National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXAK67 PAJK 030002
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
302 PM AKST MON MAR 2 2015

.SHORT TERM...RATHER QUIET DAY ACROSS THE PANHANDLE TODAY. MOST
AREAS ARE ENJOYING MOSTLY CLEAR SKIES WITH ONLY SOME HIGH CLOUDS
PASSING THROUGH. THE LACK OF CLOUDS DID RESULT IN SOME FOG AROUND
WRANGELL THIS MORNING, BUT WITH GENERAL SUBSIDENCE AND OUTFLOW
ACROSS THE PANHANDLE, WHAT FOG THERE WAS DISSIPATED QUICKLY.
OTHERWISE THE ONLY REMAINING CONCERN IS DIMINISHING OUTFLOW WINDS
IN SKAGWAY, LYNN CANAL, AND STEPHENS PASSAGE. PAGY HAS REPORTED
GUSTS UP TO 27 KT SO FAR TODAY, AND ELDRED ROCK AND FIVE FINGERS
HAVE BOTH HAD 20 TO 25 KT WINDS MOST OF THE MORNING.

THE HIGH PRESSURE IN CANADA THAT BROUGHT THE OUTFLOW WINDS WILL
BE WEAKENING AND DROPPING INTO BRITISH COLUMBIA BY THIS EVENING
BEFORE IT HEADS OFF TO THE EAST LATER TONIGHT. REPLACING IT WILL
BE A WEAKER RIDGE OVER THE PANHANDLE BY TOMORROW. THE NORTHERLY
WINDS ACROSS THE PANHANDLE WILL DIMINISH AS A RESULT AND THEN TURN
MORE SOUTHERLY AS THE WEAKER RIDGE BUILDS ON TUESDAY. WIND SPEEDS
WILL REMAIN MOSTLY 15 KT OR LESS AS FORECAST PRESSURE GRADIENTS
WILL BE RATHER LOW FOR THE NEXT 24 HOURS.

THE OTHER FEATURE OF CONCERN IS A WEAK FRONT THAT WILL BE MOVING
IN FROM THE GULF THROUGH THE NEXT 24 HOURS. NOT MUCH WIND OR
PRECIP WITH THIS FRONT AS IT IS FIGHTING THE UPPER RIDGE THAT IS
STILL PARKED OVER THE PANHANDLE. HIGHEST WINDS WILL BE TONIGHT OVER
THE NORTHERN GULF NEAR CAPE SUCKLING AS A WEAK BARRIER JET
MAGNIFIES THE FRONTAL WINDS TO 30 KT. OTHER WISE MOST WINDS WILL
BE LESS THEN 25 KT. AS FOR PRECIP YAKUTAT WILL BE THE FIRST TO
SEE PRECIP. IT IS LIKELY TO START LATE TONIGHT OR EARLY TOMORROW AND
WILL PERSIST THROUGH MOST OF TUESDAY. YAKUTAT MAY BE COLD ENOUGH
FOR THE PRECIP TO START OUT AS SNOW EARLY TUE BUT IT SHOULD
CHANGE BACK TO RAIN BY LATER IN THE MORNING AS TEMPERATURES WARM
UP AND WINDS TURN MORE SE. ANY SNOW ACCUMULATION WILL BE LESS THEN
1 INCH AS PRECIP IS EXPECTED TO BE LIGHT. FARTHER EAST THE
NORTHERN PANHANDLE WILL NOT SEE THE RAIN UNTIL TUESDAY MORNING AND
EVEN THEN IT IS SOMEWHAT UNCERTAIN EXACTLY WHEN AND HOW MUCH AS
THE UPPER RIDGE OVER THE PANHANDLE WILL BE FIGHTING THIS FRONT THE
WHOLE WAY. SOME AREAS MAY EVEN BE COLD ENOUGH FOR A MIX WITH SNOW
IN THE MORNING BUT MOST AREAS THAT GET PRECIP SHOULD BE RAIN BY
AFTERNOON WITH LITTLE IN THE WAY OF ACCUMULATION EXPECTED. THE
FARTHER EAST YOU GET THE LESS RAIN YOU WILL SEE. YAKUTAT HAS
CATEGORICAL TO LIKELY POPS, THE NORTHERN PANHANDLE HAS CHANCE TO
LIKELY, AND THE SOUTHERN PANHANDLE WILL LIKELY REMAIN MOSTLY DRY
AS THE EASTERN PART OF THE FRONT IS THE MOST AFFECTED BY THE UPPER
RIDGE.

THE ADVANCE OF THIS FRONT IS ALSO PLAYING HAVOC WITH THE
TEMPERATURE FORECAST AS VARYING CLOUD COVER WITHIN THE MODEL
SOLUTIONS RESULTS IN SPREADS OF 4 TO 7 DEGREES IN SOME LOCATIONS.
ENDED UP GOING WITH WARMING UP TEMP OVERNIGHT A FEW DEGREES FOR
THE NORTHERN PANHANDLE WITH THE INCREASING CLOUD COVER AND
LOWERING TEMPS OVER THE SOUTH WHERE MORE BREAKS WILL ALLOW AREAS
TO RADIATE OUT.

SHORT RANGE MODELS WERE IN DECENT AGREEMENT. THE GFS SEEMED TO BE
A LITTLE BIT OF AN OUTLIER AS IT WAS JUST A BIT TOO FAST BRINGING
THE FRONT INLAND COMPARED TO JUST ABOUT EVERY OTHER MODEL. DECIDED
TO GO WITH NAM AND ECMWF FOR MODEL GUIDANCE TODAY AS THESE MODELS
SEEMED TO REPRESENT CURRENT FEATURES RATHER WELL.

.LONG TERM...SERIES OF RELATIVELY WEAK WAVES WILL CONTINUE TO TRACK
INTO THE AK GULF THEN OVER THE PANHANDLE THROUGH THE EXTENDED
RANGE FORECAST. MODELS HAVE BEEN HAVING DIFFICULTY PIN POINTING
THE DETAILS OF THESE FEATURES SO THERE HAS BEEN RATHER LARGE MODEL
SPREAD AND RUN TO RUN INCONSISTENCIES. THE THERMAL PATTERN OVER
THE NORTHERN PANHANDLE HAS SHOWN A WIDE RANGE IN SOLUTIONS, MAINLY
WITH OVERNIGHT LOWS AND PRECIP TYPE. USED A BLEND OF 12Z ECMWF
WITH INHERITED GRIDS AS IT WAS MORE OF A MID RANGE SOLUTION.
FORECAST CONFIDENCE IS BELOW AVERAGE.

THE FRONT DISCUSSED IN THE SHORT TERM WILL WEAKEN AS IT MOVES OVER
THE PANHANDLE THROUGH THE NIGHT AS A SECOND SHORT WAVES TRACKS
INTO THE CENTRAL GULF FROM THE SOUTHWEST. THIS WAVE WILL BERING IN
MORE PRECIP TOT HE REGION FROM WEDNESDAY INTO THURSDAY FORMING
FROM NORTH TO SOUTH. FOR THURSDAY NIGHT INTO FRIDAY THERE WILL BE
A 995 MB LOW IN THE NORTHERN PACIFIC WITH ANOTHER WEAK WAVE
DIRECTLY TO THE NORTH TRACKING ALONG THE SOUTHERN PART OF THE AK
INTERIOR. THIS WAVE WILL DROP OVER THE PANHANDLE FROM THE NORTH TO
THE SOUTH WHERE IS INTERACTS WITH THE FRONTAL BOUNDARY FROM THE N
PACIFIC LOW. ALONG WITH ANOTHER BAND OF PRECIP THIS WAVE WILL
INCREASE WINDS OVER THE AK GULF AND PANHANDLE FOR THE WEEKEND. AT
THIS TIME NOT EXPECTING MARINE WINDS MUCH ABOVE 25 KT. FOR
SUNDAY INTO MONDAY THE NEXT SIGNIFICANT SYSTEM WILL BE REMNANTS OF
THE BERING SEA LOW THAT IS CROSSING OVER THE AK INTERIOR THROUGH
THE WEEKEND THEN REACHING THE PANHANDLE BY THE START OF NEXT WEEK.

WHILE 850 MB TEMPS WILL BE IN THE -4 TO -6C RANGE FOR THE WAVES
MOVING OVER THE NORTHERN GULF WIND FLOW WILL BE SOUTHWESTERLY
WHICH SHOULD HELP TO MODERATE TEMPS. KEEPING SOME MIX OF SNOW
OVERNIGHT FOR NORTHERN PANHANDLE BUT HAVE BACKED OFF ON SOME MIX
OF SNOW FOR LOCATIONS WHERE LOWS WILL BE JUST ABOVE FREEZING.

MODEL SPREAD BEGAN RATHER SOON WITH DIFFERENCES ALREADY WITH THE
WEDNESDAY WAVE. THE NAM WAS MORE PROGRESSIVE MOVING THE WAVE INTO
THE SOUTHEAST GULF WITH THE GEM BARELY MOVING THE LOW OUT OF THE
WESTERN GULF, THE GFS WHILE FASTER THAN THE GEM WAS STILL ON THE
SLOW SIDE. SO USED THE 12 ECMWF WHICH WHILE HAS SHOWN SOME RUN
TO RUN DIFFERENCES WAS THE MID RANGE SOLUTION. FOR THE REST OF THE
EXTENDED KEPT WITH NEW WPC WHICH WAS AN ECMWF/NAEFS ENSEMBLE
SOLUTION.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ051-052.

&&

$$

EAL/PRB

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