Small Craft Advisory 1002, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKST FRI DEC 13 2013

.ANALYSIS AND UPPER LEVELS...THE UPPER LEVEL TROUGH PERSISTS OVER THE
MAINLAND PART OF THE STATE WITH AN AXIS THAT RUNS FROM AROUND TO COLD
BAY. THE UPPER LEVEL RIDGE IN THE WESTERN BERING SEA IS HOLDING
STRONG KEEPING A STRONG NORTHERLY GRADIENT OVER THE BERING SEA AND
WESTERN ALASKA WITH SOUTHWEST FLOW ALOFT OVER SOUTH CENTRAL ALASKA.
AT THE SURFACE THE LOW IN THE GULF IS ON TRACK TO MOVE INTO WESTERN
PRINCE WILLIAM SOUND TONIGHT. THE ATMOSPHERE IS COLD ENOUGH THAT ALL
PRECIPITATION WILL BE SNOW WITH THE EXCEPTION OF THE GULF COAST FROM
SOUTHEAST PRINCE WILLIAM SOUND AND TO THE EAST. THIS AREA WILL SEE
SOME RAIN MIXED IN OVERNIGHT BEFORE A COLD FRONT SWEEPS INTO THE AREA
FROM THE GULF TOMORROW.

.MODEL DISCUSSION...MODELS ARE DOING THEIR TYPICAL DANCE WITH THE LOW
MOVING INTO THE EASTERN KENAI PENINSULA. BY SATURDAY MORNING THE NAM
AND ECMWF BOTH HAVE THE LOW CENTER MORE DIFFUSE WITH THE ACTUAL
CENTER DRIFTING WESTWARD INTO NORTHERN COOK INLET. THE GFS KEEPS THE
LOW FARTHER EAST OVER WESTERN PRINCE WILLIAM SOUND WITH A STRONGER
GRADIENT AROUND ITS CENTER. BY SATURDAY AFTERNOON ALL THREE MODELS
HAVE THE LOW IN WESTERN PRINCE WILLIAM SOUND. THESE DIFFERENCES IN
LOW TRACK CAN HAVE A LARGE IMPACT ON SNOW AMOUNTS WHICH IS WHY
UNCERTAINTY CAN STILL BE FAIRLY HIGH EVEN AS THE STORM IS UPON THE
REGION. IN THE END THIS WILL LIKELY HAVE MORE IMPACT AS FAR AS WHEN
THE SNOW WILL FALL RATHER THAN HOW MUCH. THE GENERAL STORY SO FAR FOR
THE COOK INLET REGION...INCLUDING ANCHORAGE...IS FOR SNOW THROUGH
TONIGHT WITH IT BECOMING LIGHT EARLY SATURDAY MORNING BEFORE IT
INTENSIFIES AGAIN FOR THE SATURDAY EVENING AND OVERNIGHT PERIOD.
WHILE THIS STILL SEEMS LIKELY THE WAY THE LOW DANCE ALONG THE KENAI
MOUNTAINS COULD CHANGE THAT TIMING SOME. HOWEVER THERE SHOULD STILL
BE CLOSE TO THE FORECAST AMOUNTS OVER THE REGION BY EARLY SUNDAY
MORNING.

.SHORT TERM FORECAST...
SOUTHCENTRAL...AS THE PREVIOUS SECTION MENTIONS THERE IS STILL A
LITTLE UNCERTAINTY AS TO THE TIMING OF THE HEAVIER PERIODS OF
SNOWFALL IN THE COOK INLET REGION BUT THE CURRENT FORECAST AMOUNTS
STILL LOOK GOOD. LIGHT SNOW WILL LINGER ON AND OFF THROUGHOUT THE
COOK INLET REGION SUNDAY AND THEN A CLEARING TREND WILL START SUNDAY
NIGHT OR MONDAY.
THE NORTH GULF COAST FROM CORDOVA EASTWARD WILL SEE RAIN AND SNOW
SHOWERS OVERNIGHT BEFORE THE NEXT COLD FRONT ARRIVE EARLY SATURDAY
AND BRINGS SOME GOOD SNOWFALL INTO THAT AREA FOR TOMORROW THROUGH
TOMORROW NIGHT.
THE COPPER RIVER BASIN IS IN GOOD SHAPE FOR KEEPING THE SNOW GOING AT
A GOOD RATE THROUGH THE NIGHT AND THEN BECOMING LIGHT FOR TOMORROW.

SOUTHWEST...THE LARGE RIDGE OF HIGH PRESSURE IN THE BERING SEA AND
THE LOW IN THE GULF SETS UP A PATTERN WITH STRONG NORTHERLY FLOW OVER
THE AREA. THIS WILL BRING SOME LOW WIND CHILLS TO THE KUSKOKWIM DELTA
WITH COLD TEMPERATURES AND CLEAR SKIES. THERE WILL BE SOME CLOUDS
FROM THE GULF LOW THAT ARE PUSHED OVER THE ALASKA RANGE AND ALEUTIAN
RANGE WITH SOME LIGHT SNOWFALL ALONG THESE MOUNTAINS.

ALEUTIANS/BERING SEA...WIDESPREAD STRATUS WILL PERSIST OVER THE
BERING SEA DUE TO THE COLD AIR RIDING OVER THE WARMER WATER. THE
ALASKA PENINSULA AND ALEUTIANS WILL SEE ONGOING SNOW SHOWERS AS IS
TYPICAL IN THIS PATTERN.

.LONG TERM FORECAST...THE RIDGE OVER THE BERING SEA WILL MOVE
EASTWARD AND WEAKEN DURING THE FIRST HALF OF NEXT WEEK THIS WILL
BRING CLEARING TO SOUTH CENTRAL ALASKA AND CONTINUED CLEAR SKIES TO
SOUTHWEST ALASKA. THIS WILL NOT LAST TERRIBLY LONG AS AN UPPER LEVEL
RIDGE DEVELOPS AGAIN OVER THE GULF OF ALASKA WHICH WILL BRING THE JET
STREAM AND A MORE ACTIVE WEATHER PATTERN BACK INTO SOUTHWEST AND
SOUTH CENTRAL ALASKA FOR THE SECOND HALF OF NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 131.
         WINTER WEATHER ADVISORY SNOW 101 141.
         WINTER WEATHER ADVISORY SNOW AND BLOWING SNOW 121.
MARINE...GALE 119 130 132 139 155 165 170 172 179 180 181.
         HEAVY FREEZING SPRAY 130-141 150 160 165 179 180 181.
FIRE WEATHER...NONE.

DEC 13

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1050 PM AKST FRI DEC 13 2013

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

1040 PM     SNOW             5 SSE ANCHORAGE         61.15N 149.81W
12/13/2013  M2.8 INCH                           AK   TRAINED SPOTTER

            2 3/4 INCHES AS OF 1040PM. ABOUT 2.2 INCHES AFTER 5PM.
            CAMBELL CREEK NEAR SEWARD HIGHWAY.

&&

TPEPE