Small Craft Advisory 956, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
527 AM AKST MON DEC 1 2014

.ANALYSIS AND UPPER LEVELS...

A PAIR OF SEASONABLY STRONG SURFACE LOWS CONTINUE TO CHURN OVER
THE EAST-CENTRAL AND FAR WESTERN BERING SEA...WITH THE PARENT
UPPER LEVEL TROUGH SITUATED FROM KAMCHATKA SOUTH AND EAST OVER THE
WEST-CENTRAL ALEUTIANS. STRONG UPPER LEVEL HIGH PRESSURE RIDGING
PERSISTS WITH RIDGE AXIS FROM KODIAK ISLAND NORTH AND WEST TO THE
BERING STRAIT.

BETWEEN THE BERING LOW AND THE MAINLAND RIDGE...STRONG SOUTHERLY
FLOW IS PUSHING A VERY WARM AND MOIST PACIFIC AIR MASS WITH
PRECIPITABLE WATER (PW) VALUES AT OR ABOVE 200 PERCENT OF NORMAL
OVER A STABLE COLD NEAR-SURFACE LAYER. ALONG THE SOUTHWEST
COAST...THE WARM AND MOIST PACIFIC AIR MASS IS HAVING SOME SUCCESS
ERODING THE NEAR- SURFACE COLD DOME...WITH THE 12 UTC BETHEL
SOUNDING DEPICTING A 6000-FT FREEZING LEVEL AND THE KING SALMON
SOUNDING DEPICTING AN 8000-FT FREEZING LEVEL.

WHILE THERE IS A LARGE SWATH OF OVERRUNNING PRECIPITATION
OCCURRING AS DEPICTED BY RADAR THIS MORNING...WATER VAPOR AND
INFRARED SATELLITE ALSO DETECTS SOME EMBEDDED DRIER
POCKETS...WHICH IS RESULTING IN PERIODS OF DRIZZLE AND FOG ALONG
WITH THE OCCASIONAL RAIN OVER PARTS OF THE SOUTHWEST MAINLAND.

&&

.MODEL DISCUSSION...

MODELS ARE IN FAIRLY GOOD AGREEMENT...WITH THE NOTABLE
DISCREPANCIES OCCURRING OVER THE BERING SEA AS THE TWO SURFACE
LOWS AND ASSOCIATED FRONTS INTERACT WITH EACH OTHER. THIS LENDS A
LITTLE HIGHER UNCERTAINTY FOR WINDS FOR THE BERING REGION...BUT
OTHERWISE GENERAL CONFIDENCE IN THE FORECAST IS MODERATE TO HIGH.

DOWNSTREAM...MODELS AGREE IN MOVING THE RIDGE ACROSS SOUTHCENTRAL
ALASKA AS A VERY STRONG DISTURBANCE BEGINS TO MOVE UP THE ALASKA
PENINSULA TOWARD BRISTOL BAY AND THE COOK INLET REGION TONIGHT
THROUGH TUESDAY. THUS...THE EARLY WEEK PERIOD FOR MOST OF THE
SOUTHERN ALASKA IS LOOKING QUITE UNSETTLED.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...

LIGHT OVERRUNNING SNOW WILL CONTINUE THROUGH THE MORNING AND EARLY
AFTERNOON...BUT WILL BE VERY LIGHT EXCEPT ALONG THE SOUTHERN KENAI
PENINSULA WHERE MINOR ACCUMULATIONS ARE LIKELY. MODELS DEPICT A
WARM FRONT ALOFT MOVING NORTH ACROSS THE UPPER COOK INLET AND
MAT-SU VALLEY REGIONS CURRENTLY WHICH WILL USHER IN A DRY SLOT IN
THE SNOW GROWTH LAYER. THUS...LIGHT SNOW WILL LIKELY DIMINISH TO
FLURRIES OR PATCHY FREEZING DRIZZLE FOR MUCH OF THE LATE MORNING
INTO EARLY AFTERNOON HOURS.

THE NEXT WARM FRONT MOVES SOUTH TO NORTH ACROSS THE COOK INLET
REGION THIS EVENING AND WILL LIKELY BRING A PERIOD OF SNOW AT THE
OUTSET IN TIME FOR THE AFTERNOON RUSH HOUR. WITH THE WARM FRONT
WILL COME A PUSH OF WARM AIR JUST ABOVE THE STABLE COLD DOME NEAR
THE SURFACE. 1000-850 MB THICKNESSES SUGGEST THE POTENTIAL FOR
FREEZING RAIN...OR EVEN A COLD RAIN...FROM AROUND THE ANCHORAGE
BOWL SOUTH THROUGH THE KENAI PENINSULA. CONFIDENCE IS NOT HIGH
ENOUGH TO ISSUE A FREEZING RAIN ADVISORY AT THIS POINT IN
TIME...BUT THE DAY SHIFT WILL BE MONITORING IN CASE ANY ADVISORIES
ARE REQUIRED LATER TODAY.

A STRONG COLD FRONT WILL ACCOMPANY THE STRONG DISTURBANCE MOVING
NORTH AND EAST FROM THE ALASKA PENINSULA NORTH AND EAST UP COOK
INLET TONIGHT THROUGH TUESDAY. THUS...EXPECT TO SEE A BRIEF BUT
FAIRLY INTENSE PERIOD OF SNOW TUESDAY AS THIS FRONT SPEEDS ACROSS
THE AREA FROM SOUTH TO NORTH. THE BEST ESTIMATE FOR TIMING OVER
ANCHORAGE AT THIS POINT IN TIME LOOKS TO BE IN THE LATE MORNING TO
EARLY AFTERNOON HOURS TUESDAY...AND POSSIBLY LINGERING AS LATE AS
THE BEGINNING OF THE AFTERNOON RUSH HOUR TOWARD THE MATANUSKA
VALLEY.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
LOW PRESSURE IN THE BERING SENDS ANOTHER FRONTAL SURGE OF RAIN
ACROSS THE ALASKA PENINSULA AND BRISTOL BAY EARLY THIS MORNING
AND INTO THE KUSKOKWIM LATE MORNING. SURFACE TEMPERATURES ACROSS
THE KUSKOKWIM VALLEY CONTINUE AT OR JUST BELOW FREEZING THIS
MORNING KEEPING A THREAT FOR FREEZING RAIN. TEMPERATURES SHOULD
CLIMB ABOVE FREEZING LATE AFTERNOON OR EARLY EVENING ACROSS MUCH
OF THE VALLEY WITH IMPROVING CONDITIONS. THE ALASKA RANGE WILL BE
THE EXCEPTION...HOWEVER TEMPERATURES STAY BELOW FREEZING KEEPING
PRECIPITATION ALL SNOW. PERIODS OF RAIN WILL CONTINUE TO DEVELOP
ACROSS THE ALASKA PENINSULA AND SOUTHWESTERN MAINLAND THROUGH
TUESDAY EVENING AND THEN BEGIN TO TAPER OFF SOUTH TO NORTH INTO
WEDNESDAY AS THE MAIN LOW PRESSURE SYSTEM DIVES SOUTH OF THE
ALASKA PENINSULA.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
LOW PRESSURE OVER THE WESTERN BERING ORGANIZES TODAY WITH STORM
FORCE WINDS DEVELOPING THIS MORNING ACROSS THE WESTERN
BERING/ALEUTIANS AND LASTING UNTIL THE SYSTEM DIVES SOUTHEAST OF
THE ALASKA PENINSULA LATE TUESDAY. SATELLITE DATA ALREADY
ESTIMATES GUSTY WINDS BETWEEN 40 TO 50 MPH ALONG THE BACKSIDE OF
THE LOW WITH BUOY OBSERVATIONS REPORTING WAVE HEIGHTS UP TO 22
FEET EARLY THIS MORNING. SIGNIFICANT WAVE HEIGHTS BETWEEN 25 TO
35 FEET ARE EXPECTED DURING THIS EVENT. THE STRONGEST WINDS WILL
OCCUR ACROSS THE WESTERN AND CENTRAL ALEUTIANS...HOWEVER THERE IS
STILL UNCERTAINTY WITH THE TRACK AND STRENGTH OF THIS SYSTEM WITH
THE POSSIBILITY FOR THE EASTERN ALEUTIANS TO EXPERIENCE STRONGER
WINDS THAN EXPECTED TONIGHT AND EARLY TUESDAY MORNING.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...

THE BERING TROUGH WEAKENS AS IT MOVES INTO THE NORTH PACIFIC ON
WEDNESDAY...BUT ANOTHER ARCTIC TROUGH MOVING IN FROM THE NORTH
SLOPE WILL QUICKLY REPLACE IT. WHILE MODEL AGREEMENT IS QUITE POOR
WITH THE PLACEMENT AND INTENSITY OF LOWS AT THE SURFACE ...THERE
IS GOOD AGREEMENT OF TROUGHING FROM THE BERING SEA INTO THE
NORTHEAST PACIFIC THROUGH THE END OF THE WEEK. THIS WILL KEEP
SHOWERY WEATHER AND GUSTY WINDS OVER THE BERING SEA AND THE GULF
OF ALASKA THROUGH THE REST OF THIS WEEK...WITH WAVES OF
PRECIPITATION (MAINLY IN THE FORM OF SNOW) MOVING THROUGH THE
INTERIOR. MODEL AGREEMENT THEN DIMINISHES SEVERELY INTO ON
SATURDAY...SO THE LONG TERM FORECAST RELIES HEAVILY ON WPC...WITH
GENERALLY LOW CONFIDENCE IN THE FORECAST.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...FREEZING RAIN ADVISORY 152
MARINE...STORM WARNING 177 178
		 GALE WARNING 150 155 170 172 173 174 175 176 185
FIRE WEATHER...NONE

&&

SYNOPSIS AND MODEL DISCUSSION...CC
SOUTHCENTRAL ALASKA...CC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KH
LONG TERM...DEK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1143 AM AKST MON DEC 01 2014

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

1139 AM     SNOW             5 SSE ANCHORAGE         61.15N 149.83W
12/01/2014  M0.1 INCH                           AK   NWS EMPLOYEE

1139 AM     SNOW             N AKIAK                 60.91N 161.21W
12/01/2014  E0.1 INCH                           AK   TRAINED SPOTTER

            0.1 INCHES OF SNOW THEN A TRACE OF FREEZING RAIN.

&&

DK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
301 PM AKST MON DEC 01 2014

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

0301 PM     SNOW             5 SW ANCHORAGE          61.16N 149.98W
12/01/2014  M0.2 INCH                           AK   OFFICIAL NWS OBS

            DAILY SNOW TOTAL THROUGH 3PM

&&

JPW