Gale Warning 451, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
625 AM AKST TUE DEC 1 2015

.SHORT TERM...A BROAD UPPER TROUGH WAS CENTERED IMMEDIATELY S OF
THE AK PENINSULA TUE MORNING. A MULTITUDE OF UPPER IMPULSES WERE
OBSERVED ROTATING CYCLONICALLY AROUND THE TROUGH...AND THIS WILL
CONTINUE THROUGHOUT THE SHORT TERM PERIOD. ONE IMPULSE MOVING NW
TOWARD THE NRN GULF WILL BE ACCOMPANIED BY A WEAK AREA OF SURFACE
LOW PRESSURE. THE LOW WILL SUPPORT ESELY GALE FORCE WINDS THROUGH
TUE MORNING...WITH WEAKENING SPEEDS OCCURRING THEREAFTER. FARTHER
S...A SECOND IMPULSE WAS LOCATED DUE W OF HAIDA GWAII AT 13Z.
ENHANCED ASCENT ASSOCIATED WITH THIS FEATURE...COMBINED WITH STEEP
LAPSE RATES/MODEST CAPE...IS AIDING IN ISOLATED THUNDERSTORM
DEVELOPMENT. THIS ACTIVITY WILL SPREAD N ACROSS THE SERN QUARTER
OF THE GULF DURING THE MORNING...WITH THE IMPULSE WEAKENING/BECOMING
ILL-DEFINED AS IT MOVES ACROSS THE CNTRL PANHANDLE DURING TUE
AFTERNOON. ELSEWHERE...STEEP LAPSE RATE ENVIRONMENT IS SPREADING
ACROSS THE PANHANDLE THIS MORNING...RESULTING IN A TRANSITION FROM
A STRATIFORM TO CONVECTIVE/SHOWER REGIME.

THE THIRD UPPER DISTURBANCE TO AFFECT THE REGION WILL MOVE ACROSS
THE FAR SRN PANHANDLE TONIGHT. LATEST MODEL GUIDANCE HAS CONVERGED
TOWARD A NAM/ECMWF SOLUTION...WHICH SHOWS A 990 MB SURFACE LOW
MOVING ACROSS HAIDA GWAII AT 06Z WED...WHICH THEN WEAKENS QUICKLY
AS IT ENCOUNTERS THE SRN PANHANDLE BY 12Z WED. ENHANCED ASCENT
WITH THIS DISTURBANCE WILL FAVOR LOCALLY HEAVY RAIN FOR
AKZ027...028 AND COASTAL 029. PRECIPITATION IS FORECAST TO FALL
AS SNOW /UP TO 10 INCHES/ NEAR HYDER DUE TO CONTINUED LIGHT NLY
COMPONENT AT THE SURFACE RESULTING IN TEMPERATURES HOVERING NEAR
FREEZING THROUGH TONIGHT. FARTHER N ALONG THE HAINES AND KLONDIKE
HIGHWAYS...STRATIFORM PRECIPITATION SHIELD IS CURRENTLY DEPARTING
N AND BEING REPLACED BY A MORE SHOWERY/SPORADIC PRECIPITATION
REGIME...WHICH LIKELY SIGNALS THE END OF HEAVY SNOWFALL RATES.
THUS...THE WINTER WEATHER ADVISORY FOR THE HAINES HIGHWAY WILL BE
BE EXTENDED THROUGH MID MORNING...AND THE ADVISORY FOR THE
KLONDIKE HIGHWAY IS NOW SET TO EXPIRE AT NOON. ALSO AN WINTER
WEATHER ADVISORY HAS BEEN ISSUED FOR THE HYDER AREA THROUGH 6 AM
WEDNESDAY.

.LONG TERM...THERE IS NO BIG CHANGES IN THE LONG WAVE PATTERN WITH
A MEAN TROUGH OF LOW PRESSURE EXTENDING FROM THE BERING TO
SOUTHEAST ALASKA. THE ISSUES REMAIN IN THE DETAILS OF UPPER LEVEL
ENERGY ROTATING INTO THE GULF THROUGH THE WEEK INTO THE WEEKEND.
THE GULF OF ALASKA WILL REMAIN ACTIVE WITH SURFACE LOW PRESSURE
SYSTEMS MOVING INTO THE EASTERN GULF AND WEATHER FRONT LIFTING
OVER THE PANHANDLE. THERE IS ABOVE AVERAGE FORECASTER CONFIDENCE
ON THE OVERALL SYNOPTIC PATTERN BUT BELOW AVERAGE CONFIDENCE IN
TIMING AND STRENGTHENS OF INDIVIDUAL SYSTEMS.

AT THE START OF THE LONG TERM PERIOD A LOW PRESSURE SYSTEM WILL BE
MOVING INTO CANADA AFTER IT MOVED OVER THE SOUTHERN THIRD OF THE
FORECAST AREA. THE SNOW IN HYDER WILL MIX AND TURN TO RAIN
THROUGH THE MORNING AS THE SOUTHWEST WINDS INCREASE. THE REST OF
THE FORECAST AREA SEE SCATTERED SHOWERS. THE WINDS WILL BE ON THE
LIGHTER SIDE OVER THE NORTHERN AREAS BUT THERE WILL BE A BURST OF
WINDS OVER THE SOUTHERN AREAS AS THE PRESSURES RISE FROM THE
DEPARTING LOW.

ANOTHER STRONG AND COMPLEX LOW PRESSURE SYSTEM WILL BE MOVING OUT
OF THE NORTH PACIFIC WHICH IS CURRENTLY NEAR 44N/150W. THIS LOW
WILL MOVE INTO THE FAR SOUTHERN GULF BY WEDNESDAY AFTERNOON WITH A
STRONG WEATHER FRONT LIFTING OVER THE SOUTHERN AREAS. THE FRONT IS
ASSOCIATED WITH VERY STRONG UPPER LEVEL DYNAMICS ALONG WITH VERY
UNSTABLE ATMOSPHERE. THIS WILL PRODUCE AN ENVIRONMENT MANY PRODUCE
A SLIGHT CHANCE OF THUNDERSTORMS WITH LARGE CAPE AND STEEP LAPSE
RATES OVER THE OFFSHORE WATERS AND THE EASTERN GULF WEDNESDAY
AFTERNOON/NIGHT. AS THE FRONT MOVES OVER THE SOUTHERN AREAS THERE
IS A 55KT LLJ THAT WILL PRODUCE STRONG WINDS GUSTS TO 45 MPH NEAR
POW AND THE SOUTHERN INNER CHANNELS IN THE AFTERNOON/EARLY
EVENING. THE WINDS THE MARINE WATERS WILL INCREASE FROM THE ESE TO
BE GALES TO SMALL CRAFTS OVER THE SOUTHERN HALF OF THE AREA. THE
NORTHERN AREAS WILL SEE THE LIGHT WINDS IN THE MORNING HOURS OF
WEDNESDAY TURN AROUND TO THE NORTH AND INCREASE IN THE AFTERNOON
AND CONTINUE INTO THE EVENING HOURS TO BE 25 KT IN LYNN CANAL AND
15 TO 20 ELSEWHERE.

THE RAIN WILL SPREAD OVER THE SOUTHERN AREAS THROUGH THE DAY ON
WEDNESDAY AND LIFT NORTH OVER THE NORTHERN HALF THAT EVENING. THE
NORTHERN AREAS WILL BE MOSTLY ON THE DRY SIDE THROUGH THE DAY BUT
SEE RAIN DEVELOP IN THE EVENING. THE TEMPS WILL MAINLY ABOVE
FREEZING SO AT THIS TIME DO NOT THINK THERE WILL MUCH SNOW AT SEA
LEVEL. THE FAR NORTHERN AREAS MAY SEE SOME SNOW AND ALONG THE
HAINES AND KLONDIKE HIGHWAYS AS WITH THE NORTHER WIND AT THE
SURFACE IT WILL ADVECT IN SOME COOLER AIR TO SUSTAIN SNOW. THE
FRONT WILL BEGIN TO FALL APART LATE WEDNESDAY AND INTO THURSDAY
MORNING BUT PRECIP WILL REMAIN OVER THE SOUTHERN AND COASTAL
AREAS.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY UNTIL 9 AM AKST THIS MORNING FOR AKZ019.
         WINTER WEATHER ADVISORY UNTIL NOON AKST TODAY FOR AKZ018.
         WINTER WEATHER ADVISORY UNTIL 6 AM AKST WEDNESDAY FOR AKZ029.
MARINE...GALE WARNING FOR PKZ043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ022-031-034-036-042-053.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041.

&&

GARNER/ABJ

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
1021 AM AKST TUE DEC 01 2015

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

1020 AM     SNOW             HYDER                   55.91N 130.02W
12/01/2015  M6.0 INCH                           AK   CO-OP OBSERVER

            6.0 INCHES OF SNOW ON THE GROUND IN HYDER AS OF 1000 AM.
            HEAVY SNOW CURRENTLY.

&&

DEL