Gale Warning 610, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKDT SUN SEP 6 2009

.ANALYSIS AND UPPER LEVELS...
A LOW PRESSURE SYSTEM IS MOVING EAST ALONG THE ALEUTIAN CHAIN TODAY
WITH ANOTHER LOW IN THE ARCTIC AND STILL ANOTHER IN THE PACIFIC
NORTHWEST. IN BETWEEN ALL THIS ACTIVITY IS HIGH PRESSURE OVER THE
MAINLAND OF ALASKA. WITH THE HIGH PRESSURE...THERE WERE LIGHT WINDS
AND LITTLE CLOUD COVER MAKING FOR SOME LARGE AREAS OF FOG. SOME AREAS
ALONG THE WEST COAST AND LOW LYING VALLEY LOCATIONS IN SOUTH CENTRAL
EXPERIENCED SOME DENSE FOG THIS MORNING. THE DENSE FOG IS NOT SO
QUICK TO LEAVE ALONG THE WEST COAST BUT SHOULD BURN OFF BY MID
AFTERNOON.

ALL SYSTEMS SHOULD TRANSITION EASTWARD OVER THE NEXT 24 HOURS. THERE
ARE NO STRONG SHORT WAVE TROUGHS AROUND THE LOW IN THE ALEUTIANS.
HOWEVER...A MODERATE WAVE WILL MOVE NORTH WORK AROUND THE LOW TO
BRING A FRONT INTO THE GULF OF ALASKA AND THE AKPEN TONIGHT AND
TOMORROW. IN THE MEANTIME...A SECONDARY UPPER LEVEL DISTURBANCE
ROTATING AROUND THE LOW IN THE ARCTIC WILL PUSH COLDER AIR INTO THE
BERING.

IN ADDITION...A WEAK UPPER LEVEL LOW OVER THE PRINCE WILLIAM SOUND
WILL REMAIN THROUGH THE NEXT 24 HOURS. THIS HAS ALLOWED FOR A LITTLE
POCKET OF COLD AIR TO HELP ALONG ISOLATED MOUNTAIN SHOWERS THE PAST
COUPLE DAYS. THIS WILL BE THE CASE AGAIN LATER THIS AFTERNOON AND
EVENING.

.MODEL DISCUSSION...
MODELS IN FAIRLY GOOD AGREEMENT THROUGH THE NEXT 48 HOURS EXCEPT THE
UKMET. THE ECMWF...NAM AND GFAS ARE HANDLING THE UPPER LEVEL AND
SURFACE FEATURES RELATIVELY THE SAME THOUGH THROUGH TUESDAY
AFTERNOON. THE NAM AND GFS ARE A TAD BIT SLOWER WITH THE FRONT. THIS
BEARS OUT IN ANALYSIS THIS MORNING OF THE FEATURE PUSHING THE LOW IS
RESOLVED SLOWER IN THE NAM AND GFS. THE TROUGH OVER THE ARCTIC WILL
MERGE WITH THE UPPER LEVEL LOW IN THE ALEUTIANS NEAR THE AKPEN
TUESDAY.

IN THE LONGER TERM HOWEVER...THEY ALL DIFFER ON THE SPEED OF A LOW
ROTATING OUT OF THE WESTERN PACIFIC SOUTH OF THE ALEUTIANS TUESDAY.
THIS LOW TO DEEPEN AS IT MOVES INTO THE SOUTHERN GULF WEDNESDAY AND
INTERACTS WITH THE UPPER LOW AND ITS COLDER AIR. THE MAIN UPPER LOW
TO SWING INTO THE GULF AS WELL WITH THIS FEATURE. NEW MODELS HAVE NOW
KEPT THE LOW IN THE WESTERN AND CENTRAL GULF. THE PREVIOUS GFS HAD
THIS LOW IN THE EASTERN GULF.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...
FOG AND STRATUS HANGING AROUND THE INLET AND WESTERN SUSITNA VALLEY
THIS AFTERNOON. MOST OF IT SHOULD BURN OFF OVER THE MAINLAND.
EXPECTING WITH LIGHT FLOW CONTINUING INTO TOMORROW MORNING AT
LEAST...FOG SHOULD SETTLE IN OVER THE SAME PLACES AGAIN TONIGHT.
OTHERWISE...STILL SOME INSTABILITY WITH A COLD POCKET OF AIR ALOFT IN
SOUTH CENTRAL. THEREFORE...SOME LATE AFTERNOON AND EVENING SHOWERS
MAINLY OVER THE MOUNTAINS. A LOW IN THE CENTRAL ALEUTIANS TO PUSH A
FRONT TO KODIAK BY TOMORROW AFTERNOON WITH STRONGER WINDS AS WELL. DO
NOT ANTICIPATE ANY GALES AT THIS TIME WITH THE FRONT. THE FRONT WILL
PUSH TO THE NORTHERN GULF COAST TUESDAY WITH NOT MANY SHOWERS
SPREADING INLAND. THE FRONT TO HANG ALONG THE COAST INTO WEDNESDAY AS
THE NEXT STRONGER SYSTEM MOVES INTO THE SOUTHERN GULF THAT EVENING.

.SOUTHWEST...
STRATUS AND FOG OVER THE WESTERN COAST AND INLAND ALONG THE KUSKOKWIM
RIVER. THE STRATUS HOLDING STRONG IN THE KUSKOKWIM DELTA. EVEN WHEN
IT LIFTS A BIT IN SOME PLACES THIS AFTERNOON...IT SHOULD COME BACK
RATHER QUICK IN THE EVENING. THE FOG WILL BE MORE HARD PRESSED TO
HANG IN TOO LONG AGAIN TOMORROW IN THESE AREAS AS THE LOW IN THE
CENTRAL ALEUTIANS MOVES TO BRISTOL BAY. RAIN SHOWERS SHOULD BEGIN
SPREADING INTO THE AREA LATE TONIGHT ALONG THE APKEN SOUTH OF PILOT
POINT THEN SLOWLY MOVING NORTH TOMORROW AND IN MORE EARNEST ON MONDAY
NIGHT OVER THE AREA AS THE ALEUTIAN LOW DEEPENS IN THE BRISTOL BAY
AREA. SOUTHEAST WINDS WILL PICK UP TOMORROW AND SHOULD HELP PUSH OUT
THE FOG. THE WINDS WILL BE EVEN STRONGER ON TUESDAY WITH THE DEEPER
LOW.

.BERING SEA AND ALEUTIANS...
A STACKED LOW IN THE CENTRAL ALEUTIANS BRINGING RAIN TO MOST OF THE
ALEUTIAN CHAIN TODAY. MODERATE WINDS ARE ALSO ACCOMPANYING THIS LOW.
A TROUGH DIGGING IN THE NORTHERN BERING TONIGHT TO BRING COOLER
TEMPERATURES AND ENOUGH COLD AIR ADVECTION FOR STRONGER WINDS TO PICK
UP BEHIND THE LOW IN THE CENTRAL BERING TOMORROW. THIS COLDER AIR AND
ASSOCIATED UPPER LEVEL DISTURBANCE TO INCREASE PRECIP IN THE YK DELTA
ARENAS MONDAY NIGHT AND TUESDAY. THE LOW WILL DEEPEN A BIT IN BRISTOL
BAY TUESDAY AND KEEP WINDS FROM THE NORTH QUITE STRONG TO AROUND GALE
FORCE IN THE CENTRAL BERING AND SPREADING INTO THE EASTERN BERING AS
WELL. HIGH PRESSURE PUSHING INTO THE WESTERN BERING ALSO HELPING THE
WINDS IN THE CENTRAL AND EASTERN BERING.

.LONG TERM FORECAST...
MODELS COMING CLOSER ON A SOLUTION FOR THE LOW TO ENTER THE GULF ON
WEDNESDAY. LOOKS MORE AS THOUGH THE LOW WILL BE IN THE WESTERN
PORTION OF THE GULF WITH GALE TO STORM FORCE WINDS POSSIBLE AS THE
LOW IS PROJECTED AT THIS TIME TO BE IN THE 960S. MEANWHILE...ANOTHER
LOW PUSHES INTO THE WESTERN ALEUTIANS WEDNESDAY NIGHT AND THURSDAY.
THESE LOWS TO FILL THROUGH THE END OF THE WEEK INTO NEXT WEEKEND OVER
THE WESTERN BERING AND NORTHERN GULF. OVERALL...A STAGNANT BUT ACTIVE
WEATHER PATTERN ONCE WE SETTLE INTO IT ON THURSDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 179 180 185
FIRE WEATHER...NONE

JN SEP 09