Gale Warning 157, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
603 AM AKDT TUE MAR 12 2013

.SHORT TERM...WINDY CONDITIONS HAVE ALREADY BEGUN ACROSS THE
NORTHERN PANHANDLE AS A COLD ARCTIC HIGH IN THE YUKON BEGINS TO
AFFECT THE AREA. THE VARIOUS INTERIOR PASSES NEAR YAKUTAT HAVE
BEEN BLOWING SINCE LAST EVENING WITH WINDS OF 30 TO 40 MPH
MEASURED AT HAENKY ISLAND IN DISENCHANTMENT BAY. IN LYNN CANAL,
SKAGWAY, AND CROSS SOUND THE OUTFLOW WINDS HAVE JUST STARTED TO
PICK UP IN INTENSITY IN THE LAST FEW HOURS. ELDRED ROCK IS
ALREADY MEASURING SUSTAINED WINDS OF 41 KT WITH GUSTS TO 51 KT AS
OF 4 AM. CAPE SPENCER IS NOT TOO FAR BEHIND WITH NE WINDS OF
27 KT AND GUSTS TO 47 KT. SKAGWAY HASN'T HAD ANY REALLY HIGH
GUSTS YET BUT SHOULD CATCH UP LATER THIS MORNING. THESE WINDS ARE
EXPECTED TO CONTINUE AND EVEN INCREASE THROUGH THE DAY AS THE
YUKON HIGH BUILDS FURTHER SOUTH AND MORE COLD AIR BEGINS TO FLOW
OVER THE VARIOUS PASSES. STRONG WIND HEADLINES ARE UP FOR THE
INTERIOR PASSES NEAR YAKUTAT, SKAGWAY, AND HAINES NEAR LYNN CANAL
THROUGH TONIGHT WITH GALE WARNINGS FOR THE ADJACENT MARINE ZONES.

WINDS IN OTHER OUTFLOW AREAS FARTHER SOUTH WILL BE INCREASING
TODAY AS WELL. TAKU INLET AND LATER EVEN THE STIKINE RIVER VALLEY
MAY START UP. IN JUNEAU ANOTHER STRONG WIND HEADLINE HAS BEEN
HOISTED FOR LATER THIS AFTERNOON THROUGH TONIGHT FOR THE
POSSIBILITY OF A TAKU WIND EVENT FORMING NEAR DOWNTOWN. CROSS
BARRIER FLOW IS FORECAST TO REACH 45 KT THIS EVENING WITH A
CRITICAL LEVEL AROUND 400 TO 500 MB. AN INVERSION WILL JOIN THE
INGREDIENTS LATER TONIGHT SO WIND GUSTS OF 40 TO 50 MPH ARE NOT
OUT OF THE QUESTION FOR DOWNTOWN JUNEAU AND DOUGLAS.

WITH ALL OF THIS NORTHERLY WIND THE NORTHERN PANHANDLE WILL BE
DRYING OUT AND CLEARING OUT THROUGH THE NEXT 24 HOURS. THERE ARE
STILL SOME ISOLATED SHOWERS AROUND JUNEAU, HOONAH, AND GUSTAVUS
THIS MORNING BUT THOSE SHOULD BE CLEARING OUT THROUGH THE DAY.

FARTHER SOUTH, CLOUDS AND SHOWERS WILL REMAIN THE RULE OF THE DAY
AS THE WEAK LOW THAT IS STILL OUT IN THE GULF SENDS MORE SHOWERS
INTO THE SOUTHERN PANHANDLE. WITH THE COLD AIR STILL IN PLACE
ALOFT THE POSSIBILITY OF THOSE SHOWERS BEING SNOW REMAINS.
ACCUMULATIONS SHOULD BE LIGHT AS SURFACE TEMPERATURES REMAIN ABOVE
FREEZING IN MOST PLACES THIS MORNING. THE EXCEPTION WILL BE
SOUTHERN BARANOF ISLAND WHERE SATELLITE AND RADAR ARE SHOWING A
DECENT DEFORMATION BAND TRAINING OVER THE AREA. SURFACE OBS FROM
PORT ALEXANDER SHOW TEMPERATURES OF AROUND FREEZING. WITH THE
TRAINING ACCUMULATIONS MAY REACH 1 TO 3 INCHES ALONG SOUTHERN
BARANOF ISLAND TODAY BEFORE THE BAND DISSIPATES LATER THIS
AFTERNOON. SHOWERS AND CLOUDS WILL CONTINUE TONIGHT AS WHAT IS
LEFT OF THE GULF LOW MOVES OVER THE SOUTHERN PANHANDLE TONIGHT.

SHORT RANGE MODELS WERE IN DECENT AGREEMENT TODAY WITH MOST
FEATURES WELL REPRESENTED. DECIDED ON STICKING WITH THE ECMWF AND
THE NAM FOR UPDATES FOR THE DETAILS THAT BOTH SHOW. GFS AND THE
UKMET SMOOTHED THINGS A BIT TOO MUCH TO GET AN ACCURATE FORECAST
FOR THE INNER CHANNELS. FORECAST CONFIDENCE IS A LITTLE ABOVE
AVERAGE.

&&

.LONG TERM...THE PATTERN FROM THE SHORT RANGE FORECAST CONTINUES
FOR MUCH OF THE WEEK. HAVE CONTINUED THE GUSTY OUTFLOW WIND INTO
WEDNESDAY AND WITH SCATTERED SHOWERS MAINLY OVER THE SOUTHERN
PANHANDLE. THE LOW WILL BE OFF THE FAR SE COAST ON WEDNESDAY AND
WEAKEN THROUGH THE DAY. THIS WILL CAUSE WINDS TO EASE SLIGHTLY
DURING THE AFTERNOON...HOWEVER NOT FOR LONG. ANOTHER LOW CENTER IS
PROGGED TO MOVE OUT OF THE NORTH PACIFIC THURSDAY. THIS ALONG WITH
THE HIGH PRESSURE REMAINING OVER THE YUKON WILL CAUSE NORTHERLY
OUTFLOW WINDS TO INCREASE AGAIN TO 40 MPH OR MORE.

MODELS HAVE STRUGGLED WITH THE PLACEMENT OF THIS NEW LOW. LATEST
RUNS ARE STARTING TO CONVERGE ON THE IDEA OF IT MOVING INTO THE SE
GULF THURSDAY NIGHT. THE NORTH WINDS WILL CAUSE BELOW NORMAL
TEMPERATURES OVER MUCH OF THE REGION THIS WEEK...THEREFORE THE
PRECIP WITH THIS LOW WILL MAINLY FALL AS SNOW THEN START TO CHANGE
OVER TO RAIN ALONG THE FAR SOUTHERN COAST. HAVE SNOW LIKELY FOR
THE CENTRAL PANHANDLE LATE THURSDAY NIGHT THROUGH FRIDAY. AGAIN
WITH MODELS BEING IN POOR AGREEMENT HAVE CONTINUED WITH THE WPC
FORECAST GUIDANCE...WHICH PLACES THE LOW IN AVERAGE LOCATION. NCEP
MODELS HAVE THE LOW CLOSER TO THE COAST WHICH WOULD CAUSE STRONGER
WINDS AND HEAVIER PRECIP...WHILE THE EUROPEAN AND CANADIAN
MODELS HAVE THE LOW CENTER FURTHER OUT IN THE GULF WHICH WOULD
DELAY THE ONSET OF PRECIP SOME. WILL HOLD OFF ON MENTIONING
POTENTIAL SNOWFALL AMOUNTS DUE TO THIS UNCERTAINTY...BUT SOMETHING
TO KEEP IN MIND FOR THE END OF THE WEEK.

THE LOW MOVING UP FROM THE PACIFIC WILL ALLOW TEMPERATURES TO
GRADUALLY RISE BACK NEAR NORMAL. GOING INTO THE WEEKEND AN ACTIVE
PATTERN OF LOWS TRACKING ACROSS THE GULF BEGINS. HOWEVER THEY ARE
TAKING A SLIGHTLY SOUTHERN TRACK WHICH WOULD ALLOW FOR MORE DRY
WEATHER OVER THE NORTHERN HALF OF THE REGION.

MODELS WERE IN OVERALL AGREEMENT FOR THE COLD AIR OUTBREAK IN THE
SHORT TO MID RANGE AND USED AN ENSEMBLE APPROACH WITH AN EMPHASIS ON THE
ECMWF/NAM AS ABOVE. ONCE THE SOLUTIONS DIVERGE ON FRIDAY WENT MORE
TOWARD WPC GUIDANCE AND MADE ONLY MINOR ADJUSTMENTS TO THE FORECAST.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...STRONG WIND FROM 4 PM AKDT THIS AFTERNOON THROUGH WEDNESDAY
     MORNING FOR AKZ025.
         STRONG WIND THROUGH WEDNESDAY MORNING FOR AKZ018-019.
         STRONG WIND THROUGH WEDNESDAY AFTERNOON FOR AKZ017.
MARINE...GALE WARNING FOR PKZ011>013-022-043-051.
         SMALL CRAFT ADVISORY FOR PKZ021-031-032-052-053.

&&

EAL/HANNON