Area Forecast Discussion - Southeastern

FXAK67 PAJK 092110
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
1210 PM AKST TUE FEB 9 2010
.SHORT TERM....SATELLITE IMAGERY IS SHOWING AN EXTENSIVE CLOUD
SHIELD ASSOCIATED WITH A FRONT EXTENDING NW TO SE ACROSS THE
CENTRAL GULF. AM ALSO SEEING EVIDENCE OF A WAVE DEVELOPING ALONG
THE FRONTAL BOUNDARY NEAR 55N/144W. THE FIRST BANDS OF PRE FRONTAL
PRECIPITATION HAVE ARRIVED OVER THE PANHANDLE WITH A MODERATE
BURST OF SNOW IN YAKUTAT. EASTERLY/SOUTHEASTERLY MARINE WINDS NOW
PICKING UP AS WELL WITH GALES OFF CAPE SUCKLING AND SMALL CRAFT
WINDS OFF CAPE FAIRWEATHER. AM EXPECTING TO SEE THE INCREASING
TREND IN WINDS TO CONTINUE THIS AFTERNOON AND EVENING BEFORE
DIMINISHING LATE TONIGHT.

THE FRONT WILL STALL ALONG THE OUTER COAST AS IT LOSES JET STREAM
SUPPORT AND SATELLITE IMAGERY IS ALREADY SHOWING EVIDENCE OF THIS
WITH SHEARING IN THE CLOUD MASS OVER THE EASTERN GULF. WARMER AIR
ON THE BACK SIDE OF THE FRONT WILL RESULT IN A GRADUAL WARMING
TREND OVERNIGHT AND TOMORROW PROGRESSING FROM WEST TO EAST.
INITIAL PRECIP IN THE FORM OF SNOW FOR MOST LOCATIONS EXCEPT RAIN
FROM CAPE SPENCER SOUTH TO CAPE DECISION. A COLD POOL RESULTING
FROM A WEAK HIGH IN WESTERN BRITISH COLUMBIA IS KEEPING TEMPS NEAR
OR BELOW FREEZING FROM PETERSBURG SOUTHWEST TO CAPE DECISION...SO
WHEN THE PRECIP DOES ARRIVE THERE...IT SHOULD BE SNOW WITH UP TO
AN INCH FOR LOCATIONS IN ZONES 26 AND 28. NORTH OF ANGOON ON THE
INSIDE...DAYTIME HIGHS TOPPING OUT IN THE MID 30S TODAY...BUT
THERE SHOULD BE ENOUGH COOLING AFTER SUNDOWN TO ALLOW FOR SOME
SNOW BEFORE THE WARMER LOW LEVEL AIR ARRIVES. HAVE AS MUCH AS AN
INCH OR SO FOR LOCATIONS IN AND AROUND ICY STRAIT AND GLACIER
BAY...WITH LESSER AMOUNTS FARTHER INLAND AND NORTH. LIMITED
SNOWFALL IN SKAGWAY PRIMARILY DUE TO LOWER POPS AS IT JUST DOES
NOT LOOK LIKE FRONTAL PRECIP WILL MAKE IT THAT FAR INLAND AND
NORTH. LIKEWISE FOR THE JUNEAU AREA. 

FOR TOMORROW...TEMPERATURES SLOWLY RISING THROUGH THE DAY AS
WARMER LOW LEVEL AIR PUSHES INLAND FROM THE GULF. SNOW CHANGING
TO RAIN WITH POPS DIMINISHING TO CHANCE OVER THE NORTHERN HALF AND
LIKELY OR BETTER OVER THE SOUTHERN HALF. SOUTHEASTERLY GALES OVER
THE COASTAL MARINE ZONES FROM CAPE SPENCER NORTH TOMORROW
MORNING...DIMINISHING THROUGH THE DAY. SMALL CRAFT
SOUTHERLY/EASTERLY WINDS OVER ICY STRAIT...SUMNER...AND CLARENCE
STRAIT HANGING ON THROUGH MOST OF THE AFTERNOON.

&&
.LONG TERM...EXPECT A DEEP AND LARGE VERTICALLY STACKED CYCLONE
CENTERED SOUTH OF THE ALEUTIAN CHAIN TO GRADUALLY WEAKEN AND
DISSIPATE BY LATE IN THE WEEK AS IT IT REPLACED BY A NEW DEEP AND
LARGE CYCLONE THAT LIFTS OUT OF THE NORTH PACIFIC AND INTO THE
CENTRAL GULF BY FRIDAY. THERE ARE NUMEROUS SMALLER WAVES ROTATING AROUND
THE PARENT LOW AND MODELS ARE STRUGGLING WITH TIMING AND
INTENSITY OF THESE SYSTEMS. FOR THE EARLIER PERIODS THE
DIFFERENCES HAVE LESS IMPACT ON SE ALASKA WITH STRONGEST WINDS AND
HEAVIEST PRECIP STAYING WEST OF FA. BY LATE WEEK WINDS STRONGER
WINDS PENETRATING THE EASTERN GULF AND SOUTHEAST ALASKA. WILL
CONCENTRATE ON THE FIRST 84 HRS OF FCST AND LIMIT ANY CHANGES BEYOND
DUE TO UNCERTAINTY.

WILL HAVE A STRONG OCCLUSION LIFT NORTH INTO SE GULF AND SOUTHERN
PANHANDLE EARLY THURSDAY. THE FRONT BECOMES MORE NEGATIVELY TILTED
OVER CENTRAL AND SOUTHERN. GFS HAS STORMS IN OFFSHORE WITH NAM
HAVING SOLID GALES ALL EASTERN GULF UNTIL LOW STARTS TO PULL BACK
TO NW. WILL LIKELY HAVE ADVISORY LEVEL WINDS FOR COASTAL AND
SOUTHERN BUT DO NOT SEE WINDS PENETRATING TOO FAR INLAND. RAIN
WILL BE HEAVIEST COASTAL AND SOUTHERN WITH MDT AMOUNTS AND JUST
LIGHTER AMOUNTS CENTRAL AND ONLY CHANCE NRN...HOWEVER WILL NEED TO
DEL WITH P TYPE HERE. WILL KEEP FAR NORTH ALL SNOW UNTIL SECOND
SYSTEM OVER WEEKEND AND WILL PROBABLY GO WITH A MIXED FOR CENTRAL.
THIS WILL KEEP ANY ACCUMS DOWN TO A FEW INCHES.

A SECOND STRONGER LOW DRIVES NORTH OUT OF THE EASTERN PACIFIC WITH
GFS ADVERTISING STORM TO HURRICANE FORCE WINDS IN SE GULF. MIGHT BE
A TOUCH OVERDONE BUT FITS THE TREND OF SLOWLY MOVING SEVERE
WEATHER SLOWLY EAST THROUGH THE WEEK.

.AJK WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...GALE
WARNING FOR PKZ042-043-051-052. SMALL CRAFT ADVISORY FOR
PKZ011-021-022-031>036-041.

&&

$$

FRITSCH/MM