Small Craft Advisory 107, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
459 AM AKST TUE FEB 3 2015

.ANALYSIS AND UPPER LEVELS...
HIGH PRESSURE REMAINS IN CONTROL ACROSS THE REGION THIS MORNING
WITH A CLOSED UPPER HIGH ENTRENCHED OVER THE WESTERN BERING SEA
AND DRY OFFSHORE FLOW IN PLACE OVER MUCH OF THE SOUTHERN
MAINLAND. THE PATCHY FOG THAT HAS LINGERED OVER THE COOK INLET
REGION THE PAST FEW NIGHTS IS GENERALLY DIMINISHING IN COVERAGE AS
WEAK COLD ADVECTION HAS BEGUN TO ERODE THE STRONG INVERSION THAT
HAD PREVIOUSLY BEEN IN PLACE. MEANWHILE...LIGHT SNOW SHOWERS HAVE
TAPERED OFF ACROSS THE KUSKOKWIM DELTA AS AN UPPER LEVEL
DISTURBANCE RIDING ALONG THE EASTERN PERIPHERY OF THE BERING RIDGE
DIVES SOUTHWARD TOWARDS THE ALASKA PENINSULA. THIS FEATURE COUPLED
WITH LOW LEVEL INSTABILITY OVER THE EASTERN BERING IS HELPING TO
GENERATE A FEW SHOWERS FROM THE AKPEN TO DUTCH HARBOR...BUT THOSE
SHOWERS ARE ALSO BEING LIMITED BY DRY AIR IN THE MID LEVELS AS
NOTED ON THE MORNING SOUNDING FROM COLD BAY.

&&

.MODEL DISCUSSION...
MODELS REMAIN IN EXCELLENT AGREEMENT THROUGH THE MIDDLE OF THE
WEEK AS A STABLE PATTERN DOMINATED BY HIGH PRESSURE OVER THE
BERING REMAINS IN PLACE ACROSS THE REGION. MODELS DO BEGIN TO
DIVERGE SOMEWHAT BY THURSDAY/FRIDAY AS AN UPPER TROUGH DIGS INTO
THE GULF FROM THE YUKON TERRITORY...WHICH WILL HAVE AN IMPACT ON
THE STRENGTH AND TIMING OF OUTFLOW WINDS ALONG THE GULF COAST. THE
EC REMAINS THE MOST AGGRESSIVE IN DIGGING THE TROUGH INTO THE GULF
AND DEVELOPING A CLOSED LOW...WITH THE GFS WEAKER AND FARTHER TO
THE EAST OVER THE PANHANDLE REGION. DESPITE THESE DIFFERENCES...
THE GENERAL TREND WILL BE FOR STRONGER OUTFLOW WINDS TO DEVELOP BY
THE END OF THE WEEK AS THE BERING HIGH RETROGRADES WESTWARD AND
ALLOWS COLDER AIR TO SURGE OVER THE MAINLAND IN DEEP NORTHERLY
FLOW.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
COLD AND DRY CONDITIONS WILL PERSIST OVER THE AREA FOR THE NEXT
SEVERAL DAYS AS HIGH PRESSURE BUILDS EASTWARD OVER THE MAINLAND
FROM THE BERING SEA. THIS WILL YIELD A GRADUAL INCREASING TREND
FOR OUTFLOW WINDS ALONG THE NORTH GULF COAST AS THE PRESSURE
GRADIENT SLOWLY STRENGTHENS. FOG POTENTIAL SHOULD CONTINUE TO
DIMINISH AS WEAK COLD ADVECTION CONTINUES TO ERODE THE INVERSION
AND DRY NORTHERLY FLOW REMAINS OVER THE AREA.

&&

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

SOUTHCENTRAL WILL BE CLEAR..COLD...AND DRY THROUGH WED...EXCEPT
FOR A WEAK DISTURBANCE BRINGING A CHANCE OF SNOW AND RAIN TO
KODIAK ISLAND ON TUE. HIGH PRESSURE BUILDING INTO INTERIOR AK WILL
BRING INCREASING WINDS TO CHANNELED TERRAIN OF SOUTH CENTRAL
THROUGH WED. THIS WILL BE SEEN WITH WINDS OF 20 TO AS MUCH AS 40
MPH OFF THE GLACIER IN WHITTIER...THROUGH THOMPSON PASS...AND
THROUGH THE COPPER RIVER DELTA. OTHERWISE SOME AREAS OF OVERNIGHT
FOG WILL REDEVELOP NEAR COOK INLET AS WELL AS KNIK AND TURNAGAIN
ARMS. LOW CLOUDS AND FOG WILL ALSO REDEVELOP ALONG THE COPPER
RIVER.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THE MAINLAND IS BACK TO OFFSHORE WINDS...CLEAR SKIES...AND BELOW
NORMAL TEMPERATURES. THESE CONDITIONS WILL CONTINUE TO HOLD
THROUGH WEDNESDAY AS UPPER LEVEL RIDGING BUILDS BACK OVERHEAD AND
ARCTIC AIR FILTERS IN FROM THE INTERIOR.

&&
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
SNOW AND RAIN SHOWERS WILL MAKE THEIR WAY FROM THE EASTERN
ALEUTIANS TO THE WESTERN ALEUTIANS TODAY AND TOMORROW WITH LITTLE
IMPACT. A WEAK FRONTAL BOUNDARY SOUTH OF THE CHAIN WILL KEEP
SCATTERED SNOW AND RAIN SHOWERS IN THE FORECAST FOR THE NEXT
COUPLE DAYS.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
THE MAIN FORECAST CHALLENGE IN THE EXTENDED WILL BE GUSTY
WINDS ACROSS THE SOUTHERN MAINLAND AS OFFSHORE FLOW INCREASES
IN RESPONSE TO A DEEPENING UPPER TROUGH EAST OF THE BERING RIDGE.
WINDS ARE EXPECTED TO PEAK IN STRENGTH THURSDAY MORNING THROUGH
FRIDAY AFTERNOON ACROSS CHANNELED TERRAIN OF SOUTHCENTRAL AND COOK
INLET. FRIDAY INTO SATURDAY THE FOCUS FOR WINDS SHIFTS TO THE WEST
COAST AND EASTERN BERING AS A STRONG ARCTIC SHORTWAVE FORCES A
TROUGH TO THE SOUTHERN MAINLAND. THE FRONT ASSOCIATED WITH THE
TROUGH BRINGS COLDER TEMPERATURES THROUGH THE UPCOMING WEEKEND.
DRY CONDITIONS PERSISTS ACROSS THE SOUTHERN MAINLAND AT THE END
OF THE WEEK WITH PRECIPITATION MAINLY CONFINED AROUND THE LOW
PRESSURE SYSTEM SOUTH OF THE ALASKA PENINSULA.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 155 172 174 179.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...CB
SOUTHCENTRAL ALASKA...CB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MTL
LONG TERM...KH