Small Craft Advisory 351, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
1244 PM AKDT SAT APR 26 2014

.ANALYSIS AND UPPER LEVELS...
AT THE UPPER LEVELS THE OVERALL WEATHER PATTERN IS DOMINATED BY A
VERTICALLY STACKED LOW SOUTH OF KODIAK ISLAND...WITH A MASSIVE
CIRCULATION AROUND THIS FEATURE ENCOMPASSING ALL OF THE
PANHANDLE...SOUTHERN MAINLAND...AND EASTERN BERING SEA. THIS LOW
IS SITTING IN THE BASE OF A LARGE LONGWAVE TROUGH THAT IS
SUPPORTED BY AN IMPRESSIVE 170 KT JET STREAM AROUND 45N. AT THE
SURFACE...THERE ARE MULTIPLE CIRCULATION CENTERS UNDER THE UPPER
LOW...WITH THE MOST PRONOUNCED JUST SOUTHEAST OF KODIAK ISLAND. AN
ASSOCIATED FRONT IS LOCATED OVER THE NORTHERN GULF AND IS SLOWLY
INCHING TOWARD THE COAST. STEADY RAIN IS FALLING FROM WESTERN
PRINCE WILLIAM SOUND DOWN TO THE EASTERN KENAI PENINSULA...WHILE
DOWNSLOPING INLAND IS KEEPING THE USUAL PLACES MOSTLY DRY. STRONG
EASTERLY FLOW ABOVE MOUNTAINTOP IS HELPING SOME PRECIP TO PUSH A
BIT FURTHER DOWN THE LEE-SIDE SLOPES THAN USUAL...WITH A DUSTING
OF SNOW OCCURRING EARLY THIS MORNING ALONG THE ANCHORAGE HILLSIDE.
OUT WEST...NORTHERLY FLOW ACROSS MUCH OF THE BERING IS LEADING TO
CONTINUED CLOUDY AND SHOWERY CONDITIONS...WHICH IS ALSO BEING
ENHANCED BY A RIDGE OF HIGH PRESSURE NOW BEGINNING TO NOSE INTO
THE WESTERN BERING.

&&

.MODEL DISCUSSION...
THE MODELS ARE IN OVERALL VERY GOOD AGREEMENT THAT THE COMPLEX LOW
SOUTH OF KODIAK WILL WEAKEN AND DRIFT SOUTHEAST THROUGH EARLY NEXT
WEEK. A DEVELOPMENT IN ALL RECENT MODEL RUNS HAS BEEN A WEAK
SECONDARY LOW CENTER DRIFTING NORTHWEST THROUGH THE GULF SOMETIME
ON TUESDAY ASSOCIATED WITH AN EASTERLY UPPER LEVEL WAVE. THERE
ARE STILL ISSUES WITH THE PLACEMENT AND INTENSITY OF THIS
FEATURE...AND UNTIL MORE MODEL CONSISTENCY CAN BE ESTABLISHED THE
FORECAST WILL REFLECT A MORE BROAD-BRUSHED APPROACH WITH THIS
FEATURE THAT IS A ROUGH COMBINATION OF THE FASTER AND STRONGER GFS
AND THE SLOWER AND WEAKER ECMWF. THIS LOW IS NOT EXPECTED TO HAVE
A HUGE IMPACT ON THE MAINLAND FORECAST...REGARDLESS OF
POSITION...AND IMPACTS WILL INSTEAD LIKELY BE CONFINED TO AN AREA
OF GUSTY WINDS AND RAIN ALONG SOME OF THE COASTAL MARINE ZONES.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
THE FRONT ALONG THE COAST WILL CONTINUE TO IMPACT THE SAME AREAS
OVER THE NEXT 24-36 HOURS AS THE INTENSITY OF BOTH WINDS AND
RAINFALL GRADUALLY DIMINISH. MEANWHILE THE KENAI TO ANCHORAGE TO
PALMER CORRIDOR WILL REMAIN ALMOST ENTIRELY DOWNSLOPED FOR THE
DURATION. SOME GUSTY EASTERLY WINDS ARE STILL EXPECTED TO DEVELOP
OVER THE MATANUSKA VALLEY TODAY...WHICH WHEN COMBINED WITH LOW
RELATIVE HUMIDITIES WILL STILL LIKELY CREATE SOME FIRE WEATHER
CONCERNS. THUS A RED FLAG WARNING REMAINS IN EFFECT FOR THE
MATANUSKA VALLEY THROUGH THIS EVENING. AS THE OVERALL CIRCULATION
CENTER PULLS AWAY TO THE SOUTHEAST OVER THE COMING SEVERAL
DAYS...OVERALL FLOW WILL GRADUALLY BECOME MORE NORTHERLY AND
OFFSHORE...LEADING TO DRIER AND WARMER CONDITIONS FOR MOST AREAS.
KODIAK ISLAND WILL BE THE LAST TO SEE IMPROVEMENT AS MOIST
NORTHEASTERLY ONSHORE FLOW KEEPS SHOWERS AROUND EVEN ONCE THE
STEADY RAIN COMES TO AN END TONIGHT.

SOUTHWEST ALASKA...
NORTHEASTERLY OFFSHORE FLOW WILL CONTINUE FOR THE NEXT SEVERAL
DAYS...WITH GRADUALLY DIMINISHING INTENSITY. THERE IS A MINIMAL
AMOUNT OF SHOWER ACTIVITY ASSOCIATED WITH THE MAIN LOW CENTER TO
THE SOUTH...WITH AN INCREASINGLY DRY AND SUNNY OVERALL PATTERN
CONTINUING INTO NEXT WEEK. RELATIVE HUMIDITY VALUES WILL CONTINUE
TO DROP GENERALLY INTO THE 30S INLAND EACH AFTERNOON AND EVENING
THROUGH MONDAY...WITH SOME LOCATIONS POTENTIALLY DROPPING INTO THE
20S. HOWEVER...GUSTY NORTHEASTERLY WINDS WILL BE ON THE DECLINE
AND DANGEROUS FIRE WEATHER CONDITIONS ARE NOT ANTICIPATED AT THIS
TIME. BY TUESDAY A WEAK FRONT WILL CLIP THE NORTHERN SECTIONS OF
THE AREA...WITH THE MAIN IMPACT BEING INCREASING CLOUD-COVER AND
COOLER TEMPERATURES.

BERING SEA/ALEUTIANS...
A SHORTWAVE ASSOCIATED WITH A WEAK SURFACE LOW CURRENTLY CROSSING
ACROSS THE ALASKA PENINSULA WILL MOVE OUT INTO THE PACIFIC THIS
EVENING...ALLOWING FLOW TO BECOME MORE NORTHERLY AND SHOWERY ACROSS
THE EASTERN BERING AND ALASKA PENINSULA. WITH VERY WEAK THERMAL
ADVECTION...NOT EXPECTING SHOWERS ON THE BERING SIDE OF THE
ALEUTIANS/PENINSULA TO BE TOO SIGNIFICANT. MEANWHILE...INCREASING
SUBSIDENCE ASSOCIATED WITH THE RIDGE OVER THE WESTERN BERING IS
ALLOWING THE DEVELOPMENT OF SOME SUMMER-LIKE MARINE FOG/STRATUS
AROUND THE NORTHERN BERING AND PRIBILOF ISLANDS TODAY...WHICH
SHOULD SPREAD SOUTHWARD WITH TIME. OVER THE WESTERN BERING...COLD
NORTHERLY FLOW WILL TRANSITION FAIRLY QUICKLY TO WARMER SOUTHERLY
FLOW OVERNIGHT TONIGHT AS A WEAK FRONTAL SYSTEM MOVES INTO THE
AREA. LITTLE OR NO RAINFALL WILL ACCOMPANY THE PASSAGE OF THIS
FRONT SUNDAY MORNING...INSTEAD THE LARGER IMPACT WILL BE THE
USHERING IN OF SOME OF THE WARMEST AIR OF THE YEAR SO FAR
ASSOCIATED WITH AN EVEN LARGER RIDGE BUILDING OVER THE NORTHWEST
PACIFIC.

&&

.LONG TERM FORECAST...
LONG-RANGE MODELS CONTINUE TO SUGGEST STRONGLY THAT A HIGH-
LATITUDE BLOCKING RIDGE WILL DEVELOP BY THE LATTER PART OF THE
WEEK...WITH A CLOSED HIGH SOMEWHERE IN THE VICINITY OF THE
SOUTHEAST INTERIOR MAINLAND. WITH CONFIDENCE INCREASING IN THIS
SCENARIO...CONFIDENCE IS ALSO INCREASING IN THE WARMEST
TEMPERATURES (AND SUNNY WEATHER) OF THE YEAR SO FAR SPREADING
ACROSS VIRTUALLY ALL OF THE MAINLAND AND PANHANDLE AND CONTINUING
WELL INTO THE FIRST WEEK OF MAY.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 119 120.
FIRE WEATHER...RED FLAG WARNING 111.

&&

AMD APR 14