Small Craft Advisory 178, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
330 PM AKST SAT FEB 20 2016

.SHORT TERM...A VERY STRONG WEATHER FRONT HAS FORMED OVER THE
CENTRAL GULF AND IS MOVING EAST. AS OF LATE THIS MORNING, SHIP
REPORTS WERE INDICATING 45 KT SURFACE WINDS AND OVER 15 FOOT SEAS.
THE FRONT IS FORECAST TO INTENSIFY TO 50 KTS ALONG THE OUTER COAST
NORTH OF CAPE FAIRWEATHER THIS EVENING WITH 40 TO 45 KTS TO THE
SOUTH. A WAVE DEVELOPING ALONG THE FRONT WILL MOVE NORTH LATE
TONIGHT AND BRING ANOTHER SURGE OF STORM FORCE WINDS THAT WILL
EXTEND FROM WEST OF THE DIXON ENTRANCE TO SOUTH OF ICY BAY. WINDS
WILL DIMINISH RAPIDLY WITH FRONTAL PASSAGE AND A SOUTHWEST WIND
SHIFT BY LATE TOMORROW AFTERNOON. SEAS IN THE GULF WILL BUILD
TONIGHT TO 30 FEET IN OFFSHORE MARINE ZONE 301 AND COASTAL ZONE 52
BY TOMORROW MORNING. ON THE INSIDE, SOUTH OR SOUTHEASTERLY GALE
FOR CLARENCE STRAIT AND SOUTHERN CHATHAM. EASTERLY GALES FOR
CROSS SOUND. SMALL CRAFT ADVISORIES ELSEWHERE ON THE INSIDE.

THE CLOSE PROXIMITY OF THIS STRONG FRONT HAS PROMPTED AN UPGRADE
OF THE HIGH WIND WATCH TO A WARNING FOR THE SOUTHERN OUTER COAST.
FOR TONIGHT THROUGH NOON TOMORROW. FARTHER NORTH, STRONG WINDS FOR
THE OUTER COAST FROM CAPE DECISION TO CAPE FAIRWEATHER. DID NOT
PUT A STRONG WIND HEADLINE IN ZONE 28, BUT THINK 35 MPH GUSTS ARE
ALMOST A CERTAINTY, ESPECIALLY FOR THE COASTAL COMMUNITIES NEAR
CLARENCE STRAIT.

THE WAVE WILL KEEP A SIGNIFICANT PORTION OF THE FRONTAL
PRECIPITATION OFFSHORE, BUT LAND AREAS WEST OF YAKUTAT ARE
EXPECTED TO SEE HEAVY PRECIPITATION IN THE FORM OF RAIN. AS
EXPECTED, LOW LEVEL WARM AIR ADVECTION HAS PUSHED THE SNOW LINE
NORTH OF JUNEAU AND UP INTO LYNN CANAL. PRECIPITATION TONIGHT OVER
THE FAR NORTHERN ZONES SHOULD FALL AS SNOW. AM EXPECTING UP TO 4
INCHES NEAR THE BORDER ON THE HAINES HIGHWAY WITH 2 INCHES IN
HAINES. ON THE KLONDIKE, EXPECT 1 INCH IN SKAGWAY WITH 2 INCHES
NEAR WHITE PASS. BY TOMORROW AFTERNOON, THE SNOW LINE WILL BE
PUSHED UP THE KLONDIKE TO NEAR WHITE PASS.

OVERALL, THE PREVIOUS SHORT TERM FORECAST REMAINS IN VERY GOOD
AGREEMENT WITH THE LATEST MODELS, SO VERY LITTLE WAS DONE FOR THE
AFTERNOON UPDATE. UPDATED SUNDAY WITH A BLEND OF GFS22 AND NAM
FOR PRESSURE AND WIND. MINOR ADJUSTMENTS TO POP FOR SUNDAY
AFTERNOON TO SLOW DOWN INLAND PROGRESS OF THE FRONT A LITTLE.
MINOR ADJUSTMENTS TO TEMPS PER GFS MOS. OVERALL FORECAST
CONFIDENCE IS AVERAGE.

.LONG TERM...A FAIRLY ACTIVE PATTERN REMAINS THE NORM FOR THE
PANHANDLE AS AN UPPER TROUGH OVER THE ALEUTIANS AND A RIDGE OVER
WESTERN NORTH AMERICA REMAINS FIRMLY IN PLACE. THE RESULT IS
CONTINUED SOUTHERLY FLOW OVER THE GULF AND PANHANDLE. THE GOOD
NEWS IS THAT THERE IS ENOUGH EASTERLY COMPONENT TO THE FLOW THAT
THE PACIFIC STORM TRACK TAKES MOST OF THE STORMS INTO THE WESTERN
GULF WITH THE PANHANDLE MOSTLY RECEIVING THE ASSOCIATED FRONTS.

AT THE SURFACE, THE LONG RANGE STARTS SUN NIGHT WITH THE REMAINS
OF SUNDAY'S FRONT PASSING THROUGH THE PANHANDLE. MOSTLY JUST
PRECIP LEFT BY THIS POINT WHICH WILL DIMINISH THROUGH THE NIGHT AS
THE FRONT MAKES ITS WAY INTO CANADA. AFTER THAT A DRYING TREND IS
IN THE WORKS AS FIRST A RIDGE FORMS OVER THE SOUTHERN PANHANDLE
BEFORE IT MOVES INTO BRITISH COLUMBIA MON NIGHT SWITCHING ONSHORE
FLOW ON MON INTO OFFSHORE FLOW BY TUE.

THE DRY WEATHER WILL NOT LAST AS THE NEXT GALE FORCE FRONT MAKES
ITS WAY INTO THE AREA FOR LATE TUE INTO WED. MOST MODELS ARE
FAVORING KEEPING MOST OF THE WIND AND RAIN OFFSHORE UNTIL WED.
INTO THU THE FRONT STALLS IN THE NORTHERN PANHANDLE AS A
PERSISTENT RIDGE IN BRITISH COLUMBIA STOPS ITS EASTWARD PROGRESS.
AS A RESULT WED NIGHT INTO THU NIGHT IS LOOKING RATHER WET FOR THE
NORTHERN HALF OF THE PANHANDLE AS A DECENT AMOUNT OF SUB-TROPICAL
MOISTURE IS GETTING FUNNELED INTO THE AREA BY THE FRONT. LOOKING
AT THE POSSIBILITY OF A FEW INCHES OF RAIN FROM THIS SCENARIO FOR
AREAS WEST AND NORTH OF CHATHAM STRAIT. THIS FRONT IS ALSO
BRINGING IN SOME SUBSTANTIAL WARM AIR ADVECTION. EXPECTING HIGHS
INTO THE 40S WITH LOW IN THE MID 30S BY MID TO LATE WEEK FOR MOST
LOCATIONS.

LONG RANGE MODELS WERE IN GOOD AGREEMENT OVERALL. SOME TIMING
ISSUES ON THE MID WEEK FRONT WITH GFS BRINGING THE FRONT IN SOONER
THEN THE ECMWF AND CANADIAN. DECIDED TO STICK WITH A GFS/NAM BLEND
EARLY ON BEFORE SWITCHING TO WPC FOR LATER PERIODS.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING FROM 9 PM THIS EVENING TO NOON AKST SUNDAY FOR
     AKZ027.
     STRONG WIND UNTIL 9 PM AKST THIS EVENING FOR AKZ027.
     STRONG WIND UNTIL 6 PM AKST THIS EVENING FOR AKZ022.
     STRONG WIND FROM 9 PM AKST THIS EVENING THROUGH SUNDAY MORNING
     FOR AKZ022.
     STRONG WIND THROUGH SUNDAY MORNING FOR AKZ023.
MARINE...STORM WARNING FOR PKZ041>043-051-052.
     GALE WARNING FOR PKZ022-033-036.
     SMALL CRAFT ADVISORY FOR PKZ012-013-021-031-032-034-035-053.
&&

FRITSCH/EAL

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