Small Craft Advisory 224, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT SAT MAR 15 2014

.ANALYSIS AND UPPER LEVELS...
A CLOSED UPPER LOW IS LIFTING NORTHWARD FROM THE SOUTHWEST MAINLAND
INTO THE WESTERN INTERIOR. AN ASSOCIATED TRAILING SHORTWAVE TROUGH
AXIS STRETCHES BACK ACROSS KODIAK ISLAND AND INTO THE GULF OF ALASKA.
THIS TROUGH IS BECOMING INCREASINGLY NEGATIVELY TILTED AS IT MAKES
GRADUAL PROGRESS NORTHWARD. SNOW SHOWER ACTIVITY HAS DECREASED AND
SUNSHINE HAS BROKEN OUT ACROSS MUCH OF SOUTH CENTRAL ALASKA AS
LOW-LEVEL HIGH PRESSURE HAS BUILT IN FROM THE WEST. HOWEVER...NEW
SNOW SHOWERS ARE JUST BEGINNING TO DEVELOP OVER COOK INLET ASSOCIATED
WITH THE MOVEMENT OF THE AFOREMENTIONED UPPER TROUGH. OUT WEST...AN
ARCTIC AIRMASS IS SHIFTING AWAY FROM THE BERING REGION AS FLOW
BECOMES MORE SOUTHERLY IN ADVANCE OF A MODERATE STRENGTH FRONT
CURRENTLY OVER THE CENTRAL ALEUTIANS. AREAS OF BLOWING SNOW ARE
DEVELOPING OVER THE PRIBILOF ISLANDS AHEAD OF THE FRONT...WHERE A
WINTER WEATHER ADVISORY FOR BLOWING SNOW IS IN EFFECT.

.MODEL DISCUSSION...
ALL MODELS ARE IN GOOD SYNOPTIC AGREEMENT. THE MAIN WEATHER SYSTEM
AFFECTING THE ENTIRE REGION IS THE FRONT CURRENTLY OUT OVER THE
BERING SEA. THIS FRONT WILL CONTINUE TO ELONGATE AND STRETCH
EASTWARD...WHICH RAISES THE LIKELIHOOD OF TRIPLE POINT LOW
DEVELOPMENT AT ONE OR MULTIPLE POINTS ALONG THE FRONT. THE MODELS ARE
STRUGGLING WITH SOME OF THESE EXACT DETAILS...BUT ARE GRADUALLY
COMING INTO AGREEMENT. OUT WEST...A TRIPLE POINT SHOULD FORM
NORTHEAST OF THE PRIBILOF ISLANDS OVERNIGHT AS SNOW BEGINS TO IMPACT
THE COASTLINE. THE ECMWF HAS TRENDED AWAY FROM A CLOSED UPPER LOW
SOLUTION THAT LED TO MORE CONSOLIDATED SURFACE ENERGY AND TOWARD THE
MULTIPLE-CENTERED GFS SOLUTION WHICH SEEMS VERY REASONABLE AT THIS
POINT. TO THE EAST...THE NAM AND ECMWF ARE TRYING TO FORM ANOTHER
WEAK LOW NEAR THE BARREN ISLANDS LATE SUNDAY NIGHT...WHICH WILL ALSO
BE REFLECTED IN THE AFTERNOON FORECAST. THIS WEAK LOW WILL LIKELY
SLIDE TOWARD PRINCE WILLIAM SOUND ON MONDAY AND BRING A CHANCE FOR
SOME ADDITIONAL SNOWFALL TO INTERIOR SECTIONS.

.SHORT TERM FORECAST...
SOUTHCENTRAL...TEMPERATURES HAVE REBOUNDED AROUND THE REGION TODAY
UNDER INCREASING SUNSHINE AND DIMINISHING WINDS AS THE ANCHORAGE AREA
DIGS OUT FROM A SIGNIFICANT SNOW STORM LAST NIGHT. THE CLEAR SKIES
WILL UNFORTUNATELY BE SHORT LIVED AS CLOUDS INCREASE QUICKLY THIS
EVENING IN ADVANCE OF THE SHORTWAVE TROUGH MENTIONED ABOVE. WHILE NO
REPEAT OF LAST NIGHTS SNOWFALL IS EXPECTED...MOST AREAS WILL SEE A
RETURN OF SOME GENERALLY LIGHT SNOWFALL DURING THE EVENING HOURS
BEFORE THE TROUGH PASSES AROUND MIDNIGHT. BY TOMORROW MORNING THE
BERING FRONT WILL BEGIN TO IMPACT KODIAK ISLAND...WHERE TEMPERATURES
WILL LIKELY STAY COLD ENOUGH TO SUPPORT ALL SNOW BY SHOULD WARM
ENOUGH TO AVOID BLIZZARD CONDITIONS WITH THE STRONG SOUTHEAST WINDS.
AS THIS FRONT MOVES UP THE COAST TOMORROW NIGHT THE CLASSIC UPSLOPE
LOCATIONS OF THE EASTERN KENAI PENINSULA AND WESTERN SUSITNA VALLEY
WILL SEE MODERATE TO HEAVY SNOW MOVE BACK IN. MEANWHILE ANCHORAGE AND
THE USUAL DOWNSLOPE AREAS SHOULD STAY MOSTLY DRY UNTIL A POSSIBLE
TRIPLE POINT LOW DRIFTS UP INTO PRINCE WILLIAM SOUND ON MONDAY TO
BRING ANOTHER CHANCE FOR SNOW (AS MENTIONED ABOVE).

SOUTHWEST MAINLAND...THE MAIN WEATHERMAKER WILL BE THE BERING FRONT
THAT REACHES THE COASTLINE TOMORROW MORNING. INCREASING CONFIDENCE IN
THE ORIENTATION AND TIMING OF THE FRONT HAS LED TO ELEVATED CONCERN
FOR THE POTENTIAL FOR SIGNIFICANT BLOWING SNOW ACROSS MUCH OF THE
COASTLINE. THUS WILL PLAN TO ISSUE A BLOWING SNOW ADVISORY FOR COASTS
OF BOTH THE KUSKOKWIM DELTA AND NORTHERN BRISTOL BAY. AS THE FRONT
PUSHES INLAND SUNDAY NIGHT THE REGION WILL FALL UNDER THE INFLUENCE
OF ONSHORE FLOW AND WARMING TEMPERATURES AS A VERTICALLY STACKED LOW
STALLS OVER THE NORTHERN BERING FOR THE START OF THE WEEK.

BERING SEA AND ALEUTIANS...A SIGNIFICANT FRONT MOVING INTO THE
EASTERN ALEUTIANS WILL CONTINUE TO MOVE EASTWARD TONIGHT. THE
PRIBILOFS ARE THE LARGEST AREA OF CONCERN AS THE FRONT
APPROACHES...SINCE THE COLD AIR WILL STICK AROUND THERE THE LONGEST.
TEMPERATURES ARE ALREADY WARMING...AND WILL LIKELY RISE ENOUGH TO AT
LEAST STAVE OFF BLIZZARD CONDITIONS...BUT THIS WILL NEED TO BE
WATCHED CLOSELY THIS EVENING. FURTHER SOUTH...SNOW WILL CHANGE TO
RAIN FROM THE EASTERN ALEUTIANS TO ALASKA PENINSULA TONIGHT AS STRONG
SOUTHERLY WINDS USHER IN WARMER TEMPERATURES. HIGH PRESSURE WILL
BUILD INTO THE WESTERN BERING THROUGH THE START OF THE WEEK BEFORE
ANOTHER WEATHER FRONT TRIES TO PUSH INTO THE EXTREME WESTERN
ALEUTIANS EARLY TUE MORNING.

.LONG TERM FORECAST FROM PREVIOUS FORECAST...
THE LONGWAVE TROUGH OVER THE BERING LOOKS TO BE REPLACED BY UPPER
LEVEL RIDGING BY THE MIDDLE OF NEXT WEEK AS IT GRADUALLY RETROGRADES
WESTWARD INTO EASTERN RUSSIA. THIS WILL RESULT IN A WESTWARD SHIFT IN
THE STORM TRACK WHICH WILL HELP TO KEEP UPCOMING SYSTEMS
PREDOMINANTLY OVER THE WESTERN BERING...ALLOWING FOR SOMEWHAT OF A
BREAK FROM THE RECENT ACTIVE PATTERN OVER THE SOUTHERN MAINLAND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...WINTER WEATHER ADVISORY 155 161 195
MARINE...STORM 176 177
         GALE 119 125 129 130 131 132 150 155 160 165 170 172 173 174
              175 178 179 180 181 185
         HVY FREEZING SPRAY 139
FIRE WEATHER...NONE

AMD MAR 14

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1124 AM AKDT SAT MAR 15 2014

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

1121 AM     SNOW             1 NNE RABBIT CREEK      61.10N 149.82W
03/15/2014  M19.0 INCH                          AK   TRAINED SPOTTER

            OBSERVER REPORTS STORM TOTAL OF 19.0 INCHES NEW SNOW.

&&

PETERSON

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1126 AM AKDT SAT MAR 15 2014

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

1121 AM     SNOW             5 E ANCHORAGE           61.20N 149.72W
03/15/2014  M13.5 INCH                          AK   NWS EMPLOYEE

            OBSERVER REPORTS STORM TOTAL OF 13.5 INCHES NEW SNOW.

&&

PETERSON

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1138 AM AKDT SAT MAR 15 2014

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

1121 AM     SNOW             6 SW ANCHORAGE          61.15N 149.98W
03/15/2014  M6.6 INCH                           AK   OFFICIAL NWS OBS

            NATIONAL WEATHER SERVICE FORECAST OFFICE HAD A STORM
            TOTAL OF 6.6 INCHES NEW SNOW.

&&

PETERSON

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1204 PM AKDT SAT MAR 15 2014

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

1159 AM     SNOW             POTTER MARSH            61.05N 149.79W
03/15/2014  M22.1 INCH                          AK   PUBLIC

&&

MOTTENWE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1239 PM AKDT SAT MAR 15 2014

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

1139 AM     SNOW             3 NNE BUTTE             61.58N 149.02W
03/15/2014  M6.5 INCH                           AK   TRAINED SPOTTER

            MAUD RD. NEAR BUTTE REPORTED A STORM TOTAL OF 6.5 INCHES
            NEW SNOW.

&&

PETERSON

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1254 PM AKDT SAT MAR 15 2014

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

1139 AM     SNOW             4 ESE ANCHORAGE         61.20N 149.75W
03/15/2014  M13.4 INCH                          AK   TRAINED SPOTTER

            NORTHERN LIGHTS AND PATTERSON HAD A STORM TOTAL OF 13.4
            INCHES NEW SNOW.

&&

PETERSON