Small Craft Advisory 998, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM AKST MON DEC 15 2008

.MODEL DISCUSSION...
MODELS IN RELATIVELY GOOD AGREEMENT IN THE FIRST 48 HOURS. FEEL THE
GFS IS HITTING THE SPEED OF THE SHORT WAVE TROUGH THE BEST TODAY.
AFTER THAT...THE STRENGTH OF THE RIDGE OVER THE MAINLAND IS THE KEY
TO HANDLING THE NEXT FEW DAYS. THE ECMWF HAS BEEN RATHER CONSISTENT
WITH THE RIDGE BEING QUITE STRONG OVER THE MAINLAND...AS PER
COORDINATION WITH HPC. THIS WILL HOLD ALL THE BAROCLINICITY TO THE
BERING SEA AND THE SOUTHERN GULF. OUTSIDE OF TODAYS SHORT WAVE TROUGH
MOVING ACROSS THE MAINLAND...THE RIDGE WILL BE THE RULE OVER THE
MAINLAND. FORECASTS HAVE BEEN MODELED AFTER THE ECMWF BEYOND
WEDNESDAY.

.ANALYSIS AND UPPER LEVELS...
MEAN RIDGE OVER SOUTHWEST ALASKA AND THE GULF OF ALASKA TO REMAIN
THROUGH THE WEEK. TWO STRONG POLAR LOWS TO REMAIN OVER SIBERIA AND
NEAR GREENLAND. THERE IS A SHORT WAVE TROUGH MOVING THROUGH THE RIDGE
TODAY WITH A LOW SOUTH OF THE EASTERN ALEUTIANS. ONCE THE TROUGH
MOVES THROUGH THE MAINLAND THIS EVENING...THE RIDGE WILL BUILD BACK
UP OVER WESTERN ALASKA AND THE REMAINDER OF THE MAINLAND TUESDAY. THE
TROUGH OVER THE KAMCHATKA PENINSULA TO ROTATE INTO THE WESTERN
ALEUTIANS TONIGHT. A SHORT WAVE TROUGH IN THE BASE OF THE TROUGH
SUPPORTED BY A MODERATE JET TO SPIN UP A LOW IN THE CENTRAL ALEUTIANS
TUESDAY INTO WEDNESDAY. THIS LOW TO RUN INTO THE RIDGE OVER THE
MAINLAND AND SLIDE ACROSS THE SOUTHERN GULF OVER THE WEEKEND. ANOTHER
LOW AND FRONT TO MOVE INTO THE WESTERN ALEUTIANS DURING THE WEEKEND
AS WELL. THE HIGH PRESSURE RIDGE TO REMAIN OVER THE MAINLAND.

.SHORT TERM FORECAST...
.ALEUTIANS AND BERING...
A STRONG FRONT OUT IN THE WESTERN BERING PRODUCING VERY STRONG WINDS.
ISSUED A HIGH WIND WARNING EARLIER THIS MORNING. WINDS ARE EXPECTED
TO DIMINISH THROUGH THE AFTERNOON AND EVENING. THE JET ASSOCIATED
WITH THE FRONT IS RACING TO THE NORTH AND STRETCHING THE FRONT OUT
AND MOVING THE PARENT LOW IN THE SIBERIA TONIGHT. THE FRONT WILL
WEAKEN AND PUSH TO THE CENTRAL ALEUTIANS TONIGHT WITH A SHORT WAVE
TROUGH MOVING THROUGH THE BASE OF THE TROUGH. THIS WILL DEVELOP A LOW
ALONG THE FRONT SOUTH OF ADAK TOMORROW. THE LOW WILL CONTINUE TO
DEEPEN THROUGH WEDNESDAY WITH GALE FORCE WINDS DEVELOPING ON THE BACK
OF THE LOW. THE POTENTIAL FOR BLIZZARD CONDITIONS MAY EXIST AROUND
ADAK WEDNESDAY AFTERNOON/EVENING. THE LOW WILL BEGIN TO WEAKEN
THURSDAY AS IT SLIDES TOWARD THE GULF SOUTH OF THE EASTERN ALEUTIANS.
IN THE MEANTIME...A LOW SOUTH OF DUTCH HARBOR TONIGHT TO RIDE NORTH
PAST SAINT PAUL TOMORROW AND INTO THE NORTHERN BERING WEDNESDAY.
ALONG THE WAY...RAIN PROBABLE WITH SMALL CRAFT WINDS.

.SOUTHWEST ALASKA...
THE SHORT WAVE THAT IS MOVING THROUGH THE MAINLAND TONIGHT WILL KEEP
SNOW SHOWERS THROUGH SOUTHWEST ALASKA THIS EVENING. HIGH PRESSURE TO
QUICKLY BUILD BEHIND THE SYSTEM. MODERATE OFFSHORE FLOW TO DEVELOP
AND WILL LIKELY KEEP MOST COASTAL AREAS FREE OF FOG TONIGHT. THE LOW
MOVING NORTH PAST SAINT PAUL TOMORROW AND INTO THE NORTHERN BERING
WEDNESDAY TO BRING WARMER TEMPS TO THE COAST TOMORROW AFTERNOON AND
EVENING WITH A RAIN AND SNOW MIX DEPENDING ON HOW FAR INLAND THE
LOCATION. WARMER AIR MOVES FARTHER INLAND WEDNESDAY AS THE LOW MOVES
TO THE NORTH. A LOW MOVES TO THE SOUTH OF DUTCH HARBOR THURSDAY AND
KEEPS THE STREAM OF MOISTURE OVER SOUTHWEST ALASKA.

.SOUTH CENTRAL ALASKA...
A SHORT WAVE TROUGH IS MOVING THROUGH THE AREA THIS AFTERNOON AND
EVENING. MODERATE SOUTHWEST FLOW BRINING SOME MOISTURE UP THE INLET
FOR SNOW ALONG THE KENAI THROUGH THE SUSITNA VALLEY. THE SNOW WILL
LIKELY CONTINUE INTO THE EARLY EVENING HOURS. THE PASSAGE OF THE
TROUGH ACCOMPANIED BY THE RIDGE STRONGLY BUILDING BACK UP TONIGHT
WILL END PRECIPITATION ABRUPTLY TONIGHT. SOME AREAS OF FOG WILL
DEVELOP ONCE AGAIN WITH HIGH PRESSURE IN PLACE ONCE AGAIN. A FRONT
WILL MOVE TO KODIAK TOMORROW AND REMAIN ALONG THE AREA THROUGH
THURSDAY AS THE RIDGE HOLDS THE FRONT STEADY. WARMER TEMPS TO ARRIVE
FOR SOUTH CENTRAL WEDNESDAY AS THE RIDGE AXIS MOVES SLIGHTLY TO THE
EAST OF ANCHORAGE. THIS WILL ALLOW THE WARMER SOUTHWEST FLOW TO PUSH
INTO THE AREA WITH SOME HIGHER CLOUD COVER.

.LONG TERM FORECAST...
A LOW SOUTH OF THE EASTERN ALEUTIANS THURSDAY TO SLIDE SOUTH OF
KODIAK FRIDAY WITH HIGH PRESSURE REMAINING OVER THE INTERIOR. A LOW
WILL MOVE OUT OF THE NORTHWEST PACIFIC THURSDAY AND CROSS INTO THE
WESTERN BERING INTO THE WEEKEND. THE FRONT ASSOCIATED WITH THIS LOW
TO RIDE NORTH AS IT REACHES THE CENTRAL BERING SUNDAY SINCE IT RUNS
INTO THE RIDGE IN PLACE OVER THE MAINLAND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 150 155 160 175 176 180 185
FIRE WEATHER...NONE

JN DEC 08