Heavy Freezing Spray Warning 9, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
355 AM AKST FRI JAN 10 2014

.ANALYSIS AND UPPER LEVELS...

THE RELEVANT UPPER AIR FEATURES REMAIN MUCH THE SAME AS THE LAST
THREE DAYS...WITH A CLOSED UPPER HIGH CENTERED OVER NORTHEAST SIBERIA
AND THE SIBERIAN SEA...A PACIFIC JET STREAM NOSING EAST OF THE
DATELINE...AND AN UPPER LEVEL VORTEX NEAR BANKS ISLAND EXTENDING INTO
THE NORTH SLOPE. A MIGRATORY TROUGH SOUTH OF THE GULF OF ALASKA IS
TRANSLATING TO THE EAST AS IT BREAKS AWAY FROM THE LARGER JET STREAM
SYSTEM. OVER THE BERING SEA...A STACKED LOW CONTINUES TO WEAKEN AS IT
MIGRATES TOWARD BRISTOL BAY. ACROSS SOUTHCENTRAL...THE FLOW ALOFT IS
NEARLY STAGNANT...WITH LESS THAN 30 KNOTS OF UPPER TROPOSPHERIC FLOW
TO 30000 FEET NOTED ON THE 12Z PANC SOUNDING. A WEAK TROUGH CAN BE
SEEN ON WATER VAPOR ACROSS THE NORTHERN GULF...WITH THAT FEATURE
TRACKING EAST INTO CANADA.

THE FIRST OF A SERIES OF FAST MOVING LOWS FORMING ALONG THE PACIFIC
JET IS TRACKING INTO THE WESTERN BERING...WITH NUMEROUS LOWS
EVENTUALLY EXPECTED TO TRACK INTO THE GULF OF ALASKA THROUGH EARLY
NEXT WEEK.

.MODEL DISCUSSION...

THE NUMERICAL MODELS ARE IN EXCELLENT AGREEMENT WITH THE LARGE SCALE
PATTERN THROUGH NEXT WEEK...BUT CONTINUE TO HAVE DIFFICULTIES
HANDLING THE VERY LOW AMPLITUDE AND FAST MOVING WAVE DISTURBANCES
EXPECTED TO SKIRT THE SOUTHERN PARTS OF THE BERING SEA AND GULF OF
ALASKA. NO PARTICULAR MODEL WAS FAVORED...WITH A BLEND TO THE GFS AND
ECMWF CONTINUING TO BE THE FAVORED APPROACH...WITH A BLEND TO WPC
GUIDANCE IN THE EXTENDED.

.SHORT TERM FORECAST...

SOUTHCENTRAL...
FLURRIES AND OCCASIONAL LIGHT SNOW SHOWERS WILL LINGER OVER MOST OF
THE COOK INLET REGION TODAY BEFORE DIMINISHING TONIGHT. LIGHT SNOW
SHOWERS WILL ALSO IMPACT THE GULF COAST...COPPER BASIN...AND PRINCE
WILLIAM SOUND...WITH LIGHT SNOW ACCUMULATIONS POSSIBLE BEFORE
ACTIVITY TAPERS OFF TONIGHT. LOCAL AREAS OF PATCHY DENSE FOG WILL
CONTINUE TO BE A POSSIBILITY INTO SATURDAY AS WINDS REMAIN LIGHT.

A FAST MOVING LOW WILL TRACK INTO THE GULF SATURDAY
MORNING...REACHING THE NORTHERN GULF COAST LATE SATURDAY...BRINGING
RAIN AND SNOW TO THE COAST.

SOUTHWEST...
AREAS OF FOG AND LOW STRATUS WILL REMAIN OVER MUCH OF SOUTHWEST TODAY
AS WEAK SURFACE HIGH PRESSURE PERSISTS OVER THE AREA. A FEW ISOLATED
SNOW SHOWERS ARE POSSIBLE MAINLY NEAR THE ALASKA PENINSULA...BUT
LARGELY DRY CONDITIONS ARE OTHERWISE EXPECTED. A FRONT WILL PUSH INTO
BRISTOL BAY SATURDAY...WITH RAIN AND SNOW SHOWERS TRACKING INTO THE
ALASKA PENINSULA AND COASTAL REGIONS. WITH THE INCREASING PRESSURE
GRADIENT...OFFSHORE WINDS WILL INCREASE...WITH FOG AND STRATUS
DIMINISHING OVER THE INLAND AREAS.

BERING SEA AND ALEUTIANS...
A MODERATELY STRONG LOW TRACKING INTO THE WESTERN BERING SEA THIS
MORNING WILL CONTINUE EAST THROUGH TONIGHT...WITH STORM FORCE
SOUTHWEST WINDS TRACKING OVER THE CENTRAL ALEUTIANS. RAIN AND SNOW
WILL ACCOMPANY THE FRONT...WITH MORE SHOWERY ACTIVITY BEHIND THE LOW.
THE LOW WILL REACH THE PRIBILOF ISLANDS THIS EVENING...WEAKENING TO
GALE FORCE IN THE PROCESS. RAIN AND SNOW SHOWERS WILL LINGER OVER
MUCH OF THE ALEUTIAN CHAIN THROUGH THE WEEKEND.

.LONG TERM FORECAST...

MONDAY THROUGH WEDNESDAY...TWO FAST MOVING WAVE DISTURBANCES WILL
TRACK THROUGH THE GULF OF ALASKA...WITH RAIN AND SNOW IMPACTING THE
COAST. THE GENERAL STORM TRACK WOULD GENERALLY KEEP MOST INLAND
LOCATIONS WEST OF THE COPPER BASIN ON THE DRIER SIDE...BUT THERE IS
THE POSSIBILITY...SHOULD THE LOW TRACK WEST OR INTENSIFY MORE THAN
CURRENTLY EXPECTED...THAT SOME SNOW COULD DEVELOP INLAND MONDAY AND
TUESDAY.

WEDNESDAY AND BEYOND...THE EXPECTED PATTERN WILL CHANGE DRAMATICALLY
AS A POWERFUL 220 KNOT EAST ASIAN PACIFIC JET SENDS A SERIES OF
STRONG LOWS AND A VIGOROUS WARM FRONT INTO THE BERING SEA AND GULF OF
ALASKA. THE GFS AND ECMWF ARE IN VERY GOOD GENERAL AGREEMENT WITH A
LEADING WARM FRONT TRACKING INTO SOUTHERN ALASKA WEDNESDAY. GIVEN THE
COLD AIR IN PLACE...THIS WOULD LIKELY BEGIN AS OVERRUNNING SNOW
ACROSS MOST LOCATIONS...TURNING TO RAIN ALONG THE COAST.
THEREAFTER...UNCERTAINTY RAPIDLY GROWS WITH THE TIMING AND TRACK OF
INDIVIDUAL LOWS...BUT THERE IS HIGH CERTAINTY STORMINESS WILL
INCREASE SIGNIFICANTLY ACROSS THE BERING SEA AND GULF...WITH A
CHINOOK DRIVING INTO SOUTHERN ALASKA...AND HEAVY RAIN IMPACTING
PORTIONS OF THE GULF COAST. INLAND AREAS WILL SEE THE FULL SPECTRUM
OF PRECIPITATION TYPES...INCLUDING RAIN AND FREEZING RAIN.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 155 170-175 178 180 185.
         STORM 176 177.
         HEAVY FREEZING SPRAY 185.
FIRE WEATHER...NONE.

AHSENMACHER JAN 14