Small Craft Advisory 111, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM AST FRI FEB 3 2006

.DISCUSSION...

COMPLEX FORECAST SCENARIO UNFOLDING THIS MORNING ACROSS THE FORECAST
AREA. THE HEMISPHERIC PATTERN CONSISTS OF A COMPLEX OF UPPER LOWS
ACROSS EASTERN SIBERIA AND THE BERING SEA AND BRISTOL BAY WHILE AN
UPPER RIDGE EXTENDS UP MUCH OF THE LOWER 48 WEST COAST THROUGH BC AND
WESTERN NWT. TO THE SOUTH A MAJOR 250 MB JET CAN BE FOUND WITH A
JETMAX OF OVER 150 KTS EXTENDING ACROSS MUCH OF THE NORTH PACIFIC
FROM JAPAN TO AROUND 150W. SATELLITE IMAGERY SHOWS THE MOST OBVIOUS
FEATURE TO BE THE MASSIVE STORM SYSTEM NOW LOCATED OVER THE NORTHERN
GULF OF ALASKA. AMPLE MOISTURE STREAMING NORTH INTO THE SYSTEM HAS
CREATED A BROAD BAND OF PRECIPITATION THAT EXTENDS ACROSS MUCH OF
SOUTHCENTRAL ALASKA AND THE GULF COAST THROUGH THE PANHANDLE WITH
MOST SITES NOW REPORTING RAIN THANKS TO A COMBINATION OF STRONG WARM
ADVECTION AND DOWNSLOPING WINDS THAT HAVE ALLOWED TEMPERATURES TO
WARM INTO THE MID 30S TO AROUND 40 ALONG THE GULF COAST AND ACROSS
THE MATSU AND ANCHORAGE BOWL. A TIGHT PRESSURE GRADIENT AND A BARRIER
JET OVER THE NORTHEASTERN GULF HAVE LED TO STORM FORCE WINDS OVER
THAT REGION. THE STRONG EASTERLY FLOW NORTH OF THE SYSTEM HAS ALSO
CREATED A SETUP FOR GUSTY WINDS DOWN TURNAGAIN ARM AND THROUGH THE
MATANUSKA VALLEY. SHOWERS ARE ONGOING ACROSS THE BERING SEA THROUGH
THE ALEUTIANS IN THE COLDER AIR BEHIND THE SURFACE LOW.

THE FORECAST THIS MORNING IS PROBLEMATIC DUE TO THE VERY POOR
HANDLING OF THE GULF LOW BY THE MODELS. THE GFS AND ETA DEPICT A LOW
CENTERED OVER THE SOUTHWEST END OF SHELIKOF STRAIT WHEN IN REALITY
THE LOW APPEARS TO BE SPLITTING INTO TWO OR MORE SYSTEMS...WITH ONE
NEAR THE SHELIKOF STRAIT AND A SECOND COLSED LOW DEVELOPING WELL
OFFSHORE OVER THE CENTRAL GULF AROUND 56N 156W. THE GFS DOES HINT AT
A SHORTWAVE TROUGH AND ASSOCIATED SURFACE TROUGH ROTATING ACROSS THE
NORTHERN GULF AROUND THE UPPER LOW OVER BRISTOL BAY THROUGH MONDAY.
WITH A STRONG EAST WEST PRESSURE GRADIENT SETTING UP ACROSS SOUTH
CENTRAL ALASKA BY MONDAY EVENING...HIGH WINDS ARE POSSIBLE THROUGH
TURNAGAIN ARM AND THE MATSU VALLEY. ANOTHER SHOT OF PRECIPITATION
WILL MOVE THROUGH SOUTHCENTRAL ON TUESDAY AS A SHORTWAVE MOVES ACROSS
THE SOUTHERN HALF OF THE STATE WITH DRYING BY WEDNESDAY AS A
SHORTWAVE RIDGE MOVES THROUGH.

IN THE WEST...LOOK FOR SNOW SHOWERS TO CONTINUE THROUGH MONDAY IN THE
CYCLONIC FLOW ACROSS THE BERING SEA AND ALEUTIANS. A BRIEF BREAK IN
THE SHOWERS SHOULD OCCUR AS THE AFOREMENTIONED SHORTWAVE RIDGE MOVES
ACROSS THE EASTERN ALEUTIANS AND ALASKA PENINSULA BEFORE THE NEXT
UPPER/SURFACE LOW COMBO MOVES INTO THE BERING SEA ON TUESDAY. ON
WEDNESDAY ANOTHER POWERFUL JET MAX USHERS IN THE NEXT MAJOR STORM TO
THE WESTERN ALEUTIANS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING 101 125
MARINE...HEAVY FREEZING SPRAY 130 179
         GALE 121 129 130 132 138 140 155 165 170 171 172 176 179
         STORM 120 125
FIRE WEATHER...NONE

WOOD FEB 06