Gale Warning 70, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
235 PM AKST THU JAN 15 2015

.SHORT TERM...AN UPPER-LEVEL TROUGH AND ASSOCIATED SURFACE FRONTAL
BOUNDARY ARE IN THE PROCESS OF MOVING ONSHORE OVER SERN AK THIS
AFTERNOON. GUSTS PEAKING NEAR 50-60 MPH AT HYDABURG EARLIER TODAY
HAVE QUICKLY DIMINISHED AFTER FRONTAL PASSAGE...AND A SIMILAR
PROGRESSION IS OCCURRING AT KETCHIKAN AND SURROUNDING AREA. IN
ADDITION...WINDS OVER THE OUTSIDE WATERS AS WELL AS CLARENCE
STRAIT HAVE WEAKENED BELOW 30 KT. HOWEVER...SEAS WILL CONTINUE TO
RANGE FROM 12-18 FT OVER THE GULF...AND A SWLY SWELL WILL ALLOW 8
FT WAVES TO SPREAD INTO YAKUTAT BAY. RELATIVELY LIGHT WINDS
CURRENTLY OCCURRING OVER NRN LYNN CANAL WILL INCREASE TO 25-30 KT
OUT OF THE S THIS EVENING AS THE FRONT MOVES NE ACROSS THE NRN
PANHANDLE. THESE WINDS ARE EXPECTED TO PERSIST THROUGH FRI. A
BRIEF PERIOD OF GALE FORCE SLYS WILL ALSO BE POSSIBLE OVER
STEPHENS PASSAGE THIS EVENING.

MODERATE PRE-FRONTAL RAINFALL OCCURRING ACROSS MUCH OF THE
PANHANDLE THIS AFTERNOON WILL TRANSITION TO SHOWERS TONIGHT AS
STEEPER LAPSE RATES SPREAD NEWD BEHIND THE FRONT. IN FACT...CAN
NOT COMPLETELY RULE OUT A LIGHTNING STRIKE TONIGHT OVER THE GULF
AS EMBEDDED UPPER IMPULSES INTERACT WITH A WEAKLY UNSTABLE
ENVIRONMENT. THE NEXT IN A SERIES OF UPPER DISTURBANCES CURRENTLY
POSITIONED OVER THE N-CNTRL PAC...WILL APPROACH THE SRN GULF BY
FRI AFTERNOON. A NARROW PLUME OF MOISTURE /PW VALUES AROUND 0.6
INCH/ WILL BE TRANSPORTED NEWD AHEAD OF THE UPPER WAVE. THIS
MOISTURE WILL IMPINGE ON THE CNTRL AND NRN PANHANDLE BY FRI
MORNING...WHERE POP AND QPF VALUES WILL BE MAXIMIZED DURING THE
SECOND HALF OF THE SHORT TERM PERIOD. THE PRESENCE OF MODERATE
MOISTURE AND DEEP-LAYER SWLY FLOW INTERACTING WITH THE COMPLEX
TERRAIN OVER THE NRN HALF OF THE PANHANDLE MAY YIELD LOCALLY HEAVY
RAIN. IN ADDITION...TEMPERATURES HOVERING AROUND FREEZING AT WHITE
PASS WILL FAVOR SNOW ACCUMULATION UP TO 8 INCHES TONIGHT THROUGH
FRI AFTERNOON.

TEMPERATURES ARE FORECAST TO STEADILY RISE TONIGHT FOR SKAGWAY
AND HYDER AS SLY SURFACE WINDS STRENGTHEN. SKAGWAY WILL LIKELY
RISE FROM THE MID/UPPER 30S INTO THE LOW 40S...AND HYDER WILL RISE
FROM THE MID 30S UP TO AROUND 40F. ELSEWHERE...ONLY MINOR
FLUCTUATIONS IN TEMPERATURES ARE EXPECTED DUE TO ONSHORE FLOW
MAINTAINING A MARINE BOUNDARY LAYER.

BLEND OF THE ECMWF AND ARW/NMM SHIFTED HIGHEST POPS AND QPF EWD ON
FRI. BLENDED IN 12Z NAM/GEM WITH INHERITED PRESSURE GRIDS...BUT
MODIFICATION TO WINDS WAS MINOR.

.LONG TERM...MODELS REMAIN IN GENERAL AGREEMENT THROUGH THE
WEEKEND FOR THE UPPER LEVEL RIDGE OVER SOUTHEAST ALASKA SLOWLY
DRIFTS EAST INTO BRITISH COLUMBIA AS A COUPLE OF UPPER TROUGHS
MOVING NORTH ACROSS THE EASTERN GULF AND THE PANHANDLE. SURFACE
REFLECTION FROM THE FIRST UPPER TROUGH APPEARS INSIGNIFICANT AND
BRINGS ABOUT 984 MB LOW OVER THE OFFSHORE WATERS FRIDAY NIGHT THEN
DRIFTS THE LOW NORTHWEST INTO THE NORTHERN GULF BY SATURDAY.
HOWEVER...THE RIDGE MOVING INTO BRITISH COLUMBIA WILL MAINTAIN
TIGHT PRESSURE GRADIENT AND PRODUCE GALE FORCE WINDS ACROSS THE
OUTER WATERS...OCEAN ENTRANCES OF INNER CHANNELS AND CLARENCE
STRAIT. SOLID SMALL CRAFT LEVEL WINDS WILL ALSO AFFECT MOST INNER
CHANNELS AS WELL.

THE SECOND SURFACE REFLECTION APPEARS AS A BETTER ORGANIZED
LOW...ABOUT 990 MB...ENTERING THE SOUTHEASTERN GULF SATURDAY
NIGHT. THE LOW WEAKENS TO ABOUT 998 MB SUNDAY EVENING THEN MOVES
NORTHWEST TO THE NORTHEASTERN GULF AS 1004 MB THROUGH SUNDAY
NIGHT. NOT STRONG MODEL SUPPORT FOR THE SATURDAY/SUNDAY SURFACE
LOW...BUT AN ENSEMBLE APPROACH FROM THE ECMWF...GEM AND GFS
COMPROMISED THE LOW TRACK. AS THE HIGH PRESSURE AREA OVER THE
CANADIAN CONTINENT WEAKENS...NO GALE FORCE WINDS ARE EXPECTED...BUT
SMALL CRAFT LEVEL WINDS WILL AFFECT THE OUTSIDE WATER. LIKELY TO
CATEGORICAL POPS WILL CONTINUE ACROSS SOUTHEAST ALASKA LATE
SATURDAY...THEN DIMINISH SOUTHEAST ACROSS THE PANHANDLE THROUGH
SUNDAY.

MODEL SPREAD BECOMES EVEN LARGER FOR THE EXTENDED PERIODS FOR
NEXT WEEK. HOWEVER...THE LARGE SCALE SYNOPTIC PATTERN REMAINS MUCH
THE SAME WITH A SERIES OF STORMS CONTINUING TO AFFECT ALASKA GULF
AND PUSH FRONTAL PASSAGES OVER THE PANHANDLE. SOLID SMALL CRAFT
LEVEL WINDS WILL PERSIST ACROSS THE OUTER WATERS. AS THE ORIGIN OF
THE STORMS IS LOCATED IN THE SUB-TROPICAL REGION...CONTINUED
WARMING TREND IS EXPECTED UNDER UPPER LEVEL RIDGE OVER SOUTHEAST
ALASKA WITH MOISTURE CHANNEL CONNECTED SOUTHWARD. USED THE LATEST
WPC ENSEMBLE SOLUTION FROM LATE SUNDAY NIGHT THROUGH THE END OF
THE LONG TERM PERIOD. CONTINUED WET WEATHER WITH MILD TEMPERATURES
THROUGH THE WEEKEND. OVERNIGHT LOWS WILL COOL DOWN A BIT EARLY
NEXT WEEK WITH POTENTIAL SNOW FOR THE FAR NORTHERN HIGHWAYS AND
NEAR HYDER AREA...BUT BACK TO ABOVE NORMAL TEMPERATURES BY MID
WEEK.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND UNTIL 3 PM AKST THIS AFTERNOON FOR AKZ027-028.
         STRONG WIND FROM FRIDAY EVENING THROUGH LATE FRIDAY NIGHT FOR
     AKZ027.
         STRONG WIND LATE FRIDAY NIGHT FOR AKZ023.
         WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM AKST
     FRIDAY FOR AKZ018.
MARINE...GALE WARNING FOR PKZ031-033-034-036-051-052.
         SMALL CRAFT ADVISORY FOR PKZ012-013-022-032-035-041>043.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ053.

&&

GARNER/AHN

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