Small Craft Advisory 734, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
400 PM ADT WED SEP 14 2005

.DISCUSSION...
LARGE 980 MB LOW IN THE CENTRAL BERING SEA IS SLOWING ITS NORTH
NORTHEAST MOVEMENT BUT STILL INCREASING IN STRENGTH. IT SHOULD REACH
ITS GREATES DEPTH TONIGHT AND THEN SLOWLY WEAKEN...ENDING UP AROUND
ST LAWRENCE ISLAND AT 980 MB ON FRIDAY. THE WEATHER FRONT ASSOCIATED
WITH THIS LOW IS PACKING A BIT OF A PUNCH WITH A 62 MPH GUST REPORTED
IN THE DUTCH HARBOR AREA EARLY THIS AFTERNOON. THIS FRONT WILL WEAKEN
AS IT PROCEEDS EASTWARD AND ENTERS THE WESTERN GULF OF ALASKA EARLY
THURSDAY MORNING. IT WILL THEN PROCEED INTO THE EASTERN GULF ON
FRIDAY.
AN INTERESTING FEATURE THAT IS EXPECTED TO DEVELOP ALONG THIS FRONT
INS A TRIPLE POINT LOW NEAR KODIAK ISLAND THURSDAY NIGHT. THE
STRENGTH AND EXACT POSITION AND MOVEMENT OF THIS TRIPLE POINT WILL
HAVE A LARGE IMPACT ON THE WINDS AND PRECIPITATION FROM THE MAT-SU
VALLEY SOUTHWARD OVER THE WESTERN KENAI PENINSULA. STRONG WINDS WILL
OCCUR THROUGH TURNAGAIN ARM BUT WILL BE SIGNIFICANTLY DIMINISHED IF
THIS TRIPLE POINT HEADS SOUTH OF THE KENAI PENINSULA AS SUGGESTED BY
THE GFS AND UKMET MODELS. THE MESO-ETA IS INDICATING THIS TRIPLE
POINT GOING UP COOK INLET FRIDAY MORNING. SHOULD THIS OCCUR THE WINDS
IN THE ANCHORAGE AREA WILL PERSIST LONGER AND BE STRONGER. THE
PRECIPITATION FROM THE WESTERN KENAI PENINSULA UP INTO THE MAT-SU
VALLEY WILL ALSO BE SIGNIFICANTLY INCREASED IF THIS SCENARIO PLAYS
OUT.

MODELS...THERE IS VERY NICE AGREEMENT BETWEEN THE ETA GFS AND UKMET
MODELS ON THE MAIN LOW IN THE BERING SEAS. DEPTH AND MOVEMENT OF THE
LOW IS CONSISTENT BETWEEN ALL OF THESE MODELS AND ANY SLIGHT
DIFFERENCE SHOULD NOT EFFECT THE FORECASTS IN THE FORECAST AREA.
AS DISCUSSED IN THE PREVIOUS SECTION THERE IS A DIFFERENCE IN THE
TRIPLE POINT LOCATION WITH THE ETA AS COMPARED WITH THE OTHER TWO. I
AM PRESENTLY LEANING TOWARD THE GFS/UKMET SOLUTION. THIS IS IN LARGE
PART DUE TO THE CONSISTENCY THE UKMET HAS SHOWN IN RESOLVING THIS
SYSTEM FROM MODEL RUN TO MODEL RUN. NEITHER THE ETA OR GFS HAVE BEEN
AS CONSISTENT. THIS IS STILL WORTH WATCHING SINCE THE ETAS SUPERIOR
TERRAIN RESOLUTION MAY BE SEEING SOMETHING THE OTHER MODELS CANNOT.

ANOTHER FEATURE TO KEEP AN EYE ON IS A LOW SOUTH OF THE WESTERN
ALEUTIANS THURSDAY NIGHT THAT HEADS DUE EAST THROUGH SATURDAY. EACH
MODEL HAS A DIFFERENT SOLUTION AS TO THE STRENGTH AND SPEED OF THIS
LOW. HOWEVER THE GREATEST IMPACT FROM THIS LOW WILL BE ALONG ITS
SOUTHERN FLANK WHICH WILL BE OUT OF OUR FORECAST AREA. EVEN THOUGH
ALL MODELS KEEP THIS MAINLY SOUTH OF THE FORECAST AREA IT DOES HAVE
SIGNIFICANT UPPER LEVEL SUPPORT AS THE JET STREAM IS PARKED RIGHT
OVER THE ALEUTIAN ISLANDS DURING THIS TIME FRAME. THIS COULD CAUSE
THE LOW TO MOVE FARTHER NORTHWARD AND IS PERHAPS PART OF THE REASON
THE MODELS ARE STRUGGLING TO RESOLVE THIS LOW. WE WILL HAVE TO WATCH
PROGRESSIVE MODEL RUNS AND SEE HOW IT DEVELOPS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 130 132 150 160 170 171 172 175 176 179 185.
         STORM 155 165 180.
FIRE WEATHER...NONE.

EZ SEP 05