Small Craft Advisory 779, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM ADT WED SEP 28 2005

.DISCUSSION...
STRONG LOW PRESSURE SYSTEM CENTERED NEAR KODIAK ISLAND CONTINUES TO
PRODUCE PLENTY OF WEATHER ACROSS THE STATE.  WATER VAPOR IMAGERY
SHOWS THE JET MOVING ACROSS THE SOUTHERN PORTION OF THE FORECAST AREA
AND PUSHING NORTHWARD OVER THE PANHANDLE.  300MB CHART SHOWS A 145KT
JET MAX EXITING THE TROUGH OVER THE NEXT 12 HOURS WHICH SHOULD HELP
THE LOW TO SLIDE EASTWARD TO JUST SOUTH OF THE PRINCE WILLIAM SOUND.
UPPER AIR ANALYSIS INDICATES THE LOW CENTER IS VERTICALLY STACKED BUT
TEMPERATURES ARE STILL FAIRLY COLD ALOFT WITH -24 C AT THE 500 MB
LEVEL.  THESE FACTS INDICATE THE LOW WILL WEAKEN OVER THE NEXT COUPLE
OF DAYS BUT STRONG SHOWERS CAN BE EXPECTED BEHIND THE FRONTAL SYSTEM.
THE BANDS OF SHOWERS ON THE MIDDLETON ISLAND RADAR AT THIS HOUR ARE
REFLECTING THAT FACT WELL.

AT 12Z THE MAIN OCCLUSION HAS MOVED ONTO THE MAINLAND AND IS NOW
STRETCHED ACROSS THE EASTERN PORTION OF THE KUSKOKWIM VALLEY AND UP
INTO THE TANANA VALLEY.  MODERATE RAIN MAY BE PRESENT IN UPSLOPE
AREAS WITH THE PASSING OF THE OCCLUSION.  BEHIND THE OCCLUSION
SHOWERS ARE HEAVY AT TIMES.  THESE SHOWERS MAY BE AMPLIFIED BY
SEVERAL POST FRONTAL TROUGHS...THE FIRST OF WHICH CAN BE SEEN MAKING
ITS WAY ONSHORE IN THE SOUTHCENTRAL AND EASTERN SECTIONS OF THE
FORECAST AREA.  WINDS WILL STILL BE GUSTY TODAY BUT STRONG
WINDS...GREATER THAN 45 MPH...ARE NOT EXPECTED OVER THE MAINLAND AS
THE LOW BEGINS TO WEAKEN.  MARINE AREAS MAY SEE HIGHER GUSTS AND GALE
WARNINGS ARE EXPECTED OUT WEST IN PARTICULAR.

WEST OF THE MAINLAND...ALONG THE ALEUTIANS THE FLOW HAS BECOME MORE
NORTHWESTERLY BEHIND THE MAIN LOW CENTER. STRONG WINDS WILL BE A
CONCERN FOR THE CENTRAL ALEUTIANS BUT WEST OF NIKISKI A SHORTWAVE
RIDGE IS MOVING IN SO WINDS WILL DECREASE.  SHOWERS MAY BE PRESENT
BUT MARINE STRATUS IS MORE LIKELY WITH THE INCREASINGLY STABLE
ENVIRONMENT.

MODEL DISCUSSION...MODELS SHOWED GOOD INITIALIZATION WITH UPPER AIR
DATA.  SOLUTIONS ARE VERY SIMILAR TODAY SO BOTH GFS AND ETA LOOK GOOD
FOR THE SHORT TERM.

EXTENDED OUTLOOK...GFS SHOWS SOME STRONG COLD AIR ADVECTION MOVING
FROM THE NORTHWEST OVER THE WEEKEND.  WHILE AT THIS POINT IT IS A
LITTLE EARLY FOR SNOW AT THE SURFACE HIGHER ELEVATIONS MAY SEE A GOOD
DUSTING.  BY SUNDAY A SHORTWAVE RIDGE MOVES IN TEMPORARILY CLEARING
THINGS OUT FOR THE ANCHORAGE FORECAST REGION. THIS GOOD WEATHER WILL
BE SHORTLIVED THOUGH AS THE NEXT STRONG LOW PRESSURE SYSTEM MOVES
INTO THE GULF OF ALASKA ON MONDAY.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALES 132, 150, 155, 160, 165, 180, 170

LEW SEP 05