Blizzard in Alaska, December 28 to 30, 2004

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST MON DEC 27 2004

.SHORT RANGE...990 MB LOW ABOUT 60 NM S OF MIDDLETON ISLAND
IS TRACKING E AND WILL BE 120 NM SSW OF YAKUTAT AS 978 MB
12Z TUE...TRACKING SE AND SLOWLY FILLING THEREAFTER.  THE
TRACK TO THE EASTERN GULF OF ALASKA AND THEN TOWARD THE
SE ABOUT 200 NM OFFSHORE THE PANHANDLE WILL RESULT IN
STRONG OVERRUNNING OF ARCTIC AIRMASS IN INNER CHANNELS
OF PANHANDLE ESPECIALLY FROM WRANGELL NORTH.  NOTE
HEAVY SNOW AMOUNTS NOT USED FOR SKAGWAY...AND SNOW
AMOUNTS FALL OFF IN A NORTH TOWARD SOUTH SEQUENCE
BEGINNING TUE.

ETA 12Z RUN USED AS MODEL OF CHOICE SO FAR.  12Z ETA MODEL
RAOBS COMPARE WELL WITH ACTUAL RAOBS...ESPECIALLY USING
THE ANNETTE DATA.  COMPARISON NOT QUITE AS GOOD FOR
ETA SOUNDING NEAR YAKUTAT RAOB...BUT NO LARGE PROBLEMS.
WHERE SIGNIFICANTLY DIFFERENT.

NO CHANGES TO HEAVY SNOW WARNING AND SNOW ADVISORY
FOOTPRINT...AMENDMENTS TO ZONES DO RAISE SNOW AMOUNTS
IN MOST ZONES.  THESE ADJUSTMENTS THAT RAISE THE SNOW
AMOUNTS ARE USING THE ETA MODEL VALUES...FOR QPF AND
OVERRUNNING INDEX...AS INPUT TO CODE THAT HAS A RECORD
OF SNOW AMOUNTS FOR SIMILAR MODEL VALUES IN THE PAST.

.LONG RANGE...THE HIGH PRESSURE CENTERED IN THE THE YUKON
WEDNESDAY WILL SWING INTO BC LATE THAT NIGHT. THE HIGH WILL
REMAIN IN BC THROUGH EARLY NEXT WEEK. THE ARCTIC FRONT GOING
THROUGH THE NORTHERN ZONES WEDNESDAY MORNING STALLS OVER THE
CENTRAL ZONES WEDNESDAY BUT BY THAT NIGHT THE COLD AIR FUNNELS IN
ACROSS THE SOUTHERN ZONES...SO WILL SEE TEMPS FALL INTO THE LOWER
20S ACROSS THE SOUTHERN ZONES. THE NORTHERN ZONES WILL SEE LOW
TEMPS FROM THE TEENS TO SINGLE DIGITS FROM WEDNESDAY THROUGH
SATURDAY AS THERE WILL MOSTLY CLEAR SKIES. THERE WILL BE SHOWERS
OVER THE SOUTHERN AREAS ON WEDNESDAY AS THE UPPER TROF WILL BE
OVER THE AREA. BUT THROUGH WEDNESDAY IT SHOULD DRY OUT WITH THE
UPPER FLOW SWITCHING TO THE NORTHEAST. WILL KEEP PARTLY TO MOSTLY
CLOUDY SKIES OVER THE SOUTHERN AREAS LATE IN THE WEEK AS SOME
MOISTURE FROM BC COULD COME ACROSS THE MOUNTAINS WITH THE
EASTERLY FLOW BUT BY FRIDAY IT SHOULD CLEAR OUT.

NORTHERLY WINDS WILL REMAIN VERY STRONG IN THE NORTHERN LYNN
CANAL INTO THE WEEKEND AND COULD REACH STORM FORCE BY WEDNESDAY
AFTERNOON. THE STRONG WINDS WILL SPREAD THROUGHOUT FORECAST AREA
WEDNESDAY BUT THE STRONGEST WINDS WILL BE NEAR INTERIOR PASSES
FROM WEDNESDAY NIGHT THROUGH SUNDAY WITH HIGH IN BC.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...HEAVY SNOW WARMING...ZONES 17..19..20..21..25
      ...SNOW ADVISORY...ZONES 19 AND 26
      ...WIND ADVISORY...ZONES 17 AND 23
MARINE...STORM...OUTSIDE WATERS PKZ051
      ...GALE...INSIDE WATERS PKZ034-035
                OUTSIDE WATERS PKZ041-042-043052-053
JT / ABJ