Small Craft Advisory 1077, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM AST THU DEC 20 2007

.MODEL DISCUSSION...GFS MODEL OVERALL PREFERRED IN SHORT AND MEDIUM
RANGE. FEW CHANGES LIKELY IN FORECAST PACKAGES IN THE LONG RANGE. 12Z
GFS/EC RUNS IN GOOD AGREEMENT IN THE SHORT RANGE. THESE MODELS
HAVE THE BEST HANDLE ON DEVELOPING NPAC LOW MOVING INTO THE GULF OF
ALASKA TONIGHT. NAM FORECAST POSITION IS TOO FAR EAST OF EXPECTED
FORECAST TRACK.

.ANALYSIS AND UPPER LEVELS...
.EAST...OVERRUNNING MOISTURE WITH SLOW MOVING FRONTAL TROUGH
APPROACHING COOK INLET WILL BRING SIGNIFICANT SNOW AMOUNTS TO
SOUTHERN ZONE 121 AND ALONG THE WEST SIDE OF COOK INLET AND SUSITNA
VALLEY THIS AFTERNOON THROUGH FRI MORNING. ISENTROPIC LIFT (UPGLIDE)
WILL BE THE MAJOR CONTRIBUTOR IN THE ABSENCE OF STRONG UPPER LEVEL
DYNAMICS. EXPECT SNOW TO TAPER OFF OVER THESE AREAS FRI AS EASTERLY
FLOW SETS UP IN THE LOW AND MID LEVELS. THE EASTERN KENAI PEN WILL
GET SIGNIFICANT SNOW ALSO...BUT WILL REMAIN WELL BELOW WARNING
THRESHOLDS...LITTLE SNOW IS EXPECTED OVER THE REMAINDER OF
SOUTHCENTRAL ALASKA TONIGHT/FRI. DEVELOPING LOW CENTER MOVES INTO THE
GULF IN THE CENTRAL GULF OF ALASKA TONIGHT WITH A PRESSURE IN THE
970S. EXPECT CENTER TO WEAKEN AS IT MOVES INTO PRINCE WILLIAM SOUND
FRI AND INLAND LATE FRI NIGHT. EXPECT GALES/STORMS AHEAD OF THIS
CENTER.  STRONG WIND HEADLINES LIKELY FOR ZONE 135 LATE TONIGHT AND
FRI WITH APPROACH OF LOW. TEMPERATURES LIKE THEY WILL WARM UP ENOUGH
WHERE PROLONGED BLOWING SNOW WILL BE A PROBLEM. ANOTHER SHOT OF SNOW
FOR SOUTHCENTRAL/GULF LIKELY ON SAT AS A WEATHER FRONT ASSOCIATED
WITH A LOW CENTER IN BRISTOL BAY MOVES INTO THE REGION.

.WEST...960S LOW OVER THE EASTERN ALEUTIAN ISLANDS AND REMNANTS OF
FRONTAL TROUGH OVER THE EASTERN BERING SEA WILL CONTINUE BLIZZARD
CONDITIONS OVER THE PRIBILOFS THROUGH TONIGHT. CONDITIONS WILL
IMPROVE WITH DIMINISHING WINDS FRI AS LOW CENTER WEAKENS AND SHIFTS
SOUTH. 960S LOW CENTER WEAKENS AS IT MOVES SOUTH OF UNALASKA FRI
MORNING. CENTER THEN MOVES TO OVER BRISTOL BAY IN THE 970S SAT.
CENTER WEAKENS AS IT MOVES INLAND SAT NIGHT. EXPECT WINDS WILL SETTLE
DOWN OVER MUCH OF THE BERING SEA AND SW AK AFTER THE PASSAGE OF THIS
LOW...WITH LITTLE SIGNIFICANT WINDS SUN AND MON. NEXT BIG STORM MOVES
SOUTH OF THE CENTRAL ALEUTIANS TUE.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING ZONE 195. HEAVY SNOW WARNING ZONE 121.
MARINE...STORM...120. GALES 130 150 155 160 165 170 172 176 179 AND
180.
FIRE WEATHER...NONE.

RMC DEC 07