Storm Warning 175, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKDT SAT OCT 30 2010

.MODEL DISCUSSION...MODELS ARE DOING A GOOD JOB WITH THE MONSTER LOW
RAPIDLY DEVELOPING SOUTH OF THE EASTERN ALEUTIANS. INITIALIZATION
FROM THE 12Z RUN OF BOTH THE GFS AND ECMWF ARE GOOD WHEN COMPARING
THE PRESSURE WITH THE LITTLE DATA THAT IS OUT THERE. THE ONE SYSTEM
THE MODELS ARE NOT DOING WELL IS SOUTH OF SEWARD AND PRODUCING
WIDESPREAD RAIN AND SNOW SHOWERS ACROSS THE NORTH GULF COAST REGION.
THIS LOW IS NOT RESOLVED ON ANY OF THE MODELS BUT IT WILL LIKELY MOVE
ON SHORE IN WESTERN PRINCE WILLIAM SOUND THIS EVENING AND THEN
DISSIPATE OVERNIGHT.

.ANALYSIS AND UPPER LEVELS...A STRONG JET STREAM THAT IS PUSHING 200
KT AT 250 MB RUNS SOUTH OF THE ALEUTIANS AND AROUND TO THE SOUTH OF
THE RAPIDLY STRENGTHENING LOW SOUTH OF THE ALASKA PENINSULA. THIS JET
IS FEEDING THIS LOW WHICH WILL BOTTOM OUT NEAR 940 MB. IT MIGHT EVEN
DROP INTO THE UPPER 930S MB WHICH DOES NOT HAPPEN VERY OFTEN.
WHILE THE SURFACE LOW WILL REACHED ITS LOWEST PRESSURE OVERNIGHT IT
WILL SLOWLY WEAKEN AND REMAIN VERY LARGE AS IT MOVES INTO THE GULF
SUNDAY AND MONDAY.
EVEN AS THE SURFACE LOW MOVES INTO THE GULF THE JET STREAM WILL
AMPLIFY OVER THE ALEUTIAN ISLANDS BRINGING STRONG UPPER LEVEL FLOW
FROM THE NORTHWEST THROUGH MONDAY NIGHT.

.SHORT TERM FORECAST...THE NORTH GULF COAST WILL SEE CONTINUED RAIN
AND SNOW SHOWERS THROUGH THE EVENING AS THE ATMOSPHERE IN THAT AREA
IS UNSTABLE AND THE SURFACE LOW SOUTH OF SEWARD WILL HELP TO ORGANIZE
THE SHOWERS. WINDS WILL INCREASE FROM THE EAST AND NORTHEAST OVER THE
EASTERN HALF OF THE FORECAST AREA AS THE LARGE LOW MOVES TOWARD THE
GULF. ONE GOOD THING ABOUT THE POSITION OF THE LARGE LOW IS THAT IT
IS FAR ENOUGH SOUTH THAT THE STRONGEST WINDS WILL REMAIN SOUTH OF THE
FORECAST AREA AND AREAS AFFECTED ON THE ALASKA PENINSULA WILL NOT
EXPERIENCE THE BRUNT OF THE SYSTEM.
BRISTOL BAY AND SOUTHWEST ALASKA MAY STILL SEE SOME OVERNIGHT FOG BUT
THE TIGHTENING GRADIENT SHOULD REDUCE HOW WIDESPREAD THE FOG MAY BE.

.LONG TERM FORECAST...THE LONG WAVE TROUGH WILL CONTINUE TO REMAIN
OVER THE STATE...MEANING THAT THE WEATHER WILL CONTINUE TO BE
UNSETTLED FOR MOST AREAS WITH AT LEAST TWO STORM SYSTEMS POTENTIALLY
AFFECTING THE AREA LATER IN THE WEEK AND NEXT WEEKEND RESPECTIVELY. A
PERSISTENT STRONG JET STREAM SOUTH OF THE ALEUTIANS WILL CONTINUE TO
SEND A SERIES OF STORM SYSTEMS ACROSS THE SOUTHERN BERING AND
ALEUTIANS THROUGH NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 125 138 140 141 165 171 185.
         STORM 120 130 132 150 155 170 172 175 176.
FIRE WEATHER...NONE.

OCT 10