Small Craft Advisory 371, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
100 PM ADT FRI APR 29 2005

.DISCUSSION...BIG STORY IS THE RECORD HIGH TEMPERATURES CONTINUING
OVER SOUTHCENTRAL ALASKA. TIGHT LOW PRESSURE SYSTEM ALOFT AND AT THE
SURFACE MOVING ACROSS BRISTOL BAY WITH MODERATE WINDS AND LITTLE
PRECIP. WAVE AHEAD OF IT...HAS LIGHT PRECIP WHICH STRETCHES FROM
NUNIVAK ISLAND TO COLD BAY WESTWARD TO THE CENTRAL BERING SEA. GOOD
NORTH SOUTH GRADIENT OVER SOUTHCENTRAL AND WESTERN BERING SEA
PRODUCING MODERATE NORTH TO NORTHEAST SURFACE WINDS. SKIES
PREDOMINANTLY CLEAR OVER MUCH OF THE MAINLAND OUTSIDE OF THE LOW IN
THE BRISTOL BAY AREA.

THE DETAILS OF THE MOVEMENT OF THE SYSTEMS PAST 48 HOURS IS IN DOUBT
FROM THE PERSPECTIVE OF THE NAM AND GFS. RIGHT NOW...GOING WITH THE
GFS SOLUTION AS ENSEMBLES AND EUROPEAN MODELS AGREE MORE CLOSELY WITH
THIS SOLUTION.

UPPER LEVELS...HIGH PRESSURE TO REMAIN OVER NORTHERN ALASKA THROUGH
TOMORROW. THE HIGH OVER THE MAINLAND TO GET SQUEEZED SUNDAY AS AN
UPPER LEVEL LOW MOVES WEST ACROSS THE GULF AND A SHORT WAVE TROUGH
OUT OF THE ARCTIC OCEAN PUSHES INTO NORTHWEST CANADA. THE HIGH OVER
THE MAINLAND IS EFFECTIVELY RE-CENTERED OVER SIBERIA WITH A WEAK
UPPER LEVEL TROUGH OVER THE MAINLAND BY MONDAY. IN THE MEANTIME...AN
UPPER LEVEL LOW NEAR 45N 180 TO MOVE INTO THE BASE OF THE UPPER LEVEL
LOW COMPLEX IN THE GULF OF ALASKA SUNDAY. ANOTHER UPPER LEVEL LOW
NEAR THE SOUTHERN TIP OF THE KAMCHATKA PENINSULA MOVES INTO THE NORTH
PACIFIC AND MERGES WITH THE UPPER LEVEL COMPLEX...RE-CENTERING IT
NEAR 40N 170W BY TUESDAY. THE RESULTANT SYSTEM DEVELOPS A RIDGE ALONG
THE GULF COAST FROM THE KENAI PENINSULA TO THE PACIFIC NORTHWEST.
ALONG WITH THIS ACTION...A SHORT WAVE TROUGH MOVES OUT OF THE ARCTIC
OCEAN TUESDAY NIGHT INTO THE NORTHERN BERING SEA FURTHER PUSHING THE
HIGH INTO WESTERN SIBERIA.

AT THE SURFACE...HIGH PRESSURE OVER THE BERING SEA AND NORTHWEST
CANADA WITH A LOW MOVING SOUTHWEST OVER THE BRISTOL BAY AREA. THIS
LOW TO MOVE INTO THE CENTRAL BERING SEA BY TOMORROW AFTERNOON. THE
PARENT LOW TO THIS FEATURE IS OVER THE SOUTHEASTERN GULF. THAT LOW TO
DISSIPATE SUNDAY AS IT MOVES WEST THROUGH THE GULF. THE PRESSURE
GRADIENT ASSOCIATED WITH THIS WEAKENING LOW TO PRODUCE MODERATE EAST
WINDS IN THE GULF AND ASSOCIATED STRAITS AND BAYS. ASSOCIATED
MOISTURE WITH THIS FEATURE TO BRING SCATTERED SHOWERS TO THE GULF
COAST WITH POSSIBLE SHOWERS OVER THE HIGHER TERRAIN IN SOUTHCENTRAL.
A LOW INTENSIFIES SUNDAY OVER THE NORTH PACIFIC NEAR 40N 160W WHICH
IS ASSOCIATED WITH THE CURRENT LOW NEAR 40N 180. THIS LOW LIFTS NORTH
A BIT MONDAY AS ANOTHER LOW MOVES INTO THE NORTH PACIFIC AND PUSH
MOISTURE AND THE WEAKENING LOW INLAND OVER SOUTHWEST AND SOUTHCENTRAL
ALASKA. THE HIGH PRESSURE OVER THE CENTRAL AND WESTERN BERING IS
PUSHED FARTHER NORTH AND WEST. THE OTHER LOW BECOMES THE DOMINANT LOW
NEAR 40N 165W TUESDAY NIGHT WITH THE FIRST LOW MOVING NORTH NEARER
THE ALASKA PENINSULA. THE RESULTANT SURFACE PRESSURE PUSHES A RIDGE
ALONG THE NORTHERN GULF COAST AND PANHANDLE WITH A TROUGH REMAINING
FROM SOUTHWEST TO NORTHEAST ALASKA. HIGH PRESSURE ALSO RETURNS TO
MUCH OF THE BERING SEA. A GOOD PRESSURE GRADIENT DEVELOPS IN THE GULF
AND OVER THE SOUTHERN BERING SEA AND CENTRAL AND EASTERN ALEUTIAN
CHAIN DURING THIS TIME.

A LARGE PERCENTAGE OF THE PRECIPITATION WILL BE SCATTERED IN NATURE
DUE TO THE INSTABILITY OF THE AIR MASS AT THIS TIME AND REALLY NO
ORGANIZED FRONTS MOVING THROUGH THE AREAS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...NONE
FIRE WEATHER...RED FLAG ZONE 101

JN APR 05