Heavy Snow Warning 2, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST MON DEC 3 2007

.SYNOPSIS...
.SHORT RANGE...HIGH PRESSURE OVER NORTHWEST CANADA STILL PERSISTS
AND WILL SLOWLY WEAKEN THROUGH THE NEXT 24 HOURS.  STRONG OUT
FLOW THROUGH INTERIOR PASSES WITH GUSTS OVER 40 MPH AND IN SOME
CASES ABOVE 60 MPH.  TAKU WINDS IN THE LOCAL JUNEAU AREA HAVE HAD
GUSTS TO 65 MPH OVER DOUGLAS ISLAND.  CLOUD STREETS FORMING OVER
THE EASTERN GULF AS THE ARCTIC STREAMS FROM THE PANHANDLE INTO
THE EASTERN GULF IS VISIBLE ON SATELLITE IMAGERY.

A LOW OVER NORTHEAST PACIFIC IS MOVING NORTHEAST AND EXPECTED
OVER NORTHERN VANCOUVER ISLAND EARLY TUESDAY WITH AN OCCLUDED
BAND ON THE NORTH SIDE WILL BRING A CHANCE OF SNOW TO ZONE 28 AND
29 ON TUESDAY AND HAS JUST SOME HIGH CLOUDS IN THE AREA DURING
THE DAY MONDAY.

A SURFACE LOW OVER THE NORTHERN PACIFIC WILL WEAKEN AS IT MOVES
NORTHEAST ACROSS THE NORTHERN GULF AND TO THE KENAI PENINSULA
TUESDAY AFTERNOON.  FLOW ABOUT THIS WILL BRING SOUTH WINDS OVER
THE YAKUTAT ZONE AND WILL START TO SPREAD SOME SNOW ONSHORE
MAINLY WEST OF YAKUTAT IN THE MORNING AND WILL SPREAD INTO THE
YAKUTAT  AREA BY AFTERNOON. ACCUMULATION IN THE YAKUTAT AREA BY
AFTERNOON SHOULD BE LESS THAN A FEW INCHES AT INITIAL GLANCE BUT
WILL BE FINE TUNING THAT THROUGH THE AFTERNOON BY ISSUANCE TIME.

EXPECT THAT WINDS WILL BE SETTLING DOWN THROUGH THE EVENING HOURS
AND OVERNIGHT SO SHOULD SEE LESS GALES IN THE
FORECASTS...ALTHOUGH GUSTS FROM INTERIOR PASSAGES WILL LIKELY
PERSIST INTO THE EARLY MORNING HOURS WILL ALSO SLOWLY IMPROVING.

.LONG RANGE...MODELS CONTINUE TO BE IN GOOD AGREEMENT THROUGH THE
END OF THE WEEK WITH NO MAJOR CHANGES NEEDED TO THE FORECAST.

A 1040 MB ARCTIC HIGH OVER NORTHWEST CANADA WILL WEAKEN AND MOVE
SOUTH THROUGH WED NIGHT. AN OCCLUDED FRONT ASSOCIATED WITH A
WEAKENING LOW THAT MOVES NORTHWEST ACROSS SOUTHWEST ALASKA AND
MERGES WITH A MUCH DEEPER LOW OVER THE BERING WILL MOVE INTO THE
NORTHERN AND CENTRAL GULF TUE NIGHT...THEN DISSIPATE AS IT MOVES
INTO THE PANHANDLE THROUGH WED NIGHT. GALE FORCE TO SMALL CRAFT
WINDS FROM THIS FRONT WILL CONTINUE OVER THE NORTHERN OUTSIDE
WATERS AND OFFSHORE WATERS INTO TUE NIGHT...THEN DIMINISH INTO
WED AS THE FRONT WEAKENS.

MAIN THREAT FOR PRECIPITATION FROM THIS FRONT WILL BE ALONG THE
NORTHERN AND NORTHEAST GULF COAST AS FAR SOUTH AS CROSS SOUND.
COLD AIR IN PLACE WILL ALLOW SNOW TO CONTINUE IN YAKUTAT THROUGH
TUE EVENING BUT SHOULD CHANGE TO RAIN LATE TUE NIGHT AS SOUTHERLY
FLOW BRINGS WARMER AIR NORTH. NAM QPF AMOUNTS SUGGEST ADV/WARNING
AMOUNTS ARE POSSIBLE IN YAKUTAT BEFORE CHANGING TO RAIN...BUT
WILL EVALUATE 18Z MODELS BEFORE DECIDING ON ISSUING ADV/WATCH.
SNOW WILL DEVELOP WED MORNING ALONG THE COAST AS FAR SOUTH AS
CROSS SOUND BUT WILL LIKELY CHANGE TO RAIN BY AFTERNOON AS WARMER
AIR MOVES IN.

ELSEWHERE...TEMPERATURES WILL MODERATE CLOSER TO NORMAL AS THE
ARCTIC HIGH WEAKENS AND MOVES SOUTH. WEST TO SOUTHWEST ONSHORE
FLOW FROM FREDERICK SOUND NORTHWARD WILL KEEP SKIES CLOUDY TO
MOSTLY CLOUDY TUE NIGHT THROUGH WED NIGHT WITH A CHANCE OF SNOW.
SOUTH OF FREDERICK SOUND...WEAK UPPER LEVEL RIDGING WILL KEEP A
SOMEWHAT DRIER NORTHWEST FLOW OVER THE REGION WITH MID AND UPPER
LEVEL CLOUDS INCREASING WED AFTERNOON THROUGH WED NIGHT AS THE
DISSIPATING FRONT MOVES ACROSS.

THE NEXT OCCLUDED FRONT MOVES EAST INTO THE PANHANDLE THU NIGHT
INTO EARLY FRI AND WILL BRING A BAND OF SMALL CRAFT WINDS INTO
THE NORTHERN AND EASTERN GULF. PRECIP TYPE COULD BE A SNOW OR
SNOW AND RAIN MIXED AT THE START OVER FAR EASTERN AREAS. MODELS
BEGIN TO DIVERGE IN THE TIMING AND STRENGTH OF THE NEXT COUPLE OF
SYSTEMS THAT APPROACH FROM THE WEST OR SOUTHWEST OVER THE WEEKEND
AND EARLY NEXT WEEK...NO CHANGES WILL BE MADE TO THE CURRENT
TIMING OF THE SYSTEMS.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...HIGH WIND WARING AKZ025 (JUNEAU AREA)
      ...WIND ADVISORY AKZ017>023-025>029
      ...WIND CHILL ADVISORY AKZ018 (ABOVE 1500 FT)

MARINE...GALE PKZ011>013-021-022-031-043-051-052
      ...SMALL CRAFT PKZ032>036-041-042

BMB/TAR