Small Craft Advisory 755, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
412 PM AKST SUN DEC 9 2012

.SHORT TERM... AT 2100 UTC SATELLITE AND RADAR SHOWS A LARGE
CONCENTRATION OF CONVECTIVE SHOWERS OVER THE EASTERN GULF AND
SOUTHEAST ALASKA...EXCEPT OVER THE OUTER COASTAL WATERS SOUTH OF
SITKA WHERE SHOWERS ARE MORE SCATTERED MOST STATIONS IN THE
PANHANDLE AND NORTHEAST GULF COAST ARE REPORTING ONSHORE
SOUTHWEST WINDS WITH ABOVE FREEZING TEMPERATURES AND
RAIN...HOWEVER IN THE CHILKAT RIVER VALLEY PERSISTENT NORTHWEST
WINDS HAVE KEPT TEMPERATURES IN THE 20S WITH SNOW. SHOULD SEE THE
WINDS SWITCH IN HAINES OVERNIGHT WHICH WILL CAUSE TEMPERATURES TO
RISE AND SNOW TO MIX WITH RAIN.

 MODELS ARE SIMILAR DIFFERENT IN THE TONIGHT PERIOD ALTHOUGH
SIGNIFICANT DIFFERENCES BEGIN GROW ON MONDAY AS A NEW LOW MOVES
NORTHEASTWARD INTO THE CENTRAL GULF OF ALASKA AND DEEPENS TO
990 MB. PREFER THE ECMWF WHICH IS A BIT SLOWER AND A BIT WEAKER
WITH THE RETURN TO NORTHERLY FLOW LATE MONDAY. EXPECT SHOWERS
WILL DIMINISH OVER NIGHT AND EARLY MONDAY BUT STEADY RAIN WILL
BEGIN TO SPREAD INTO THE PANHANDLE MONDAY AFTERNOON WITH THE
APPROACHING LOW. WINDS WILL INCREASE TO GALES IN THE OFFSHORE
LATE MONDAY WITH THE LOW.

.LONG TERM...CONFIDENCE IN THE POSITION OF THE NORTHERN GULF LOW
AS IT MOVES EASTWARD INTO THE PANHANDLE HAS NOT BEEN THE BEST FOR
A COUPLE OF DAYS NOW. CONFIDENCE STILL NOT THE BEST...BUT HAVE
OPTED FOR A SHIFT IN THINKING TODAY. THE ECMWF HAS FOLLOWED THE
GFS...THE MODEL OF CHOICE OVER THE LAST COUPLE OF DAYS...MUCH
BETTER THAN THE NAM. BUT THE ECMWF SEEMS TO HAVE CUT OFF THE
NORTHERLY FLOW IN THE MID WEEK BY NOT SUSTAINING AN INVERTED
TROUGH IN THE NORTHEAST GULF AS THE GFS DOES. SO HAVE DECIDED TO
SWITCH THINGS AROUND AND FOLLOW THE ECMWF'S LOW AS IT DIPS INTO
THE SOUTHERN PANHANDLE TUESDAY. LIKEWISE...ECMWF PREFERS STRONGER
RIDGING IN THE NORTHEAST GULF TUESDAY NIGHT AND IS MORE AGGRESSIVE
IN THE NEXT FRONTAL PASSAGE AND HENCE NEXT WAVE OF PRECIP INTO THE
NORTHERN GULF LATE TUESDAY NIGHT INTO WEDNESDAY.

THE CHANGE ALSO HAS STRENGTHENED THE LOW TO AT LEAST GALE FORCE
FOR THE SOUTHERN OUTSIDE WATERS MONDAY NIGHT. INSIDE CHANNELS WILL
UNDERGO A FLIP FROM MONDAY NIGHT INTO TUESDAY NIGHT FOR THE
GLACIER BAY...LYNN CANAL AND EVEN STEPHENS PASSAGE AT TIMES.
DIRECTIONAL WORDING WAS DIFFICULT FOR FREDERICK SOUND DUE TO A LOT
OF COMPLEX TERRAIN AND SOME GAP FLOWS.

THE PREVIOUSLY ADVERTISED BREAK IN THE CLOUDS AND THE WEATHER IS
STILL ON TAP FOR YAKUTAT AND THE NORTHERN PANHANDLE TUESDAY INTO
TUESDAY NIGHT BUT IT WILL BE A QUICK ONE...18 HOURS IF WE ARE
LUCKY. TUESDAY WORDED PRECIP IN THE SOUTHERN AND CENTRAL PANHANDLE
AS SHOWERS. HOWEVER...THE PRECIP TUESDAY NIGHT MOVING INTO THE
NORTHEAST GULF IS WORDED AS STRATIFORM.

IN THIS PROGRESSIVE PATTERN...PHASE DIFFERENCES BETWEEN MODELS ARE
MORE AND MORE PREVALENT THE MORE IN THE FUTURE YOU GO. ECMWF
TRANSITIONED ACCEPTABLY WITH HPC GUIDANCE FOR EXTENDED. ALL MODELS
ADVERTISING A NEW LOW TO ARRIVE IN THE GULF SOMETIME AROUND
FRIDAY...BUT DIFFER IN POSITION AND INTENSITY. ANOTHER LOW WILL
UNDERCUT THIS LOW SUNDAY. THE PROGRESSIVE WESTERLIES WILL KEEP
POPS HIGH THROUGH THE END OF THE FORECAST PERIOD.

MODEL OF CHOICE WAS ECMWF...BUT BLENDED WITH PREVIOUS
FORECAST...WHICH WAS VERY GFS-CENTRIC...SO IN A SENSE HAVE
CUSHIONED THE CHANGES MADE. CONFIDENCE IN FORECAST AVERAGE FOR
MIDRANGE AND IN THE EXTENDED RANGE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ012-022-033.
         SMALL CRAFT ADVISORY FOR PKZ011-013-021-031-032-034>036-041>043-
     051-052.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ053.

&&

CFD/JWA

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
1018 PM AKST SUN DEC 09 2012

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0700 AM     SNOW             2 W JUNEAU              58.30N 134.47W
12/09/2012  M6.0 INCH                           AK   NWS EMPLOYEE

            MEASURED 6 INCHES OF SNOW IN 9 HOURS AT BLUEBERRY HILLS
            RD. ELEVATION 420 FEET.

&&

NAH