Small Craft Advisory 342, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
348 PM AKDT SAT APR 23 2016

.SYNOPSIS...A NEARLY STATIONARY 990 MB SURFACE LOW IS CENTERED
OVER THE CENTRAL GULF AK SAT AFTERNOON. SATELLITE IMAGERY SHOWS AN
ARCHING FRONTAL SYSTEM WRAPPED AROUND THE LOW CENTER CIRCULATION
AND EXTENDING FROM PRINCE WILLIAM SOUND TO KETCHIKAN AT 3 PM. RAIN
AND FOG ARE REPORTED THROUGHOUT THE INNER CHANNELS HOWEVER RAIN
HAS BEGUN TAPERING OFF ALONG THE VERY OUTER COAST.

&&

.SHORT TERM...A SLOW MOVING WEATHER PATTERN IN STORE FOR SAT NIGHT
AND SUNDAY. THE LOW CENTER OVER THE GULF AK WILL WOBBLE AROUND AND
WEAKEN THE NEXT 24 HRS. SLY FLOW ALOFT WILL CONTINUE TO BRING IN
MOISTURE AND LAYERED CLOUDS. THERE IS A SHARP DIFFERENCE IN THE
SENSIBLE WEATHER ON EITHER SIDE OF THE FRONTAL BOUNDARY WHICH RUNS
ROUGHLY FROM YAKUTAT TO ADMIRALTY ISLAND TO PRINCE OF WALES SAT
AFTERNOON. TO THE EAST OF THE FRONT THERE IS STEADY RAIN...LOW
CLOUDS AND LOW VISIBILITIES. AVERAGE RAINFALL TOTALS SO FAR TODAY
ARE ON THE ORDER OF ONE HALF INCH. TO THE WEST OF THE FRONTAL
BOUNDARY RAIN ENDS AND CLOUD HEIGHTS AND VISIBILITIES ARE HIGHER.
THE FRONTAL BOUNDARY WILL EDGE SLOWLY EAST INTO THE COASTAL
MOUNTAINS BY SUN MORNING. WITH AMPLE LOW LEVEL MOISTURE PRESENT IT
IS POSSIBLE PATCHY FOG MAY FORM OVERNIGHT SHOULD ANY PARTIAL
CLOUD BREAKS DEVELOP.

TODAYS MODEL RUNS CONSISTENTLY STEERED THE GULF AK LOW A BIT
FARTHER SOUTH TOWARD THE PANHANDLE THAN PREVIOUSLY SHOWN. THAT
WAS THE ONLY ADJUSTMENT MADE TO THE FORECAST WHICH ONLY SLIGHTLY
ALTERED THE PREVIOUS OFFSHORE WIND FORECASTS. THE SLOW MOVEMENT OF
SYSTEMS AND PERSISTENT WIND SPEED AND DIRECTIONS OFFSHORE WILL
HELP A SW SWELL DEVELOP ON THE ORDER OF 15 TO 20 FT THE NEXT 24
HRS. EXPECT A BAND OF GALES TO WRAP UNDER THE CENTER OF THE LOW
AND LIFT N ACROSS OUR OFFSHORE WATERS TONIGHT AND SUN. USED A
COMBINATION OF THE NAM AND AKGFS UPDATE FORECASTS. MODEL
AGREEMENT WAS QUITE HIGH TODAY OVER THE SHORT TERM. FORECASTER
CONFIDENCE IN THE WEATHER TREND IS AVERAGE OR SLIGHTLY HIGHER.

.LONG TERM...MODELS REMAIN IS GOOD AGREEMENT ALOFT THROUGH EARLY
WEDNESDAY MORNING. AT THE SURFACE, ALL ARE NOW INDICATING
SIGNIFICANT WAVE DEVELOPMENT ALONG A FRONTAL BOUNDARY EARLY
TUESDAY OVER THE EASTERN GULF. CANADIAN MODEL IS THE MOST
AGGRESSIVE AND ECMWF IS THE FARTHEST NORTH AND EAST WITH THIS
FEATURE. CONTINUE TO PREFER THE MIDDLE GROUND GFS SOLUTION. ONCE
THE WAVE/SURFACE LOW PASSES NORTH, THE ASSOCIATED FRONT WILL SWING
NORTH OVER THE PANHANDLE. EVEN SO, HAVE ONLY SPOTTY CATEGORICAL
POP ASSOCIATED WITH THIS FRONT AND QPF VALUES ARE QUITE TAME. RIDGING
WILL BUILD IN OVER THE PANHANDLE FROM THE SOUTHEAST POST-FRONTAL
AND BRIEFLY TEND TO DRIER CONDITIONS LATE TUESDAY NIGHT AND EARLY
WEDNESDAY, BUT THE NEXT TWO FRONTS WEDNESDAY AFTERNOON THROUGH
THURSDAY NIGHT WILL PREVENT ANY SIGNIFICANT DRYING.

MAINTAINED GALES OVER THE CENTRAL GULF AND COASTAL WATERS WEST OF
ICY BAY FOR MONDAY / MONDAY EVENING. INCREASED SOUTHEASTERLIES TO
30 KT FOR ALL OUTER COAST WATERS MONDAY NIGHT THROUGH TUESDAY
MORNING WITH SOME SMALL CRAFT WINDS GETTING INTO THE INNER
CHANNELS LATE MONDAY NIGHT. USED GFS40 WITH A LITTLE HELP FROM THE
CANADIAN NH FOR UPDATES TO PRESSURE MONDAY NIGHT THROUGH TUESDAY
NIGHT. POP AND QPF PRIMARILY FROM GFS. NO OTHER SIGNIFICANT
CHANGES. OVERALL FORECAST CONFIDENCE IS AVERAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ041>043-051-052.
     SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ022-053.
&&

TA/FRITSCH

VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU