Gale Warning 54, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
658 AM AKST SUN JAN 16 2011

.SHORT TERM...ANOTHER COMPLEX FORECAST OVER SE AK WITH STRONG
WINDS FROM THE NORTH AND WINTER WEATHER OVER THE SOUTHERN HALF OF
THE PANHANDLE. THE LATEST SATELLITE IMAGERY SHOWS A LOW PRESSURE
SYSTEM OVER THE SE GULF WITH A WEATHER FRONT LIFTING OVER THE
SOUTHERN HALF OF THE PANHANDLE. THE LOW WILL SLOWLY TRACK TO THE
NORTHEAST THROUGH THE NEXT 24 HRS AND BE OVER CANADA BY LATE
TONIGHT. AS THE LOW LIFTS INTO CANADA THE STRONG PRESSURE
GRADIENT OVER THE NORTHERN HALF OF THE AREA WILL WEAKEN THROUGH
THE EVENING THE STRONG WINDS WILL SLOWLY DECREASE. A UPPER LEVEL
LOW OVER THE KENAI THIS MORNING WILL DRIFT ACROSS THE NORTHERN
GULF THIS AFTERNOON AND FORM A WEAK SURFACE LOW. THIS FEATURE
WILL MOVE OVER THE NORTHERN HALF OF THE FORECAST AREA THROUGH
TONIGHT TO BRING IN A BOUT OF WINTER WEATHER.

 THE ARCTIC BOUNDARY IS LOCATED JUST SOUTH OF PAKW/PAKT LINE AND
AS THE WARM AIR LIFTS NORTH IT IS PRODUCE SIGNIFICANT AMOUNT OF
SNOW OVER ZONE 26 AND 29. A DEFORMATION BAND IS IN THE PROCESS OF
SETTING UP THIS MORNING AND WILL MOVE OVER ZONE 26 AND SNOW FALL
RATES WILL INCREASE THROUGH THE DAY WITH STORM TOTAL OF 10 TO
15 INCHES FOR ZONES 26. THE STRONG ISENTROPIC LIFT OVER MISTY
FJORDS WILL CONTINUE TO PRODUCE HEAVY SNOW WITH AMOUNTS RANGING
FROM 20 TO 30 INCHES. SO WITH THAT SAID HAVE EXTENDED THE WSW FOR
SNOW THROUGH LATE THIS EVENING AS PRCIP WILL NOT BEGIN TO
DIMINISH UNTIL THE LOW MOVES THROUGH DIXON ENTRANCE AND INTO
CANADA. THERE IS A POCKET OF FREEZING RAIN NORTH OF PAKW AND
SOUTH OF PAWG SO ISSUED A FREEZING RAIN ADVY THROUGH THIS
AFTERNOON FOR ZONE 27 AND 28 ALONG WITH MINOR SNOW FALL AMOUNTS.
FURTHER NORTH THERE WILL PERIODS OF LIGHT SNOW OVER THE NORTH
CENTRAL AREAS WITH SOME MOISTURE LIFTING OVER THE ARCTIC AIR BUT
AMOUNTS WILL BE ON THE LIGHT SIDE AS THERE WILL NOT BE THAT MUCH
MOISTURE. THE BIGGEST FORECAST ISSUE IS THE STRONG WINDS FROM THE
NORTHEAST ALONG WITH COLD WIND CHILLS. THE STRONG WINDS GUSTS
WILL BEGIN TO DIMINISH THIS EVENING AS THE GRADIENT WILL RELAX AS
THE LOW LIFTS INTO CANADA AND THE SURFACE HIGH OVER NW CANADA
WILL WEAKEN. THERE IS STORM FORCE WINDS OVER THE NORTHERN INNER
CHANNELS THIS MORNING WITH GALES OVER THE REST OF THE MARINE
WATERS WITH STRONG GUSTS FROM INERTIOR PASSES. THESES WINDS WILL
DIMINISH THROUGH TONIGHT BE LESS THAN 25 KT.

 FOR TONIGHT...MOST OF THE PRECIP WILL DIMINISH OVER THE SOUTHERN
HALF BUT INCREASE OVER THE NORTHERN HALF AS THE STRONG UPPER LOW
MOVES OVER THE AREA. AS THIS HAPPENS IT WILL PRODUCE OCEAN EFFECT
SNOW WITH AMOUNTS RANGING FROM 2 TO 4 INCHES BUT THERE IS A
CHANCE THAT THERE MAY BE MORE AS THE OROGRAPHIC ALONG WITH
ISENTROPIC LIFT WILL ENHANCE SNOW AMOUNTS.

.LONG TERM...THE COMING WEEK WILL BE A PERIOD OF TRANSITION BACK TO WARMER THAN
NORMAL TEMPERATURES AND PRECIP AMOUNTS RETURNING TO MORE NORMAL
AMOUNTS ACROSS THE PANHANDLE. THE MID LEVEL RIDGING OVER NW
CANADA AND INTERIOR ALASKA THAT HAS BEEN KEEPING THE SUBTROPICAL
JET WELL SOUTH OF THE PANHANDLE WILL SPLIT AND PART OF IT WILL
MOVE OVER SIBERIA WITH A SECOND WEAKER PIECE MOVING EASTWARD INTO
WESTERN CANADA. THIS WILL ALLOW FOR A LONGWAVE TROUGH TO DEVELOP
A STRENGTH OVER TIME ALONG THE ALEUTIAN CHAIN. BEING DOWNSTREAM
FROM THIS FEATURE WILL MEAN THE PANHANDLE WILL RETURN TO
SOUTHWESTERLY MID LEVEL FLOW WITH THE SUBTROPICAL JET SHIFTING
NORTHWARD ALLOWING MORE MOISTURE TO RETURN TO THE PANHANDLE BY
MID WEEK ALONG WITH WARMING TEMPERATURES. THE 00Z ECMWF CONTINUES
TO HAVE SOME RUN TO RUN CONSISTENCY ISSUES WITH A DEVELOPING GALE
FORCE LOW IN THE NORTHERN GULF WEDNESDAY AFTERNOON WITH THE
SOLUTION THIS MORNING BEING MUCH FURTHER EAST THAN YESTERDAYS RUN
ALONG FURTHER EAST THAN THE 00Z ECMWF ENSEMBLE SOLUTION. THE 00Z
GFS OPERATIONAL RUN HAS MUCH BETTER SUPPORT FROM THE 00Z
ENSEMBLES WITH THE TIMING OF A GALE FORCE FRONTAL BOUNDARY MOVING
ACROSS THE PANHANDLE ON WEDNESDAY. FOR THESE REASONS BLENDED
TOWARD THE GFS SOLUTION DAY 4 ONWARD KEEPING SOME OF THE ENSEMBLE
DOMINANT HPC SOLUTION. DAY 2 AND 3 USED A BLEND OF THE 00Z
NAM/GFS HAS THESE MODELS HAD THE BEST DEPICTION OF AN OVERRUNNING
PRECIP EVENT FOR THE CENTRAL PANHANDLE MONDAY AND TUESDAY.

AFTER HAND OFF WITH THE SHORT TERM WILL SEE SOUTHWESTERLY MID
LEVEL FLOW INCREASE ACROSS THE CENTRAL PANHANDLE ALONG WITH MID
LEVEL PVA AND THIS WILL LEAD TO PERIODS OF LIGHT TO MODERATE
SNOWFALL...ESPECIALLY ALONG THE ICY STRAIT CORRIDOR FROM ELFIN
COVE TO JUNEAU. WILL HAVE TO MONITOR FUTURE MODEL RUNS...AS
PRECIP ATTM REMAIN BELOW ADVY LEVELS BUT IF THE ONSHORE FLOW
BECOMES MORE PRENNOUNCED WILL HAVE AT LEAST ADVY SNOW FOR THE
CENTRAL PANHANDLE MONDAY INTO TUESDAY. WINDS ON MONDAY AND
TUESDAY WILL REMAIN BELOW 25 KNOTS IN MOST LOCATIONS WITH THE
SURFACE PRESSURE GRADIENT WEAKENING...HOWEVER WILL SEE SMCR LEVEL
REMAINS ACROSS THE EASTERN GULF AS THE 850 MB WINDS WILL REMAIN
WESTERLY NEAR 35 TO 40 KNOTS. TUESDAY NIGHT AND INTO WEDNESDAY
WILL MID LEVEL RIDING MOVE ACROSS THE PANHANDLE AND THIS WILL
DECREASE PRECIP CHANCE...HOWEVER THE SURFACE FLOW WILL REMAIN
ONSHORE AND SO EXPECT AT LEAST CLOUDY SKIES IN MOST LOCATIONS.

ON WEDNESDAY A GALE FORCE FRONT WILL APPROACH THE OUTER COAST AND
MOVE ACROSS THROUGH THURSDAY AND THIS WILL LEAD TO THE MOST
DRAMATIC WARMING OF SURFACE TEMPERATURES AS 850 MB TEMPERATURES
RISE ABOVE -3 C IN ALL LOCATIONS AND THIS WILL PUSH THE RAIN/SNOW
LINE NORTHWARD TO ACROSS THE EXTREME NORTHERN PANHANDLE. ATTM
EXPECT THE BARRIER FLOW TO ENHANCE WINDS TO 40 KNOTS ACROSS THE
NORTHERN GULF WEDNESDAY AFTERNOON AND WILL HAVE WIND ADVY GUSTS
ACROSS THE OUTER COAST INTO WEDNESDAY EVENING. THESE WINDY
CONDITIONS WILL ADVECT ACROSS THE REST OF THE PANHANDLE THROUGH
THURSDAY WITH SOUTHERLY WINDS ALL THE WAY NORTH INTO SKAGWAY BY
THE END OF THE WEEK.

ANOTHER GALE FORCE LOW MOVES INTO THE GULF TOWARD THE END OF THE
WEEK AND THE 00Z MODELS ARE STRUGGLING WITH THE EXACT TRACK OF
THIS SURFACE LOW AND HOW MUCH NORTHERN STREAM ENERGY WILL DIVE
SOUTHWARD AND HELP THE RAIN/SNOW LINE MOVE FARTHER SOUTHWARD AND
BACK INTO THE NORTHERN PANHANDLE. WILL HAVE MONITOR FUTURE MODELS
AS GIVEN THE 00Z ENSEMBLE SOLUTION DO EXPECT A WARMER PATTERN
WITH THE CONTINUED SOUTHWEST MID LEVEL FLOW.

FORECAST CONFIDENCE IS AVERAGE THROUGH THE LONG TERM PERIOD AS
MODELS ARE COMING INTO BETTER AGREEMENT ON THE OVERRUNNING PRECIP
EVENT FOR MONDAY AND TUESDAY...BUT ARE STILL STRUGGLING WITH THE
EXACT PRECIP AMOUNTS. TEMPERATURES WILL CONTINUE TO WARM THROUGH
THE NEXT WEEK WITH THE RAIN/SNOW LINE PUSHING NORTHWARD ALL THE
WAY TO THE NORTHERN ROADWAYS BY MID WEEK. PRECIP AMOUNTS WILL
RETURN NORMAL AS THE TEMPERATURES WARM AND THE SOUTHWESTERLY MID
LEVEL FLOW INCREASES IN STRENGTH THROUGH THE WEEK.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER STORM WARNING UNTIL MIDNIGHT AKST TONIGHT FOR AKZ026-029.
         FREEZING RAIN ADVISORY UNTIL 4 PM AKST THIS AFTERNOON FOR AKZ027-
     028.
         WIND ADVISORY UNTIL 6 PM AKST THIS EVENING FOR AKZ017-019-020-
     022-025.
         WINTER STORM WARNING UNTIL 6 PM AKST THIS EVENING FOR AKZ018.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ011-013.
         HEAVY FREEZING SPRAY WARNING FOR PKZ031.
         HEAVY FREEZING SPRAY WARNING FOR PKZ012.
         STORM WARNING FOR PKZ011>013.
         GALE WARNING FOR PKZ021-022-031>035-041.
         SMALL CRAFT ADVISORY FOR PKZ036-042-043-051-052.

&&

ABJ/PSS