Gale Warning 351, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
120 PM AKDT FRI APR 10 2009

.ANALYSIS AND UPPER LEVELS...A LONGWAVE TROUGH IS SITUATED OVER
WESTERN ALASKA ANCHORED BY A LOW SOUTH OF KODIAK ISLAND. MOIST
SOUTHERLY FLOW CAN BE FOUND OUT AHEAD OF THIS TROUGH OVER THE
SOUTHERN MAINLAND...WITH COLD AIR POURING SOUTH ACROSS THE EASTERN
BERING SEA.

.MODEL DISCUSSION...A NAM/GFS BLEND WAS USED FOR THE FIRST FEW DAYS
OF THE FORECAST AS LITTLE DISCREPANCIES WERE NOTED IN EITHER MODEL.
THE LOW IN THE GULF WILL MEANDER FOR SEVERAL DAYS BEFORE SKIRTING SE
SUNDAY AFTERNOON. TIMING BETWEEN MODELS IS ALSO GOOD OUT WEST WITH
REGARDS TO A FRONT APPROACHING THE WESTERN ALEUTIANS ON SATURDAY.
BEYOND THE WEEKEND...MODELS SOLUTIONS BEGIN TO DIVERGE...BUT THE
OVERALL PATTERN REMAINS VIRTUALLY UNCHANGED. HPC GUIDANCE HAS BEEN
MOST CONSISTENT IN THE LONGER RANGE AND THUS WAS RELIED ON HEAVILY
FOR THE LATTER PART OF THE FORECAST.

.SHORT TERM FORECAST...EAST TO SOUTHEAST FLOW WILL CONTINUE THE RAIN
SHADOW OVER THE ANCHORAGE BOWL AND WEST KENAI PENINSULA. MODERATE TO
HEAVY SNOW WILL CONTINUE TONIGHT ALONG PRINCE WILLIAM SOUND
(ESPECIALLY THE WEST SIDE) WITH A MIX OF RAIN AND SNOW FURTHER EAST.
THE FRONTAL BOUNDARY CURRENTLY JUST OFF THE NORTH GULF COAST WILL
PUSH INLAND OVERNIGHT PROMOTING A BRIEF SURGE OF MOISTURE INTO THE
COPPER RIVER BASIN. MORE OF A SHOWERY REGIME TAKES OVER FOR THE
WEEKEND AS THE LOW SLOWLY PULLS AWAY AND FILLS.

A WEAK CIRCULATION UNDER THE MAIN TROUGH OUT WEST CONTINUES TO
PROMOTE LIGHT SNOW SHOWERS AND AREAS OF FOG UNDER LIGHT ONSHORE FLOW.
COLD ADVECTION POURING DOWN THE BACK SIDE OF THE LOW IS AIDING IN
GUSTY GAP WINDS ALONG THE AKPENN. THESE WINDS WILL DIMINISH OVERNIGHT
AS THE LOW MOVES EAST. BRIEF HIGH PRESSURE IN THE BERING WILL RESULT
IN RATHER BENIGN WEATHER WITH THE EXCEPTION OF AREAS OF FOG. THE NEXT
FRONT APPROACHES THE WESTERN ALEUTIANS ON SATURDAY BRINING GALE FORCE
WINDS AND MAINLY RAIN. THIS FRONT AND ASSOCIATED LOW GETS SHUNTED TO
THE SOUTH AND EAST AS THE HIGH OVER THE CENTRAL BERING HOLDS STRONG.

.LONG TERM FORECAST...AS STATED ABOVE...MODELS BECOME CONFUSED AFTER
THE WEEKEND, BUT THE BASIC PATTERN REMAINS UNCHANGED. NORTH PACIFIC
LOWS MOVE INTO THE WESTERN ALEUTIANS...BUT THEN ARE SHUNTED SOUTH AND
MOVE INTO THE SOUTHERN GULF OF ALASKA. THIS TYPE OF PATTERN KEEPS THE
MAINLAND MOSTLY DRY WITH SEASONABLE TEMPERATURES.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 172 175 176.
FIRE WEATHER...NONE.

JCA