Area Forecast Discussion
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FXAK67 PAJK 281430
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
530 AM AKST WED JAN 28 2015

.SHORT TERM...A BROAD LOW PRESSURE AREA OVER THE NORTH PACIFIC AND
GULF OF ALASKA. THE MAIN LOW CENTER IS SOUTH OF THE EASTERN
ALEUTIANS AND WILL CONTINUE TO ROTATE SOUTHWARD INTO THE NORTH
PACIFIC. AN EXTENDED TROUGH IS INTO THE GULF OF ALASKA ASSOCIATED
WITH THE FRONT LIFTING THROUGH THE PANHANDLE. RAIN IS OVER THE
SOUTHERN PANHANDLE WITH THE RAIN SNOW LINE MOVING NORTHWARD TO
NEAR ICY STRAIT TO NEAR JUNEAU BY LATE AFTERNOON AND EVENING.
NORTHERLY WINDS THROUGH LYNN CANAL WILL CONTINUE TO REINFORCE COLD
AIR IN THE NORTHERN LYNN CANAL AND THUS WILL KEEP THE
PRECIPITATION AS SNOW OVER THAT REGION.

SNOW STARTING IN THE JUNEAU AREA, STARTING EARLY WEDNESDAY MORNING
AND THINK THE SNOW WILL LIKELY CHANGE OVER TO RAIN AT THE LOWER
LEVELS THROUGH THE AFTERNOON...ALTHOUGH SNOW LEVEL ONLY RISING TO
ROUGHLY A 1000 FEET. THROUGH MORNING TO MID DAY TEMPERATURES AHEAD
OF THE FRONT WARMING TO AND SLIGHTLY ABOVE FREEZING WITH THE DEW
POINT KEEPING PRECIPITATION AS A WET SNOW.

STILL A BAND OF GALE FORCE WINDS ALONG THE OUTER COAST THROUGH EARLY
WEDNESDAY AHEAD OF THE FRONT. GALES INTO CLARENCE STRAIT TODAY AS
WELL WHILE THE FRONT WILL GO. NORTH WINDS IN THE LYNN CANAL ARE TO
SMALL CRAFT LEVELS WILL LOWER TO JUST UNDER SMALL CRAFT LEVELS.

MISTY FJORDS HANG ON TO SOME COOLER TEMPERATURES AND AN OFFSHORE FLOW
SO EXPECTING SOME COOLER TEMPERATURES SO AM EXPECTING SOME SNOW
WITH ACCUMULATIONS UP TO 2 TO 5 INCHES PERHAPS OVERNIGHT.

.LONG TERM...LARGE UPPER-LEVEL VORTEX OBSERVED S OF THE ALEUTIANS
THIS MORNING IS FORECAST TO REMAIN QUASI-STATIONARY THROUGH MOST
OF THE LONG TERM PERIOD AS A RIDGE BUILDS FROM W TO E ACROSS
INTERIOR AK AND NWRN CANADA. THIS WILL LIKELY LOCK SERN AK INTO A
COLDER/DRIER PATTERN /RELATIVE TO THE PAST MONTH/ WITH PERIODS OF
OCCASIONALLY STRONG OUTFLOW WINDS.

THU INTO FRI...A DEEP LAYER OF DRY AIR IS FORECAST TO SPREAD FROM
S TO N OVER THE PANHANDLE AS MIDLEVEL HEIGHTS RISE OVER THE ERN
GULF. AS A RESULT...PRECIPITATION CHANCES WILL DIMINISH TO ZERO
OVER SRN AREAS BY THU NIGHT...WITH LINGERING LIGHT SNOW/RAIN
OCCURRING OVER NRN AREAS ENDING BY FRI NIGHT. THE WEEKEND WILL
THEN BE DOMINATED BY STRONG OUTFLOW WINDS AS HIGH PRESSURE BUILDS
OVER NWRN CANADA AND A SERIES OF FRONTAL BOUNDARIES
STALL/DISSIPATE OVER THE SRN GULF. GALES ARE PROBABLE FOR MANY OF
THE INNER CHANNELS SAT INTO SUN...WITH THE EXCEPTION OF CLARENCE
STRAIT...AND STRONG TO POTENTIALLY HIGH WINDS WILL DEVELOP OVER
SKAGWAY. ELSEWHERE...CROSS BARRIER FLOW IS FORECAST TO INTENSIFY
INVOF DOWNTOWN JUNEAU...AND A PRONOUNCED BOUNDARY LAYER INVERSION
WILL BE IN PLACE. IN ADDITION...MODEL GUIDANCE SHOWS A MIDLEVEL
VORT LOBE STALLING OVER THE AREA...WHICH WILL POTENTIALLY AID IN
MINIMIZING WIND SPEEDS ABOVE THE CROSS BARRIER WIND
MAXIMA...FAVORING THE DEVELOPMENT OF A CRITICAL LEVEL. THUS...A
TAKU WIND EVENT IS LOOKING MORE LIKELY.

A VERY DRY AIRMASS USHERED IN BY OFFSHORE WINDS WILL GREATLY
INHIBIT PRECIPITATION CHANCES DURING THE WEEKEND INTO EARLY NEXT
WEEK OVER THE NRN HALF OF THE CWA. UNCERTAINTY EXISTS OVER THE SRN
HALF...WHERE AN UPPER DISTURBANCE WILL APPROACH SUN AND MON.
THE GFS...AND THE GEM TO A LESSER EXTENT...ARE MOST AGGRESSIVE IN
SPREADING MOISTURE NWD...WHILE THE ECMWF MAINTAINS DEEP-LAYER
DRYNESS OVER THE ENTIRE REGION.

BLENDED IN THE ECMWF WITH INHERITED PRESSURE GRIDS THROUGH 15Z
SAT...THEN MAINTAINED PREVIOUS FORECAST THEREAFTER. USED A
COMBINATION OF THE ECMWF AND NAM FOR UPDATES TO POP GRIDS THROUGH
12Z SUN. POP FIELD WAS DECREASED SLIGHTLY GOING INTO EARLY NEXT
WEEK DUE TO THE DRY SIGNAL IN THE ECMWF...BUT WASN/T ENTIRELY
DIMINISHED TO ZERO DUE TO WETTER GFS SOLUTION.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ022-036-041>043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011>013-021-031>035-053.

&&

$$

BEZENEK/GARNER

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






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