Small Craft Advisory 163, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
331 PM AKST MON FEB 27 2012

.SHORT TERM...A FRONT DEPARTING THE REGION TO THE EAST HAS
CAUSED SNOW SHOWERS TO BECOME MORE SCATTERED THIS AFTERNOON FROM
WEST TO EAST. GUSTY SELY WINDS HAVE ALSO ACCOMPANIED THE FRONT
AND WILL DIMINISH THIS EVENING AS THE FRONT MOVES AWAY. UP TO AN
ADDITIONAL 1-3 INCHES IS POSSIBLE TONIGHT IN SHOWERS.

 AS THE ASSOCIATED LOW PRESSURE SYSTEM MOVES MORE INTO THE EAST-
CENTRAL GULF...EXPECT EASTERLY WINDS THROUGH E-W ORIENTED INSIDE
WATERS TO INCREASE. HAVE GONE WITH MAINLY SMALL CRAFT
ADVISORIES...HOWEVER SOME HIGHER GUSTS ARE POSSIBLE OUT OF
INTERIOR PASSES LATE TONIGHT AND TOMORROW. THESE GUSTY AREAS
INCLUDE BUT ARE NOT LIMITED TO DISENCHANTMENT BAY AND CROSS
SOUND.

 TEMPERATURE TRENDS TONIGHT WILL VARY WITH CLOUD COVER. THE
COASTAL AREAS WILL LIKELY SEE SOME BREAKS LATE TONIGHT RESULTING
IN COOLER TEMPERATURES WHILE INSIDE AREAS WILL SEE TEMPERATURES
REMAINING FAIRLY STEADY IN THE LOW 30S.

 USED MAINLY THE NAM12 AND ECMWF FOR UPDATES TODAY. BIGGEST
FORECAST CHALLENGE WAS SNOWFALL AMOUNTS. SNOW FLAKE TYPE AND
TEMPERATURES ALOFT RESULTED IN LESS ACCUMULATIONS. CONTINUED THE
ADVISORY THIS EVENING FOR THE KETCHIKAN AND PETERSBURG AREAS AS
THEY WILL SEE SNOW LASTING THE LONGEST.

 &&

 .LONG TERM...AT MID LEVELS A WIDE TROUGH OF LOW PRESSURE WILL
REMAIN OVER THE AK GULF AND PANHANDLE THROUGH MID WEEK. THIS WILL
KEEP CHANCE OF SHOWER ACTIVITY OVER THE REGION. AT THE SURFACE
ELONGATES LOW PRESSURE SYSTEM WITH A SERIES OF SHORT WAVES WILL
REMAIN ALONG THE COAST. PRECIPITATION AMOUNTS WILL NOT BE
SIGNIFICANT. BY THURSDAY A 972MB LOW PRESSURE SYSTEM WILL MOVE
EASTWARD ALONG THE ALEUTIANS MOVING OVER KODIAK BY FRIDAY. THE
ASSOCIATED WEATHER FRONT WILL MOVE ACROSS THE AK GULF REACHING
THE PANHANDLE THURSDAY EVENING. PRECIP WILL BE A MIX OF SNOW AND
RAIN WITH MOSTLY SNOW FOR THE NORTHERN PANHANDLE WITH AMOUNTS OF
2 TO 5 INCHES POSSIBLE. WINDS ALONG THE COASTAL WATERS WILL PICK
UP TO GALE FORCE WITH THE APPROACHING FRONT. REMNANTS OF THIS LOW
WILL REMAIN IN THE NORTHEAST GULF THROUGH THE WEEKEND HOWEVER
FAIR AMOUNT OF UNCERTAINTY IN THE NEXT SYSTEM MOVING INTO THE AK
GULF.

 MODELS ARE IN FAIR AGREEMENT THROUGH THE END OF THE WEEK BEFORE
LARGE DIFFERENCES DEVELOP. GFS HAS BEEN MORE CONSISTENT RUN TO
RUN COMPARED TO THE ECMWF. THE 12Z ECMWF HAS FALLEN MORE IN LINE
THE THE 12Z GFS WITH RESPECT TO THE TIMING OF THE THURSDAY FRONT.
STILL SOME QUESTION REGARDING PRECIPITATION TYPE WITH WARM
SURFACE AIR IN PLACE BUT COLDER 850 TEMPS MOVING IN. WARM SECTOR
OF THE THURSDAY LOW DOES NOT PUSH TOO FAR NORTH AND WITH MID
LEVEL ZONAL FLOW WARM AIR SHOULD BE KEPT OVER THE SOUTHERN
PANHANDLE. USED A BLEND OF 12Z GFS AND ECMWF WITH INHERITED GRIDS
THEN TRANSITIONED TO NEW HPC GUID FROM DAY 4 ONWARD. OVERALL
CHANGES WERE MINOR. FORECAST CONFIDENCE IS AVERAGE WITH RESPECT
TO SYNOPTIC PATTERN BUT STILL QUESTION REGARDING PRECIPITATION
TYPE AND ULTIMATELY SNOW ACCUMULATION WITH THE THURSDAY FRONT.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY UNTIL 6 PM AKST THIS EVENING FOR AKZ026-
     028.
MARINE...GALE WARNING FOR PKZ036.
         SMALL CRAFT ADVISORY FOR PKZ012-013-021-022-031-033>035-043.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041-042-051-052.

&&

HANNON/PRB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
113 PM AKST MON FEB 27 2012

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

1100 AM     HEAVY SNOW       ANNETTE                 55.04N 131.59W
02/27/2012  M1.3 INCH                           AK   OFFICIAL NWS OBS

1100 AM     HEAVY SNOW       10 N KETCHIKAN          55.48N 131.65W
02/27/2012  M3.6 INCH                           AK   CO-OP OBSERVER

            TONGASS HIGHWAY

1100 AM     HEAVY SNOW       9 N PETERSBURG          56.94N 132.96W
02/27/2012  M3.0 INCH        PKZ034             AK   CO-OP OBSERVER

1100 AM     HEAVY SNOW       PETERSBURG              56.81N 132.96W
02/27/2012  M5.0 INCH                           AK   CO-OP OBSERVER

1100 AM     HEAVY SNOW       SE JUNEAU               58.30N 134.41W
02/27/2012  M11.3 INCH                          AK   CO-OP OBSERVER

            SNETTISHAM

1100 AM     HEAVY SNOW       EAGLECREST              58.27N 134.51W
02/27/2012  M3.1 INCH                           AK   CO-OP OBSERVER

            BASE

1100 AM     HEAVY SNOW       JUNEAU                  58.30N 134.41W
02/27/2012  M3.0 INCH                           AK   CO-OP OBSERVER

            WATER TREATMENT PLANT

1100 AM     HEAVY SNOW       JUNEAU                  58.30N 134.41W
02/27/2012  M3.5 INCH                           AK   OFFICIAL NWS OBS

            AIRPORT

1100 AM     HEAVY SNOW       JUNEAU                  58.30N 134.41W
02/27/2012  M3.2 INCH                           AK   OFFICIAL NWS OBS

            JUNEAU FORECAST OFFICE

1100 AM     HEAVY SNOW       JUNEAU                  58.30N 134.41W
02/27/2012  M3.5 INCH                           AK   NWS EMPLOYEE

            MENDENHALL VALLEY RIVERSIDE AT STEPHEN RICHARDS

1100 AM     HEAVY SNOW       DOUGLAS                 58.27N 134.39W
02/27/2012  M3.0 INCH                           AK   NWS EMPLOYEE

            WEST JUNEAU DOUGLAS ISLAND

1100 AM     HEAVY SNOW       SITKA                   57.05N 135.34W
02/27/2012  M1.5 INCH                           AK   CO-OP OBSERVER

1100 AM     HEAVY SNOW       PELICAN                 57.95N 136.21W
02/27/2012  M2.7 INCH                           AK   CO-OP OBSERVER

1100 AM     HEAVY SNOW       HOONAH                  58.11N 135.44W
02/27/2012  M2.7 INCH                           AK   CO-OP OBSERVER

1100 AM     HEAVY SNOW       SE ANGOON               57.50N 134.59W
02/27/2012  M3.2 INCH                           AK   CO-OP OBSERVER

            BARTLETT COVE

1100 AM     HEAVY SNOW       8 NE SKAGWAY            59.56N 135.17W
02/27/2012  M3.0 INCH                           AK   CO-OP OBSERVER

1100 AM     HEAVY SNOW       WHITE PASS              59.62N 135.14W
02/27/2012  M8.0 INCH                           AK   CO-OP OBSERVER

1100 AM     HEAVY SNOW       40 NW HAINES            59.65N 136.25W
02/27/2012  M4.0 INCH        XXX                XX   CO-OP OBSERVER

            HAINES CUSTOMS

1100 AM     HEAVY SNOW       HAINES                  59.24N 135.44W
02/27/2012  M5.5 INCH                           AK   CO-OP OBSERVER

1100 AM     HEAVY SNOW       YAKUTAT                 59.54N 139.73W
02/27/2012  M9.1 INCH                           AK   OFFICIAL NWS OBS

&&
SNOWFALL TOTALS FROM 4 PM FEB 26 - 11 AM FEB 27

GLS