Small Craft Advisory 224, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
5 AM AKST THU MAR 10 2011

.SHORT TERM...EARLY MORNING SATELLITE LOOP SHOWS A WEAKENING LOW
OVER DIXON ENTRANCE WITH AN OCCLUDED FRONT EXTENDING EASTWARD FROM
THE LOW CENTER. PRECIPITATION BANDS WRAP AROUND THE LOW WITH
RAIN/SNOW MIX FALLING ACROSS THE SOUTHERN PANHANDLE FROM KLAWOCK
EAST TO KAKE TO PETERSBURG AND WRANGELL. CLOUDINESS SLIGHTLY
INCREASES ACROSS THE CENTRAL PANHANDLE THROUGH SOUTH OF JUNEAU BUT
THE NORTHERN AREAS REMAINED CLOUD FREE. EARLY MORNING MERCURY
READINGS RANGE FROM THE LOWER TO MIDDLE TEENS ACROSS THE NORTHERN
MOST AREAS AND WIND SHELTERED INLAND LOCATIONS...TO THE MIDDLE 20S
IN THE CENTRAL PANHANDLE TO THE MIDDLE TO UPPER 30S OVER THE
SOUTHERN ZONES. PERSISTING HIGH PRESSURE OVER THE NORTHWESTERN
CANADA PRODUCES CONTINUED OFFSHORE LOW LEVEL FLOW ACROSS THE
NORTHERN HALF OF THE PANHANDLE WITH STORM FORCE WINDS ACROSS THE
NORTHERN MOST INNER CHANNELS WITH HEAVY FREEZING SPRAY AND GALE
FORCE WINDS OVER THE REST OF THE NORTHERN INNER CHANNELS AND
NORTHERN OUTSIDE COASTAL WATERS WITH FREEZING SPRAY.

MODELS ARE IN FAIR AGREEMENT WITH THE WEAKENING LOW OVER THE
SOUTHERN PANHANDLE DISSIPATING LATE THIS EVENING WHILE LIFTING A
LITTLE TO COAST MOUNTAIN EARLY TONIGHT. HIGH PRESSURE WILL PERSIST
OVER THE NORTHWESTERN CANADA CONTINUING TO PRODUCE OFFSHORE FLOW
ACROSS THE NORTHERN HALF OF THE PANHANDLE THROUGH LATE TONIGHT. AN
UPPER LEVEL SHORTWAVE TROUGH EXTENDING SOUTHWESTWARD FROM THE
NORTHERN CANADA WILL CONTINUE TO MAINTAIN COLD AIR MASS ACROSS THE
FORECAST DOMAIN...ESPECIALLY OVER THE NORTHERN PANHANDLE. THE NAM
HANDLES THE LOW TRACK BEST AND WAS OPTED TO REFRESH THE INHERITED
GRIDS FOR TODAY AND TONIGHT.

AS THE WEAKENING LOW ACROSS THE SOUTHERN AREAS DISSIPATING...POPS
WILL DECREASE ACROSS THE SOUTHERN AREAS LATE THIS AFTERNOON INTO
THE EARLY EVENING HOURS THEN CONTINUE TAPERING OFF EASTWARD ACROSS
THE HYDER AREA INTO THE CANADIAN SIDE THROUGH LATE THIS EVENING.
ACROSS THE SOUTHERN AREAS...SNOW LEVEL WILL BE ABOVE 1K FEET TODAY
AND LOWERING TO AROUND 500 FEET TONIGHT..EXCEPT NEAR HYDER. MOS
GUIDANCE SUGGESTED MUCH COLDER TEMPERATURES TODAY AND TONIGHT BUT
DUE TO NORTHWARD INCREASING CLOUDS...LOWERED TEMPERATURES ONLY
SEVERAL DEGREES. DUE TO THE PERSISTING HIGH OVER THE
NORTHWESTERN CANADA AND LOW PRESSURE AREA ACROSS THE
GULF...NORTHERLY PRESSURE GRADIENT WILL REMAIN TIGHT ACROSS THE
NORTHERN PANHANDLE WITH ADVISORY LEVEL WIND GUSTS NEAR AND OUT OF
INTERIOR PASSES AND BAYS. KEPT THE WIND ADVISORY FOR ZONES
17/18/19/25 THROUGH EARLY FRIDAY MORNING.

.LONG TERM...
OMEGA BLOCK STILL HOLDING WITH UPR HIGH CENTER STATIONARY OVR THE
BERING STRAIT THIS MORNING. WEAK TROF ALF PERSISTS OVR NORTHERN
PANHANDLE AND WILL HOLD INTO FRI. UPR LOW DEVELOPS OFF JET BY 00Z SAT
WITH SOME COLD AIR SW OF THE CHARLOTTES OVR A SFC GALE CENTER AROUND
990 MB. ALL 00Z OPS MODELS FORECAST THIS DEVELOPMENT BUT TRACK VARIES
GREATLY BY 00Z SUN. POOR CONFIDENCE IN LATCHING ONTO AN ONE OF THESE
INCLUDING ENSEMBLE MEANS. STARTED OUT DOING ALL SORTS OF FANCY COMBOS
AND ENDED UP USING PREVIOUS DAY SHIFTS PLAN BUT A LITTLE DRIER THAN
HPC POPS. 00Z ECMWF BRINGS DEVELOPS A STORM FORCE CENTER 964 MB NEAR
50N 140W BY 00Z MON WHICH WOULD CONTINUE STRONG OFFSHORE WIND AND
SUPPORTS DRY IDEA. ALL MODELS RAPIDLY FILL THIS STORM AND HPC AND
10/06Z GFS SUPPORT DEVELOPING ANOTHER RIGHT OFF VANCOUVER ISL. VERY
UNCOMFORTABLE HANGING ON TO ANY OF THESE SO WILL STAND PAT AND HOPE
THAT 12Z CYCLE BRINGS SOME AGREEMENT. - JC
&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WIND ADV TIL 5 AM AKST FRI AKZ017>019-025.
         WIND ADV TIL 5 AM AKST THIS MORNING FOR AKZ023.
MARINE...HEAVY FREEZING SPRAY WARNING FOR PKZ011-012-013-031.
         STORM WARNING PKZ012.
         GALES PKZ011-013-021-022-031>035-043-051.
         SMALL CRAFT ADVISORY PKZ036-042-052.
         SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ041.
&&

AHN