Small Craft Advisory 121, NWS Anchorage, AK

AREA FORECAST DISCUSSION SOUTHWEST ALASKA
500 PM AST SUN FEB 6 2005
.DISCUSSION...

ANALYSIS - MAJOR UPPER LOW COMPLEX OVER THE NW PACIFIC THIS MORNING
AS PART OF A 4-WAVE HEMISPHERIC PATTERN AT HIGHER LATITUDES. THIS
PATTERN IS IMBALANCED WITH THE ANCHOR NEAR GREENLAND. THE UPPER LOW
CENTER OVER ADAK SUPPORTS A VERY MATURE 966 MB STORM CENTER THERE. AN
EXTENSIVE FRONTAL SYSTEM HAS GONE ALOFT OVER THE INTERIOR THIS
MORNING BUT THE ASSOCIATED COLD FRONT IS THROUGH BRISTOL BAY TO A
DEVELOPING WAVE NEAR 52N 152W AT 15Z. GOES-10 REVEALS A SECONDARY
SYSTEM NEAR 45N 170W IN THE S QUAD OF THE MAIN LOW. WARM ADVECTION
AHEAD OF THIS SYSTEM HAS BROUGHT DROUGHT ENDING PRECIP TO MUCH OF
THIS GIGANTIC FORECAST AREA AND HAS BUILD A SIGNIFICANT UPPER RIDGE
ALONG 145W THIS MORNING. THIS SUPPORTS A 1037 MB HIGH CELL ON THE
CANADIAN SIDE OF THE CENTRAL ALCAN. ALL FOUR RADARS SHOW EXTENSIVE
PRECIP BANDS MOVING TOWARD THE NE AT 16Z. THE PLANETARY SCALE JET AT
250 MB 12Z IS ALMOST 2/3 AROUND THE HEMISPHERE STARTING IN THE
EASTERN ATLANTIC THROUGH INDIA THEN MERGING WITH THE POLAR JET ACROSS
THE N PACIFIC AT 150 KT TO AN EXIT NEAR 40N 152W - A GOOD POSITION
FOR THE DEVELOPING WAVE.

AER FORECASTS - ALL MODELS DEVELOP A 1003 MB WAVE JUST OFF KODIAK AT
00Z TODAY. BASED ON INITIALS WHERE DID IT COME FROM? FORTUNATELY
NATURE HAS ALREADY REVEALED HERSELF ON SATELLITE IMAGERY BUT THIS
WAVE MAY BE ALREADY DEEPER. THIS WAVE WILL CAUSE THE LOW LEVEL FLOW
TO BECOME MORE EASTERLY ONTO THE NORTH GULF COAST WHICH WILL CAUSE A
LITTLE MORE PRECIP SHADOW ON THE LEE SIDES. ALL MODELS INSIST THAT
THIS WAVE FIZZLES OUT BY 12Z MON. THE NEXT DEVELOPER IS THE SECONDARY
WHICH DEEPENS TO 978 MB JUST S OF SITKINAK BY 06Z TUE. ETA IS BEST ON
THIS ONE. GFS DRIVESW THIS LOW ACROSS THE KENAI PENINSULA TUE WHILE
THE 12Z ETA LETS IT DIE OUT OFF SEWARD 00Z WED. NOT MUCH CONFIDENCE
ON THE DEPTH OF LOWS MOVING INTO THE GULF IN MEDIUM RANGE FORECASTS.

ALU FORECASTS - THE MAIN SURFACE LOW SIMPLY FILLS THROUGH THE NEXT 48
HOURS WITH SOME EASTWARD MOVEMENT. ALL MODELS HAVE A SECONDARY LOW
DEVELOP NEAR BETHEL BY 18Z MON WITH A TROUGH UP INTO THE INTERIOR.
THE 12Z EAT IS PREFERRED ON THIS FEATURE BECAUSE THE GFS LOOKS TOO
DEEP AS IT MOVES FURTHER INTO WESTERN AK. A SERIES OF SECONDARY LOWS
DEVELOP ON THE S QUAD OF THE OLD MAIN LOW AND MOVE INTO THE WESTERN
GULF THROUGH WED.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...WIND ADVSRY 101 125 181 185 187 191. SNOW ADVSRY 145.
MARINE...GALES 120 130 138 150 155 170 172 176 185.
         HVY FRZ SPRAY 185.
FIRE WEATHER...NONE.

JC FEB 05