Gale Warning 111, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
1215 PM AKST FRI FEB 26 2010

.ANALYSIS AND UPPER LEVELS...
AN UPPER LEVEL LOW IS CENTERED NEAR NORTON SOUND AND IS BECOMING
NEARLY STATIONARY. WITH SOUTHWEST FLOW STILL PRESENT OVER
SOUTHCENTRAL ON THE SOUTHEAST SIDE OF THE UPPER LOW...A FEW FLURRIES
ARE STILL BEING SQUEEZED OUT...BUT THESE SHOULD TAPER OFF SOON. A
WEAK RESIDUAL SURFACE TROUGH IS ALSO PRESENT ALONG THE NORTH GULF
COAST WITH LOCALLY GUSTY OFFSHORE WINDS. A COL IS PRESENT OVER THE
EASTERN BERING AND ALASKA PENINSULA...BUT HEADING FURTHER SOUTH
THERE IS A VERY STRONG STORM FORCE TO POSSIBLY HURRICANE FORCE
SURFACE LOW PRESSURE SEVERAL HUNDRED MILES SOUTH OF THE EASTERN
ALEUTIANS. THIS LOW HAS GOOD UPPER LEVEL JET SUPPORT BUT THE
STRONGEST WINDS AND MOST OF THE PRECIP WILL REMAIN SOUTH OF THE
ALEUTIANS AND ALASKA PENINSULA WITH THIS SYSTEM. AN UPPER LEVEL
RIDGE IS PRESENT OVER THE WESTERN BERING/ALEUTIANS. VERY COLD AIR IS
PRESENT OVER THE INTERIOR...STRETCHING SOUTHWEST INTO MUCH OF THE
BERING SEA.

.MODEL DISCUSSION...
GOOD MODEL AGREEMENT AND HIGH CONFIDENCE IN THE FORECAST THROUGH
SUNDAY. THEN MODEL AGREEMENT GRADUALLY BEGINS TO DEGRADE.

THE STRONG LOW SOUTH OF THE EASTERN ALEUTIANS TODAY WILL STAY SOUTH
OF THE AREA MOVING EAST ALONG 46N...BUT SEVERAL TRIPLE POINTS WILL
FORM TO ITS NORTH ALONG A FRONT AND MOVE INTO THE WESTERN GULF OF
ALASKA. MODEL AGREEMENT SUNDAY NIGHT ONWARD IS NOT SO GOOD REGARDING
WHERE EXACTLY THE TROUGH AXIS SETS UP IN THE WEST/NORTHWEST
GULF...AND A COMPROMISE SOLUTION IS PROBABLY PRUDENT FOR NOW.

OUT WEST...ALL MODELS BRING A STRONG LOW TO NEAR THE WESTERN
ALEUTIANS MONDAY MORNING AND THEN INTO THE SOUTHERN BERING.
HOWEVER...MODELS DO DISAGREE AS TO WHETHER THIS WILL BE A HURRICANE
FORCE LOW OR A STORM FORCE LOW (12Z GFS IS STRONGEST WITH 85 KT
BOUNDARY LAYER WINDS) AND THEY DISAGREE A BIT ON THE TRACK...BUT
GIVEN THAT THIS IS STILL A COUPLE DAYS OUT...MODELS ARE DOING JUST
FINE. MODELS FALL APART AS TO WHERE THIS LOW HEADS IN THE MIDDLE OF
THE WEEK AFTER IT LEAVES THE BERING. MOST MODELS BRING ANOTHER VERY
STRONG LOW ALONG A SIMILAR TRACK THROUGH THE BERING/ALEUTIANS
THURSDAY/FRIDAY.

.SHORT TERM FORECAST...
SOUTHCENTRAL...
WEAK RIDGING WILL DEVELOP TONIGHT OVER SOUTHCENTRAL WITH DECREASING
CLOUDS AND ANY REMAINING FLURRIES WILL TAPER OFF. HOWEVER...THE
BREAK WILL BE SHORT-LIVED. A FEW TRIPLE POINT LOWS WILL DEVELOP
ALONG THE FRONT RUNNING OUT AHEAD OF THE MONSTER NORTH PACIFIC LOW.
THESE TRIPLE POINTS LOWS WILL MOVE TO JUST EAST OF KODIAK
SUNDAY...THEN GRADUALLY ELONGATE INTO A TROUGH AXIS OVER THE
NORTHWEST GULF. GALE FORCE WINDS CAN BE EXPECTED OVER MARINE AREAS
WITH THIS SYSTEM. CLOUDS WILL INCREASE LATE SATURDAY AND PRECIP WILL
BEGIN SATURDAY NIGHT. PRECIP WILL GENERALLY BEGIN AS SNOW...AND
ANCHORAGE COULD SEE A LIGHT OVERRUNNING EVENT SATURDAY NIGHT BEFORE
THE DOWNSLOPE KICKS IN. KODIAK WILL BE A TRICKY FORECAST...WITH
PRECIP BEGINNING AS SNOW...POSSIBLY CHANGING TO RAIN BUT HIGHLY
SENSITIVE TO THE LOW TRACK...THEN CHANGING BACK TO SNOW. THE PRINCE
WILLIAM SOUND AREA WILL BEGIN AS SNOW BUT PROBABLY CHANGE TO RAIN AT
SEA LEVEL SUNDAY OR SUNDAY NIGHT. AGAIN...THOUGH...THIS IS HIGHLY
SENSITIVE TO THE LOW TRACK AND IF THE LOW TRACKS FURTHER EAST THEN
ALL BETS ARE OFF. UNSETTLED WEATHER SHOULD CONTINUE INTO MONDAY AS
THE TROUGH AXIS OVER THE NORTHWEST GULF ELONGATES AND NEARLY STALLS.

SOUTHWEST MAINLAND...
THE UPPER LEVEL LOW OVER NORTON SOUND IS NOT TOO MUCH OF A
WEATHER-MAKER FOR THE SOUTHWEST...WITH MOSTLY CLEAR SKIES AND COLD
TEMPERATURES CONTINUING INTO SATURDAY. SOME SNOW ASSOCIATED WITH THE
GULF LOW SHOULD SNEAK WEST ACROSS THE ALEUTIAN RANGE SUNDAY AND
SUNDAY NIGHT...BUT THE KUSKOKWIM DELTA SHOULD REMAIN DRY AND VERY
COLD. MAY NEED WIND CHILL ADVISORIES AT SOME POINT OVER THE NEXT FEW
DAYS FOR THE KUSKOKWIM DELTA AS WINDS PICK UP A BIT.

BERING SEA/ALEUTIANS...
COLD...SHOWERY NORTHERLY FLOW CONTINUES OVER MUCH OF THE REGION.
ESPECIALLY COLD IS SAINT PAUL WHERE THE PROXIMITY OF THE ICE EDGE IS
MAKING TEMPS STRUGGLE TO TOP ZERO. NORTHERLY FLOW OVER THE EASTERN
BERING AND ALASKA PENINSULA WILL FURTHER INCREASE TONIGHT AND
SATURDAY AS THE MONSTER LOW SOUTH OF THE AREA MOVES EAST AND HELPS
TO DRAW THE COLD AIR FURTHER SOUTH. A GALE FORCE FRONT SOUTH OF A
PARENT LOW NEAR KAMCHATKA WILL MOVE THROUGH WESTERN ALEUTIANS
SATURDAY BUT GRADUALLY FALL APART AS IT MOVES INTO THE HIGH PRESSURE
IN THE CENTRAL BERING. THIS WILL BE CHILD'S PLAY COMPARED TO
UPCOMING POTENTIALLY VERY STRONG LOW PRESSURE SYSTEMS NEXT
WEEK...THE FIRST OF WHICH COMES AROUND MONDAY.

.LONG TERM FORECAST...
VERY ACTIVE PATTERN CONTINUES NEXT WEEK WITH THE UPPER LEVEL JET
STREAM FINALLY FURTHER NORTH AND IN OUR AREA. ACTIVE WEATHER WILL BE
PRESENT OVER THE ENTIRE AREA...BUT ESPECIALLY IN THE
BERING/ALEUTIANS WHERE A COUPLE STRONG SURFACE LOWS SHOULD MOVE
THROUGH.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING ZONES 130 132 138 140 150 155 165 170 171 172
          175 176 351 352 411 412 413.
         HEAVY FREEZING SPRAY WARNING ZONES 130 140 150 155 160 165
          170 171 172 411 412 413 414.
FIRE WEATHER...NONE.

FOISY FEB 10