Gale Warning 341, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST WED DEC 19 2007

.SYNOPSIS...
.SHORT RANGE...
ALL 12Z MODELS REVIEWED INSIST ON BUILDING AN UPR RIDGE OVER THE
CENTRAL GULF BY 12Z THU FOR WNW FLOW ALF OVER THE PANHANDLE. BY
00Z FRI ALL MODELS PROGRESS THE UPR RIDGE OVR THE PANHANDLE WITH
THE AXIS INLAND BY 06Z FRI. UNFORTUNATELY THE SFC FEATURES ARE
NOT AS CONSISTENT. DUE TO THE JET SPLIT MENTIONED ABOVE...AN EXIT
WILL FORM WELL S OF THE GULF TO SUPPORT A SFC LOW DEVELOPMENT.
THERE IS NO AGREEMENT IN THE MODELS AND ENSEMBLES AS TO WHERE
THIS LOW WILL DEVELOP OR STRENGTH OR TRACK. WILL PLAY A GENERAL
THEME FOR THU FOR INCREASING CLOUDS LATE THU AND TO INCREASE POPS
AT THE VERY END OF THE SHORT TERM. WILL USE AK-GFS-40 FOR WIND AS
THE COMPROMISE. CONFIDENCE POOR AT TRANSITION TIME.

.LONG RANGE...
VERY PROGRESSIVE PATTERN CONTINUES THROUGH THE LONG RANGE.  GIVEN
THE NATURE OF THIS PATTERN...MODELS CONTINUE TO SHOW POOR RUN TO
RUN AND INTER-MODEL CONSISTENCY.  IT WILL BE DIFFICULT TO
PINPOINT THE TIMING AND MAGNITUDE OF SURFACE FEATURES. DESPITE
THE LACK IN CONFIDENCE FOR ANY ONE MODEL...HAVE DECIDED TO USE
THE 12Z GFS AS A GUIDE THROUGH THE PERIOD (AS COORDINATED WITH
PAFC).  WHILE THE MODELS REMAIN SKEWED...THE GENERAL PATTERN
SEEMS TO HAVE SHIFTED AWAY FROM THE GOING FORECAST. HAVE OPTED TO
LIMIT FORECASTED WINDS TO 40 KT BEYOND SATURDAY AND FOCUS ON MORE
CLIMATIC PRECIPITATION VALUES.  THUS WILL LIMIT POPS TO CHANCE OR
LIKELY EACH DAY.

THURSDAY NIGHT...MODELS HINT AT SEVERAL WAVES DEVELOPING ABOUT A
MEAN UPPER LEVEL TROUGH IN THE VICINITY OF THE ALEUTIANS.  AS PER
THE GFS/ECM/UKMET...THE FIRST OF THESE LOWS DEEPENS TO AROUND 965
TO 972 MB AS IT MOVES NORTHWARD ACROSS THE CENTRAL GULF TOWARDS
PRINCE WILLIAM SOUND/KENAI PENINSULA.  SIGNIFICANT WINDS ARE
EXPECTED TO SPREAD ACROSS THE GULF NEAR THE LOW AND AHEAD OF AN
ASSOCIATED OCCLUDED FRONT OVERNIGHT.  STORM FORCE WINDS IN THE
OUTSIDE WATERS AND NORTHERN COASTAL ZONES ARE EXPECTED BY LATE
THURSDAY NIGHT WHILE GALES FORM IN THE SOUTHERN COASTAL ZONES.
ADDITIONALLY...THIS SCENARIO WILL BRING WIND ADVISORY LEVEL
CONDITIONS TO AT LEAST THE COASTAL ZONES.

AS THIS LOW DISSIPATES IN THE NORTHERN GULF FRIDAY AFTERNOON...A
SECOND WAVE IS EXPECTED TO FORM ALONG THE OCCLUSION AND CLIP THE
SOUTHERN PANHANDLE...LIKELY BRINGING ANOTHER SHOT OF STRONG WINDS
TO THAT AREA.  A THIRD POTENTIAL WAVE TRAVELING ALONG THE
SOUTHERN SPLIT OF THE JET WILL PASS JUST SOUTH OF DIXON ENTRANCE
ON SATURDAY.

THE JET SWINGS ANOTHER STRONGER LOW NORTHEASTWARD FROM THE
NORTHERN PACIFIC SATURDAY NIGHT.  THERE IS GOOD MODEL CONSENSUS
THAT THIS LOW WILL DEEPEN TO THE UPPER 950S TO LOWER 960S AND
SWING INTO THE EASTERN GULF SUNDAY AFTERNOON.  WHILE STORM FORCE
WINDS ARE INDICATED WITH THIS SYSTEM...HAVE LIMITED WIND TO 40KT.
THE LOW EVENTUALLY MOVES INLAND OVER THE NORTHERN PANHANDLE BY
MONDAY AFTERNOON. NO REST FOR THE WEARY HOWEVER.  THE JET GUIDES
YET ANOTHER LOW INTO THE GULF ON TUESDAY AND WEDNESDAY.

OVERALL...THIS PATTERN POINTS AT AN ONSHORE/MARITIME PATTERN FOR
THE BULK OF THE FORECAST PERIOD.  EXPECT TEMPERATURES TO WARM
FROM SOUTH TO NORTH AHEAD OF THE FIRST BIG LOW.  SIGNIFICANT
SNOWFALL IS PROBABLE AT THE ONSET OF PRECIPITATION FOR THE
NORTHERN HALF.  AS THE AIR MODERATES...RAIN WILL MIX WITH SNOW IN
THE CENTRAL WHILE THE LYNN CANAL AREA AND INLAND VALLEY AREAS
WILL HOLD ONTO SNOW.  AGAIN...WILL DEFER TO FUTURE MODEL RUNS TO
JUMP ON ANY HIGHLIGHTS.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...SNOW ADV 28.
MARINE...SMCR 11 12 13 31 34 41 42 51 52.