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FXAK67 PAJK 070000
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
300 PM AKST FRI MAR 6 2015

.SHORT TERM...SATELLITE IMAGERY THIS AFTERNOON SHOWING A HIGH
PRESSURE RIDGE OVER THE AK PANHANDLE, A STRONG 988 MB LOW IN THE
BERING SEA TRACKING EAST AND A WEAKENING 998 MB LOW IN THE NORTH
PACIFIC RETROGRADING TO THE WEST. CURRENTLY 500 MB VORT MAX OVER
THE PANHANDLE RIDGE MOVING OVER THE PANHANDLE ENHANCING LIFT.
ALONG WITH COOLER AIR ALOFT THIS IS PRODUCING SCATTERED RAIN
SHOWERS OVER THE CENTRAL AND NORTHERN PANHANDLE BUT WITH NUMEROUS
CLEAR BREAKS. AS THE VORT MAX TRACKS EAST SHOWER ACTIVITY FROM THIS
DISTURBANCE WILL DIMINISH BUT THROUGH THE NIGHT WILL HAVE INCREASED
PRECIP POTENTIAL FROM THE TWO LOWS IN OUR VICINITY. TO THE SOUTH
BANS EMANATING FORM THE N PACIFIC LOW WILL NEAR THE SOUTHERN
PANHANDLE TONIGHT. SINCE THE LOW IS PULLING AWAY TO THE WEST WITH
LESS SUPPORT ALOFT NOT EXPECTING MUCH FROM THIS SYSTEM TO REACH
THE SOUTHERN PANHANDLE. TO THE NORTH THE LOW ADVANCING FROM THE
BERING SEA IS MUCH BETTER ORGANIZED AND WILL BEGIN TO MOVE IN
PRECIP TO THE NORTHERN COASTAL PANHANDLE THROUGH THE EVENING. AS
THE WAVE PROGRESSES TO THE SOUTHEAST THROUGH SATURDAY POPS WILL
INCREASE OVER THE NORTHERN AND CENTRAL PANHANDLE. WHILE THERE IS
SOME COLDER AIR ALOFT WITH THE MID LEVEL TROUGH MOVING OVER THE
AREA CURRENT SATELLITE APPEARS MORE STRATIFORM THEN SHOWERY IN
NATURE. WHILE THE COLDER AIR ALOFT WILL EVENTUALLY MIX DOWN TO THE
SURFACE THE PANHANDLE WILL STILL BE ABOVE NORMAL FRIDAY NIGHT AND
SATURDAY DUE TO WARMING AIR RIDGING UP FROM THE N PACIFIC LOW.

PRESSURE GRADIENT BETWEEN THE PANHANDLE RIDGE AND LOW OVER THE
YUKON INCREASED BIT FASTER TODAY WITH GUSTY WINDS OVER THE
NORTHERN INNER CHANNELS. N LYNN CANAL PICKED UP TO SMALL CRAFT
LEVELS TODAY WITH 15 TO 25 MPH WINDS OVER SKAGWAY. PRESSURE
GRADIENT WILL CONTINUE TO TIGHTEN WAS THE BERING SEA LOW ADVANCES
EASTWARD. FOR NOW KEEPING N LYNN JUST BELOW GALE FORCE FOR SATURDAY
AND KEEPING SKAGWAY GUSTS JUST BELOW 40 MPH, BUT BOTH AREAS COULD
NEAR THESE HIGHER THRESHOLDS. SMALL CRAFT LEVEL WINDS WILL DEVELOP
IN S LYNN CANAL AND STEPHENS PASSAGE AS WELL ON SATURDAY WITH
WINDS PICKING UP TO 20 KT ELSEWHERE.

MODELS IN FAIR AGREEMENT THIS AFTERNOON WITH NAM/ECMWF/GEM STILL
IN LINE WITH INHERITED GRID. BUMPED UP WINDS TONIGHT SLIGHTLY
FOLLOWING THE CURRENT WIND TREND. BACKED OFF ON SOME PRECIP OVER
THE NORTH CENTRAL PANHANDLE AS MODELS WERE BIT OVER ZEALOUS WITH THE
SHOWER ACTIVITY OVER THE RIDGE. FORECAST CONFIDENCE IS AVERAGE.

.LONG TERM...THE BERING SEA LOW DISCUSSED ABOVE WILL FEATURE
PROMINENTLY IN THE EARLY PORTION OF THE EXTENDED RANGE FORECAST.
AS THE LOWS TRACKS EAST ACROSS THE INTERIOR, THE ASSOCIATED FRONT
WILL DRAG ACROSS THE FAR NORTHERN GULF AND THEN SAG SOUTHEAST
ACROSS THE PANHANDLE. IN ADDITION TO RAIN NEAR SEA LEVEL, THE
FRONT WILL BRING SIGNIFICANT SNOWFALL TO HIGHER ELEVATIONS WITH
CLOSE TO 4 INCHES ALONG THE KLONDIKE HIGHWAY NEAR WHITE PASS AND 2
TO 3 INCHES ALONG THE HAINES HIGHWAY. AS THE FRONT PASSES TO THE
EAST AND THE PARENT LOW MOVES INTO THE YUKON, A STRONG SOUTHERLY
PRESSURE GRADIENT WILL GENERATE SOUTHERLY GALE FORCE WINDS IN
NORTHERN LYNN CANAL SATURDAY NIGHT AND SUNDAY. HIGH END SMALL
CRAFT WINDS FOR SOUTHERN LYNN CANAL DURING THE SAME TIME PERIOD.

IN THE WAKE OF THIS FIRST LOW, ANOTHER WILL FORM NEAR PRINCE
WILLIAM SOUND AND PUSH SHOWERS EAST. PRECIPITATION FROM THIS
FEATURE WILL BE ON THE LEADING EDGE OF STRONG LOW LEVEL COLD AIR
ADVECTION. BY SUNDAY AFTERNOON, EXPECT SNOW NEAR SEA LEVEL TO
BEGIN VICINITY YAKUTAT AND SPREAD EAST AND SOUTH WITH MEASURABLE
ACCUMULATIONS ALL THE WAY DOWN TO THE DIXON ENTRANCE LASTING
POTENTIALLY THROUGH TUESDAY AFTERNOON. 48 HOUR TOTALS GENERALLY IN
THE 2 TO 4 INCH RANGE IN A SWATH OF MAXIMUM ACCUMULATIONS EXTENDING
SOUTHEAST FROM YAKUTAT TO NEAR WRANGELL. THE COLD AIR WILL BEGIN
TO RETREAT TO THE NORTH BY MID WEEK AS A LOW WEST OF WASHINGTON
STATE AT THAT TIME BEGINS TO TRACK NORTH, BRINGING WARMER LOW
LEVEL AIR AND A FRONT WITH IT.

USED A BLEND OF NAM AND ECMWF FOR UPDATES TO PRESSURE AND WIND
THROUGH MONDAY NIGHT WITH WPC THEREAFTER. POP AND QPF FROM ECMWF
AND GEM WITH SOME HELP FROM GFS AT TIMES. TEMPS UNCHANGED. OVERALL
FORECAST CONFIDENCE IS AVERAGE.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-013-031.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041.

&&

$$

PRB/FRITSCH

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