Gale Warning 137, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
201 PM AKST SAT MAR 7 2009

.SHORT TERM...COLD ADVECTION AND LOSS OF CLOUD COVER WILL
ENHANCE THE  TEMPERATURE FALLS TONIGHT.  GOOD MODEL CONSENSUS ON
THE ARCTIC HIGH  PRESSURE IN Y.T., AND WIND CHILLS WITH STRONGER
OUTFLOW OF ARCTIC  AIRMASS IS BEING INCLUDED.  FREEZING SPRAY
ALSO SHOULD BE DEVELOPING AT THIS TIME AND THIS EVENING SHOULD
BEGIN TO INCLUDE MOST OF LYNN CANAL  AS WELL AS OUT OF INTERIOR
INLETS AND PASSES FROM THE STIKINE RIVER N.   MODELS CHOSEN
MOSTLY FOR TERRAIN DETAIL IN OUTFLOW SO NAM MOST USED,  WITH GEM
AND WRF LIKELY TO BE FACTORED IN.  CHANGES TO EXISTING FORECAST
PACKAGE ARE PRIMARILY TO RAISE THE N OUTFLOW WINDS AND LOWER
TEMPERATURES, PLEASE NOTE MARINE AMDS FOR INNER CHANNELS.
OVERNIGHT LOW TEMPERATURES ARE BEING LOWERED ABOUT 5 DEG F.  ONE
MODEL EXCEPTION  TO THE ABOVE IS THAT THE OVERNIGHT LOW TEMP FCST
WILL USE GFS THAT  HAS BEEN BIAS CORRECTED FOR THE LAST 30 DAYS.

 THE COLD FRONT THAT MOVED ONSHORE YESTERDAY WAS FAST MOVING AND
IS OVER 300 MI EAST AND 600 SE OF THE PANHANDLE.  THE ONSHORE
FLOW OF A COLD MARITIME AIRMASS GENERATED A CLOUD MASS OVER THE
PANHANDLE THAT  IS BEING DISSIPATED IN A NW TOWARD SE SEQUENCE.
USING GOES VISIBLE  THE REMAINING CEILINGS ARE FROM SUMNER STRAIT
TO THE S.

 SEVERAL ADJUSTMENTS ARE UNDERWAY THAT RESULT IN DRYING ON ALL
LEVELS. THE HIGH AMPLITUDE RIDGE ALOFT EXTENDS NNW FM OVER COLD
BAY TOWARD WRANGELL ISLAND, RUSSIA.  THIS LARGE-SCALE RIDGE ALOFT
IS MOVG ENE  AND WILL SUPPORT THE INTENSIFICATION OF ARCTIC HIGH
PRESSURE IN YUKON  TERRITORY FROM NOW THROUGH SUNDAY.

.LONG TERM...THE MODELS ARE IN FAIR AGREEMENT THROUGH THE MID-
RANGE BUT THEY ARE STILL HAVING PROBLEMS WITH THE MOVING THE UPPER
RIDGE EAST OF THE PANHANDLE. FOR THE AFTERNOON PACKAGE USED MAINLY
THE OPERATIONAL EC AS THE GFS IS CONTINUING TO PUSH THE UPPER HIGH
TO FAST INTO CANADA BY THURSDAY WHILE THE EC IS KEEPING THE AXIS OF
THE HIGH OVER THE PANHANDLE. THE EC SOLUTION IS SUPPORTED BY THE
NAEFS MEAN ALONG WITH HPC GUIDANCE. THERE IS AVERAGE TO BELOW
AVERAGE CONFIDENCE IN THE FORECAST FROM THURSDAY INTO NEXT WEEKEND
DUE TO THE AMOUNT OF SPREAD IN SOLUTIONS BETWEEN THE OPERATIONAL
MODELS AND ENSEMBLE MEMBERS.

THE UPPER RIDGE OVER THE GULF SUN AFTERNOON WILL BEGIN TO DRIFT
EAST AND BECOME LESS AMPLIFIED THROUGH TUE. AS THIS HAPPENS THE
NICE CLOUDS WILL BEING TO INCREASE FROM THE WEST THROUGH MONDAY.
AS THE ONSHORE FLOW INCREASE AND A WEAK SURFACE LOW LIFTING INTO
THE NORTHERN GULF THIS WILL INCREASE THE THREAT OF PRECIP OVER
PAYA BY LATE MONDAY AFTERNOON AND NIGHT ALONG WITH A CHANCE OVER
THE NORTHERN HALF OF THE PANHANDLE. BY TUE THERE WILL BE A CHANCE
OF SOME SIGNIFICANT SNOW ACCUMULATIONS DUE TO MOISTURE ADVECTION
AND LIFTING MECHANISMS WITH THE ARCTIC FRONT STILL OVER SE AK.
WILL NEED TO KEEP AN EYE ON THIS.

AS THE RIDGE AXIS SETS UP OVER THE PANHANDLE OVER FROM WED THROUGH
THE END OF THE WEEK WARM AIR WILL CONTINUE TO MOVE OVER THE AREA
WITH UPPER LEVEL FLOW FROM THE SOUTH. THIS WILL RAISE FREEZING
LEVELS ACROSS THE AREA WITH RAIN POSSIBLE BY THE END OF THE WEEK.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADVISORY FROM 4 AM TO 4 PM AKDT SUNDAY FOR AKZ019-025-029.
         WINTER WEATHER ADVISORY UNTIL 6 AM AKDT SUNDAY FOR AKZ018.
         WIND ADVISORY FROM 4 AM TO 7 AM AKDT SUNDAY FOR AKZ018.
MARINE...GALE WARNING FOR PKZ011>013-022-031-034.
         SMALL CRAFT ADVISORY FOR PKZ021-032-033-035-036-
         041>043-051-052.

&&

JBT/ABJ