Small Craft Advisory 17, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE ANCHORAGE AK
529 AM AKST WED JAN 7 2015

.ANALYSIS AND UPPER LEVELS...

THE PATTERN REMAINS DOMINATED BY HIGH LATITUDE BLOCKING...WITH THE
MAIN BLOCK OF INTEREST CENTERED OVER THE CHUKCHI SEA AND NORTHWEST
ALASKA. A CLOSED UPPER LOW IS STALLING OUT OVER THE EASTERN BERING
SEA...WITH THE NORTH PACIFIC TROUGH SLOWLY LIFTING NORTH INTO THE
GULF OF ALASKA. AT THE SURFACE...A STRONG 1050 ARCTIC HIGH IS
CENTERED OVER THE NORTHERN YUKON. WITH WEAK LOW PRESSURE IN THE
GULF...THIS IS PROMOTING A DECENT OFFSHORE PRESSURE
GRADIENT...WITH THE COLDEST AIR OF THE WINTER ENCOMPASSING MOST OF
SOUTHERN ALASKA. WITH TIME...THE NORTH PACIFIC TROUGH WILL SPREAD
CLOUDS AND PRECIPITATION INTO SOUTHERN ALASKA HEADING THROUGH THE
WEEKEND. BY LATE THIS WEEKEND INTO NEXT WEEK...THE STAGE IS
SETTING FOR ANOTHER SERIES OF CHINOOK WARMING EVENTS ACROSS
SOUTHERN ALASKA AS A LARGE ALEUTIAN LOW ONCE AGAIN PARKS ITSELF
OVER THE CENTRAL ALEUTIANS.

&&

.MODEL DISCUSSION...

MODELS ARE IN GOOD AGREEMENT WITH THE LARGE SCALE PATTERN THROUGH
THE MIDDLE OF NEXT WEEK AS SOUTHERN ALASKA TRANSITIONS INTO
ANOTHER ACTIVE PATTERN. AS USUAL...THE DETAILS OF SMALLER SCALE
FEATURES BECOMES LESS CERTAIN MUCH EARLIER. THE LARGEST
DISCREPANCY EARLY ON IS WITH RESPECT TO THE DEVELOPMENT OF A
SECONDARY LOW SOUTH OF KODIAK ISLAND THURSDAY AFTERNOON INTO
FRIDAY. THE GFS...NAM...AND GFS PARALLEL ALL DEVELOP THIS LOW
WHILE THE ECMWF FAVORS A SINGLE LOW OVER THE EASTERN BERING. FOR
THIS FORECAST...THE ECMWF WS FAVORED IN THE SHORT TERM...WITH THE
GFS AND ECMWF FAVORED IN THE MID TERM TOWARD DAY 3 AND 4.
THEREAFTER A WPC BLEND WAS FAVORED AS THE PATTERN BECOMES QUITE A
BIT MORE ACTIVE.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
HIGH PRESSURE OVER SOUTHERN ALASKA WILL GIVE WAY TO AN APPROACHING
FRONT ON THURSDAY AND THURSDAY NIGHT. THE MAIN FORECAST PROBLEM IS
THE CHANCE OF FREEZING RAIN. SOUTHEAST FLOW ALOFT WILL CONFINE MOST
OF THE PRECIPITATION TO THE COASTAL AREAS...ESPECIALLY THE EASTERN
KENAI PENINSULA. THE INLAND VALLEYS OF THE EASTERN KENAI HAVE THE
BEST CHANCE OF SEEING SOME FREEZING RAIN ON THURSDAY BEFORE
CHANGING OVER TO RAIN BY THE EVENING. INLAND AREAS ALONG COOK
INLET FROM CLAM GULCH NORTH THROUGH ANCHORAGE INTO THE
MATANUSKA/SUSITNA VALLEYS WILL HAVE FAIRLY LOW POPS...BUT ANY
PRECIPITATION THAT FALLS WILL LIKELY BE OF THE FREEZING VARIETY.

&&

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

WARM AIR FLOWING OVER TRAPPED COLD AIR WILL RESULT IN A MIX OF
SNOW...FREEZING RAIN...AND RAIN AS THE COLD AIR IS ERODED OVER THE
BRISTOL BAY ZONE. FREEZING RAIN WILL CONTINUE IN SOME AREAS THROUGH
TONIGHT...WITH OTHER AREAS...ESPECIALLY WEST OF KING SALMON...RECEIVING
MEASURABLE SNOWFALL. SOME FREEZING RAIN WILL REACH AS FAR NORTH AS
BETHEL LATE TODAY AND TONIGHT...WHILE THE LOWER KUSKOKWIM WILL
HAVE LIMITED AMOUNTS OF SNOW TONIGHT AND THURSDAY.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...

RAIN AND SNOW WILL AFFECT THE AKPEN AND EASTERN ALEUTIANS OVER THE
NEXT COUPLE OF DAYS...WITH SNOW FOR THE PRIBILOFS. OTHERWISE THE
WESTERN HALF OF THE CHAIN WILL BE GENERALLY DRY EXCEPT FOR THE
OCCASIONAL SNOW SHOWER ON NORTH FLOW.

&&

.LONG TERM FORECAST (FRIDAY THROUGH WEDNESDAY)...
LATE IN THE WORK WEEK...A LONG WAVE TROUGH STRETCHING FROM THE
EASTERN BERING INTO THE GULF OF ALASKA WILL SLOWLY SLIDE NORTHWARD
ONTO THE MAINLAND...ALLOWING RIDGING CURRENTLY ENTRENCHED OVER
THE AREA TO RETREAT INTO THE YUKON TERRITORY. AFTERWARDS...ALL THE
MODELS ARE IN GOOD SYNOPTIC AGREEMENT WITH A LARGE LOW COMPLEX
REMAINING IN PLACE FROM THE BERING AND GULF WITH THE BLOCKING
RIDGE PERSISTENT OVER WESTERN NORTH AMERICA. ONCE THIS PATTERN
SETS UP THIS WEEKEND...THERE IS LITTLE CHANCE OF IT BREAKING DOWN
THROUGH THROUGH THE MIDDLE OF NEXT WEEK. THIS GENERAL TREND WILL
BRING TROUGHS AND FRONTS ROTATING UP TOWARDS THE GULF...WTIH A
CONTINUED STORMY WEATHER AND GENERALLY WARMING TEMPERATURES.
HOWEVER THE SPECIFIC TIMING OF THESE INDIVIDUAL FEATURES WILL BE
DIFFICULT TO TRACK BEYOND THE FIRST FEW DAYS OF THE FORECAST.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...FREEZING RAIN ADVISORY 161.
MARINE...GALE 119 120 127 130 131 132 136 137 138 139 150 160 180
         HEAVY FREEZING SPRAY 180 181 185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...JA
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DS
LONG TERM...DEK