Gale Warning 480, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE ANCHORAGE AK
215 PM AKDT WED AUG 13 2014

CORRECTED TYPO

.ANALYSIS AND UPPER LEVELS...
A LONGWAVE TROUGH EXTENDS OUT OF THE ARCTIC AND CONNECTS WITH AN
UPPER LEVEL LOW SOUTH OF THE ALASKA PENINSULA WHICH IS THE MAIN
FORCE BEHIND THE WEATHER PATTERN OVER THE STATE. A FAIRLY STRONG
WEATHER FRONT CONNECTED WITH THIS LOW HAS MOVED THROUGH THE GULF
OF ALASKA AND IS PUSHING INLAND FROM THE NORTH GULF COAST. THIS
HAS BROUGHT SIGNIFICANT RAINFALL TO NUMEROUS COASTAL LOCATIONS AND
STEADY RAINFALL TO INLAND LOCATIONS IN SOUTHCENTRAL ALASKA.
ANOTHER UPPER LEVEL WAVE IS TRACKING TOWARD THE GULF OF ALASKA AND
WILL MOVE ACROSS THE GULF TONIGHT AND THEN INLAND ON THURSDAY.
SOUTHWEST ALASKA REMAINS UNDER WEAK UPPER LEVEL FLOW UNDER THE
LONGWAVE TROUGH WHICH IS DESTABILIZING THE ATMOSPHERE AND CAUSING
SHOWERS AND A GOOD CHANCE OF THUNDERSTORMS.
&&

.MODEL DISCUSSION...
MODELS ARE IN VERY GOOD SYNOPTIC AGREEMENT AND THE DIFFERENCES
COME IN HOW THEY ARE MOVING THE SHORT WAVES OVER THE REGION. THE
NAM REMAINS A BIT OF AN OUTLIER AS HAS BEEN THE CASE THE LAST
NUMBER OF MODEL RUNS. THE GFS AND GEM REGIONAL MODELS WERE MOSTLY
USED FOR THE AFTERNOON FORECAST PACKAGES.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
THE HEAVY RAINFALL ALONG THE EASTERN KENAI PENINSULA CAUSED A FLOOD
ADVISORY TO BE IN EFFECT THIS MORNING NEAR SEWARD. THIS ADVISORY
WAS LATER CANCELED AS THE RESURRECTION RIVER CRESTED AND BEGAN TO
DROP IN CONJUNCTION WITH THE HEAVIEST RAINFALL MOVING OUT OF THE
AREA. THE ACCUMULATION OF A NUMBER OF DAYS OF RAINFALL OVER THE
HARDING ICEFIELD HAS FUELED THE RISE IN THE KENAI AND KASILOF
RIVERS. A FLOOD ADVISORY IN EFFECT THROUGH THE WEEKEND FOR THESE
RIVERS AS IT WILL TAKE A WHILE FOR THE KENAI MOUNTAINS TO DRAIN
OUT THE RAINFALL FROM THE PAST FEW DAYS. ANOTHER ROUND OF RAINFALL
IS EXPECTED TO MOVE THROUGH SOUTHCENTRAL TOMORROW AS ANOTHER UPPER
LEVEL DISTURBANCE FROM THE PACIFIC MOVES OVER THE REGION.

SOUTHWEST ALASKA...
SHOWERS AND SOME THUNDERSTORMS ARE LIKELY ACROSS THE BRISTOL BAY
AND KUSKOKWIM DELTA REGIONS THIS AFTERNOON AND EVENING AND THEN
AGAIN TOMORROW LATE AFTERNOON AND EVENING. THE ATMOSPHERE WILL
REMAIN GENERALLY UNSTABLE UNDER THE UPPER LEVEL TROUGH AND THERE
WILL CONTINUE TO BE PLENTY OF MOISTURE AVAILABLE FOR THE SHOWERS
AND THUNDERSTORMS.

BERING SEA/ALEUTIANS...
THE BERING SEA FROM THE PRIBILOF ISLANDS WESTWARD REMAINS UNDER
WIDESPREAD FOG AND LOW STRATUS. THERE ARE SOME BREAKS OVER THE
EASTERN BERING SEA AND ALASKA PENINSULA. THE ATMOSPHERE OVER THE
ALASKA PENINSULA IS UNSTABLE THIS AFTERNOON AND SOME LOCALLY HEAVY
SHOWERS MAY DEVELOP THROUGH THE EVENING IF THERE ARE ENOUGH
BREAKS IN THE CLOUDS ALLOWING SURFACE WARMING.

&&

.LONG TERM FORECAST...
THE ACTIVE AND WET PATTERN WILL CONTINUE THROUGH THE WEEKEND AS
THE NEXT SYSTEM MOVES ALONG THE ALEUTIAN CHAIN AND THEN
APPROACHES THE SOUTHERN MAINLAND BY EARLY SATURDAY. GUIDANCE HAS
SHIFTED THIS SYSTEM WESTWARD IN THE PAST 24 HOURS...NOW BRINGING
THE LOW CENTER INTO THE BRISTOL BAY REGION AS THE ASSOCIATED FRONT
MOVES OVER KODIAK ISLAND AND THEN TO THE NORTHERN GULF COAST. THIS
WILL RESULT IN ANOTHER ROUND OF STEADY RAINFALL ALONG THE COAST
WITH NUMEROUS SHOWERS OVER INLAND LOCATIONS. CONDITIONS THEN LOOK
TO IMPROVE DURING THE WEEK AS THE LOW DEPARTS AND IS REPLACED BY A
RELATIVELY WEAK FLOW PATTERN WHICH WILL YIELD MAINLY DIURNAL
SHOWER ACTIVITY ACROSS THE MAINLAND. MEANWHILE...A LONGWAVE TROUGH
WILL REMAIN ANCHORED OVER THE BERING AND BRING CONTINUED SHOWER
POTENTIAL TO THAT REGION INTO NEXT WEEK.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...FLOOD ADVISORY 121.
MARINE...NONE.
FIRE WEATHER...NONE.
&&

EZ/CB AUG 14