Gale Warning 367, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
537 AM AKST MON NOV 16 2009

.SHORT TERM...SATELLITE IMAGERY THIS MORNING SHOWS A BROAD UPPER
LEVELS TROUGH OVER THE GULF. AT THE SURFACE A WEAKENING LOW IN
THE N GULF CONTINUES TO BRING SHOWER ACTIVITY TO PAYA AND WILL
LINGER THERE FOR THE NEXT DAY OR SO. TO THE SOUTH A SERIES OF LOW
PRESSURE SYSTEMS ARE TRACKING OUT OF THE NORTHERN PACIFIC TOWARDS
THE QUEEN CHARLOTTES. THE FIRST LOW HAS BEGUN A NORTHERLY TRACK
ALONG THE COAST...PREVIOUS MODEL RUNS HAD THE SYSTEM A BIT MORE
TO THE EAST. THE FRONTAL BAND ASSOCIATED WITH THIS LOW BRING
MIXED PRECIPITATION TO THE SOUTHERN PANHANDLE WITH SOME GUSTY
WINDS. THE THROUGH IS THE WINDS GUST WHILE HIGH WILL BE SHORT
LIVED...SO DECIDED AGAINST A WIND ADVISORY. AGAIN WILL HAVE TO
KEEP AN EYE ON THE GUSTS TO SEE IF THE SECONDARY WRAP KEEPS THE
GUSTS HIGH. THE NEXT TWO LOWS WILL BEGIN TO MERGE TOGETHER
CAUSING A MORE NEGATIVE TILT TO LOW NUMBER ONE AND TRACK THAT LOW
MORE TO THE NORTH WEST. A THIRD STRONGER SYSTEM WILL DEVELOP INTO
TUESDAY WITH COLD AIR MOVING IN FROM THE BERING SEA. THE NORTHERN
PANHANDLE LOOKING TO STAY DRY WITH NORTHERLY FLOW. FOR THE
CENTRAL PANHANDLE EXPECTED THE EASTERLY DOWN SLOPE TO KEEP THE
AREAS DRY. PAPG IS THE QUESTION FOR THE DAY AS SNOW GUIDANCE IS
JUST NEAR WINTER ADVISORY LEVELS. SOME UNCERTAINTY IF THERE WILL
BE A MIX OF RAIN TO KEEP SNOW AMOUNTS DOWN. DEW POINTS SHOULD BE
LOW ENOUGH TO KEEP ALL SNOW BUT WITH UNCERTAINTY KEPT SNOW TOTAL
AT 2 TO 4 INCHES. THE SOUTHERN PANHANDLE SHOULD SWITCH TO ALL
RAIN THROUGH THE MORNING WITH THE WARM AIR BROUGHT UP FROM THE
SOUTH.

 USED THE UKMET AS THE GFS KEEP THE LOW A BIT TOO FAR TO THE EAST
AND DID NOT RESOLVE THE INTERACTION OF THE NEXT TOW SYSTEMS AS
WELL AS THE UK. 500MB PVA IN THE GFS LOOKED TO BE WRAPPED INTO
THE LOW WITH THE UK PVA ALONG THE EDGE. THE EC WAS A BIT TOO
QUICK WITH THE NORTHERLY PROGRESSION OF THE LOW AND THE NAM JUST
DID NOT INITIALIZED VERY WELL.

 WITH THE COMPLEX FORECAST CONFIDENCE IS BELOW AVERAGE.
INTERACTION OF THE SYSTEMS IN THE N PACIFIC AND S GULF WILL BE
THE BIGGEST QUESTION.

&&

.LONG TERM...UPPER LEVEL AGREEMENT ACTUALLY PRETTY GOOD THROUGH
00Z ON THE 24TH BETWEEN GFS AND ECMWF. BIGGEST DIFFERENCES
OCCURRING NEXT WEEKEND WHEN ECMWF IS MORE AGGRESSIVE IN TRACKING
SEVERAL UPPER LEVEL SHORT WAVES ACROSS THE NORTHERN GULF. MAJOR
THEMES IN THE EXTENDED RANGE INCLUDE AN UPPER LOW DROPPING OUT OF
THE INTERIOR AND INTO THE CENTRAL GULF ON THURSDAY. THIS FEATURE
WEAKENS RAPIDLY AS FAIRLY LARGE SHORT WAVE SWEEPS EAST ACROSS THE
GULF AND INTO THE WEST COAST EARLY THIS WEEKEND.
THEREAFTER...SEVERAL SHORT WAVES ROTATING AROUND AN UPPER LOW IN
THE NORTHWEST PORTION OF THE INTERIOR SWING THROUGH THE GULF AND
ACROSS THE PANHANDLE MAKING FOR AN UNSETTLED...ONSHORE WEATHER
REGIME.

AT THE SURFACE...SOME SIGNIFICANT GFS ENSEMBLE SPREAD AT THE START
OF THE EXTENDED RANGE FORECAST BUT WELL SOUTH OF THE PANHANDLE.
OPERATIONAL GFS AND EC BOTH RESOLVING TWO SEPARATE LOWS IN THE
GULF AT THE START WHEREAS ENSEMBLE MEAN SMOOTHS THEM OVER INTO ONE
ELONGATED FEATURE. FIRST SIGNIFICANT MODEL DIVERGENCE AT THE
SURFACE DEALS WITH INTENSITY OF A LOW FORECAST TO ENTER THE
SOUTHEAST GULF FROM THE SOUTH ON THURSDAY. GFS MAINTAINS THIS
FEATURE SIGNIFICANTLY DEEPER THAN EITHER GFS OR UKMET. OPTED FOR
THE 16/00Z UKMET/ECMWF SOLUTION AND AS A RESULT...BACKED OFF ON
THE WINDS OVER THE SOUTHERN PORTIONS OF THE PANHANDLE AND
ASSOCIATED MARINE ZONES. 06Z GFS REMAINS OUT OF STEP WITH EUROPEAN
GUIDANCE. BY SATURDAY...EC AND GFS IN MUCH BETTER AGREEMENT WITH A
A 978-982 MB LOW IN CENTRAL TO NORTHERN GULF. MAJOR DIFFERENCE
WITH REGARD TO PANHANDLE WEATHER HAS TO DO WITH THE SHAPE AND TIME
OF ARRIVAL OF THE ASSOCIATED FRONT ALONG THE OUTER COAST. WENT
WITH MORE OF AN EC SOLUTION WHICH BETTER DEPICTED THE EXPECTED WARM
TYPE OCCLUSION AND A WEAK TRIPLE POINT LOW FORMING WEST OF PRINCE
OF WALES ISLAND.

NOT A LOT OF CHANGES TO DAILY HIGH AND LOW TEMPERATURES WITH
DAYTIME HIGHS SUPPORTING AT LEAST A RAIN-SNOW MIX...IF NOT
STRAIGHT SNOW...UNTIL NEXT WEEKEND WHEN AN APPROACHING WARM FRONT
WILL ELIMINATE SNOW FROM THE FORECAST FOR ALL BUT THE FAR NORTHERN
INNER CHANNELS AND YAKUTAT. HOWEVER...BEFORE THE TRANSITION TO
STRAIGHT RAIN...MANY LOCATIONS COULD SEE FROM 1 TO 3 INCHES OF NEW
SNOW LATE FRIDAY NIGHT OR EARLY SATURDAY MORNING AS MID LEVEL
MOISTURE APPROACHING FROM THE SOUTH OVER RUNS LOW LEVEL COLD AIR.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-013-031-033>036-041-042.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ043-051-052.

&&

PRB/FRITSCH