Gale Warning 133, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
321 PM AKST SUN MAR 2 2014

.SHORT TERM...STRONG HIGH PRESSURE EXTENDING WEST INTO THE
PANHANDLE CONTINUES TO PRODUCE GUSTY OUTFLOW WINDS WITH CLEAR AND
COLD CONDITIONS ACROSS THE PANHANDLE. FREQUENT GUSTS BETWEEN
50 AND 55 MPH HAVE BEEN REPORTED IN THE DOWNTOWN JUNEAU AND TAKU
INLET AREA TODAY. THE OTHER USUAL OUTFLOW SPOTS INCLUDING THE
STIKINE RIVER VALLEY AND PORTLAND CANAL HAVE ALSO BEEN QUITE
GUSTY. THIS PATTERN HAS ALSO BEEN PRODUCING SMALL CRAFT AND SOME
GALE FORCE WINDS IN THE INNER CHANNELS WITH THE STRONGEST WINDS
NEAR INTERIOR PASSES. THE SHORTWAVE FEATURE THAT DROPPED SOUTH
OVER THE PANHANDLE OVERNIGHT AND THIS MORNING HAS HELPED TO
STRENGTHEN A BROAD CLOSED UPPER LOW OVER THE FAR SOUTHEAST
PANHANDLE. THIS WILL RESULT IN CONTINUED COLD AIR ADVECTION ALOFT
THROUGH MONDAY AFTERNOON.

AS HAS BEEN THE CASE FOR THE PAST SEVERAL DAYS, WINDS WILL BE THE
MAIN CONCERN THROUGH MONDAY AFTERNOON. GENERAL TREND WILL BE A
SLIGHT STRENGTHENING IN WINDS LATER THIS EVENING AND OVERNIGHT AS
PRESSURE GRADIENT TIGHTENS AGAIN. HIGH PRESSURE BEGINS TO SLOWLY
WEAKEN ON MONDAY WITH WINDS GRADUALLY SUBSIDING. FOR TONIGHT,
EXPECT GALE FORCE WINDS TO CONTINUE IN LYNN CANAL WITH SMALL CRAFT
WINDS OVER A MAJORITY OF THE OTHER INNER CHANNELS. STRONG GUSTS OF
AROUND 50 KT WILL CONTINUE OUT OF INTERIOR PASSES ESPECIALLY IN
THE INNER CHANNELS THAT ARE SITUATED ALONG THE COAST MOUNTAINS.
HAVE CONTINUED STRONG WIND HEADLINES FOR THE SKAGWAY, HAINES AND
JUNEAU ZONES THROUGH MIDDAY MONDAY BEFORE PRESSURE GRADIENT
WEAKENS ENOUGH THAT GUSTS ARE EXPECTED TO FALL BELOW THE STRONG
WIND CRITERIA OF 40 MPH. FOR THE DOWNTOWN JUNEAU AREA, CROSS
BARRIER FLOW WEAKENS TO AROUND 30 KT BY MONDAY AFTERNOON. WHILE
THERE WILL STILL LIKELY BE SOME GUSTIER WINDS, EXPECT THESE TO
STAY IN THE 30 TO 35 MPH RANGE. EXTENDED THE STRONG WIND HEADLINE
THROUGH TONIGHT FOR THE HYDER AREA AND PORTLAND CANAL AS SURFACE
GRADIENT REMAINS TIGHT BUT THESE WINDS SHOULD ALSO BEGIN TO
DIMINISH ON MONDAY AS THE GRADIENT RELAXES A BIT. BY MONDAY
AFTERNOON, GRADIENT IS EXPECTED TO HAVE WEAKENED ENOUGH THAT SMALL
CRAFT WINDS WILL BE CONFINED TO NORTHERN LYNN CANAL IN THE INNER
CHANNELS. DUE TO THE COLDER TEMPERATURES HAVE INCLUDED FREEZING
SPRAY IN THE NORTHERN AND CENTRAL INNER CHANNELS. DID INCLUDE
HEAVY FREEZING SPRAY FOR NORTHERN LYNN CANAL AND STEPHENS PASSAGE
MAINLY NEAR TAKU INLET AND INTERIOR PASSES.

ONCE AGAIN CAN EXPECT SIGNIFICANT TEMPERATURE DIFFERENCES BETWEEN
WIND SHELTERED AND OUTFLOW AREAS TONIGHT. WIND SHELTERED AREAS
ACROSS THE NORTH WILL FALL INTO THE SINGLE DIGITS WITH HIGHER
ELEVATIONS OF THE HIGHWAYS BELOW ZERO. EVEN IN WINDY AREAS, LOW
TEMPERATURES WILL BE COLDER THAN LAST NIGHT AS COLD AIR ADVECTION
PERSISTS OVER THE AREA. 1000-850MB THICKNESSES FALL BETWEEN 20 TO
30 METERS OVERNIGHT AND INTO TONIGHT SO HIGH TEMPERATURES WILL
STRUGGLE TO CLIMB ABOVE FREEZING ON MONDAY, RANGING FROM THE 20S
UP NORTH TO AROUND FREEZING IN THE SOUTHERN PANHANDLE. SOME MID
AND HIGH CLOUDS WILL STREAM INTO THE SOUTHERN PANHANDLE EARLY
SUNDAY IN ASSOCIATION WITH THE UPPER LOW LEADING TO PARTLY TO
MOSTLY CLOUDY SKIES. OTHERWISE, LOOKS LIKE ANOTHER CLEAR BUT
COLDER DAY OVER SOUTHEAST ALASKA.

USED THE 12Z NAM FOR UPDATES FOR THE FORECAST OVER THE NEXT 24
HOURS AS IT BEST INITIALIZED THE PRESSURE PATTERN OVER THE
PANHANDLE. FORECASTER CONFIDENCE IS ABOVE AVERAGE ON CLEAR AND
COLDER CONDITIONS WITH WEAKENING OUTFLOW WINDS NEAR THE END OF THE
SHORT RANGE PERIOD ON MONDAY AFTERNOON.

&&

.LONG TERM...MONDAY NIGHT THE UPPER LEVEL LOW WILL STILL BE OVER
CENTRAL B.C. AND THE FAR SE CORNER OF THE PANHANDLE. THIS WILL
CAUSE SOME PARTLY CLOUDY SKIES OVER THE HYDER AREA AND KEEP A
N-NELY FLOW ALOFT OVER THE REGION. THIS FLOW PATTERN WILL ALSO
CONTINUE THE CAA OUT OF CANADA THROUGH THE MID RANGE. THEN AS THE
LOW MOVES EAST ON TUESDAY FLOW WILL START TO BACK MORE N-NWLY.

A WEAK TROUGH OVER THE NORTHERN GULF WILL CAUSE SOME SNOW SHOWERS
TO DEVELOP AND MOVE INTO THE YAKUTAT AREA LATE MONDAY NIGHT
THROUGH TUESDAY OR EVEN INTO WEDNESDAY.

UPPER LEVEL FLOW OVER THE REGION LOOKS RATHER WEAK WEDNESDAY AND
THURSDAY. DESPITE THIS THE SURFACE PRESSURE PATTERN WILL REMAIN
THE SAME WITH NORTHERLY OUTFLOW WINDS OCCASIONALLY INCREASING DUE
TO SYSTEMS IN THE GULF INCREASING THE PRESSURE GRADIENT. THEN
THURSDAY NIGHT AN UPPER LEVEL RIDGE WILL START TO BUILD ALONG THE
COAST MOUNTAINS AND SHIFT FLOW TO BE MORE SWLY AND ONSHORE FOR
FRIDAY THROUGH THE WEEKEND. THIS SHIFT IN THE UPPER LEVEL WINDS AT
THE END OF THE WEEK WILL TRANSLATE TO A PATTERN CHANGE AWAY FROM
CLEAR/COLD/DRY TO WARMER/WET.

MODELS HAVE GONE BACK AND FORTH WITH THE FIRST FRONT TO MOVE INTO
THE AREA AFTER OUR LONG HIATUS. LATEST RUNS ARE IN AGREEMENT THAT
PRECIP WILL MOVE INTO THE AREA FRIDAY THROUGH FRIDAY NIGHT THEN
STICK AROUND THROUGH THE WEEKEND. COLD AIRMASS IN PLACE SHOULD
ALLOW FOR AN OVERRUNNING EVENT BEFORE WINDS SHIFT TO THE SOUTH AND
REALLY WARM THINGS UP. TIMING OF THAT SHIFT AND TEMPERATURE
INCREASE WILL BE CRITICAL FOR SNOW AMOUNTS. HAVE INCREASED
TEMPERATURES THROUGH THE END OF THE WEEK SOME AND INTRODUCED A MIX
OF RAIN AND SNOW.

USED AN ENSEMBLE APPROACH THROUGH THE EXTENDED FORECAST PERIOD
WITH A TRANSITION TO MORE NATIONAL WPC GUIDANCE FROM FRIDAY
ONWARD. ADJUSTED TEMPERATURES WITH THE GFS...DECREASED THEM IN THE
SHORTER TERM WITH CAA CONTINUING AND GRADUALLY UPWARD THROUGH THE
END OF THE WEEK. FORECAST CONFIDENCE IS AVERAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND THROUGH MONDAY MORNING FOR AKZ018-019-025.
         WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM AKST MONDAY
     FOR AKZ018.
         STRONG WIND THROUGH LATE TONIGHT FOR AKZ029.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ012-031.
         GALE WARNING FOR PKZ012-013.
         SMALL CRAFT ADVISORY FOR PKZ021-022-031-032-034-035-041>043.

&&

TPS/FERRIN