Small Craft Advisory 318, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKDT WED MAY 4 2011

.ANALYSIS AND UPPER LEVELS...
THERE ARE TWO CLOSED LOWS OVER THE SOUTHERN PORTION OF THE AREA THIS
MORNING...ONE SOUTH OF THE CENTRAL ALEUTIANS AND ONE IN THE SOUTHERN
GULF OF ALASKA. A LONG WAVE TROUGH CONTINUES TO SIT OVER MAINLAND
ALASKA...AND WILL MOVE EASTWARD INTO EASTERN ALASKA BY THURSDAY
NIGHT. THERE IS A PERSISTENT AREA OF RAIN OVER THE ALASKA PENINSULA
AS WELL AS PRINCE WILLIAM SOUND AND EASTERN KENAI PENINSULA INTO THE
ANCHORAGE AREA.

.MODEL DISCUSSION...
THE MODELS ARE IN GOOD AGREEMENT OVERALL THIS MORNING...ALTHOUGH
THERE ARE SOME DIFFERENCES IN THE DETAILS. WHILE NONE OF THE MODELS
HAVE HANDLED THE SYSTEM THAT IS AFFECTING SOUTH CENTRAL ALASKA
PARTICULARLY WELL THIS MORNING...THE NAM SEEMS TO BE DOING THE BEST
WITH THE DETAILS SO IT WAS USED FOR ANY CHANGES IN THE SHORT TERM.
THE NAM WAS ALSO USED FOR ANY CHANGES OVER THE ALEUTIANS AND
SOUTHWEST ALASKA. MODELS DIVERGE FOR THE WEEKEND INTO NEXT WEEK...SO
A BLEND TOWARD THE LATEST ECMWF MODEL RUN AND HPC GUIDANCE WAS USED.

.SHORT TERM FORECAST...
PRECIPITATION IS BECOMING MORE WIDESPREAD ACROSS THE ANCHORAGE BOWL
THROUGH THE KENAI PENINSULA THIS MORNING...AND WILL CONTINUE TO BE
FAIRLY CONSTANT THROUGH TONIGHT FOR MOST OF THE AREA AS THE UPPER LOW
REMAINS NEARLY STATIONARY. SOME SNOW AT HIGHER ELEVATIONS IS
EXPECTED...AND EVEN SOME WET SNOW IS POSSIBLE AT LOWER ELEVATIONS
AROUND ANCHORAGE THIS EVENING. THE PRECIPITATION OVER THE ALASKA
PENINSULA WILL CONTINUE THROUGH THE DAY AS WELL...WHILE SKIES ARE
EXPECTED TO BECOME PARTLY CLOUDY TO MOSTLY SUNNY ACROSS MUCH OF THE
SOUTHWEST MAINLAND LATER TODAY AS SURFACE WINDS BECOME MORE NORTHERLY
AND BRING IN DRIER AIR. THE DRIER AIR WILL CONTINUE SOUTHEASTWARD AS
THE UPPER LOW GRADUALLY MOVES OFF TO THE EAST AND PRECIPITATION WILL
ONCE AGAIN BECOME MORE SHOWERY ACROSS SOUTH CENTRAL ALASKA BY
THURSDAY.

.LONG TERM FORECAST...
WHILE THE MODELS ARE AT ODDS OVER THE WEATHER FOR THE WEEKEND INTO
EARLY NEXT WEEK...IN GENERAL IT LOOKS LIKE ANOTHER UPPER TROUGH WILL
MOVE OVER THE MAINLAND WHILE A MORE PROGRESSIVE UPPER PATTERN TAKES
SHAPE OVER THE BERING SEA. IF A RIDGE DEVELOPS OVER THE BERING SEA
NEXT WEEK AS THE MODELS INDICATE...QUIETER WEATHER WILL RETURN FOR
MUCH OF THE STATE.

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

SCHRECK