Gale Warning 851, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM AKST SUN DEC 21 2008

.MODEL DISCUSSION...THE MODELS ARE CHANGING A BIT ON THE WAY THEY
WANT TO RESOLVE THE BERING SEA LOW. IT IS A SIGNIFICANT ENOUGH SHIFT
THAT THERE WILL BE AN IMPACT ON THE NORTHERN GULF AS WELL. THE BIG
SHORT TERM QUESTION REVOLVES AROUND A TRIPLE POINT LOW THAT WILL
DEVELOP SOUTHWEST OF THE BERING SEA AND MOVE VERY QUICKLY EASTWARD IN
THE JET STREAM AND ARRIVE JUST NORTH OF BRISTOL BAY MONDAY NIGHT. THE
BIG ISSUE WITH THIS SYSTEM IS THAT ALL THE MODELS ARE NOW WANTING TO
BRING THIS LOW INTO THE NORTHERN GULF TUESDAY AFTERNOON. MOST LIKELY
SCENARIO THEN IS THAT THE LOW WILL GET CAUGHT IN THE JET STREAM AND
MOVE SOUTHEASTWARD OUT OF THE AREA. OFTEN THE LOW WILL LINGER IN THE
NORTH GULF COAST AREA BUT THE JET STREAM WILL PROBABLY BE TOO STRONG
TO LET THAT HAPPEN WITH THIS LOW.
IN ADDITION TO THE SHORT TERM GULF THERE IS A LARGE QUESTION WITH THE
MID RANGE TIME FRAME IN THE BERING SEA AS WELL. A LOW WILL ENTER THE
WESTERN BERING SEA TUESDAY NIGHT AND MOVE NORTHEASTWARD. THE GFS AND
NAM HAVE BEEN STRENGTHENING THIS LOW AMD MOVING IT NORTHWARD IN
SUCCESSIVE RUNS. THE ECMWF AND UKMET HAVE BEEN INSISTING THAT IT WILL
BE MUCH WEAKER AND FARTHER SOUTH. THIS WILL HAVE TO BE WATCHED
CLOSELY AS IT DEVELOPS.

.ANALYSIS AND UPPER LEVELS...THE UPPER LEVEL RIDGE THAT HAS BEEN OVER
THE MAINLAND PART OF THE STATE WILL BREAK DOWN AND MOVE EASTWARD OVER
THE NEXT DAY OR TWO. A BROAD UPPER LEVEL LOW WILL MOVE TO THE
NORTHERN BERING SEA AND INTO THE INTERIOR BY TUESDAY. THE JET STREAM
IS SPLIT WITH A PORTION OF IT JUST SOUTH OF THE ALASKA PENINSULA AND
KODIAK ISLAND. THIS SECTION OF THE JET WILL DESCEND SOUTHWARD WHILE
THE PORTION OF IT THAT IS COMING OFF OF JAPAN AND OVER SOUTHERN
KAMCHATKA WILL MOVE INTO THE BERING SEA BY MONDAY. THIS JET WILL
STRENGTHEN AND SHOULD RUN WEST TO EAST OVER THE BERING SEA AND THEN
TURN SOUTHEASTWARD OVER THE GULF OF ALASKA BY TUESDAY. A RATHER ZONAL
FLOW WILL SET UP ALOFT BY LATE IN THE WEEK.

.SHORT TERM FORECAST...FOG HAS BECOME A LARGE ISSUE IN THE ANCHORAGE
AREA TODAY WITH A DENSE FOG ADVISORY ISSUED. CONDITIONS MAY IMPROVE
THIS EVENING AS MID LEVEL CLOUDS MOVE INTO THE AREA FROM THE SOUTH.
PRECIPITATION IS HARD TO FIND AROUND THE FORECAST AREA THIS AFTERNOON
WITH SOME SHOWERS AROUND THE PRIBILOF ISLANDS AND ALASKA PENINSULA
BEING THE ONLY SPOTS. THIS WILL CHANGE OVERNIGHT AND INTO TOMORROW AS
A FRONT MOVES INTO SOUTHWEST ALASKA AND THEN INTO THE SOUTH CENTRAL
REGION.

.LONG TERM FORECAST...A ZONAL FLOW WILL DEVELOP THIS WEEK AND BRING
SYSTEMS THROUGH THE AREA QUICKLY. BY NEXT WEEKEND A BLOCKING RIDGE
MAY TRY TO BUILD INTO THE BERING SEA AND WESTERN ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 132 138 150 155 160 165 170 171 172 175 176 179 180 185
FIRE WEATHER...NONE

DEC 08