Small Craft Advisory 414, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
419 PM AKDT THU MAY 14 2015

.ANALYSIS AND UPPER LEVELS...
THE MAIN FEATURE DRIVING THE WEATHER PATTERN IS A STRONG RIDGE OF
HIGH PRESSURE OVER WESTERN CANADA AND EXTENDING INTO EASTERN
ALASKA AND THE NORTHEAST PACIFIC. THIS RIDGE HAS BEEN AND WILL
CONTINUE TO BLOCK ALL ARRIVING SYSTEMS FROM THE WEST...SHUNTING
THEM NORTH THROUGH WESTERN ALASKA OR SOUTH INTO SOUTHERN
CALIFORNIA. THERE IS AN UPPER LOW TO THE SOUTH OF THE ALASKA
PENINSULA EXTENDING NORTHWEST INTO THE BERING SEA. THERE IS A
LONG STREAM OF MOISTURE BETWEEN THIS LOW AND THE RIDGE THAT IS
CURRENTLY OVER WESTERN ALASKA...AND IT EXTENDS ACROSS KODIAK AND
THEN WELL SOUTH INTO THE PACIFIC. THERE IS ANOTHER LOW OVER THE
WESTERN BERING...WITH AN ASSOCIATED SURFACE LOW DEVELOPING TO THE
SOUTHWEST OF THE WESTERN ALEUTIANS.

&&

.MODEL DISCUSSION...
THE NUMERICAL MODELS ARE IN GOOD AGREEMENT IN THE SHORT TERM.
THERE ARE OF COURSE SOME SMALL DIFFERENCES ON SURFACE LOW
LOCATIONS AND HOW THEY HANDLE THE MOISTURE/RAINFALL...BUT THESE
ARE FAIRLY EASY TO HANDLE IN THE FORECAST. FORECAST CONFIDENCE IS
THEREFORE HIGHER THAN NORMAL.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
A MOIST SOUTHEAST FLOW EXISTS AT MOST LEVELS ABOVE SOUTHCENTRAL
WHILE A WEAK FRONTAL BOUNDARY STRETCHES FROM KODIAK ISLAND
SOUTHEASTWARD IN THE GULF. THE FRONT AND UPPER LEVEL TROUGH WILL
CONTINUE TO MOVE SLOWLY TOWARD THE COOK INLET REGION FRIDAY AND
FRIDAY NIGHT ACTING TO SPREAD RAIN ALONG THE NORTH GULF COAST
WHILE THE COOK INLET REGION REMAINS MOSTLY DOWNSLOPED AND DRY.
THE SYSTEM MOVES INLAND WHILE THE FRONT DISSIPATES INTO SATURDAY
RETURNING CLEAR AND DRY CONDITIONS WITH ABOVE NORMAL TEMPERATURES.
GAP WINDS WILL CONTINUE ALONG TURNAGAIN ARM AND THE NORTH GULF
COAST THROUGH LATE FRIDAY NIGHT AS THE FRONT APPROACHES. GUSTY
SOUTHEAST WINDS ARE POSSIBLE ON FRIDAY NIGHT AS THE UPPER TROUGH
AND FRONT MOVE THROUGH THE ANCHORAGE AREA.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THE CURRENT WET PATTERN PERSISTS THROUGH SATURDAY AS THE LOW
SOUTHWEST OF THE ALASKA PENINSULA SLOWLY TRACKS EAST AND THEN
NORTH. GENERAL WINDS WILL BE OUT OF THE SOUTHEAST WITH GUSTY
CONDITIONS MAINLY ACROSS THE ALEUTIAN RANGE. GUSTY WINDS CAN BE
EXPECTED ACROSS THE SOUTHWEST REGION AS THE CENTER OF THE LOW
LIFTS TOWARD THE KUSKOKWIM ON SATURDAY.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
RAIN CONTINUES TO DEVELOP TONIGHT ALONG THE LOW JUST SOUTHWEST OF
THE ALASKA PENINSULA...THEN SPREADS NORTH TO BRISTOL BAY. AT THE
SAME TIME...ANOTHER FRONT MOVES INTO THE WESTERN AND CENTRAL
ALEUTIANS. MOST OF THE RAIN OCCURS ACROSS THE ALEUTIAN CHAIN
THROUGH FRIDAY WITH INCREASED CHANCES FOR RAIN FRIDAY NIGHT INTO
SATURDAY ACROSS THE CENTRAL BERING AS THE UPPER LOW ACROSS THE
CENTRAL ALEUTIANS MOVES NORTH.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...SUNDAY THROUGH
THURSDAY)...
ON SUNDAY...THE NORTH AMERICAN RIDGE WILL CONTINUE TO EXERT INCREASING
INFLUENCE OVER SOUTHCENTRAL ALASKA AS A LARGE TROUGH REMAINS OVER
THE BERING SEA. THERE IS INCREASING CONFIDENCE THE RIDGE AXIS WILL
SLOWLY BUILD WITH TIME...KEEPING PRECIPITATION AND MOISTURE ACROSS
SOUTHWEST ALASKA AND KODIAK ISLAND...WITH DRIER AND WARMER WEATHER
OVER THE REMAINDER OF SOUTHCENTRAL. THE ECMWF HAS BEEN LEADING THE
WAY WITH THIS SCENARIO...AND THE FORECAST HEAVILY FAVORS THAT. THE
GFS HAS BEEN SLOWLY TRENDING AWAY FROM WIDESPREAD WET WEATHER OVER
THE LAST TWO DAYS. THIS GENERAL PATTERN WILL PERSIST THROUGH NEXT
WEEK...WITH THE POTENTIAL FOR SOME OF THE WARMEST WEATHER OF THE
YEAR ACROSS SOUTHCENTRAL. THE BERING AND ALEUTIANS WILL REMAIN
STORMIER AND WETTER AS THE PACIFIC STORM TRACK REMAINS WEST OF THE
BLOCKING HIGH.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...RED FLAG WARNING 141.

&&

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