Storm Warning 58, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1115 AM AST SAT DEC 22 2007

.SYNOPSIS...
.SHORT RANGE...AT 1800 UTC THE 990 MB LOW IS NEAR HYDABURG AND
SHOULD CONTINUE EASTWARD ACROSS SOUTHERN SE AK INTO BC THIS
AFTERNOON. WINDS HAVE DIMINISHED ALREADY SO ADVISORIES WERE
CANCELED. IT IS STILL RAINING OVER MUCH OF THE PANHANDLE EXCEPT
FOR SNOW IN THE NORTHERN THIRD...BUT INTENSITIES HAVE DIMINISHED.
PRECIPITATION SHOULD BECOME MORE SCATTERED THROUGH THE AFTERNOON
BUT SNOW ACCUMULATIONS OF 1-2 INCHES ARE STILL POSSIBLE IN
NORTHERN INTERIOR SECTIONS THIS AFTERNOON.

ANOTHER MAJOR STORM IS STRENGTHENING IN THE NE PACIFIC AROUND
1000 NM SOUTHWEST OF SITKA MOVING TOWARD THE CENTRAL PANHANDLE.
THIS LOW IS EXPECTED TO DEEPEN TO 965 MB AND BE WITHIN 150 NM
SOUTHWEST OF SITKA SUN BEFORE STARTING TO WEAKEN AND TURN
EASTWARD MAKING LANDFALL OVER CENTRAL SE AK LATE SUN.

EXPECT WIND/STORM WARNINGS IN SOUTHERN PUBLIC/MARINE ZONES AND
ADVISORY/GALES IN ADJACENT ZONES WITH THIS SYSTEM. PRECIPITATION
WILL START UP OVERNIGHT WITH RAIN OVER SOUTHERN TWO THIRDS OF SE
AK AND SNOW TO THE NORTH. NE GLF COAST WILL SEE SOME
PRECIPITATION SUN WITH MIN GALES OFFSHORE.

.LONG RANGE...
FAST PROGRESSIVE PATTERN AFFECTING SE AK. ONE SFC LOW EXITS THE
ARE SUN NIGHT BUT ANOTHER WEAKER SYSTEM SWINGS IN FROM THE WEST
MON NIGHT. MODELS INDICATING ACTIVE STORM TRACK SHIFTS A BIT
FARTHER SOUTH AS THE WEEK PROGRESSES.

ALL MODELS IN AGREEMENT ON THE GENERAL PATTERN THROUGH EXTENDED
RANGE. TODAYS RUNS LIMIT HEAVY PCPN ON SUNDAY TO FAR SOUTH
COMPARED TO FRI RUNS. THIS DUE TO SOUTHWARD ADJUSTMENT OF LOW
TRACK SUN NIGHT WHICH NOW CUTS EAST ACROSS CENTRAL ZONES RATHER
THAN FARTHER NORTH.

ANOTHER SIGNIFICANT DIFFERENCE IN DETAILS IS EVIDENT WITH NEG
TILT SFC TROUGH IN NE GULF LATER MON AND MON NIGHT. GFS DEVELOPS
DISTINCT DOUBLE SFC LOW STRUCTURE WHERE EURO MODELS SHOW MORE
DEFINED TROUGH EXTENDING FROM MAIN LOW OVER N CENTRAL GULF. WILL
MAINTAIN CURRENT GRID FCSTS WITHOUT DOUBLE LOW AND COORDINATE
WITH ANCHORAGE FCSTRS ON THEIR PREFERENCE FOR LOW CENTER
PLACEMENT MON NIGHT. END RESULT WILL BE BANDS OF PRECIP LIFTING
NE INTO PANHANDLE EARLY TUE. BASED ON MODEL 850 MB TEMPS...PRECIP
TYPE WILL PROBABLY BE SNOW EAST OF A PAYA-GLACIER BAY-TAKU LINE
AND RAIN WEST OF PASI-PAKT LINE. PCPN TYPE WILL BE MIXED RN-SN IN
BETWEEN SUCH AS CHATHAM STR AND PAPG-PAWG AREAS.

A RELAXED GRADIENT AND GREAT SPACING BETWEEN STORMS WED-THUR
SHOULD ALLOW FOR A BREAK IN THE HEAVY WEATHER AND HIGH WIND
EVENTS. HIGH PRESSURE BUILDS IN TEMPORARILY FROM THE WEST WED AND
MAKES FOR ONSHORE FLOW. A BIT OF POST FRONTAL COOLING ALOFT WILL
MAINTAIN SHOWERY BUT RATHER CALM WEATHER MID WEEK. GLOBAL MODELS
STILL INDICATING STORM DEVELOPMENT LATE IN THE WEEK.  TA

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...WIND WRN...AKZ027-028
      ...WIND ADV...AKZ022-023-026-029
MARINE...STORM...PKZ036-041>043-310.
      ...GALE...PKZ033-035-051.
      ...SCA...PKZ021-022-031-032-034-052.