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FXAK67 PAJK 261442
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
542 AM AKST FRI DEC 26 2014

.SHORT TERM...SOME WINDS ARE A BIT OUT OF WHACK TONIGHT BASED ON
MODEL GUIDANCE. YAK HAS BEEN GUSTING OVER 20 KTS FOR A COUPLE OF
HOURS...SEEMS TO BE RELATED TO SHOWER INFLUX...THIS NOW DYING DOWN
AS GRADIENT WEAKENS OVER THE NEXT FEW HOURS. CAPE SPENCER HAS SUSTAINED
21 KNOTS G41 BUT HAS NOT REPORTED SINCE 10Z AND OBS LOOK A BIT
QUESTIONABLE. WE CURRENTLY HAVE 20KTS IN GRIDS. ELDRED ROCK HAS BEEN
MAINTAINING SOUTH WINDS 21G34 BUT EXPECT A GRADUAL DECREASE THERE.
FAIRLY QUIET DAY EXPECTED WITH RELATIVELY WEAK GRADIENTS AND
MOSTLY LIGHT LIQUID PRECIPITATION DEVELOPMENT ACROSS PANHANDLE.
YAK AND THE SOUTHERN PANHANDLE SHOULD GET THE MAX QPF BUT A HALF
INCH IS OPTIMISTIC IN BOTH AREAS. WEAK LOW CROSSES THE GULF
HEADING EAST AT ABOUT 54N AND TAKING AN ESELY TRACK ONCE IT NEARS
THE SOUTHERN GULF. UTILIZED MOSTLY NAM/EC MODELS TO ADJUST
MOISTURE FIELDS IN THE FORECAST. BUMPED UP THE SNOW LEVEL AT
SKAGWAY AND THOUGH HAINES WILL GET SOME SNOW WE DON`T EXPECT
SIGNIFICANT ACCUMULATION. FORMATTER ISSUES WITH SNOW/RAIN AND ZONE
PIXELS LED TO EXTENSIVE MANUAL ALTERATION OF SEVERAL ZONE
PRODUCTS. ADJUSTED SOME TEMPERATURES, MOSTLY DOWNWARD LATE
TONIGHT, BASED ON MOS PREDICTIONS. FOR TONIGHT BUMPED UP THE LYNN
CANAL WINDS TO 20 KNOTS AT HANDOFF BASED ON ENHANCED NORTHERLY
GRADIENT GETTING UP TO 3.5MB SKAGWAY-JUNEAU. DID THE SAME FOR
CLARENCE STRAIT TONIGHT. ALSO TWEAKED DIRECTIONS IN THE EAST-
WEST CHANNEL PORTIONS IN ICY STRAIT, FREDERICK SOUND AND SUMNER
STRAIT TO THE APPROPO ORIENTATION FOR A NORTHERLY GRADIENT LATE
TONIGHT. AS THE WEAK LOW EXITS TONIGHT ANTICYCLOGENESIS BEGINS
OVER THE AREA, SPREADING NORTH TO SOUTH, ALONG WITH STRENGTHENING
OF THE YUKON/NORTH BC CONTINENTAL ANTICYCLONE...THE RESULT IS
RAPID DRYING AND COOLING OCCURRING OVERNIGHT. POTENTIAL OF PATCHY
FOG IN THE WAKE OF THE LOW PRIOR TO RAPID DRYING LATE TONIGHT,
MOSTLY IN CENTRAL AND NORTHERN PORTIONS OF THE PANHANDLE. FOR
NORTHERN/WESTERNMOST ZONES THE FOG POTENTIAL APPEARS TO BE LOWER
AS DRYING WILL SET IN EARLIER.

.LONG TERM...PREVIOUS THINKING ON PATTERN AND ITS IMPACT ON
WEATHER FOR SOUTHEAST ALASKA REMAINS THE SAME. HIGHLY AMPLIFIED
UPPER LEVEL RIDGE WILL BRING A DRY AND SUNNY WEEKEND TO SOUTHEAST
ALASKA. MODELS HAVE CONTINUED TO TREND TOWARD A SLOWER EASTWARD
PROGRESSION WITH THE FRONT FOR NEXT WEEK. THIS IS NOT EXTREMELY
UNEXPECTED HOWEVER WITH SUCH AN AMPLIFIED RIDGE OUT AHEAD OF THE
FRONT. THE ECMWF IS THE SLOWEST OF THE MODELS, NOT BRINGING
PRECIPITATION INTO A MAJORITY OF THE PANHANDLE UNTIL TUESDAY
NIGHT. THE GFS IS SLIGHTLY QUICKER AND BRINGS PRECIPITATION INLAND
ON TUESDAY AFTERNOON. THIS SYNOPTIC SETUP WOULD FAVOR THE SLOWER
SOLUTION SO OPTED TO GO MAINLY WITH A ECMWF AND NAM BLEND WHICH
SLOWED POPS DOWN A BIT FROM THE PREVIOUS FORECAST. THERE IS STILL
RELATIVELY GOOD MODEL AGREEMENT THAT THIS HIGH AMPLITUDE RIDGE
WILL REESTABLISH ITSELF BY LATE NEXT WEEK WITH DRY CONDITIONS AGAIN
PREVAILING OVER SOUTHEAST ALASKA. THERE ARE ALSO INDICATIONS OF A
MORE SUBSTANTIAL SHOT OF COLD AIR AS STRONG SURFACE HIGH PRESSURE
BUILDS IN FROM THE NORTH WITH THIS RIDGE.

NORTHERLY WINDS WILL REACH AROUND 30 KTS IN THE NORTHERN INNER
CHANNELS THIS WEEKEND AS HIGH PRESSURE STRENGTHENS OVER THE YUKON.
THIS WON`T BE A PROLONGED OR STRONG OUTFLOW EVENT AS THE HIGH IS
PROGRESSIVE. THE WINDS WILL SHIFT TO MORE OF THE EAST-WEST
CHANNELS BY EARLY NEXT WEEK AS THE HIGH SLIDES SOUTHEAST INTO
BRITISH COLUMBIA. WINDS WILL GRADUALLY DIMINISH THROUGH THE
WEEKEND AS THE GRADIENT RELAXES WITH THE WEAKENING HIGH TO THE
EAST.

WHILE THE NORTHERN PANHANDLE MAY START AS SNOW WITH THE INCOMING
FRONT EARLY TO MID NEXT WEEK, EXPECT THAT WARM AIR ADVECTION BOTH
ALOFT AND AT THE SURFACE WILL SWITCH PRECIPITATION OVER TO RAIN.
THE USUAL PLACES, HAINES AND SKAGWAY WILL NEED TO BE MONITORED TO
DETERMINE HOW MUCH LOW LEVEL COLD AIR IS ABLE TO REMAIN IN THOSE
AREAS. HAVING SAID THAT, MOST OF THE FRONTS ENERGY WILL BE AIMED
INTO THE NORTHERN GULF. THE HIGHLY AMPLIFIED RIDGE WILL WEAKEN THE
FRONT AS IT PUSHES INTO THE PANHANDLE SO AM NOT EXPECTING A LARGE
AMOUNT OF PRECIPITATION.

USED THE 00Z NAM/ECMWF FOR UPDATES TO THE PREVIOUS FORECAST
PACKAGE. THE MAIN CHANGE MADE WAS TO FURTHER DELAY THE FRONT
EARLY NEXT WEEK. FORECASTER CONFIDENCE IS BETTER THAN AVERAGE FOR
THE EXTENDED RANGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-041>043.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ022-051>053.

&&

$$

WESLEY/TPS

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