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000
FXAK67 PAJK 280101
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
401 PM AKST SAT DEC 27 2014

.SHORT TERM...MOST OF THE PANHANDLE HAS CLEARED OUT NICELY TODAY
AS YESTERDAY`S LOW HAS MOVED INTO SOUTHERN BRITISH COLUMBIA AND
NORTHERLY OUTFLOW REPLACES IT. SOME LOW TO MID LEVEL CLOUDS STILL
LINGER IN THE SOUTHERN INNER CHANNELS ACCORDING TO SATELLITE
IMAGES AND OBSERVATIONS BUT THOSE SHOULD DIMINISH THROUGH THE
AFTERNOON. A STRONG AREA OF HIGH PRESSURE IS BUILDING IN THE YUKON
FUELING THE START OF SOME OUTFLOW WINDS. ELDRED ROCK WINDS
INCREASED TO NORTH 25 KT OVER NIGHT AND FIVE FINGERS HAS JUST
INCREASED TO 25 KT AROUND MID DAY. FARTHER SOUTH THE DIXON
ENTRANCE WEST BUOY AND LINCOLN ROCK ARE STILL SHOWING NW WINDS TO
25 KT DUE TO LINGERING PRESSURE GRADIENT FROM THE RETREATING LOW
IN BRITISH COLUMBIA. THE SOUTHERN PANHANDLE WINDS SHOULD DIMINISH
THIS EVENING AS THE LOW CONTINUES TO PULL AWAY.

MAIN FORECAST CONCERNS FOR THE NEXT 24 HOURS ARE WINDS AND
TEMPERATURES AS THE PANHANDLE WILL BE MOSTLY CLEAR AND DRY.
OUTFLOW WINDS WILL CONTINUE TO INCREASE THROUGH TOMORROW AS SOME
COOLER AIR BEGINS TO FILTER THROUGH THE MOUNTAIN PASSES AND
PRESSURE GRADIENTS TIGHTEN UP. WINDS WILL NOT BE REALLY HIGH AS
THERE IS NO LOW IN THE GULF THAT WOULD TIGHTEN UP THE GRADIENT
ALONG THE COAST MOUNTAINS ANY MORE THAT IT WILL BE. HOWEVER, WITH
A 4 TO 5 MB FORECAST GRADIENT BETWEEN JUNEAU AND SKAGWAY DECIDED
TO BUMP LYNN CANAL TO MIN GALE FOR SUN. STEPHENS PASSAGE AND CROSS
SOUND WILL ALSO BE WINDY. BOTH PLACES ARE FORECAST TO INCREASE TO
25 KT BY SUN IN THE OUTFLOW CONDITIONS. DOWNTOWN JUNEAU AND
DOUGLAS WILL LIKELY SEE SOME GUSTY WINDS ON SUN AS WELL AS CROSS
BARRIER FLOW INCREASES TO 30 TO 40 KT AND SOME COOLER AIR BRINGS
IN A WEAK INVERSION ABOVE RIDGE TOP. LIMITING THIS MOUNTAIN WAVE
POTENTIAL HOWEVER, IS A VERY LOW ALMOST NONEXISTENT CRITICAL LEVEL
AROUND 800 MB. GIVEN THE STRENGTH OF THE CROSS BARRIER FLOW
DECIDED TO HOIST A STRONG WIND HEADLINE FOR DOWNTOWN JUNEAU AND
DOUGLAS FOR SUN AS THERE WILL LIKELY BE GUSTS TO 40 MPH BY MIDDAY
EVEN WITH THE LESS THEN FAVORABLE CRUCIAL LEVEL AND WEAK
INVERSION.

AS FOR TEMPERATURES, THE COLD AIR MASS IN CANADA IS NOT THAT
STRONG WITH FORECAST 850 MB TEMPS ONLY REACHING DOWN TO -12 TO
-16 C IN CANADA AND -5 TO -9 C ACROSS THE PANHANDLE. AS A RESULT
HIGH TEMPS FOR SUN WILL NOT BE THAT MUCH COOLER THAN WHAT WE HAVE
BEEN SEEING RECENTLY. EXPECTED HIGHS ON SUN WILL BE IN THE UPPER
20S AND 30S ACROSS THE PANHANDLE. IT IS TONIGHT`S LOW TEMPS THAT
WILL BE NOTICEABLE COOLER BUT IT WILL MOSTLY BE DUE TO RADIATIONAL
COOLING FROM THE CLEARER SKIES. OVERNIGHT LOWS WILL RANGE FROM THE
20S IN WINDY AREAS TO THE UPPER SINGLE DIGITS IN WIND SHELTERED
INLAND AREAS.

MAINLY STUCK CLOSE TO HI-RES MODEL GUIDANCE TODAY AS THESE TEND TO
CATCH THE LOCALIZED AREAS OF HIGHER WINDS ASSOCIATED WITH THE
OUTFLOW WINDS BETTER. FAVORED THE NAM AND HRRR MODELS TODAY FOR
THAT REASON WHICH HELPED FLESH OUT THE NORTHEAST WINDS THAT WILL
BE COMING OUT OF CROSS SOUND AND THE PASSES EAST OF YAKUTAT.

.LONG TERM...UPPER LEVEL RIDGE OF HIGH PRESSURE OVER THE EASTERN
GULF WILL CONTINUE THE DRY WEATHER SUNDAY NIGHT THROUGH MONDAY. THE
RIDGE STARTS TO SHIFT TO THE EAST ON TUESDAY THEN TIP OVER/FLATTEN
TUESDAY NIGHT WHICH WILL ALLOW FOR AN APPROACHING SYSTEM TO GET
THROUGH...ALTHOUGH WILL WORK TO WEAKEN IT.

THE SURFACE HIGH OVER THE YUKON WILL START TO SHIFT SOUTH INTO
B.C. SUNDAY NIGHT THEN CONTINUE SOUTH ON MONDAY. THIS WILL SHIFT
THE PRESSURE ORIENTATION FROM NORTHERLY OUTFLOW WINDS TO AN
EASTERLY OUTFLOW. THEN THE RIDGE WILL ORIENT ALONG THE COASTAL
MOUNTAINS LATE MONDAY INTO TUESDAY AND CAUSE WINDS TO SHIFT
SOUTHERLY THROUGH THE INSIDE WATERS. THIS WILL WARM THINGS BACK UP
THROUGH MID WEEK AS PRECIP MOVES BACK IN. MANY PLACES WILL START
OFF AS SNOW WITH THE WEAKENING FRONT TUESDAY NIGHT...BUT THEN
CHANGE OVER TO MAINLY RAIN FOR WEDNESDAY. SINCE THE FRONT WILL BE
WEAKENING THINK THAT PRECIP/SNOW AMOUNTS WILL BE MINIMAL. HAVE
ABOUT 2 INCHES AT MOST.

MODELS START TO DIVERGE FOR THE SECOND HALF OF NEXT WEEK...BUT ARE
SHOWING MULTIPLE UPPER LEVEL TROUGHS MOVING SOUTH OVER THE COASTAL
MOUNTAINS FROM THE ARCTIC THURSDAY THROUGH THE WEEKEND WHILE THE
RIDGE OF HIGH PRESSURE REFORMS OVER THE WESTERN GULF. AT THE
SURFACE HIGH PRESSURE LOOKS TO REBUILD OVER CANADA AND WILL
INCREASE NORTHERLY OUTFLOW WINDS AGAIN. THE UPPER LEVEL PASSING
FROM THE NORTH ARE A UNIQUE PATTERN...MAKING FOR SOME FORECASTER
UNCERTAINTY. GUT FEELING IS THAT IT WILL BRING IN SOME COLDER AIR
AND JUST HIGH CLOUDS AS THEY PASS.

THE ECMWF HAS BEEN FLIP FLOPPING WITH EACH MODEL RUN WITH A NEW LOW
MOVING ACROSS THE GULF ON FRIDAY IN THE 00Z RUN AND NOTHING WITH THE
12Z RUN. THE 12Z RUN WAS MUCH CLOSER TO THE GFS AND WHAT WPC
HAD...SO WENT WITH THIS MORE CONSISTENT IDEA. DECREASED
TEMPERATURES FOR THE END OF THE FORECAST BUT WILL NEED TO DECREASE
THEM MORE IF THE TREND TOWARD THE NORTHERLY OUTFLOW PATTERN
CONTINUES.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR
     AKZ025.
MARINE...GALE WARNING FOR PKZ012.
         SMALL CRAFT ADVISORY FOR PKZ013-022-031-034>036-041>043-052.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ051.

&&

$$

EAL/FERRIN

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