Gale Warning 19, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
436 PM AKST WED JAN 25 2012

.SHORT TERM...EARLY AFTERNOON SATELLITE IMAGERY REVEALS A
WEAKENING LOW IN THE FAR NORTHERN GULF SLOWLY MOVES NORTHWESTWARD
TO NEAR PRICE WILLIAM SOUND WITH AN OCCLUDED FRONT STRETCHING
EASTWARD ACROSS THE SOUTHERN YUKON. A RIDGE OF HIGH PRESSURE
SLOWLY BUILDS ACROSS SOUTH OF DIXON ENTRANCE AND OVER BRITISH
COLUMBIA. BETWEEN THE HIGH OVER PACIFIC NORTHWEST AND THE LOW IN
THE NORTHERN GULF...TIGHTENED SOUTHEASTERLY PRESSURE GRADIENT
PRODUCES MODERATE TO STRONG SOUTHEAST TO SOUTH WINDS ACROSS THE
INNER CHANNELS. INCREASED INSTABILITY ACROSS THE FORECAST AREA
HAS TRIGGERED ISOLATED THUNDERSTORMS DEVELOPING OVER THE
IMMEDIATE CENTRAL PANHANDLE COASTAL SECTIONS. BEHIND THE TRAILING
EDGE OF THE EXITING FRONTAL BOUNDARY...DIMMED SUNSHINE FILTERED
OUT MOMENTARILY THROUGH THINNING CLOUDS...BUT SCATTERED SNOW
SHOWERS CONTINUE ACROSS SOUTHEAST ALASKA WITH TEMPERATURES REMAIN
IN THE LOWER 30S.

 MODELS ARE REMAINING IN GENERAL AGREEMENT WITH THE LOW IN THE
FAR NORTHERN GULF SLOWLY MOVING NORTHWESTWARD. THE LOW WILL
BECOME QUASI STATIONARY OVER PRINCE WILLIAM SOUND THIS EVENING
AND CONTINUE TO WEAKEN THERE THROUGH LATE THURSDAY. A COLD AIR
ADVECTION WILL CONTINUE ACROSS THE FORECAST DOMAIN. THE
ASSOCIATED WEAK TROUGH WILL MOVE NORTHEASTWARD ACROSS THE EASTERN
GULF AND THE PANHANDLE THROUGH THURSDAY...PRODUCING SCATTERED TO
NUMEROUS SNOW SHOWERS WITH SNOW ACCUMULATION GENERALLY 1 TO
3 INCHES. THE GENERAL SOUTHERLY FLOW WILL WEAKEN AS THE HIGH IN
THE PACIFIC NORTHWEST MOVES EAST AND CONSEQUENTLY PRESSURE
GRADIENT RELAXES TONIGHT AND THURSDAY...BUT KEEPING SMALL CRAFT
WINDS/SEAS OVER THE OUTER WATERS THROUGH THURSDAY AND ACROSS
SOUTHERN TWO THIRD OF THE INNER CHANNELS FOR THIS EVENING.
REFRESHED THE INHERITED FORECAST PACKAGE WITH THE 00Z ECMWF FOR
ITS MOST CONSISTENCY.

 &&

.LONG TERM /THURSDAY NIGHT THRU WEDNESDAY/...GENERALLY WET
WEATHER PATTERN TO CONITNUE. LONGER RANGE MODELS INDICATE A WARMER
SW FLOW LIFTS NORTHWARD FROM CENTRAL PACIFIC INTO PANAHNDLE NEXT
WEEK BUT TIMING ON THAT WARM UP VARIES AND CONFIDENCE IS AVERAGE
OR LESS.

STRONGEST JET IMPINGING WEST COAST NORTH AMERICA IS CENTERED OVER
WA/OR TODAY. GFS DEPICTION OF JET EXTENDS ALL THE WAY ACROSS
PACIFIC. COLD AIR MASS CONTINUES TO BE CENTERED OVER WRN AK
ASSOCIATED WITH UPPER LEVEL TROF. FLOW AROUND THIS TROF WILL BE
SENDING SEVERAL WAVES AND BANDS OF SHOWERS EAST ACROSS THE GULF
INTO PANHANDLE. FIRST HINT AT WARM UP AFFECTS SRN HALF OF
PANHANDLE STARTING SAT AND CONTINUING INTO SUN. USED EC MODEL
BASED ON SUPERIOR INITIALZATION SFC AND ALOFT RATHER THAN MUCH
WETTER GFS SAT-SUN. THE EC LIFTS A SURFACE LOW PRESSURE CENTER
INTO THE SRN OUTER COAST STARTING FRI. THIS CHANGE IN THE FCST
RESULTED IN LOWERING OR DELAYED CHANCE OF PRECIP FOR NRN
PANHANDLE. RISING SNOW LEVELS AND PRECIP TYPE CHANGING TO RAIN AND
COULD BE A SLOW MOVER FRI NIGHT-SAT FOR HEAVY RAIN AND MELTING
SNOW MAINLY S OF FREDERICK SOUND. NE OUTFLOW WIND FARTHER NORTH
WILL HELP KEEP TEMPS COOL ENOUGH FOR SNOW.

THE WEEKEND SYSTEM LOOKS LIKE IT WILL BE COMPRISED OF SEVERAL LOW
CENTERS SPINNING AROUND EACH OTHER AS THEY LIFT N UP THE COAST.
THIS WILL LIKELY MAKE FOR VERY TRICKY/CHANGING MARINE WIND
FORECASTS SAT-MON. NEXT WEEK THE STRONG /180 KTS/ WEST TO EAST
PAC JET AXIS BECOMES SITUATED JUST SOUTH OF THE GULF BUT THE GLOBAL
MODELS SHOW IT SPLITTING AT 140W LEAVING THE PANHANDLE IN A COL.
HOWEVER THE COMBINATION OF VARIABLE MODEL SOLUTIONS IN GENERAL AND
DIFFERING IDEAS ON THE STRENGTH OF THE WARM UP NEXT WEEK LEAVE ME
TO MAKE NO COMMITMENTS AFTER MON. CONTINUED WITH EXISTING FORECAST
WITH MINOR ADJUSTMENTS TO MATCH CLOSER WITH HPC /NATIONAL CENTER/
FORECASTER GUIDANCE FOR AK NEXT WEEK.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-022-031-033>036-041>043-051-052.

&&

AHN/TA