Small Craft Advisory 874, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
347 PM AKST SUN DEC 25 2011

.SHORT TERM...CURRENTLY THE REGION IS BETWEEN SYSTEMS WITH A
WEAKENING SURFACE RIDGE OVER THE PANHANDLE. COLD AIR ADVECTION
CONTINUES THIS EVENING WITH SCATTERED SNOW SHOWERS AND PARTLY TO
MOSTLY CLOUDY SKIES. A LOW PRESSURE SYSTEM IN MOVING INTO THE
CENTRAL GULF WILL CAUSE WINDS TO INCREASE TONIGHT ACROSS THE
GULF. EXPECT STRONG WINDS TO MOVE INTO THE SOUTHERN COASTAL AREAS
LATE TONIGHT. HAVE ISSUED A HIGH WIND WARNING FOR THE COASTAL
AREAS FROM ELFIN COVE SOUTH AND INTO KETCHIKAN WHERE GUSTS UP TO
60 MPH ARE POSSIBLE THROUGH MONDAY AFTERNOON ALONG A FRONTAL
BOUNDARY. ELSEWHERE STRONG WINDS WITH GUSTS OF UP TO 50 MPH ARE
EXPECTED ALONG THE FRONT AND HAVE STRONG WIND HEADLINES FOR THOSE
AREAS...REPLACING THE WATCHES THAT WERE PREVIOUSLY IN PLACE.
PRECIPITATION ASSOC WITH THIS FRONT WILL START OFF AS SNOW EARLY
IN THE MORNING THEN MIX WITH RAIN IN THE CENTRAL AREAS...AND
CHANGING TO ALL RAIN OVER THE FAR SOUTH. OUT THE HAINES HIGHWAY
HAS THE GREATEST LIKELIHOOD OF SNOW ACCUMULATIONS WHERE 3 TO
5 INCHES IS EXPECTED DURING THE DAY MONDAY. HAVE ISSUED A WINTER
WEATHER ADVISORY FOR AREAS WEST OF 24 MILE ALONG THE HAINES
HIGHWAY WHICH IS VALID THROUGH MONDAY EVENING.

 MODELS ARE IN GOOD AGREEMENT IN THE SHORT TERM. ADJUSTED
PRESSURE WITH THE SREF AND WINDS WITH THE GFS AS THEY SHOWED THE
STRONGER WINDS ALONG THE FRONT THE BEST...HOWEVER STILL ADJUSTED
THEM UP SLIGHTLY HIGHER IN THE MORE PRONE LOCATIONS.

&&

.LONG TERM...WEAKENING MONDAY STORM FORCE LOW WILL MOVE NORTH INTO
THE PRINCE WILLIAM SOUND REGION AS A SHORT WAVED DEVELOPED ALONG
THE SOUTHERN END OF THE FRONT WILL MOVE OVER THE PANHANDLE AND
INTO BRITISH COLUMBIA. WINDS AND PRECIP WILL DIMINISH EARLY
MONDAY EVENING INTO MONDAY NIGHT. WITH COLDER TEMPERATURES PRECIP
WILL TRANSITION TO SNOW WITH ACCUMULATIONS OF 1 TO 4 INCHES OVER
THE NORTHERN REGIONS. MAIN AREA OF CONCERN FOR SNOW FALL IS HAINES
BUT IF LOW LEVEL WINDS SHIFT NORTH MAY NOT SEE AMOUNTS EXCEED ADVY
LEVELS. HIGH PRESSURE RIDGE WILL BUILD OVER THE PANHANDLE TUE.
PRECIP WILL CONTINUE WITH ONSHORE FLOW ALONG THE EASTERN AREAS.
THE NEXT SYSTEM MOVING ALONG THE NORTH PACIFIC WILL TRACK INTO THE
SOUTHERN AK GULF WED, FINAL TRACK OF THE LOW STILL VERY UNCERTAIN.
REMAINDER OF THE WEEK INDICATE NEXT SYSTEM THU AND FRI WILL MOVE
JUST SOUTH OF THE PANHANDLE BUT LOTS OF MODEL DISCREPANCIES SO NOT
MUCH CONFIDENCE IN THAT SOLUTION. FOR THE WEEKEND INTO THE NEW
YEAR INDICATION OF YET ANOTHER STRONG LOW MOVING INTO THE GULF,
WILL HAVE TO WATCH AND WAIT FOR THAT ONE.

MODELS WERE AGAIN IN GOOD AGREEMENT FOR THE START OF THE LONG TERM
WITH BEST MATCH BETWEEN THE GFS AND EC. BOTH INITIALIZED WELL
COMPARING SURFACE AND SATELLITE FEATURES. EC WAS STILL A BIT
FASTER MOVING THE WEAKENING LOW NORTH COMPARED TO THE GFS. NAM WAS
AN OUTLIER WITH THE LOW CENTER MOVED MUCH FURTHER EAST. 00Z AND
12Z MODELS QUICKLY DIVERGE WITH RESPECT TO THE NEXT SYSTEM MOVING
INTO THE GULF ON WED. 12Z GFS MOVED TO LOW MUCH FURTHER NORTH
WHILE THE 00Z/12Z EC MOVED THE LOW OVER THEN CENTRAL PANHANDLE 00Z
WED. THE 18Z GFS RUN KEPT THE LOW A BIT FURTHER SOUTH BUT KEPT THE
LOW IN THE EASTERN GULF THEN MOVED THE LOW TOWARD PRINCE WILLIAM
SOUND THURSDAY. RUN TO RUN CONSISTENCY HAS BEEN RATHER POOR LATELY
AND WITH SUCH A LARGE MODEL SPREAD DECIDED NOT TO MAKE ANY
SIGNIFICANT UPDATES TO THE GRIDS DAY 3 ONWARD. NEW HPC GRIDS USED
A BLEND OF GFS AND EC ENSEMBLE MEANS AND WHILE IT DID HAVE SOME
DIFFERENCES FELT THERE WOULD BE NO ADDED BENEFIT TO UPDATE THE
LONG TERM FORECAST. FORECAST CONFIDENCE IS ABOUT AVERAGE FOR THE
START OF THE LONG TERM BUT DROPS SIGNIFICANTLY BY WED DUE TO MODEL
SPREAD AND RUN TO RUN INCONSISTENCY.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM 3 AM AKST MONDAY THROUGH MONDAY MORNING FOR
     AKZ020-024-026-029.
         HIGH WIND WARNING FROM 3 AM TO 4 PM AKST MONDAY FOR AKZ022-023-
     027-028.
         STRONG WIND MONDAY MORNING FOR AKZ019-021-025.
         WINTER WEATHER ADVISORY FROM 3 AM TO 9 PM AKST MONDAY FOR AKZ019.
         STRONG WIND FROM MONDAY MORNING THROUGH MONDAY AFTERNOON FOR
     AKZ018.
         STRONG WIND FROM 3 AM AKST MONDAY THROUGH MONDAY AFTERNOON FOR
     AKZ017.
MARINE...STORM WARNING FOR PKZ022-036-043.
         GALE WARNING FOR PKZ011>013-021-033>035-041-042-051>053.
         SMALL CRAFT ADVISORY FOR PKZ031-032.

&&

HANNON/PRB