Gale Warning 797, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM ADT SAT OCT 21 2006

.DISCUSSION...

ANALYSIS...A 987 MB SURFACE LOW IS MAKING LANDFALL JUST EAST OF THE
COPPER RIVER DELTA (AT 21Z). RAIN CONTINUES TO FALL ACROSS EASTERN
PRINCE WILLIAM SOUND WITH SNOW AT HIGHER ELEVATIONS. WIDESPREAD SNOW
IS FALLING IN THE COPPER RIVER BASIN AND A SNOW ADVISORY IS IN EFFECT
THROUGH 9 PM THIS EVENING. WITH TEMPERATURES NEAR FREEZING...THE SNOW
IS VERY WET. GUSTY WINDS HAVE KICKED IN ON THE WEST SIDE OF THE LOW
WITH WIDESPREAD 20 TO 30 KTS AND FEW ISOLATED GALES. WATER VAPOR
IMAGERY SHOWS UPPER TROUGH CENTERED OVER GULF SLOWLY LIFTING
NORTHEASTWARD...SO BACK EDGE OF PRECIP WILL FOLLOW. OUT WEST THERE
IS A STRONG NEAR ZONAL UPPER JET EXTENDING FROM ASIA TO SOUTH OF THE
ALEUTIANS. THIS IS HELPING TO PUSH THE GULF TROUGH EASTWARD. THERE IS
ONE LOW RIDING ALONG THE NORTHERN EDGE OF THE JET BETWEEN THE EASTERN
ALEUTIANS AND THE PRIBILOF ISLANDS. IT IS MOVING QUICKLY EASTWARD AND
BRINGING ONLY A 6 TO 8 HOUR PERIOD OF RAIN AS IT MOVES THROUGH. GALE
FORCE WINDS ARE FOUND MAINLY SOUTH OF THE LOW ALONG AND BEHIND THE
OCCLUSION...CURRENTLY FROM THE SOUTHERN AKPENN TO THE CENTRAL
ALEUTIANS. ANOTHER LOW IS FOUND ALONG THE COLD FRONT WHICH EXTENDS
SOUTHWEST INTO THE NORTH PACIFIC. FINALLY...A DYING LOW IS SPINNING
EAST OF SAINT LAWRENCE ISLAND IS STILL PRODUCING SOME IMPRESSIVE
SHOWERS FROM ALONG THE WEST COAST.

MODEL ANALYSIS...MODELS INITIALIZED VERY WELL BUT SOLUTIONS BEGIN TO
DIVERGE AT ABOUT 24 HOURS. MODELS HAVE BEEN HAVING TROUBLE THE LAST
FEW DAYS DEALING WITH THE EVOLUTION OF LOWS IN FAST FLOW. RUN-TO-RUN
CONSISTENCY IS POOR. WITH LOW OVER SOUTHERN BERING PREFER GFS/UKMET
SOLUTION OVER NAM AS LOW TRANSITIONS INTO THE GULF. THE NEXT LOW
MOVING FROM KAMCHATKA INTO THE CENTRAL BERING IS MUCH STRONGER WITH
THE LATEST RUN. WILL TREND TOWARD THE NEW GFS SOLUTION WITH THIS LOW.

SOUTHCENTRAL FORECAST...SNOW WILL GRADUALLY DIMINISH TONIGHT FROM
PRINCE WILLIAM SOUND INTO THE COPPER RIVER BASIN AS SURFACE LOW/UPPER

TROUGH MOVE INTO THE INTERIOR. GUSTY WINDS ON THE BACK SIDE WILL
ALSO DIMINISH. BERING LOW WILL TRANSITION TO THE GULF TONIGHT AND
SUNDAY BRINGING LIGHT RAIN TO THE COAST AND A CHANCE OF SHOWERS TO
THE COPPER RIVER BASIN AS IT QUICKLY RACES NORTHEASTWARD INTO THE
YUKON. THE FRONTAL LOW CURRENTLY OVER THE PACIFIC WILL RIDE THE JET
EASTWARD ACROSS THE SOUTHERN GULF AND INTO SOUTHEAST ALASKA LATE
MONDAY. ONLY IMPACT WILL BE GUSTY WINDS ON BACK SIDE OF LOW IN COLD
ADVECTION. LOOK FOR THE REST OF SOUTHCENTRAL ALASKA TO REMAIN DRY
THROUGH THE NEXT FEW DAYS WITH SEASONABLY COOL TEMPERATURES.

SOUTHWEST ALASKA/BERING SEA/ALEUTIANS FORECAST...SOUTHERN BERING
LOW WILL QUICKLY TRACK ACROSS BRISTOL BAY AND THE AKPENN TONIGHT
BRINGING A SHOT OF WIND AND RAIN...MAINLY TO ITS SOUTH. A SHORT-WAVE
RIDGE WILL BUILD IN BEHIND THE LOW AND TRANSPORT SOME COLD AIR
SOUTHWARD. THIS WILL GENERATE SOME GUSTY NORTHWEST WINDS ACROSS
THE EASTERN BERING AND THROUGH GAPS IN THE AKPENN SUNDAY NIGHT
INTO MONDAY. AS MENTIONED IN THE MODEL DISCUSSION...LOW CONFIDENCE
WITH NEXT LOW MOVING TO WESTERN ALEUTIANS SUNDAY NIGHT. MODELS DO
ALL INDICATE AN AMPLIFYING TROUGH AS SHORT-WAVES DROP INTO THE
WESTERN BERING SEA. IF THIS DOES OCCUR...EXPECT A STRONGER LOW AND
STRONGER WINDS AS MUCH COLDER AIR IS TRANSPORTED SOUTHWARD INTO THE
WESTERN BERING. IN ANY CASE LOOK FOR RAIN AND WINDS TO PICK BACK
UP ACROSS BERING SEA REGION FIRST HALF OF THE WEEK. LOOK FOR MOST OF
SOUTHWEST ALASKA TO REMAIN DRY THROUGH THE NEXT SEVERAL DAYS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...SNOW ADVISORY ZONE 141.
MARINE...GALES 130 150 155 AND 176.

SEB OCT 06