Small Craft Advisory 186, NWS Juneau, AK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
523 AM AKST TUE MAR 6 2012

.SHORT TERM...EARLY MORNING SATELLITE IMAGERY REVEALS A WARM
FRONT APPROACHING THE PANHANDLE COAST WITH A PRE-FRONTAL BOUNDARY
HAS MOVED ONSHORE AND BROUGHT SNOW UNDER COLD AIR AT LOW LEVEL IN
PLACE. WATER VAPOR IMAGERY SHOWS A JET MAX OVER THE NORTHERN GULF
CURVING SOUTHEASTWARD. STEADY SNOW CONTINUES ACROSS THE FORECAST
DOMAIN WITH TEMPERATURES IN THE UPPER 20S TO THE LOWER 30S.
SOUTHERLY PRESSURE GRADIENT HAS MAINTAINED FAIRLY STRONG SOUTH
WINDS OVER THE NORTHERN INNER CHANNELS.

 MODELS ARE IN GENERAL AGREEMENT WITH THE WARM FRONT CONTINUES TO
MOVE EASTWARD ACROSS SOUTHEAST ALASKA THROUGH LATE TONIGHT. THE
FRONT WILL WEAKEN THIS AFTERNOON WITH WARM AIR ADVECTION
OCCURRING ALONG THE PANHANDLE COAST SLOWLY SPREADING EAST THROUGH
THE EVENING HOURS. ACROSS THE CENTRAL AND SOUTHERN AREAS...MIXED
PRECIPITATION WILL BEGIN EARLY THIS AFTERNOON FROM THE
WEST...THEN CHANGING OVER RAIN AND DIMINISHING AS THE WEAKENING
WARM FRONT DRIFT THROUGH EASTWARD. REFRESHED THE INHERITED
FORECAST PACKAGE WITH THE GFS FOR ITS BEST CONSISTENCY.

 ALONG THE FRONTAL BOUNDARY...SMALL CRAFT WINDS OVER THE OUTER
WATERS WILL DIMINISH IN THE AFTERNOON. GALE FORCE WINDS ACROSS
NORTHERN LYNN CANAL WILL EASE TO SMALL CRAFT THIS AFTERNOON. AS
THE FRONT MOVES EAST...SMALL CRAFT WINDS WILL LIKELY TO PICK UP
AGAIN OVER THE SOUTHERN COASTAL WATERS LATE TONIGHT. LONG PERIOD
SOUTHWEST TO WEST SWELLS WILL MAINTAIN ROUGH SMALL CRAFT 10 TO
12 FT SEAS ACROSS THE OUTER WATERS.

.LONG TERM...LIMITED CHANGES TO GENERALLY THE WED/THU TIME
FRAME. STILL SOME CASTING ABOUT ON WHERE THAT LATE WEEK LOW WILL
GO. LATEST MODELS ARE A BIT SLOWER THAN THE PREVIOUS SET MAINLY
DUE TO STRENGTHENING THE SFC LOW A BIT MORE. CURRENT FORECAST FOR
THAT SYSTEM STILL LOOKS REASONABLE SO BASICALLY LEFT IT AND THE
SYSTEMS AFTERWARD AS IS. USED THE 00Z GFS FROM 15Z WED TO 18Z
THU...THEN LEFT 00Z FRI ONWARD AS IS PRESSURE WISE.

 WHAT WAS ADJUSTED WAS THE PRECIP SPREADING NWD A LITTLE FASTER
THAN PREVIOUSLY FORECASTED FOR LATE WED INTO WED NIGHT. A TRICKY
ASPECT OF THIS IS HOW MUCH COLDER AIR WILL WORK ITS WAY INTO THE
NRN AREAS BEFORE MID-LEVEL WARM ADVECTION COMMENCES LATER WED.
MAY HAVE PTYPE CONCERNS FOR THE FAR NRN INNER CHANNEL AREA WED
NIGHT...BUT FOR NOW KEPT THE PTYPE AS RAIN THERE. IF THERE IS
ONLY A SLIGHT SWD ADJUSTMENT TO THE COLDER AIR COMING IN THE N
WILL LIKELY NEED TO HAVE SNOW PUT BACK IN. PAYA SHOULD GET INTO
THE COLDER AIR BEFORE PRECIP RETURNS LATER WED NIGHT OR THU
MORNING...SO THEY WILL LIKELY START OUT AS SNOW. TOO EARLY TO
TELL HOW MUCH SNOW HOWEVER AS THAT WILL DEPEND ON STORM TRACK AND
DEPTH. TOO DEEP OF A SYSTEM AND DOWNSLOPE WOULD BEGIN TO DIMINISH
THE PRECIP AS THE LOW HEADS NWD INTO THE ERN GULF. INITIAL BATCH
OF PRECIP WILL DEVELOP ALONG AND E OF AN INVERTED TROF THAT WILL
MOVE INTO THE SERN GULF WED AND CONTINUE TO SLOWLY DRIFT NWWD WED
NIGHT INTO THU. PRECIP WITH THE MAIN LOW SHOULD MOVE IN THU OR
THU NIGHT. STAY TUNED...

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...WINTER WEATHER ADVISORY UNTIL 5 PM AKST THIS AFTERNOON FOR
     AKZ018-019-021-024-026.
         WINTER WEATHER ADVISORY UNTIL NOON AKST TODAY FOR AKZ020-022-027-
     028.
         WINTER STORM WARNING UNTIL 5 PM AKST THIS AFTERNOON FOR AKZ025.
         WINTER WEATHER ADVISORY UNTIL 9 AM AKST THIS MORNING FOR AKZ017.
MARINE...GALE WARNING FOR PKZ012.
         SMALL CRAFT ADVISORY FOR PKZ011-013-021-022-031>036-041>043-051-
     052.

&&

AHN/RWT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
116 PM AKST TUE MAR 06 2012

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

1130 AM     HEAVY SNOW       3 SE YAKUTAT            59.52N 139.67W
03/06/2012  M9.5 INCH                           AK   OFFICIAL NWS OBS

            YAKUTAT WEATHER OFFICE REPORTED 9.5 INCHES OF SNOW SINCE
            YESTERDAY WITH THE MAJORITY OF THE SNOW ON MONDAY NIGHT.

&&

NCB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JUNEAU AK
347 PM AKST TUE MAR 06 2012

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

0342 PM     HEAVY SNOW       9 N JUNEAU              58.43N 134.41W
03/06/2012  M15.2 INCH                          AK   NWS EMPLOYEE

            15.2 INCHES SINCE 3 PM MONDAY AFTERNOON AT THE NATIONAL
            WEATHER SERVICE OFFICE IN JUNEAU.

0342 PM     HEAVY SNOW       9 NNW JUNEAU            58.42N 134.51W
03/06/2012  M7.8 INCH                           AK   OTHER FEDERAL

            7.8 INCHES MEASURED AT JUNEAU AIRPORT SINCE 3 PM MONDAY
            AFTERNOON

&&

EAL