Small Craft Advisory 283, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
356 PM AKDT SAT APR 28 2012

.SHORT TERM...EARLY AFTERNOON SATELLITE LOOP REVEALS A WEAKENING
FRONT...ASSOCIATED WITH A DISSIPATING LOW EAST OF KODIAK...MOVES
NORTHWARD ACROSS THE PANHANDLE WITH SCATTERED RAIN SHOWERS. ALONG
AND BEHIND THE WEAKENING FRONT...WINDS ARE GENERALLY LESS THAN
10 KNOTS OVER THE PANHANDLE WITH A LITTLE HIGHER ACROSS THE OUTER
WATERS. ANOTHER DEVELOPING LOW IS ENTERING THE FAR SOUTHWEST GULF
AND A FRONTAL BOUNDARY FORMS ALONG THE SOUTHERN GULF...SLOWLY
PROPAGATING NORTHEASTWARD.

 MODELS ARE IN GENERAL AGREEMENT WITH THE DEVELOPING LOW ENTERING
THE FAR SOUTHWEST GULF TRACKS NORTHEAST THIS EVENING AND REACHES
THE NORTHERN GULF BY SUNDAY MORNING..THEN BECOMES STATIONARY
THERE THROUGH LATE SUNDAY NIGHT. REFRESHED THE INHERITED FORECAST
PACKAGE WITH THE NAM12 FOR ITS SUPERIOR PERFORMANCE OF HANDLING
THE LOW DRIFTING NORTHEAST ACROSS THE WESTERN GULF INTO THE
NORTHERN GULF.

 THE ASSOCIATED OCCLUDED FRONT WILL ENTER THE EASTERN GULF
TONIGHT THEN MOVE ONSHORE OVER THE PANHANDLE ON SUNDAY. LIKELY TO
CATEGORICAL POPS WILL SPREAD OVER THE PANHANDLE LATE THIS EVENING
AND CONTINUE THROUGH SUNDAY. THE ONSET OF RAIN BAND WILL LIKELY
BE A BIT DELAYED ACROSS THE SOUTHERN AREAS UNTIL SUNDAY AFTERNOON
DUE TO THE NORTHEASTWARD TRACK OF THE LOW.

 AHEAD AND ALONG THE FRONTAL PASSAGE...SMALL CRAFT WINDS/SEAS
WILL BEGIN TO AFFECT THE OUTER WATERS TONIGHT THEN CONTINUE
THROUGH SUNDAY. THE WINDS WILL EVENTUALLY INCREASE TO GALE FORCE
ACROSS THE NORTHERN OUTSIDE WATERS ON SUNDAY MORNING. SMALL CRAFT
WINDS WILL ALSO AFFECT THE WESTERN INNER CHANNELS AND OCEAN
ENTRANCES AS WELL ON SUNDAY. THE FRONT WILL WEAKEN AS IT MOVES
ONSHORE OVER THE PANHANDLE...BUT THE IMMEDIATE COASTAL SECTIONS
WILL EXPERIENCE WINDS UP TO 20 MPH ON SUNDAY.

&&

.LONG TERM...RELATIVELY STABLE EXTENDED RANGE PATTERN WHICH
FEATURES UPPER LEVEL LOW PRESSURE OVER THE INTERIOR OF THE STATE
THAT DROPS DOWN TO THE GULF...AT TIME AS A TROUGH AND AT TIMES AS
A CLOSED LOW. FORECAST UNCERTAINTY IN THE LONG RANGE PRIMARILY A
FUNCTION OF THE NUMEROUS UPPER LEVEL SHORT WAVES WHICH ROUND THE
BASE OF THE UPPER OVER THE UPCOMING WEEK.

MODEL AGREEMENT IS BETTER TODAY AND THE PRECIP PATTERN REMAINS ON
THE MOIST SIDE FOR THE WEEK AHEAD WITH MUCH OF IT A FUNCTION OF
THE AFOREMENTIONED UPPER LEVEL SHORT WAVES. CHARACTERIZED PRECIP
THAT WILL BEGIN IN THE SHORT RANGE AS STRATIFORM RAIN THROUGH
MONDAY NIGHT. BASED ON SHORT WAVES AND EXPECTED ATMOSPHERIC INSTABILITY,
USED SHOWER TERMINOLOGY TUESDAY THROUGH WEDNESDAY. MODELS
INDICATING THE NEXT WELL ORGANIZED FRONT SHOULD ARRIVE LATE IN THE
WEEK, SO HAVE STRATIFORM TERMINOLOGY BACK IN THE FORECAST THURSDAY
ON INTO THE WEEKEND.

NO SNOW IN THE FORECAST, ALTHOUGH IT WILL BE A CLOSE ONE FOR
LOCATIONS NEAR YAKUTAT MONDAY NIGHT. ADDITIONALLY, AM EXPECTING
TRACE TO ONE HALF INCH OF SNOW ACCUMULATION DURING THE NIGHTS THIS
WEEK ALONG THE HAINES AND KLONDIKE HIGHWAY. NO IMPACT TO ROAD
CONDITIONS OR ICING EXPECTED.

WINDS AT THE BEGINNING OF THE EXTENDED RANGE FORECAST WILL BE
WINDING DOWN ALONG THE OUTER COAST AS THE FRONT WEAKENS. SMALL
CRAFT WINDS FROM THE DIXON ENTRANCE TO CAPE SUCKLING SUNDAY NIGHT
WILL DIMINISH TO 20 KT OR LESS BY MONDAY MORNING. LIKEWISE FOR
CROSS SOUND, SOUTHERN CHATHAM STRAIT, AND THE WESTERN PORTIONS OF
SUMNER STRAIT. OTHERWISE, WINDS 20 KT OR LESS OVER MARINE ZONES
AND INNER CHANNELS THROUGH FRIDAY DAY.

STANDARDIZED ANOMALIES FOR HEIGHTS, 850MB TEMPS, PRECIP, WIND AND
SURFACE PRESSURE ALL WITHIN PLUS OR MINUS ONE STANDARD DEVIATION
IN BOTH ECMWF AND GFS. FOR PRESSURE AND WIND USED A BLEND OF NAM,
GFS, AND ECMWF THROUGH MONDAY. BLENDED HPC WITH BOTH ECMWF AND GFS
AT TIMES FOR THE REMAINDER OF THE FORECAST. UPDATED TO TEMPS
PRIMARILY WITH BIAS CORRECTED MOS THROUGH WEDNESDAY NIGHT AND GFS
ENSEMBLE THEREAFTER. POP FIELDS ARE A BLEND OF GFS, ECMWF, AND
OFFICIAL THROUGHOUT. FORECAST CONFIDENCE IS AVERAGE.

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ043-051-052.
         SMALL CRAFT ADVISORY FOR PKZ011-021-022-033-035-041-042.

&&

AHN/FRITSCH