Small Craft Advisory 112, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
431 AM AKST SUN FEB 2 2014

.SHORT TERM...DOMINANT WEATHER FEATURE FOR THE SHORT TERM
PORTION OF THE FORECAST IS STRENGTHENING HIGH PRESSURE OVER THE
YUKON AND NORTHERN BRITISH COLUMBIA. SOME WEAK UPPER LEVEL
SHORTWAVE ENERGY WILL MOVE SOUTH OVER THE PANHANDLE TODAY BUT
EXPECT THIS TO PRODUCE NOTHING MORE THAN A FEW HIGH CLOUDS AT
BEST.

WINDS WILL BE THE MAIN CONCERN THROUGH TONIGHT WITH A TIGHTENING
PRESSURE GRADIENT AS THE SURFACE HIGH BUILDS TO THE NORTH AND
EAST. EXPECT SMALL CRAFT TO LOW END GALE FORCE WINDS TO CONTINUE
IN LYNN CANAL. WINDS AT THE SKAGWAY AIRPORT HAVE REMAINED
GENERALLY CALM OVERNIGHT AS GRADIENT ORIENTATION IS MORE NORTHWEST
AND NOT FAVORABLE FOR GENERATING WIND AT THE AIRPORT. THIS WILL
CHANGE THROUGH THE MORNING AS HIGH BUILDS TO THE EAST AND GRADIENT
REORIENTS TO MORE OF A NORTH-NORTHEAST GRADIENT. WINDS WILL
INCREASE RAPIDLY AS THIS DOES SO AND CONTINUE THROUGH TONIGHT WITH
GUSTS TO 35 MPH. OUTFLOW WINDS WILL ALSO BE INCREASING AS THE NE
GRADIENT STRENGTHENS. THE OTHER WIND AREA OF CONCERN IS THE
DOWNTOWN JUNEAU AND DOUGLAS AREA WITH OUTFLOW INCREASING TODAY
AND REACHING 35-40 KTS BY LATE TONIGHT. OTHER FACTORS FOR A TAKU
WIND EVENT ARE MARGINAL BUT THINK OUTFLOW ALONE WILL RESULT IN
STRONG WIND GUSTS TO 40 MPH BEGINNING THIS EVENING AND CONTINUING
OVERNIGHT.

EXPECT SUNNY SKIES TODAY WITH ONLY THE POTENTIAL FOR A FEW
PASSING HIGH CLOUDS AS UPPER LEVEL ENERGY MOVES OVER THE AREA.
CLEAR SKIES CONTINUE TONIGHT WITH TEMPERATURES PLUMMETING AFTER
SUNSET EARLY THIS EVENING. THERE WILL BE A WIDE RANGE IN
TEMPERATURES FOR SOME AREAS BOTH TODAY AND TONIGHT. THIS MORNING
THE TEMPERATURE RANGE IS ALREADY APPARENT WITH HAINES IN THE LOWER
30S THIS MORNING, BUT MUCH OF THE REMAINDER OF THE NORTHERN
PANHANDLE IN THE LOW TO MID 20S. ANOTHER WARM SPOT IS DOWNTOWN
JUNEAU WHERE NE DOWNSLOPE WINDS RESULTED IN TEMPERATURE SHOOTING
UP TO 40 DEGREES IN THE PAST HOUR. THESE TYPES OF LARGE
TEMPERATURE RANGES WILL CONTINUE THROUGH TODAY WITH OUTFLOW WINDS
CONTINUING. AS USUAL WIND SHELTERED AREAS WILL BE SEVERAL DEGREES
COLDER THAN AREAS EXPERIENCING THE OUTFLOW WINDS TONIGHT.

USED A BLEND OF THE ECMWF AND NAM FOR THE FIRST 24 HOURS OF THE
SHORT TERM PERIOD. FORECASTER CONFIDENCE IS ABOVE AVERAGE ON SUNNY
AND DRY CONDITIONS WITH INCREASING OUTFLOW WINDS THROUGH THE DAY
AND INTO TONIGHT.

&&

.LONG TERM...QUIET WEATHER WEEK AHEAD WITH EACH DAY BEING FAIRLY
SIMILAR TO THE NEXT. THE REGION WILL REMAIN IN A DRY OUTFLOW WIND
REGIME. AT THE SURFACE HIGH PRESSURE WILL HOLD IN THE YUKON AND
B.C. WITH A TIGHT PRESSURE GRADIENT ALONG THE COASTAL MOUNTAINS.
THEREFORE EXPECT N-NELY WINDS AREAWIDE WITH GUSTS OUT OF INTERIOR
PASSES. THE SET UP WILL REMAIN FAVORABLE FOR TAKU WINDS...AS
DISCUSSED ABOVE...THROUGH MONDAY AFTERNOON AND MAY CONTINUE
THROUGH MONDAY NIGHT. EXPECT GUSTS OF AROUND 45 MPH FOR DOWNTOWN
JUNEAU AND DOUGLAS.

THERE WILL ALSO BE A THERMAL GRADIENT ALONG THE COASTAL MOUNTAINS
WITH 850MB TEMPERATURES COOLING EACH DAY. UNDER MOSTLY CLEAR SKIES
WIND SHELTERED AREAS WILL BE COLDER EACH PASSING NIGHT. DAYTIME
HIGHS WONT HAVE MANY HOURS TO RECOVER SINCE THE MINIMUMS HAVE BEEN
AROUND 7/8AM AND THE HIGHS HAVE BEEN IN THE EARLY AFTERNOON. THE
WINDIER OUTFLOW AREAS WILL REMAIN NEARLY 10 DEGREES
WARMER...ESPECIALLY IN THE TAKU WIND AREA SINCE THAT IS ENHANCED BY
DOWNSLOPE EFFECTS.

THE NEXT CHANCE OF PRECIPITATION LOOKS TO BE AT THE END OF THE WEEK.
MODELS ARE STARTING TO COME INTO BETTER AGREEMENT ON A SYSTEM
APPROACHING FROM INTERIOR ALASKA AND DEVELOPING A LOW CENTER IN THE
NORTHERN GULF ON FRIDAY. HOWEVER...THERE ARE SOME DIFFERENCES ON THE
STRENGTH AND TIMING OF HOW LONG THE SNOW STICKS AROUND. THE NEW 06Z
RUN OF THE GFS HAS PRECIP OVER YAKUTAT QUICKLY MOVING OFF INTO THE
GULF WITH THE ENERGY BECOMING WRAPPED UP INTO A STRONGER LOW
PRESSURE SYSTEM CROSSING THE NORTH PACIFIC ON SATURDAY. PREVIOUS
RUNS OF THE GFS WERE EVEN BRIEFER WITH THE SNOW...WITH LITTLE QPF.
THE ECMWF HAS HAD A STRONGER LOW WITH MORE QPF FOR YAKUTAT AND A
LITTLE DOWN TO THE JUNEAU AREA...THEN AGAIN THE PRECIP GETS PULLED
OUT INTO THE GULF BY THE STRONGER SYSTEM TO THE SOUTH. THIS STRONGER
SYSTEM TO THE SOUTH WOULD CAUSE MORE NORTHERLY OUTFLOW WINDS AND
COULD BRING PRECIP TO THE SOUTHERN AREAS TOWARD THE END OF NEXT
WEEKEND.

MODELS WERE IN GOOD AGREEMENT THROUGH THE MID RANGE AND MATCHED WELL
WITH THE GOING FORECAST. LITTLE CHANGES WERE MADE IN THE SHORTER
TERM. DECREASED TEMPERATURES SLIGHTLY THROUGH THE FORECAST AND
ADJUSTED UP FOR WINDY LOCATIONS AS MENTIONED. FORECAST CONFIDENCE IS
ABOVE AVERAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM THIS EVENING THROUGH MONDAY EVENING FOR AKZ025.
MARINE...GALE WARNING FOR PKZ012.
         SMALL CRAFT ADVISORY FOR PKZ013-021-022-031-035.

&&

TPS/FERRIN