UPPER LOW OVER SOUTHWEST ALASKA CONTINUES TO MOVE TOWARD THE
BERING SEA WHILE THE UPPER TROUGH OVER THE CENTRAL INTERIOR OF THE
STATE WEAKENS AS HIGHER PRESSURE BUILDS ALONG THE ARCTIC COAST AND
THE EASTERN GULF. ANOTHER AREA OF LOW PRESSURE SOUTH OF THE ALEUTIAN
CHAIN WHICH HAS KEPT A WEAK BAROCLINIC ZONE OVER THE AREA ALSO SIGNS
OF WEAKENING.

AT THE SURFACE...THE INVASION OF COLD AIR OVER THE SOUTHERN INTERIOR
HAS HELP TIGHTEN THE PRESSURE GRADIENT OVER SOUTHCENTRAL ALASKA AND
CREATE GUSTY NORTH WINDS THROUGH CHANNELED TERRAIN. THE COLD AIR ALSO
FORMED AN ARCTIC FRONT OVER THE SOUTHERN COPPER RIVER BASIN AND
SUSITNA VALLEY. WEAK SOUTHERLY FLOW IS BEGINNING TO DEVELOP OVER THE
GULF OF ALASKA AND IS PUSHING WARMER, MOIST AIR ONTO THE COAST AND IS
PRODUCING SNOW ALONG THE FRONT.

EASTERLY FLOW CONTINUES OVER SOUTHWEST ALASKA AND THE BERING SEA.
CLOUDS AND SOME LIGHT SNOW OVER SOUTHWEST ALASKA ARE MAINLY DUE TO
THE UPPER LOW MOVING THROUGH THE AREA.

.SHORT TERM FORECAST...
AN UPPER RIDGE WILL SLOWLY BUILD OVER SOUTHEAST ALASKA THROUGH
TUESDAY WHILE THE UPPER LOW OVER SOUTHWEST ALASKA MOVES SOUTH OF THE
CENTRAL ALEUTIANS MONDAY THEN BECOMES NEARLY STATIONARY TUESDAY. THIS
WILL DEVELOP A STRONG SOUTHERLY FLOW OVER MOST OF THE SOUTHERN
MAINLAND TUESDAY.

SOUTHCENTRAL ALASKA AND THE GULF...
A WARM OCCLUSION SOUTH OF THE GULF WILL MOVE NORTH INTO THE NORTHERN
GULF TONIGHT THEN WEAKEN ALONG THE GULF COAST SUNDAY MORNING. THE
ARCTIC FRONT OVER THE SOUTHCENTRAL INTERIOR WILL MOVE NORTH OF THE
ALASKA RANGE BY SUNDAY AFTERNOON. SNOW ASSOCIATED WITH THE OCCLUSION
WILL CONTINUE OVER KODIAK ISLAND AND THE CENTRAL GULF COAST THROUGH
SUNDAY MORNING THEN CHANGE TO SHOWERS SUNDAY AFTERNOON. A SECOND
WEATHER FRONT WILL BRING RAIN AND SNOW INTO THE GULF MONDAY AFTERNOON
THEN SPREAD IT INTO THE GULF COAST MONDAY EVENING. AREAS OF SNOW WILL
DEVELOP OVER THE SOUTHCENTRAL INTERIOR MONDAY NIGHT.

SOUTHWEST ALASKA...
A MODERATE LOW PRESSURE CENTER SOUTH OF THE ALASKA PENINSULA WILL
MOVE NORTH TO NEAR DILLINGHAM SUNDAY MORNING THEN DISSIPATE AS IT
MOVES INLAND. SNOW ALONG THE ALASKA PENINSULA WILL MOVE INTO BRISTOL
BAY TONIGHT THEN BECOME SNOW SHOWERS OVER THE OVER THE SOUTHWEST
INTERIOR SUNDAY. A SECOND WEATHER FRONT WILL MOVE THROUGH THE AKPEN
MONDAY MORNING AND INTO SOUTHWEST ALASKA MONDAY AFTERNOON AND
EVENING.

BERING SEA AND ALEUTIANS...
EAST TO NORTHEAST FLOW WILL CONTINUE OVER MOST OF THE BERING SEA
THROUGH MONDAY NIGHT. SCATTERED SNOW SHOWERS WILL CONTINUE OVER THE
NORTHERN AND WESTERN BERING AND THE WESTERL ALEUTIANS THROUGH MONDAY
NIGHT. A SERIES OF LOW PRESSURE SYSTEM WILL MOVE UP THROUGH THE
EASTERN ALEUTIANS THROUGH MONDAY NIGHT. PERIODS OF SNOW WILL CONTINUE
OVER THE EASTERN ALEUTIANS AND SOUTHEAST BERING SEA THROUGH MONDAY
NIGHT.

.LONG TERM FORECAST...
THE SOUTHERLY FLOW INTO THE SOUTHERN MAINLAND WILL CONTINUE THROUGH
WEDNESDAY WITH TEMPERATURES CONTINUING TO WARM THROUGH THE PERIOD.
PRECIPITATION SHOULD CHANGE TO MOSTLY RAIN ALONG THE GULF COAST AND
WILL BE  MIXTURE OF RAIN AND SNOW OVER SOUTHCENTRAL INTERIOR BY THE
MIDDLE OF THE WEEK. COOL TEMPERATURES WILL PERSIST OVER SOUTHWEST
ALASKA AND THE BERING SEA, SO PRECIP WILL REMAIN MOSTLY SNOW IN THESE
AREAS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 140, 150, 172, 176, 179, 180, 181.
FIRE WEATHER...NONE.

NM MAR 08