Small Craft Advisory 55, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
559 AM AKST SAT JAN 16 2016

.SHORT TERM...SURFACE ANALYSIS SHOWS A FRONT APPROACHING SE AK
FROM THE S WITH GALES OVER THE OUTER COAST EARLY THIS MORNING.
FURTHER N...SOME FOG/STRATUS DEVELOPED LAST NIGHT AND IS SLOWLY
DISSIPATING THIS MORNING AS MIXING INCREASES IN RESPONSE TO THE
TIGHTENING PRESSURE GRADIENT. THIS FRONT WILL SPREAD INCREASED
WINDS AND PRECIP NORTH ACROSS SE AK TODAY WITH GUSTS TO 40 MPH
OVER THE SOUTHERN PANHANDLE DIMINISHING THIS AFTERNOON. MARGINAL
CROSS BARRIER FLOW THIS MORNING...SO MAINTAINED THE LOCALLY WINDY
WORDING NEAR JUNEAU WITH GUSTS TO 35 MPH DURING THIS EVENT. PRECIP
OVER THE SRN PANHANDLE WILL PUSH N INTO THE CENTRAL PANHANDLE LATE
THIS MORNING AND INTO THE NRN PANHANDLE THIS AFTERNOON. EARLY
MORNING TEMPS OVER THE NRN INNER CHANNELS CONTINUE TO CLIMB SO
EXPECT PRECIP TO BE LIQUID EXCEPT FOR SOME LIGHT SNOW POSSIBLE IN
WIND SHELTERED AREAS AND IN AKZ018-019 WHERE MIXED PRECIP AT THE
COAST WILL TRANSITION TO SN ALONG THE HIGHWAYS. HOWEVER...NO
SIGNIFICANT ACCUMULATIONS EXPECTED. PRECIP CHANCES WILL DIMINISH
OVERNIGHT BEFORE ANOTHER WAVE OVER THE E PACIFIC MOVES N INTO THE
E GULF AND STRENGTHENS.

MODELS REMAIN IN GOOD AGREEMENT WITH THE FRONT TODAY BUT
BEGIN TO DIVERGE SOME OVERNIGHT AS THE NEXT SYSTEM APPROACHES.

.LONG TERM...IN A REPETITIVE WEATHER PATTERN SUCH AS THE ONE WE
ARE EXPERIENCING WITH A BIG UPPER LOW ANCHORED OVER THE GULF OF
ALASKA AND WAVES AND TRIPLE POINT FEATURES FOLLOWING THE FLOW
AROUND THE BROAD UPPER LOW TO THE NORTH THEN NORTHWEST ALONG OUR
COASTLINE, WE OFTEN HAVE TO WATCH AND LEARN AND CALIBRATE THE
FORECAST ACCORDINGLY.

GIVEN A STRONGER SYSTEM PROJECTED BY THE MODELS THAN THE STORM
CURRENTLY IMPACTING THE SOUTHERN PANHANDLE, IT STILL SEEMS
POSSIBLE THAT HIGH WINDS COULD DEVELOP FOR PRINCE OF WALES ISLAND
AND THE SOUTHERN INNER CHANNELS SUNDAY AFTERNOON INTO SUNDAY
EVENING. THERE ARE SOME SUBTLE DIFFERENCES WITH THEIR MOVEMENT.
SUNDAY'S SYSTEM WILL APPEAR TO TRACK LESS OFFSHORE THAN THE
CURRENT SYSTEM, WHICH SUGGESTS MORE WIND. WHILE THE ECMWF DISPLAYS
SIMILAR STRENGTHS, THE GFS ON THE OTHER HAND CLEARLY SUGGESTS A
STRONGER SYSTEM FOR SUNDAY THAN THE ONE TODAY. WITH THESE
FACTORS, WE STILL LIKE THE HIGH WIND WATCH FOR 27/28 BUT ARE NOT
YET CONFIDENT ENOUGH TO REPLACE WITH A WARNING. IN ADDITION, STORM
FORCE WINDS THROUGH THE SOUTHERN OUTSIDE WATERS LOOK GOOD AS WELL.

FARTHER NORTH, WE ARE LEARNING THAT A SIMILAR NORTHERLY GRADIENT
THIS MORNING THAT WE BELIEVE WILL RE-OCCUR ON SUNDAY IS YIELDING A
MERE 15 TO 25 MPH NEAR SEA LEVEL BUT 20 TO 30 MPH UP AT WHITE
PASS. THUS OUR WIND SPEEDS FOR SKAGWAY AND WHITE PASS
SUNDAY/SUNDAY NIGHT ARE NOT HAS HIGH WITH THIS PACKAGE, AND WE
HAVE SLIGHTLY REDUCED THEM.

WORKING OUR WAY INTO JUNEAU, WE FIND THAT INDEED OUTFLOW WINDS
HAVE TRANSFERRED THEMSELVES TO THE SURFACE NEAR DOWNTOWN JUNEAU
OVERNIGHT, AND HAVE EVEN EXPANDED PAST LEMON CREEK NEAR THE
AIRPORT NEIGHBORHOOD. GIVEN A POTENTIALLY STRONGER SYSTEM, THIS
RAISES CONFIDENCE THAT IT WILL BE A WINDY PERIOD NEAR DOWNTOWN
SUNDAY INTO SUNDAY NIGHT. MEANWHILE, THE TEMPERATURES HAVE RISEN
IN ACCORD WITH WINDSPEEDS DOWNTOWN. THE BANANA BELT THAT CURVES
FROM THANE INTO DOWNTOWN AND AROUND THE BRIDGE INTO WEST JUNEAU
AND DOUGLAS IS ROASTING. IT WOULD SEEM TO APPEAR THAT SNOW CHANCES
FOR SUNDAY NIGHT ARE SHARPLY FALLING JUST AS OUR FORECAST
TEMPERATURES MAY ALREADY BE TOO CHILLY. HOWEVER, SNOW REMAINS A
SAFER BET NORTH OF THE AIRPORT. LOOK FOR DOWNTOWN AREA
TEMPERATURES TO BE WARMED IN LATER ISSUANCES.

FOR SUNDAY AND SUNDAY NIGHT WE REDUCED QPF...ESPECIALLY OVER THE
NORTH GIVEN THE ORIENTATION OF THE SYSTEM. IN ADDITION, WE HAVE
NUDGED THE RAIN-SNOW LINE TO THE NORTH A LITTLE AND MOVED LOW
TEMPERATURES FOR SUNDAY NIGHT GENERALLY TO LATE EVENING TO ALLOW
A SLOW WARMING TREND OVERNIGHT INTO MONDAY MORNING. ANY SNOW THAT
DOES FALL ACROSS THE CENTRAL INNER CHANNELS WILL BE LIGHT AND
SHOULD QUICKLY CHANGE TO RAIN BY MONDAY MORNING. HOWEVER, THERE IS
THE POTENTIAL FOR SOME ADVISORY SNOWFALL ACROSS THE HAINES ROAD
LATE SUNDAY NIGHT INTO MONDAY MORNING.

A THIRD SYSTEM LOOKS TO AFFECT THE PANHANDLE ON MONDAY...BUT THIS
LOOKS WEAKER THAN SUNDAY'S STORM. WE EDITED WINDS AS 00Z GFS AND
00Z ECMWF CAME INTO MUCH BETTER ALIGNMENT INTO MONDAY. GALES WILL
PERSIST ACROSS MUCH OF THE SOUTHERN OUTSIDE WATERS WELL INTO
MONDAY.

LOOKING INTO MID-WEEK AND BEYOND ANOTHER A SYSTEM OF DEEPER
PACIFIC ORIGINS LOOKS TO PLANT ITSELF INTO THE GULF MID-WEEK AND
RAISE WIND SPEEDS ONCE AGAIN. AS THIS SYSTEM APPROACHES, THERE MAY
BE A BRIEF BREAK IN PRECIP FOR MUCH OF THE PANHANDLE GIVEN
RIDGING AHEAD OF IT; HOWEVER, TIMING OF ANY BREAKS ARE NOT VERY
CLEAR AS OF YET, THUS YOU WILL STILL FIND A WET FORECAST. WITH
THE NEW SYSTEM'S TRAJECTORY, THOUGH, TEMPERATURES MAY NEED TO BE
TRENDED UPWARD AND THE SNOW IN THE EXTENDED FORECAST MAY NEED TO
BE SHIFTED NORTHWARD AWAY FROM OUR TINY PORTION OF THE GREAT LAND.

WE USED ECMWF AND GFS FOR UPDATES MONDAY/MONDAY NIGHT AND MADE
MINOR TWEAKS FOR SUNDAY/SUNDAY NIGHT AS GREAT AGREEMENT WITH
CURRENT FORECAST CONTINUES. CONFIDENCE IS AVERAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 9 AM AKST THIS MORNING FOR AKZ027-028.
         HIGH WIND WATCH FROM SUNDAY AFTERNOON THROUGH SUNDAY EVENING FOR
     AKZ027.
         HIGH WIND WATCH FROM SUNDAY AFTERNOON THROUGH SUNDAY EVENING FOR
     AKZ028.
MARINE...GALE WARNING FOR PKZ022-041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ012-013-021-031-033>036.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ053.

&&

BC/JWA

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