Small Craft Advisory 211, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
423 PM AKST THU MAR 7 2013

.ANALYSIS AND UPPER LEVELS...

A POWERFUL AND SPRAWLING OCCLUDED CYCLONE IS CURRENTLY CENTERED OVER
THE AKPEN LATE THIS AFTERNOON. WHILE THE CENTER OF THE SURFACE LOW IS
LOCATED JUST SOUTH OF COLD BAY...AN ELONGATED SURFACE TROUGH AXIS
EXTENDS NORTHWARD INTO BRISTOL BAY. THE CYCLONE DEEPENED TO NEARLY
954 HPA...MUCH DEEPER THAN EXPECTED FROM THE PREVIOUS DAY. A VERY
WELL DEFINED JET STREAK ORIENTED NEARLY SOUTH TO NORTH CAN BE SEEN ON
SATELLITE...WITH A WELL DEFINED MOISTURE SOURCE ORIGINATING FROM 30N.
NEAR THE BASE OF THE UPPER LOW...ROTATING AROUND THE SOUTHEAST
PERIPHERY...IS A DEEPENING UPPER LEVEL POTENTIAL VORTICITY ANOMALY
THAT IS TRACKING NORTHEAST. THIS FEATURE WILL MOVE OVER THE ALASKA
PENINSULA INTO SOUTHWEST ALASKA THIS EVENING...WITH COLD AIR AND LOW
EQUIVALENT POTENTIAL TEMPERATURE AIR PUSHING INLAND. FARTHER EAST...A
VERY SHARP UPPER LEVEL RIDGE AXIS OVER EASTERN ALASKA WILL SLOWLY
BREAKDOWN AS THE UPPER TROUGH AND EMBEDDED POTENTIAL VORTICITY
ANOMALY SLOWLY TRANSLATE NORTHEASTWARD OVER THE NEXT 36 HOURS.

.MODEL DISCUSSION...

MODELS ARE NOW IN VERY AGREEMENT OVERALL WITH THE DEVELOPMENT OF THE
POWERFUL CYCLONE OVER THE NEXT 36 HOURS...ALTHOUGH THERE ARE MINOR
DISCREPANCIES WITH SMALLER EMBEDDED FEATURES WITHIN THE LOW. THE
VARIOUS GLOBAL AND HIGH RESOLUTION MODELS DIVERGE TOWARDS SATURDAY
EVENING INTO SUNDAY AS A LOW AMPLITUDE SHORTWAVE TROUGH TRACKS EAST
THROUGH THE BERING AND INTO SOUTHWEST ALASKA. THIS FEATURE IS
EXPECTED TO DIVE INTO THE NORTHERN GULF AND AMPLIFY ON SUNDAY...BUT
TO WHAT DEGREE AND THE EXACT TRACK IS NOT WELL KNOWN AT THIS TIME. A
VARIOUS BLEND OF THE GLOBAL MODELS WAS FAVORED SATURDAY AND BEYOND.

.SHORT TERM FORECAST...

SOUTHCENTRAL...
THE SOUTHEAST TO NORTHWEST ORIENTED WARM FRONT IS CURRENTLY SITUATED
OVER THE CENTRAL GULF...AND HAS ALREADY CLEARED KODIAK ISLAND. A VERY
WELL DEFINED MOISTURE RIVER ON RADAR AND SATELLITE CAN BE SEEN
IMPACTING THE KENAI PENINSULA...WITH SNOW MIXED WITH RAIN DEVELOPING
ACROSS PORTIONS OF THE SOUTHERN KENAI INCLUDING HOMER AND SELDOVIA.
FARTHER NORTH...LOCATIONS UP COOK INLET WILL GENERALLY REMAIN UNDER
THE INFLUENCE OF DRY DOWNSLOPE FLOW. AS THE FRONT SLIDES
EASTWARD...THE PRESSURE GRADIENT WILL CONTINUE TO TIGHTEN INTO THIS
EVENING...WITH TURNAGAIN ARM WINDS PEAKING THIS EVENING BEFORE
DIMINISHING THROUGH THE OVERNIGHT HOURS. WINDS ALONG THE HILLTOP AND
DOWN INTO THE EAST ANCHORAGE HILLSIDE WILL ALSO BEGIN TO TO INCREASE
AS THE UPPER RIDGE OVER EASTERN ALASKA BREAKS DOWN. WINDS ACROSS THE
ANCHORAGE BOWL WILL ALSO PICKUP BY THIS EVENING AS THE LOW TRACKS
NORTH OVER BRISTOL BAY...BUT HIGH WINDS ARE NOT EXPECTED OVER THE
LOWER ELEVATIONS.

FARTHER EAST...THE FRONT AND ASSOCIATED MOISTURE RIVER WILL DIRECT
PRECIPITATION OVER PWS AND THE COASTAL RANGES. A MIX OF RAIN AND SNOW
WILL CHANGE TO MOSTLY RAIN ALONG THE COAST...WITH INTERIOR LOCATIONS
INCLUDING VALDEZ REMAINING MOSTLY SNOW. BLIZZARD CONDITIONS ARE
EXPECTED TO DEVELOP ACROSS THOMPSON PASS BY LATE THIS EVENING AS
HEAVY SNOW DEVELOPS AND SOUTHEAST WINDS INCREASE INTO THE 30 TO 45
MPH RANGE.

SOUTHWEST ALASKA/ALASKA PENINSULA...
AS THE SURFACE TRACKS TO THE NORTH...POWERFUL NORTHWEST WINDS WILL
BEGIN TO INCREASE THIS EVENING AND OVERNIGHT ACROSS THE WESTERN
ALASKA PENINSULA. ABUNDANT SNOW SHOWERS WRAPPING AROUND THE LOW WILL
ACCOMPANY THE WINDS...WITH BLIZZARD CONDITIONS EXPECTED TO DEVELOP
OVER THE WESTERN PENINSULA THIS EVENING AND OVERNIGHT.

OVER BRISTOL BAY REGION AND NEAR THE ALEUTIAN RANGE OVER MAINLAND
SOUTHWEST ALASKA...EAST SOUTHEASTERLY WINDS WILL REMAIN STRONG AS THE
LOW TRACKS JUST OFF THE BRISTOL BAY COAST. ALONG THE WESTERN CAPES TO
DILLINGHAM...A COLD FRONT WILL BEGIN TO SLOWLY SLIDE EASTWARD...WITH
SNOW SHOWERS DEVELOPING OVER THE AREA. THE FRONT WILL CONTINUE TO
TRACK TO THE EAST FRIDAY AND IS EXPECTED TO CLEAR THE REGION BY
FRIDAY EVENING...WITH LINGERING SNOW SHOWERS INTO EARLY SATURDAY.

BERING SEA AND ALEUTIANS...
SNOW SHOWERS AND STRONG NORTHWEST WINDS STRETCHING FROM THE PRIBILOF
ISLANDS TO UNALASKA WILL SLOWLY DIMINISH AS THE UPPER LOW BEGINS TO
ACCELERATE EASTWARD. WEAK HIGH PRESSURE WILL RAPIDLY MOVE IN BEHIND
THE SYSTEM...BRINGING AN END TO BLIZZARD CONDITIONS LATE TONIGHT. A
FEW WEAK UPPER DISTURBANCES WILL TRACK ACROSS THE BERING THROUGH THE
WEEKEND...BUT RATHER QUIESCENT WEATHER FOR THE REGION WILL SETTLE IN
AS HIGH PRESSURE ALOFT TAKES HOLD HEADING INTO NEXT WEEK.

.LONG TERM FORECAST...

SUNDAY AND BEYOND...ALL GLOBAL MODELS CONTINUE TO DEPICT A HIGH
AMPLITUDE RIDGE AXIS BUILDING OVER THE BERING SEA LATE SATURDAY INTO
SUNDAY. A SHARP UPPER LEVEL SHORTWAVE IN NORTHWEST FLOW IS EXPECTED
TO QUICKLY TRACK ACROSS SOUTHWEST ALASKA AND THE AKPEN LATE SATURDAY
THEN AMPLIFY OVER THE GULF OF ALASKA ON SUNDAY. THE GLOBAL GUIDANCE
DIFFERS SUBSTANTIALLY WITH THE TRACK OF THIS FEATURE WITH THE GFS
FAVORING A NORTHWARD TRACK ALONG THE GULF COAST...WITH THE ECMWF
FAVORING MORE OF A SOUTHERN TRACK OVER THE CENTRAL GULF. EITHER
WAY...COLD AIR WILL FILTER IN BEHIND THE WAVE SUNDAY...WITH THE
THREAT FOR SNOW SHOWERS FROM KODIAK TO THE GULF COAST AND INTO THE
INTERIOR... INCLUDING THE ANCHORAGE BOWL.

MONDAY THROUGH WEDNESDAY...ALL GLOBAL MODELS INCLUDING THE GFS AND
ECMWF ENSEMBLES DEPICT A HIGH AMPLITUDE RIDGE BUILDING OVER THE
BERING AND EXTENDING THROUGH THE ARCTIC CIRCLE. WITH THE POLAR VORTEX
DISPLACED FROM THE ARCTIC...AND ANOTHER HIGH AMPLITUDE BLOCK OVER
GREENLAND...THIS WILL FAVOR THE DEVELOPMENT OF A COLDER AND DRIER
OFFSHORE FLOW PATTERN OVER ALASKA. JUST HOW COLD...HOWEVER...REMAINS
THE BIGGER QUESTION AS THE ECMWF AND GFS DIFFER IN JUST HOW FAR THE
POLAR AIR OVER THE NORTHWEST TERRITORIES RETROGRADES INTO ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...BLIZZARD WARNING 131 181 185 195
         HIGH WIND WARNING 101 161.
MARINE...GALES 120 125 130 132 136 137 138 140 160 172 175 176 180
               185 351 352 411 413.
         STORMS 150 155 165 170 171 179 412 414.
         HEAVY FREEZING SPRAY 160 179 412 414.
FIRE WEATHER...NONE.

AHSENMACHER MAR 13

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1215 AM AKST FRI MAR 08 2013

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

 657 PM     NON-TSTM WND GST DUTCH HARBOR            53.90N 166.55W
03/07/2013  M85 MPH                             AK   ASOS

 830 PM     NON-TSTM WND GST MCHUGH CREEK            61.00N 149.43W
03/07/2013  M82 MPH                                  HANDAR

1000 PM     NON-TSTM WND GST GLEN ALPS          AK   61.09N 149.69W
03/07/2013  M95 MPH                                  HANDAR

&&

KUTZ