Small Craft Advisory 1029, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AKST SAT DEC 19 2009

.ANALYSIS AND UPPER LEVELS...
UPPER LEVEL...A MULTI-CENTERED LOW PRESSURE AREA IS CURRENTLY
CENTERED OVER THE BERING SEA. AN UPPER RIDGE LIES OVER THE EASTERN
GULF AND EASTERN ALASKA. A STRONG SOUTHERLY FLOW IS BEGINNING TO FORM
OVER WESTERN ALASKA.
AT THE SURFACE...THE SURFACE PATTERN GENERALLY MIRRORS THE UPPER AIR
PATTERN. AN AREAS OF HIGH PRESSURE COVERED THE EASTERN GULF OF
ALASKA, SOUTHEAST ALASKA AND YUKON TERRITORY. A STRONG 964 MB LOW
LIES OVER THE SOUTH-CENTRAL BERING SEA AND ANOTHER 966 MB LOW IS OVER
THE WESTERN ALEUTIANS. A WEATHER FRONT LIES OVER THE KENAI PENINSULA
AND WESTERN GULF OF ALASKA.

MODEL DISCUSSION...
MODELS INITIATE WELL BUT THE VARIOUS SOLUTIONS OVER THE BERING SEA
BEGIN TO DIVERGE BY SUNDAY NIGHT. THE NAM AND GFS ARE IN CLOSER
AGREEMENT THAN THE EUROPEAN MODEL THROUGH SUNDAY NIGHT BUT DEVELOP
SIGNIFICANT DIFFERENCES BY MONDAY AFTERNOON. NEEDLESS TO SAY, OVERALL
CONFIDENCE BEYOND THE FIRST 24 HOURS IS RATHER LOW DUE TO THE HIGH
LEVEL OF UNCERTAINTY IN THE MODELS.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...
THE WEATHER FRONT OVER THE THE WESTERN BERING WILL SWING NORTHEAST
AND DISSIPATE ALONG THE CENTRAL GULF COAST AND THE EASTERN BERING BY
SUNDAY AFTERNOON. SOUTHERLY FLOW WILL PERSISTING THROUGH MONDAY OVER
THE WESTERN GULF WILL CONTINUE TO FEED A WARM MOIST AIR MASS INTO
SOUTH-CENTRAL ALASKA. SNOW MAINLY ALONG THE CENTRAL GULF COAST, OVER
KENAI PENINSULA AND THE WEST SIDE OF THE SUSITNA VALLEY WILL CONTINUE
THROUGH MONDAY. TEMPERATURES THROUGH THE REGION WILL GRADUALLY RISE
THROUGH MONDAY AS A WARMER AIRMASS MOVES INTO THE AREA.

.SOUTHWEST ALASKA...
STRONG MOIST FLOW FROM THE SOUTH WILL REMAIN OVER SOUTHWEST ALASKA
THROUGH MONDAY. FLOW FROM THE SOUTHEAST AT LOWER LEVELS WILL TENDED
TO PRODUCE MODERATE TO HEAVY SNOW MAINLY NORTH AND WEST OF KING
SALMON IN THE BRISTOL BAY ZONE AND GENERALLY WEST OF SLEETMUTE IN THE
SOUTHERN KUSKOKWIM VALLEY ZONE. AREAS OF STRONG WINDS WILL CONTINUE
TO BLOW OUT OF THE PASSES ALONG THE ALASKA AND ALEUTIAN RANGE THROUGH
MONDAY. POSSIBLE BLIZZARD CONDITIONS MAY DEVELOP ALONG THE KUSKOKWIM
DELTA COAST AS INCREASING WINDS AND FALLING SNOW REDUCE VISIBILITIES
IN BLOWING SNOW. ISOLATED POCKETS OF FREEZING RAIN WILL DEVELOP
TONIGHT AND SUNDAY OVER THE BRISTOL BAY ZONE.

.BERING SEA/ALEUTIANS...
A SERIES OF PROGRESSING LOWS WILL GENERATE SOME GALE FORCE WINDS
ACROSS MUCH OF THE ALEUTIANS AND THE BERING SEA SUNDAY. RAIN AND
SNOW IS EXPECTED ACROSS MUCH OF THE ALEUTIAN CHAIN DUE TO WARMER
TEMPERATURES.

.LONG TERM FORECAST...
THE MODELS TEND TO WEAKEN THE UPPER LOW OVER THE WESTERN BERING
THROUGH WEDNESDAY WHILE THE UPPER RIDGE OVER THE EASTERN MAINLAND
DRIFTS EAST INTO CANADA. THE SOUTHERLY FLOW OVER WESTERN ALASKA WILL
WEAKEN A BIT AND SPREAD INTO SOUTH-CENTRAL ALASKA THROUGH THE FIRST
HALF OF NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING...131 155
MARINE...STORM...150 155 160 165 172
         GALE...130 132 138 170 176 179 180 185
FIRE WEATHER...NONE

NM DEC 09