Gale Warning 256, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM ADT TUE OCT 9 2007

.SYNOPSIS...
.SHORT RANGE...LITTLE CHANGE TO SHORT RANGE FCST PKG AND LAST OF
FOG BURNING OFF IN PNHDL AT THIS TIME. NAM TO GFS MODEL CONSENSUS
IS GOOD...THE ONLY SGFNT ADJUSTMENT TO THEIR SOLUTION IS THAT THE
LOW TRACKING N TOWARD THE SRN PNHDL SHOULD HOLD TOGETHER TO ABOUT
4 MB AS IT TRACKS N INTO THE SRN PNHDL.

INTERACTION OF LARGE SCALE CIRCULATIONS BETWEEN LOWS IS MAIN
SUBJECT FOR TODAY THROUGH WED.  968 MB LOW 500 NM S OF KETCHIKAN
IS TRACKING N AND IS BEGINNING TO WEAKEN.  THE WEAKENING IS
CAUSED BY THE WARM SECTOR RIDGE ALOFT OVER THE WESTERN GULF THAT
IS IN TURN BEING PUMPED UP BY A CYCLOGENETIC 988 MB LOW 500 NM S
OF COLD BAY.  THE ZONAL TRACK OF THE SECOND LOW WILL AID IN
SETTING UP A CYCLONIC INTERACTION BETWEEN THE TWO.  THE CENTER OF
THE INTERACTION WILL ALSO BE MOVING ZONALLY RESULTING IN LOW ONE
HAVING THE NORTHWARD TRACK.  LOW ONE SHOULD STAY CLOSED TO AT
LEAST 4 MB LONGER THAN EITHER THE NAM OR THE GFS ARE DEPICTING
HOWEVER...THIS IS DUE TO THE LOWS INTERACTING ENOUGH TO LIMIT TO
SLOW THE FILLING.

18Z WED THE NORTHBOUND LOW WILL STILL BE FILLING AND ABOUT 983 MB
100 NM S OF KETCHIKAN.  00Z THU THERE SHOULD BE TWO LOWS
ASSOCIATED WITH WHAT HAS BEEN LOW ONE...PRIMARILY BECAUSE THE
UPPER LEVEL SUPPORT WILL BE TRACKING TOWARD DEASE LAKE AND AS IT
DOES SO THE REMAINS OF THE SURFACE LOW WILL BE FILLING OUT OF
EXISTENCE IN NORTHERN MISTY FJORDS WHILE A NEW SURFACE LOW WILL
BE DEVELOPING ABOUT 100 NM E OF WRANGELL.

.LONG RANGE...THE MODELS THIS MORNING ARE IN FAIR AGREEMENT WITH
THE LARGE SYNOPTIC SCALE FEATURES THROUGH THE REST OF THE WEEK.
WILL MAKE MINOR CHANGES THROUGH THURSDAY NIGHT USING THE 12Z
GFS40. AFTER THAT WILL DO A 50/50 BLEND WITH THE 12Z ECMWF AS
THERE IS SOME TIMING ISSUES OF THE FRONT AND MOVEMENT OF THE LOW
LIFTING INTO THE GULF LATE THURSDAY INTO FRIDAY.

AT THE UPPER LEVELS...A TROF WILL BE MOVING THROUGH THE PANHANDLE
WED NIGHT WITH CONTINUED ONSHORE FLOW THROUGH THURSDAY. A
SHORTWAVE TROF WILL BE LIFTING OUT OF THE NORTH PACIFIC INTO THE
WESTERN GULF LATE THURSDAY NIGHT AND THEN SPIN UP INTO A LOW AS
IT LIFTS INTO THE NORTHERN GULF THROUGH FRIDAY. THIS LOW WILL
CONTINUE INTO THE INTERIOR THROUGH FRIDAY NIGHT BUT THERE WILL BE
ANOTHER TROF THAT WILL MOVE INTO THE GULF FOR THE WEEKEND.

AT THE SURFACE...THE OLD LOW OVER THE SOUTHERN AREAS WILL BE
REDEVELOPING IN CANADA THROUGH WED NIGHT AS A WEAK RIDGE BUILDS
OVER THE PANHANDLE THROUGH THURSDAY. WITH THE ONSHORE FLOW ALOFT
AND THE SHORTWAVE MOVING ONSHORE SHOWERS WILL BE LIKELY OVER MOST
OF THE FORECAST AREA. THERE MAY BE SOME DRYING OVER THE SOUTHERN
AREAS WITH THE RIDGE DEVELOPING BUT STILL THINK THERE WILL BE A
CHANCE OF PRECIP.

A LOW WILL BE DEVELOPING IN THE WESTERN GULF THURSDAY. A STRONG
WAVE WILL DEVELOP ALONG THE FRONT THURSDAY NIGHT AND BECOME THE
DOMINATE FEATURE INTO FRI. THIS WAVE WILL DEVELOP INTO A CLOSED
977MB LOW AND BE AROUND THE CENTRAL GULF BY FRIDAY AFTERNOON.
THERE IS SOME DIFFERENCE IN THE DEPTH AND THE TIMING ON THE FRONT
SO SPLIT THE DIFFERENCE BETWEEN THE GFS AND THE ECMWF. THE FRONT
WILL PRODUCE VERY STRONG WINDS OVER THE COASTAL AREAS WITH GALE
OVER MOST OF THE FORECAST AREA BUT WITH A SMALL AREA OF STORM
FORCE WINDS GENERATED DUE TO A BARRIER JET THAT WILL DEVELOP
FRIDAY AFTERNOON ALONG THE FAIRWEATHER GROUNDS. WIND OVER THE
INNER CHANNELS WILL BE THE STRONGEST (GALES) OVER EAST/WEST
CHANNELS AS THE PRESSURE GRADIENT WILL FAVOR THAT ORIENTATION.
THE COASTAL AREAS WILL SEE WIND ADV LEVEL WINDS FROM THE MORNING
THROUGH THE EARLY AFTERNOON BUT THE INNER CHANNELS WILL SEE GUSTS
INCREASE TO 35 MPH OVER EVEN TO 40 MPH...BUT WILL WAIT TO SEE TO
MAKE THAT CALL. RAIN WILL BEGIN TO MOVE OVER THE PANHANDLE
THROUGH FRIDAY MORNING...RAIN MAYBE HEAVY AT TIMES AS THIS SYSTEM
WILL TAP INTO SOME TROPICAL MOISTURE. THE FRONT WILL BE THROUGH
THE FORECAST AREA BY FRIDAY NIGHT AND THE RAIN WILL BECOME
SHOWERS AND THE WINDS WILL SLOWLY DIMINISH. THESE CONDITIONS WILL
PERSIST THROUGH THE WEEKEND.

BY EARLY NEXT WEEK THE UPPER JET WILL BE FURTHER SOUTH SO MOST OF
THE UPPER LEVEL DISTURBANCES WILL BE PUSHED TO THE SOUTH OF THE
FORECAST AREA.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...NONE
MARINE...PKZ012-036-041>043