Small Craft Advisory 798, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT SAT OCT 12 2013

.ANALYSIS AND UPPER LEVELS...
A PROGRESSIVE LONGWAVE PATTERN CONTINUES ACROSS ALASKA...WITH THE
LONGWAVE TROUGH OVER THE EASTERN BERING SEA TODAY. THIS LOW IS NEARLY
VERTICALLY STACKED THIS AFTERNOON...BUT AS THE UPPER LOW WEAKENS AND
MOVES OFF TO THE NORTHEAST TONIGHT AND SUNDAY THE SURFACE LOW WILL
MOVE INTO THE NORTHERN GULF OF ALASKA. SURFACE WINDS AROUND THE LOW
HAVE BEEN GUSTING AROUND 45 TO 55 KTS...AND AHEAD OF THE FRONT THEY
HAVE BEEN GALE FORCE TO OCCASIONALLY MINIMAL STORM FORCE.

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT TO START OUT...HOWEVER THERE ARE SOME
DIFFERENCES IN THE TRACK OF THE CURRENT EASTERN BERING LOW AS IT
MOVES INTO THE BARREN ISLANDS/NORTHERN GULF AREA. THE GFS IS THE
FARTHEST SOUTH NEAR KODIAK CITY SUNDAY NIGHT...WHILE THE
NAM...ECMWF...AND WRF ARE ALL SHOWING THE LOW RIGHT OVER THE BARREN
ISLANDS. THE NAM IS THE PREFERRED MODEL FOR THIS LOW. MODEL
DIFFERENCES INCREASE AS THE NEXT LOW MOVES INTO THE WESTERN BERING.
WITH JET PLACEMENT IN THIS AREA...THE ECMWF TRACK SEEMS THE MOST
REALISTIC SO IT HAS BECOME THE PREFERRED MODEL TOWARD THE END OF THE
SHORT TERM.

.SHORT TERM FORECAST...
AS THE LOW IN THE EASTERN BERING SLOWLY MOVES INTO THE NORTHERN GULF
OF ALASKA BETWEEN THIS EVENING AND SUNDAY NIGHT...IT WILL QUICKLY
WEAKEN. BEFORE IT WEAKENS THOUGH...STRONG WINDS WILL PERSIST ACROSS
THE BACKSIDE OF THE LOW AS WELL AS THROUGH THE TYPICAL GAPS OF THE
ALASKA RANGE AND OTHER RANGES OF THE SOUTH CENTRAL MAINLAND. THE
PRESSURE GRADIENT WILL INCREASE AS A FRONT SWINGS ACROSS THE WESTERN
TO NORTHERN GULF TONIGHT...THUS PRODUCING WINDS AT OR ABOVE 75 MPH
FOR WESTERN TURNAGAIN ARM AND SLIGHTLY LOWER FOR EASTERN TURNAGAIN
ARM OVERNIGHT. THE HIGH WIND WARNING THAT WAS ISSUED EARLIER TODAY
WILL CONTINUE...WITH A STRONG WIND HEADLINE SUFFICING FOR EASTERN
TURNAGAIN ARM. A STORM FORCE BARRIER JET WILL ALSO DEVELOP TONIGHT
AS THE FRONT SWINGS TO ALONG THE NORTH GULF COAST. WINDS WILL PEAK
AFTER MIDNIGHT TONIGHT AND DIMINISH THROUGH THE DAY SUNDAY AS THE
FRONT MOVES ONSHORE AND WEAKENS.

THE NEXT LOW IN THE WESTERN BERING SEA BY THE END OF THE SHORT TERM
WILL BRING ANOTHER ROUND OF GALE FORCE WINDS TO THE WESTERN AND
CENTRAL ALEUTIANS AS WELL AS THE WESTERN BERING SEA. WITH THIS
PROGRESSIVE WEATHER PATTERN...SHORT BREAKS IN PRECIPITATION CAN BE
EXPECTED BEFORE ANOTHER ROUND OF PRECIPITATION MOVES THROUGH.

.LONG TERM FORECAST...
THE GENERAL PATTERN WILL CONSIST OF THE MEAN LOW POSITION OVER THE
BERING SEA AND THE MEAN RIDGE POSITION JUST TO THE EAST OF ALASKA.
THIS WILL USHER IN A PATTERN THAT FAVORS WARM...WET...AND POSSIBLY
WINDY CONDITIONS FOR SOUTHERN ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...HIGH WIND WARNING 101.
MARINE...STORM WARNING 119.
         GALE WARNING 120 130 131 132 139 141 150 155 160 165 170
                      171 172 173 174 175 176 177 178 179 185.
FIRE WEATHER...NONE.

SCHRECK