Small Craft Advisory 900, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
300 PM ADT FRI OCT 26 2007

.MODEL DISCUSSION...THE GOOD IS THAT IN THE SHORT TERM THE MODELS ARE
ARE ALIGNED WELL AND SEEM TO BE WORKING OUT.
THE BAD IS THAT THERE IS WHAT APPEARS TO BE AN EXTRA-TROPICAL SYSTEM
THAT WILL MOVE INTO THE ALEUTIANS LATE THIS WEEKEND THAT IS CAUSING
THE MODELS DIFFICULTY. THE GFS LOOKS TO BE HANDLING THE SYSTEM THE
BEST OUT OF ANY OF THEM. IT HAS BEEN SPEEDING UP THE STORMS TRACK BUT
KEEPS DROPPING THE PRESSURE DOWN TO 950 MB OR A LITTLE LESS. THE
ECMWF SEEMED TO BE DOING WELL UNTIL THE LAST RUN WHEN IT SHIFTED THE
LOW MUCH FARTHER SOUTH AND THEN DROP THE PRESSURE BUT NOT AS DEEP AS
THE GFS. THIS SERIOUS JUMP IN THE SOLUTION IS CAUSE FOR CONCERN. IN
ADDITION TO THIS THE ECMWF IS BRINGING THE LOW RIGHT UP COOK INLET
AND DROPPING A NEW LOW INTO THE BERING SEA IN THE  MIDDLE OF NEXT
WEEK. THE GFS KEEPS THE LOW STRONGER AND IN THE NORTHERN GULF OF
ALASKA WITHOUT THE BERING SEA LOW. THIS GFS SOLUTION LOOKS A LOT MORE
REASONABLE THAN THE ECMWF.
THE UGLY IS THE UKMET SOLUTION WHICH DOWNPLAYS THE EXTRA-TROPICAL
SYSTEM AND HAS A MUCH DIFFERENT TRACK THAN THE OTHER MODELS. THIS
LOOKS TO BE THE TYPICAL PROBLEM WHERE THE MODELS DO NOT REALIZE THE
DEPTH OF THE MOISTURE AND THE POTENTIAL FOR THE SYSTEM TO RAPIDLY
DEEPEN.

.ANALYSIS AND UPPER LEVELS...THE LONGWAVE TROUGH REMAINS OVER
MAINLAND ALASKA THIS AFTERNOON AND WILL REMAIN THERE FOR AWHILE.
THE LOW THAT WAS IN THE GULF OF ALASKA THIS MORNING HAS NOW HEADED
INLAND SOUTHEAST OF YAKUTAT. ANOTHER LOW IS SOUTHWEST OF ST PAUL AND
WILL MOVE SOUTHEAST TONIGHT BEFORE DISSIPATING EAST OF KODIAK SUNDAY.

.SHORT TERM FORECAST...A SNOW ADVISORY WAS ISSUED THIS MORNING FOR
THE SUSITNA VALLEY FROM CHULITNA TO BROAD PASS. THE RAIN SHOWERS THAT
WERE OVER THE COOK INLET AREA TURNED TO SNOW ALONG THE SOUTHERN
SLOPES OF THE ALASKA RANGE AND HAVE BEEN DROPPING A SIGNIFICANT
AMOUNT OF SNOW THERE TODAY. THIS SHOULD LIGHTEN UP BY EARLY EVENING.
THIS OVERALL PATTERN WILL KEEP SOUTHEAST TO SOUTHWEST FLOW OVER
MAINLAND ALASKA THROUGH MOST OF THE WEEKEND. THIS WILL PRODUCE RAIN
AND SNOW SHOWERS AS A RESULT.

.LONG TERM FORECAST...THE BIG STORY IN THE LONG TERM WILL BE THE
STRONG STORM MOVING INTO THE ALEUTIAN ISLANDS AND ALASKA PENINSULA
EARLY NEXT WEEK. THIS SYSTEM LOOKS TO BE EXTRA-TROPICAL AND WILL
RAPIDLY DEEPEN AS IT HEADS INTO ALASKAN WATERS. THIS SYSTEM SHOULD BE
WARM ENOUGH TO BE MOSTLY RAIN AND NOT TURN TO SNOW EXCEPT WEST OF THE
LOW AS IT BRINGS IN COLDER AIR OUT OF THE WESTERN BERING SEA. THIS
SHOULD KEEP IT FROM GETTING INTO BLIZZARD CONDITIONS WITH THIS SYSTEM
WHICH WOULD BE A CONSIDERATION IF IT WAS A BIT COLDER. STRONG WIND
WILL BE THE BIGGEST ISSUE WITH THIS STORM.
THIS SYSTEM SHOULD THEN MOVE INTO THE GULF OF ALASKA IN THE MIDDLE OF
NEXT WEEK AND AS MENTIONED EARLIER THE TRACK IS STILL VERY UNCERTAIN.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 170 172 175.
FIRE WEATHER...NONE.

OCT 07