Small Craft Advisory 112, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
1100 AM AST THU FEB 22 2007

.SYNOPSIS...
.SHORT RANGE...FOR THE MOST PART...SNOW IS SLOWLY WINDING DOWN
ACROSS THE SOUTHERN PART OF THE PANHANDLE THIS MORNING. NARROW
BAND OF PRECIPITATION CONTINUES TO MOVE SLOWLY EASTWARD ACROSS
THE PANHANDLE. WEAK SURFACE LOW CONTINUES ITS SOUTHEASTWARD TRACK
AND WAS LOCATED DUE WEST OF THE QUEEN CHARLOTTES.

THIS FORECAST WILL RELY HEAVILY ON THE NAM-12 SOLUTIONS. IN THE
EASTERN PART OF THE DOMAIN...THE NAM SEEMED TO HANDLE THE
SYNOPTIC SITUATION THE BEST OF THE OTHER MODELS ALTHOUGH IT WAS
VERY POOR OVER THE FAR WESTERN GULF AND THE ALEUTIANS. THE NAM
WAS VERY GOOD WITH THE INITIALIZATION AND EARLY TRACK OF THE WEAK
LOW WEST OF THE CHARLOTTES.

ANOTHER WEAK WAVE IS EXPECTED TO DEVELOP LATE TONIGHT ON THE
ARCTIC BOUNDARY THAT HAS REMAINED NEARLY STATIONARY OVER THE
CENTRAL PANHANDLE. THE STRONGEST FORCING ASSOCIATED WITH THIS
WAVE IS NOT EXPECTED UNTIL LATER TOMORROW NIGHT.

PRESSURE GRADIENT HAS RELAXED SOME THIS MORNING ACROSS BUT THIS
WILL ONLY BE TEMPORARY. AS THE WEAK WAVE DEVELOPS ALONG THE
ARCTIC BOUNDARY AND THE ARCTIC RIDGE STRENGTHENS...THE GRADIENT
WILL ONCE AGAIN TIGHTEN BACK UP AND WINDS WILL INCREASE
ACCORDINGLY. IT IS POSSIBLE WIND ADVISORIES WILL BE NEEDED OVER
THE NORTHERN PANHANDLE AND FOR OUTFLOW REGIONS IN ZONE 17.

.LONG RANGE...THE LONGWAVE PATTERN FRI NIGHT THROUGH SUN WILL
FEATURE AN UPPER LEVEL RIDGE OVER THE ALEUTIANS AND BERING SEA
WITH A TROUGH/LOW OVER THE GULF OF ALASKA AND NORTHERN EAST
PACIFIC. AN ARCTIC SURFACE HIGH WILL PERSIST OVER NORTHWEST
CANADA AND BEGIN TO WEAKEN SUN NIGHT. A LOW CURRENTLY BEING
HANDLED BEST BY THE UKMET NEAR 48N 164W IS FORECAST TO TRACK
SOUTH OF THE PANHANDLE INTO THE QUEEN CHARLOTTES FRI NIGHT...THEN
LINGER OVER SOUTHWEST CANADA THROUGH SUN NIGHT.

THE HIGH WILL KEEP VERY COLD TEMPS OVER THE NORTHERN TWO THIRDS
OF THE PANHANDLE THROUGH THE WEEKEND. THE HIGH TO THE NORTH AND
LOW TO THE SOUTH WILL INCREASE THE PRESSURE GRADIENT OVER THE
FORECAST AREA THROUGH EARLY SUN EVENING KEEPING LOCALLY WINDY
CONDITIONS OVER THE CENTRAL AND NORTHERN PANHANDLE. WIND ADV
GUSTS OUT OF PASSES WILL CONTINUE THROUGH SUN OVER THE NORTHEAST
GULF COAST (ZONE 17). WIND ADV GUSTS WILL DEVELOP ONCE AGAIN OVER
THE NORTHEAST PANHANDLE (ZONES 18 AND 19) FRI NIGHT THROUGH SUN
EVENING. GALE TO SMALL CRAFT WINDS AND FREEZING SPRAY WILL
CONTINUE OVER THE NORTHERN TO NORTH-CENTRAL INNER CHANNELS.
STRONG GUSTS OUT OF BAYS AND PASSES WILL PERSIST OVER THE
NORTHERN OUTSIDE WATERS.

WILL USE THE UKMET/GFS SOLUTION IN HANDLING THE FRONT ASSOCIATED
WITH THE LOW THAT WILL BRING PRECIPITATION MAINLY TO THE SOUTHERN
HALF OF THE PANHANDLE FRI NIGHT AND SAT...A PERIOD OF OVERRUNNING
LIGHT PRECIP AS FAR NORTH AS JUNEAU IS POSSIBLE FRI EVENING.
PRECIP TYPE WILL BE MAINLY SNOW EXCEPT OVER THE SOUTHERN THIRD
WHERE THE TYPE WILL BE TRICKY. THE GFS/UKMET DO SUGGEST SOME WARM
AIR DOES MOVE NORTH WITH A MIX OR CHANGE TO RAIN POSSIBLE OVER
THE FAR SOUTHERN AREAS. QPF AMOUNTS SUGGEST THAT SNOW ADVISORY
AMOUNTS WILL BE POSSIBLE FOR AREAS SOUTH OF FREDERICK SOUND FRI
NIGHT AND SAT. WARNING AMOUNTS ARE NOT OUT OF THE QUESTION BUT
CONFIDENCE IS NOT HIGH ENOUGH TO FORECAST THAT AS OTHER
SOLUTIONS...LIKE THE NAM...KEEP THE HEAVIEST PRECIP SOUTH OF THE
PANHANDLE. AN INCREASE IN OFFSHORE FLOW OVER THE NORTHERN HALF OF
THE PANHANDLE WILL BRING PERIODS OF CLEAR SKIES SAT AND SUN.

LOW CONFIDENCE IN THE LONGWAVE PATTERN MON THROUGH THU AS MODELS
CONTINUE TO MAKE SIGNIFICANT CHANGES THEIR SOLUTIONS FROM RUN TO
RUN. CURRENT FORECAST HAS A REASONABLE SOLUTION...SO WILL STICK
WITH THAT FORECAST WHICH FEATURES DRIER CONDITIONS NORTH TO
CHANCE TO LIKELY POPS SOUTH AND BELOW NORMAL TEMPS.

.AJK...WATCHES/WARNINGS/ADVISORIES
PUBLIC...HEAVY SNOW WARNING TIL NOON AKZ026
         WIND CHILL ADVISORY TIL 6 AM FRI AKZ018 ALONG THE
         KLONDIKE HIGHWAY
         WIND ADVISORY TIL 6 PM TONIGHT AKZ017

MARINE...GALE WARNING PKZ011>013
         SCA PKZ021>022-031-041>043-051>052

MLR/TAR

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE JUNEAU AK
1047 PM AST THU FEB 22 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0707 AM     HEAVY SNOW       PETERSBURG              56.82N 132.94W
02/22/2007  M10.0 INCH                          AK   CO-OP OBSERVER

            10 INCHES OF SNOW MEASURED IN DOWNTOWN PETERSBURG SINCE
            1530 LST YESTERDAY.

0707 AM     HEAVY SNOW       9 S PETERSBURG          56.69N 132.94W
02/22/2007  M8.8 INCH                           AK   TRAINED SPOTTER

            8.75 INCHES OF SNOW AT 9 MILES SOUTH OF PETERSBURG IN
            LAST 12 HOURS.

1000 AM     HEAVY SNOW       9 S WRANGELL            56.34N 132.39W
02/22/2007  M16.0 INCH       PKZ036             AK   TRAINED SPOTTER

            16.0 INCHES OF SNOW IN 12 HOURS UP TO 6 AM. LITTLE
            ADDITIONAL ACCUMLATION BETWEEN 6 AND 10 AM.

0300 PM     HEAVY SNOW       WRANGELL                56.47N 132.39W
02/22/2007  M17.0 INCH                          AK   AWOS

            24 HOUR SNOWFALL TOTAL

&&

TRF