Gale Warning 469, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
344 PM AKST THU DEC 22 2011

.SHORT TERM...A STORM FORCE LOW IN THE NORTH CENTRAL GULF AND
ITS ASSOCIATED FRONTAL BAND IS BRINGING STRONG WINDS AND
WIDESPREAD RAIN TO THE REGION. THESE CONDITIONS ARE EXPECTED TO
CONTINUE THROUGH TONIGHT WITH SNOW AT HIGHER ELEVATIONS SUCH AS
HYDER AND EAGLE CREST. LATE TONIGHT THE MAIN TROUGH WILL PASS
WITH SELY WINDS SHIFTING TO THE SW FOR A TIME AND A RIDGE OF HIGH
PRESSURE BUILDING IN BEHIND IT. AS THE RIDGE BUILDS IN THE N-S
PRESSURE GRADIENT WILL INCREASE...CAUSING SOUTHERLY WINDS TO
REMAIN STRONG...DESPITE THE LLJ ALONG THE FRONT HAVING PASSED.
RAIN WILL TURN TO SHOWERS BEHIND THE FRONT AND MIX WITH SNOW
EARLY FRIDAY MORNING ACROSS NORTHERN AREAS.

 MAIN FORECAST CHALLENGE FOR THIS PACKAGE WAS WIND SPEEDS. MOST
AREAS HAVE SEEN WINDS INCREASE THROUGH THE DAY WITH PEAK WINDS OF
40 MPH RANGING TO 85 KNOTS AT LINCOLN ROCK. THESE WERE
UNDERESTIMATED BY THE MODELS...SO THAT WAS THE MAIN CHANGES THAT
WERE MADE. OTHERWISE MODELS WERE IN GOOD AGREEMENT AND USED AN
ENSEMBLE APPROACH TO UPDATE THE GOING FORECAST. FORECASTER
CONFIDENCE IS ABOUT AVERAGE.

 &&

 .LONG TERM...ACTIVE STORM TRACK AIMED AT SOUTHEAST AK CONTINUES
THROUGH EARLY NEXT WEEK. COLDER AIR WILL MOVE SOUTH FROM THE AK
INTERIOR WRAPPING INTO SOUTHEAST AK NEXT WEEK. WEATHER WILL
REMAIN TO BE WET AND BREEZY WITH A MIX OF RAIN AND SNOW.

 FOR FRIDAY EVENING A 980 MB LOW NEAR 50N 150W WILL TRACK ALONG
THE SOUTHERN AK GULF AS A TRIPLE POINT LOW FORMS ALONG OCCLUDED
FRONT IN THE CENTRAL AK GULF. THIS SECONDARY LOW WILL MOVE INLAND
JUST NORTH OF YAKUTAT BAY FRIDAY NIGHT AS THE PARENT LOW DEEPENS
AS IT TRACKS NORTHEAST INTO THE EASTERN AK GULF THROUGH SAT
EVENING. WITH SOME COLDER AIR MOVING IN WILL SEE PRECIPITATION
BECOME A RAIN SNOW MIX BUT AT THIS TIME NOT EXPECTING ANY
SIGNIFICANT ACCUMULATIONS. NEXT LOW FOR MONDAY WILL HAVE A
SIMILAR TRACK, MOVING ACROSS THE SOUTHERN AK GULF THEN TRACKING
NE INTO THE CENTRAL GULF TOWARDS YAKUTAT BAY. REMNANTS OF THIS
LOW BECOME QUASI STATIONARY IN THE NORTHERN GULF TUE INTO WED AS
NEXT SERIES OF LOW PRESSURE SYSTEMS MOVE ACROSS THE NORTHERN
GULF.

 MODELS WERE IN FAIR AGREEMENT FOR THE START OF THE LONG TERM
WITH NAM BECOMING AN OUTLIER FAIRLY QUICKLY. WHILE GFS
INITIALIZATION WAS A BIT BETTER THAN EC WHEN COMPARING RH TO
WATER VAPOR SATELLITE LIKED THE EC INITIALIZATION OVER GFS WHEN
COMPARING SURFACE PRESSURE FEATURES. MODELS BEGIN TO DIVERGE BY
00Z MON WITH THE STRENGTH OF THE NEXT GULF LOW WITH 00Z GFS
SHOWING A DEEPER LOW CENTER COMPARED TO THE EC. 12Z GFS AND EC
WERE IN FAIR AGREEMENT BUT STARTING TO SEE SOME RUN TO RUN
INCONSISTENCIES IN THE EC. THAT SAID STILL USED THE 12Z TO NUDGE
GRIDS THROUGH DAY 4 THEN TRANSITIONED TO HPC GUID WHICH WAS
WEIGHED TO THE EC ENSEMBLE. FORECAST CONFIDENCE IS ABOUT AVERAGE
AT THE START OF THE LONG TERM THEN DROPS BELOW AVERAGE BY THE
START OF NEXT WEEK.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND THROUGH LATE TONIGHT FOR AKZ020-024-026.
         HIGH WIND WARNING UNTIL 9 PM AKST THIS EVENING FOR AKZ023-027-
     028.
         STRONG WIND FROM 9 PM THIS EVENING TO MIDNIGHT AKST TONIGHT FOR
     AKZ023-027-028.
         STRONG WIND THROUGH FRIDAY MORNING FOR AKZ025.
         STRONG WIND UNTIL MIDNIGHT AKST TONIGHT FOR AKZ022.
         STRONG WIND UNTIL 3 AM AKST FRIDAY FOR AKZ021.
         STRONG WIND THROUGH FRIDAY MORNING FOR AKZ018-019.
         STRONG WIND UNTIL 9 PM AKST THIS EVENING FOR AKZ017.
MARINE...STORM WARNING FOR PKZ036.
         GALE WARNING FOR PKZ011>013-022-031>035-041>043.
         SMALL CRAFT ADVISORY FOR PKZ021-051>053.

&&

HANNON/PRB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
1115 AM AKST THU DEC 22 2011

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

1115 AM     NON-TSTM WND GST KETCHIKAN               55.34N 131.65W
12/22/2011  M61 MPH                             AK   MESONET

            AT 853 AM, GUST 61 MPH MEASURED AT KETCHIKAN AIRPORT
            TOWER...ELEVATION 90 FT.

&&

TPS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
200 PM AKST THU DEC 22 2011

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

0142 PM     SNOW             40 NW HAINES            59.65N 136.25W
12/22/2011  M6.5 INCH        XXX                XX   CO-OP OBSERVER

            AT 830 AM, 24 HOUR SNOWFALL OF 6.5 INCHES MEASURED AT
            HAINES CUSTOMS. CHANGED TO RAIN SHORTLY AFTER WITH LITTLE
            ADDITIONAL ACCUMULATION. DRIZZLE FALLING AS OF 145 PM.

0142 PM     SNOW             6 NE SKAGWAY            59.54N 135.21W
12/22/2011  M7.0 INCH                           AK   CO-OP OBSERVER

            AT 830 AM, 24 HOUR SNOWFALL OF 7 INCHES MEASURED AT
            SKAGWAY CUSTOMS. CHANGED TO RAIN SHORTLY AFTER WITH
            LITTLE ADDITIONAL ACCUMULATION. MODERATE RAIN FALLING AS
            OF 145 PM.

&&

TPS