Small Craft Advisory 163, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AST WED FEB 14 2007

.DISCUSSION...

WITH THE UPPER JET WELL TO THE SOUTH AND GENERALLY WEAK FLOW ACROSS
THE STATE THE WEATHER IS SLOW TO CHANGE. CURRENT SHORT-TERM FORECASTS
LOOK GOOD AND ONLY MINOR ADJUSTMENTS WILL BE MADE WITH THE NEW
PACKAGE THIS AFTERNOON.

THE LOW COMPLEX SOUTH OF THE EASTERN ALEUTIANS/AKPENN HAS DEVELOPED
TWO CENTERS OF ROTATION. THIS HAS TIGHTENED UP THE PRESSURE GRADIENT
A LITTLE MORE THAN THOUGHT SO THAT GALES ARE BEING OBSERVED ALONG
THE COASTAL WATERS SOUTH OF THE AKPENN AND EASTERN ALEUTIANS. EXPECT
WINDS TO REALLY LIGHTEN UP THIS AFTERNOON/EVENING BEHIND THE OCCLUDED
FRONT. PRECIPITATION TYPE FORECAST IS A BIT TRICKY FOR THESE AREAS.
COLD BAY 12Z SOUNDING SHOWS LOTS OF LOW LEVEL COLD AIR IN PLACE WITH
ABOVE FREEZING TEMPS LIMITED TO THE SURFACE. WARMER AIR ALOFT WILL
MOVE IN THIS AFTERNOON AS OCCLUDED FRONT REACHES LAND.
HOWEVER...ADVECTION IS WEAK...THERE IS NO BIG PUSH FROM THE
SOUTH...AND MODELS SHOW TEMPS ALOFT WILL REMAIN BELOW FREEZING.
THEREFORE...THINK PRECIP WILL BE MAINLY SNOW...POSSIBLY MIXED WITH
RAIN ALONG THE PACIFIC COAST WHERE THE MARINE LAYER MAY BE WARM
ENOUGH TO MELT THE FALLING SNOW. THE LOW WILL SLOWLY DRIFT OFF TO
THE EAST AND DISSIPATE TONIGHT THROUGH FRIDAY JUST LEAVING SCATTERED
SNOW SHOWERS IN ITS WAKE.

FOR SOUTHCENTRAL ALASKA THERE ARE A FEW SHOWERS LEFT FROM A FRONT
THAT FELL APART ALONG THE COAST LAST NIGHT. BUT FOR THE MOST PART
THERE ARE JUST MID TO HIGH LEVEL CLOUDS. AN UPPER LEVEL TROUGH AXIS
LYING EAST-WEST OVER THE CENTRAL GULF WILL MOVE NORTHWARD ACROSS
SOUTHCENTRAL TONIGHT. ONCE AGAIN EXPECT MINIMAL IMPACT WITH A FEW
SHOWERS ALONG THE COAST AND CLOUDS ELSEWHERE. REMNANTS OF AKPENN
LOW WILL REMAIN OUT OVER THE GULF SO EXPECT CONTINUED DRY CONDITIONS
ACROSS MOST OF SOUTHCENTRAL.

SOUTHWEST ALASKA...SATELLITE IMAGERY SHOWS MOISTURE SPREADING FROM
THE GULF/SOUTHCENTRAL TO SOUTHWEST ALASKA. AS UPPER TROUGH MOVES
NORTHWARD TONIGHT MAY SEE A FEW AREAS OF LIGHT PRECIP. WILL THEN
DRY OUT FOR THE REST OF THE WEEK.

THE NEXT BIG STORM TO AFFECT THE ANCHORAGE AOR IS CURRENTLY SPINNING
OFF THE COAST OF CHINA. MODEL RUN-TO-TUN CONSISTENCY WITH THIS SYSTEM
IS FAIR...SPEED IS VERY CONSISTENT WHILE DEPTH OF LOW ONCE IT REACHES
THE ALEUTIANS HAS FLUCTUATED FROM RUN-TO-RUN. THE LATEST GFS IS UP TO
6 MB WEAKER THAN THE PREVIOUS SOLUTION AND IN LINE WITH THE OTHER
MODELS. ALSO...MODELS INDICATE TRIPLE POINT DEVELOPMENT FROM 42 TO 48
HOURS. WITH UPPER JET SUPPORT AND LOTS OF COLD AIR BEING PULLED INTO
THE SYSTEM FROM SIBERIA THIS MAKES A LOT OF SENSE. THIS TRIPLE POINT
LOW WILL QUICKLY BECOME THE DOMINANT LOW THAT MOVES TO THE WESTERN
ALEUTIANS FRIDAY AFTERNOON AND INTO THE CENTRAL BERING FRIDAY NIGHT.
CONSISTENT WITH THE CURRENT FORECAST EXPECT WIDESPREAD MAX GALES
(POSSIBLY A FEW AREAS OF MIN STORMS) WITH THIS SYSTEM. STRONG WARM
ADVECTION AHEAD OF IT WILL PRODUCE RAIN ACROSS THE
ALEUTIANS/AKPENN/CENTRAL BERING AND SNOW ON THE BACK SIDE OF THE LOW
ACROSS THE WESTERN ALEUTIANS. ITS WAY TOO EARLY...BUT AS THE SYSTEM
GETS CLOSER WILL NEED TO TAKE A LOOK AT THE POTENTIAL FOR BLIZZARD
CONDITIONS ON THE BACK SIDE OF THE LOW SINCE COLD ADVECTION LOOKS TO
BE SIGNIFICANT AND WINDS WILL BE STRONG.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...NONE.

SEB FEB 07