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FXAK67 PAJK 271305
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
405 AM AKST FRI FEB 27 2015

.SHORT TERM...RATHER QUITE WEATHER FORECAST IN STORE THROUGH
FRIDAY NIGHT: DRY, CLEAR SKIES, LIGHT WINDS, MILD DAY TIME TEMPS
AND COOL OVERNIGHT TEMPS. THE INVERTED TROUGH CURRENTLY EXTENDING
OVER THE PANHANDLE COAST WILL WEAKEN AND SHIFT TO THE EAST AS HIGH
PRESSURE CURRENTLY MOVING OVER THE CENTRAL GULF PROGRESSES
EASTWARD MOVING OVER THE PANHANDLE BY LATE FRIDAY. HIGH PRESSURE
OVER THE YUKON IS SHIFTING TO THE SOUTHEAST INTO BRITISH COLUMBIA.
THUS THE PRESSURE GRADIENT BETWEEN THE INVERTED TROUGH AND THE
YUKON HIGH THAT PRODUCED SMALL CRAFT WINDS OVER THE CENTRAL AND
NORTHERN INNER CHANNEL WILL WEAKEN WITH WINDS DIMINISHING THROUGH
THE DAY. AS THE AK GULF HIGH MOVES IN WILL SEE WINDS SHIFT FROM
NORTHERLY TO SOUTHERLY. WESTERLY WINDS OVER THE AK GULF WILL ALSO
BECOME LIGHT WITH THE BUILDING HIGH. DRY WEATHER WITH CLEAR SKIES
WILL LAST THROUGH FRIDAY NIGHT. TEMPERATURE WERE THE ONLY THING
THAT HAD SOME MODEL SPREAD. DAY TIME HIGHS WILL BE IN THE MID 40S
BUT POSSIBLY A FEW DEGREES HIGHER WITH THE LIGHTER WINDS AND
INSOLATION. OVERNIGHT LOWS IN THE MID 20S WITH RADIATIONAL COOLING
TONIGHT COULD BE A BIT COLDER THAN PREVIOUS NIGHTS AS WINDS WILL
HAVE DROPPED. MOS GUIDANCE AS STILL SHOWING A SPREAD SOMETIMES
UP TO 5 DEGREES, SO KEPT WITH A MID RANGE SOLUTION.

MODELS WERE STILL IN GOOD AGREEMENT AND HAVE SHOWN LITTLE CHANGE
FROM PREVIOUS RUNS. THE GFS DOES HAVE THE INVERTED TROUGH AXIS TO
FAR OFFSHORE BUT THE NAM/ECMWF WILL STILL IN LINE. REFRESHED
INHERITED GRIDS WITH 06Z NAM, LITTLE TO NO CHANGE RESULTED.
FORECAST CONFIDENCE IS ABOVE AVERAGE.

.LONG TERM...MODELS REMAIN IN GENERAL AGREEMENT FOR NEAR ZONAL
UPPER FLOW OVER SOUTHEAST ALASKA ON SATURDAY FOLLOWED BY AN UPPER
TROUGH BREAKING THE ZONAL FLOW SATURDAY NIGHT MOVES SOUTHEAST
ACROSS THE PANHANDLE THROUGH SUNDAY NIGHT AS UPPER RIDGE REBUILDS
OVER THE GULF. THE ASSOCIATED SURFACE LOW FORMS IN THE NORTHERN
GULF AND DRIFTS SOUTHEASTWARD ACROSS THE EASTERN GULF AND THE
PANHANDLE SATURDAY NIGHT INTO SUNDAY. REFRESHED THE INHERITED
FORECAST WITH THE NAM AND ECMWF THROUGH SUNDAY NIGHT FOR THEIR
GOOD CONSISTENCY. WITH THE DEVELOPING LOW IN THE NORTHERN
GULF...MID TO HIGH CLOUDS SHIELDS WILL CONTINUE TO INCREASE FROM
THE WEST ACROSS THE PANHANDLE ON SATURDAY. AS THE LOW DRIFTS
SOUTHEAST...POPS WILL GRADUALLY INCREASE OVERNIGHT SATURDAY INTO
EARLY SUNDAY. THE SYSTEM IS EXPECTED TO MOVE SOUTHEAST AWAY FROM
THE SOUTHERN PANHANDLE BY SUNDAY EVENING.

FOR EARLY NEXT WEEK...IN THE WAKE OF THE EXITING SYSTEM AND AHEAD
OF THE REBUILDING RIDGE...DRY WEATHER WILL RETURN TO SOUTHEAST
ALASKA AS A SHORT BREAK. EXPECT ENHANCED RADIATIONAL COOLING AT
NIGHT AND INCREASING INSOLATION DURING THE DAY...RESULTING QUITE
BIG DIURNAL TEMPERATURE FLUCTUATION. ANOTHER UPPER LEVEL
DISTURBANCE WILL MOVE OVER THE WESTERN GULF AND PUSH THE RIDGE
EAST TO CANADA BY WEDNESDAY. MODEL DIVERGENCE BECOMES LARGER AT
THIS POINT AND USED THE WPC ENSEMBLE SOLUTIONS FROM MONDAY ONWARD.
CLOUDS WILL AGAIN INCREASE LATE TUESDAY ACROSS SOUTHEAST ALASKA
WITH INCREASING POPS THROUGH LATE WEDNESDAY.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012.

&&

$$

PRB/AHN

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