Small Craft Advisory 697, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
343 PM AKST MON NOV 7 2011

.SHORT TERM...A COLD UPPER LEVEL TROUGH IS MOVING ACROSS
SOUTHEAST ALASKA TODAY. THE SURFACE TROUGH IS LAGGING AND STILL
ACROSS THE EASTERN GULF. THIS WILL CONTINUE EAST THIS AFTERNOON
AND PUSH ACROSS SOUTHEAST ALASKA TONIGHT. RADAR AND SATELLITE
SHOW NUMEROUS SHOWERS ACROSS THE EASTERN GULF THAT ARE MOVING
ONSHORE IN WESTERLY FLOW. DID HAVE ISOLATED THUNDERSTORMS AS
UPPER TROUGH WENT THROUGH SITKA THIS MORNING BUT OVERALL
INDIVIDUAL SHOWERS ARE WEAKENING AND NO FURTHER ELECTRICAL
ACTIVITY EXPECTED. WILL STILL HAVE ICE PELLETS WITH STRONGER
SHOWERS THIS AFTERNOON.

 EXPECT PRECIP TO BECOME MAINLY SNOW SHOWERS NORTH OF FREDERICK
SOUND TONIGHT AS CAA IN LOWER LEVELS CONTINUE. THE AMOUNT OF
PRECIP WILL TAPER OFF AT THE SAME TIME SO SNOW AMOUNTS WILL
MAINLY BE LESS THAN 1 TO LOCALLY 2 INCHES. WESTERLY ACROSS THE
GULF WEAKENS THIS EVENING AND GAINS A SOUTHERLY COMPONENT AHEAD
OF NEXT FRONT LATER TONIGHT. AS LOW MOVES INTO CENTRAL GULF HILL
HAVE AN EASTERLY BARRIER JET DEVELOP AND REACH GALE FORCE BY
TUESDAY AFTERNOON ACROSS THE NORTHEAST GULF. SOLID SLY SCMR WINDS
AND STRONG WIND HEADLINE FOR SKAGWAY THIS AFTERNOON WILL DIMINISH
THROUGH THE EVENING AND EXPECT WIND TO SHIFT TO THE NORTH AHEAD
OF APPROACHING SYSTEM ON TUESDAY.

 RAIN...POSSIBLY MIXED WITH SNOW...WILL SPREAD TO THE CENTRAL
COAST BY EARLY TUESDAY. WILL START NORTHERN COAST OUT AS SNOW AND
THEN GO TO RAIN IN THE AFTERNOON WITH WAA. FOR INSIDE WATERS
EXPECT SNOW FOR NORTHERN PANHANDLE ON TUESDAY THAT WILL MIX WITH
RAIN FROM THE SOUTH DURING THE AFTERNOON. AGAIN AMOUNTS NOT
EXPECTED TO BE VERY MUCH SO WILL KEEP SNOW AMOUNTS TO AN INCH OR
TWO.

 GOOD MODEL AGREEMENT THROUGH THE SHORT TERM. USED AN AVERAGE OF
ALL MODEL POSITIONS FOR LOW CENTER AND FRONTAL POSITION BUT
TRENDED TO STAY WITH THE DEEPEST CENTRAL PRESSURE TO BARRIER GALE
IN NE GULF.

.LONG TERM...THE FORECAST MODELS CONTINUE TO BE IN GOOD AGREEMENT
THROUGH MOST OF THE WEEK BUT ARE STILL STRUGGLING OVER THE
WEEKEND. THE GFS CONTINUES TO SHOW A LOW MOVING INTO THE AND THE
NEW EC IS NOW SHOWING SOMETHING CLOSE TO THAT SOLUTION. THERE IS
ALSO ENSEMBLE MEAN AGREEMENT WITH THE LOW MOVING INTO THE SOUTHERN
GULF. AFTER THAT THERE IS SOME INDICATION THAT THERE WILL BE
ANOTHER SHOT OF COLD AIR LATE IN THE WEEKEND INTO EARLY NEXT WEEK.
FORECAST CONFIDENCE IN THAT PORTION OF THE FORECAST IS ABOUT
AVERAGE TO ABOVE AVERAGE THROUGH FRIDAY. USED A BLEND OF THE
NAM/EC THROUGH THURSDAY AFTERNOON THEN UPDATED THE EXTENDED PORTION
TO HPC.

AT THE START OF THE LONG RANGE PERIOD A LOW WILL BE WEAKENING OVER
THE NORTHERN GULF. A UPPER TROF WILL BE MOVING ACROSS THE NORTHERN
GULF AND PANHANDLE AND FALLING APART BUT WILL KEEP SOME PRECIP
OVER THE COAST AND SOUTHERN AREAS BUT THE NORTHERN INNER CHANNELS
WILL SEE THE PRECIP TAPPER OFF THROUGH THE NIGHT. THE WINDS OVER
THE GULF WILL BE WEAKENING ALONG WITH THE WINDS OVER THE INNER
CHANNELS. A LOW PRESSURE SYSTEM WILL LIFTING NORTH FROM THE EASTERN
PACIFIC THROUGH WED AND KEEP RAIN GOING OVER THE SOUTHERN AREAS
BUT THE NORTHERN AREAS WILL DRY OUT WITH JUST A CHANCE OF SOME
PRECIP THROUGH WED.

A UPPER LEVEL TROF WILL DRIFT ACROSS WEST AK AND INTO THE NORTHERN
GULF THROUGH THURSDAY AND DEVELOP A 985MB LOW. THIS WEATHER SYSTEM
WILL INCREASE WINDS TO GALES AS THE LOW DRIFTS EAST WITH MODERATE
PRECIP BY THURSDAY. THE WINDS OVER THE INNER CHANNELS WILL ALSO
INCREASE TO SMALL CRAFTS WILL SOME AREAS OF GALES. P-TYPE WILL
MAINLY BE LIQUID BUT THERE MAYBE AREAS OVER THE FAR NORTHERN AREAS
WHERE SNOW WILL BE MIXED IN. ONCE THE UPPER AND SURFACE LOW DRIFT
EAST OF THE AREA AN UPPER HIGH WILL BUILD AND ADVECT SOME COLDER
AIR OVER THE FORECAST AREA FRIDAY NIGHT AS A LOW PRESSURE SYSTEM
TRACKS ACROSS THE SOUTHERN GULF.

A LARGE UPPER LEVEL LOW WILL DROP SOUTH FROM THE ARCTIC AND SEND
COLD AIR OVER THE AREA OVER THE WEEKEND WITH ANOTHER LOW PRESSURE
SYSTEM OVER THE NORTHERN GULF. THIS WILL INCREASE THE THREAT FOR
FROZEN PRECIP BUT THERE IS DIFFERENCES IN THE MODELS SO THE
CONFIDENCE IS ON THE LOWER SIDE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ012-021-022-033>036-041-042-053.

&&

MM/ABJ