Gale Warning 938, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKST WED NOV 10 2010

.MODEL DISCUSSION...

MODELS ARE IN GOOD AGREEMENT THROUGH THE SHORT TERM. SIGNIFICANT
DIFFERENCES ARISE IN THE MID AND LONG TERM PERIODS AS MODELS USUALLY
HAVE TROUBLE HANDLING PATTERN CHANGES. THE MAIN AREA OF CONCERN WAS
ADDING AND MAKING ANY NECESSARY CHANGES WITH THE LOW THAT WILL BEGIN
TO AFFECT THE GULF TODAY AND THE REST OF SOUTHCENTRAL BY TONIGHT.

.ANALYSIS AND UPPER LEVELS...

A LARGE AND DEEP UPPER TROUGH ENCOMPASSES THE BERING SEA EXTENDING
DOWN TO THE NORTH PACIFIC. A LOW IS STRENGTHENING SEVERAL HUNDRED
MILES SOUTH OF THE ALASKA PENINSULA THIS MORNING AND WILL BE PUSHED
TOWARDS THE GULF BY A STRONG JET STREAK. STRONG GALE TO STORM FORCE
WINDS WILL BE COMMON IN THE GULF AS WELL AS ADJACENT COASTAL
WATERS...INCLUDING LOWER COOK INLET TONIGHT AS THE INITIAL FRONT
MOVES ONSHORE. THE ACTUAL LOW WILL WEAKEN DURING THE DAY THURSDAY
BEFORE MAKING LANDFALL THURSDAY NIGHT ON THE KENAI PENINSULA AND
MOVING INLAND. A SECOND WEAKER LOW ON THE BACK SIDE OF THE TROUGH
WILL FOLLOW ONSHORE SOMETIME LATE FRIDAY. IN THE BERING...THE LARGE
UPPER LOW WILL CONTINUE TO SIT AND SPIN MULTIPLE LOW PRESSURE
DISTURBANCES AROUND IT INTO THE WEEKEND. WINDS SHOULD STAY ON THE LOW
SIDE BUT SHOWER CHANCES SHOULD REMAIN HIGH.

.SHORT TERM FORECAST...

SOUTH AND EAST OF THE ALASKA RANGE...

THE CULPRIT IN THE FORECAST OVERNIGHT AND THIS MORNING HAS BEEN
FOG...OR THE LACK THEREOF IN SOME PLACES. A WEAK DISTURBANCE MOVING
ACROSS THE AREA HAS PROBABLY HELPED PROVIDE ENOUGH LIFT TO KEEP THE
STRATUS DECK JUST ABOVE THE SURFACE IN MOST PLACES...AS WELL AS TO
ALSO SQUEEZE OUT A FEW FLURRIES. THE EXCEPTION APPEARS TO BE OUT OVER
THE INLET AND NORTH TOWARDS TALKEETNA...WHERE VISIBILITIES HAVE
OCCASIONALLY DROPPED TO ONE QUARTER MILE. WITH THE DENSE FOG ADVISORY
ALREADY OUT IN MOST PLACES UNTIL LATE MORNING...AND SHORTWAVE RIDGING
MOVING OVERHEAD PROVIDING SOME SUBSIDENCE OVER THE AREA THIS
MORNING...WILL LIKELY DROP THE ADVISORIES IN MOST PLACES BUT ISSUE
STRONG WORDING IN TEXT FORECASTS.

OTHERWISE...THE MAIN AREA OF CONCERN COMES WITH THE FRONT ASSOCIATED
WITH THE NORTH PACIFIC LOW MOVES NORTH THROUGH THE GULF. WILL MENTION
STRONG WINDS FOR KODIAK ISLAND TODAY...AND STORM FORCE WINDS WILL
MOVE THROUGH THE OFFSHORE REGION AND NEARBY COASTAL ZONES BY TONIGHT.
UPSLOPE AND ONSHORE FLOW WILL BRING FAIRLY HEAVY PRECIPITATION TO THE
SOUTH AND EAST FACING AREAS...WHILE DOWNSLOPE CONDITIONS ON NORTH AND
WEST FACING SLOPES WILL KEEP THOSE ON THE DRY SIDE FOR MOST OF THIS
STORM THROUGH FRIDAY NIGHT.

SOUTHWEST ALASKA...

NORTHERLY OFFSHORE FLOW WILL KEEP MOST OF THIS REGION DRY...THOUGH
THERE WILL LIKELY BE SOME SHOWERS ON THE BACK SIDE OF THIS LOW AS IT
MOVES NORTH THROUGH THE GULF. THERE IS THE CONCERN FOR SOME LIGHT
FREEZING RAIN TO FALL IN THE BRISTOL BAY ZONE...ESPECIALLY NEAR
DILLINGHAM...AS COLD AIR HAS BECOME ENTRENCHED NEAR THE SURFACE
AND WARMER AIR OVERRUNS IT ALOFT. A DISTURBANCE ROTATING AROUND THE
PARENT LOW IN THE BERING SEA COULD BRING ANOTHER SHOT AT SOME LIGHT
SNOW AND/OR FREEZING RAIN FRIDAY AFTERNOON AND EVENING MAINLY ALONG
THE COAST.

BERING SEA REGION...

THE UPPER LEVEL LOW OVER THE REGION WILL SLOWLY MOVE EAST TOWARDS THE
BRISTOL BAY REGION. COLD NORTHERLY FLOW WILL USHER IN WIDESPREAD
LIGHT SNOW SHOWERS TO MOST OF THE REGION ON THE BACK SIDE OF THE LOW
BY FRIDAY.

.LONG TERM FORECAST...

IT APPEARS MODELS ARE TRYING SLOWLY RETROGRADE THE EXISTING NORTHERN
HEMISPHERIC UPPER LEVEL PATTERN OF TROUGHS AND RIDGES WESTWARD LATE
THIS WEEKEND INTO EARLY NEXT WEEK. IF MODELS ARE CORRECT...THIS WOULD
LEAD TO UPPER LEVEL RIDGING OVER THE GULF...WITH ANOTHER RIDGE
EXTENDING NORTH AND WEST INTO THE NORTHERN BERING SEA. IF THIS WERE
TO VERIFY...COLDER AIR FROM THE NORTH AND WEST COULD ARRIVE IN
SOUTHCENTRAL ALASKA SOMETIME NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALES...125 129 140 160
         STORMS...120 130 132 138 150 155
FIRE WEATHER...NONE.

CC NOV 10