Small Craft Advisory 275, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT THU APR 12 2012

.ANALYSIS AND UPPER LEVELS...
AN UPPER LEVEL RIDGE PERSISTS OVER THE NORTHERN INTERIOR OF THE STATE
WHILE A TROF DIGS OVER THE CENTRAL ALEUTIANS. TO THE WEST OF THE
UPPER LEVEL TROF IS A HIGHLY AMPLIFIED RIDGE OVER THE WESTERN BERING
AND KAMCHATKA PENINSULA. AS THIS TROF CONTINUES TO DIVE SOUTH...A
SURFACE LOW WILL CONTINUE TO DEVELOP SOUTH OF THE EASTERN ALEUTIANS.
THIS LOW WILL BE THE MAIN WEATHER MAKER ACROSS OUR DOMAIN THROUGH THE
WEEKEND. THE MAJORITY OF THE STATE IS EXPERIENCING ABOVE AVERAGE
TEMPERATURES AND RELATIVELY BENIGN WEATHER UNDER THE CURRENT UPPER
PATTERN.

.MODEL DISCUSSION...MODELS ARE IN EXCELLENT AGREEMENT IN THE SHORT
TERM WITH MINOR DIFFERENCES IN THE MEDIUM TO LONG RANGE. A COMPARISON
OF THE MSLP AGAINST THE 18Z INFRARED SATELLITE DEPICTS A SLIGHT
PREFERENCE TO THE NAM/ECMWF DUE TO THE POSITION OF THE LOW IN THE
NORTH PACIFIC. THE MINOR DIFFERENCES WILL NOT HAVE A MAJOR IMPACT ON
THE FORECAST AS ALL MODELS SHOW A VERY SIMILAR EVOLUTION OF THE
SYNOPTIC PATTERN. FOR THE SHORT TERM...THE NAM WAS PREFERRED AND THEN
A GRADUAL BLEND TOWARD THE ECMWF/GFS IN THE MEDIUM RANGE WAS USED.

.SHORT TERM FORECAST...
SOUTHCENTRAL...MOSTLY SUNNY SKIES AND ABOVE AVERAGE TEMPERATURES
PREVAILING OVER MOST OF THE STATE. AN EASTERLY UPPER LEVEL
DISTURBANCE MOVING OVER THE COPPER RIVER BASIN HAS ONLY MANAGED TO
RESULT IN INCREASED MID AND HIGH LEVEL CLOUDS OVER THE REGION. A FEW
SHOWERS ARE STILL POSSIBLE MAINLY OVER THE MOUNTAINS THIS AFTERNOON
AND AGAIN ON FRIDAY THANKS TO THE RELATIVELY WARM AIR AT THE SURFACE
AND COLD AIR ALOFT. BESIDES THE STRAY SHOWERS ALONG THE ALASKA AND
TALKEETNA RANGES...MOSTLY SUNNY SKIES WILL CONTINUE UNTIL THE FRONTAL
BOUNDARY ASSOCIATED WITH THE DEVELOPING NORTH PACIFIC LOW APPROACHES
FROM THE GULF. CLOUDS WILL BE ON THE INCREASE SATURDAY EVENING WITH
RAIN OVER KODIAK AND ALONG THE COAST.

SOUTHWEST...SUNNY SKIES ALSO PREVAILING OUT WEST EXCEPT FOR LOCAL
AREAS OF STRATUS AND FOG MAINLY ALONG THE BRISTOL BAY COAST. LIGHT
SOUTHWESTERLY WINDS WILL CONTINUE IN THIS REGION WHICH WILL LEAD TO
WIDESPREAD STRATUS AND FOG AGAIN TONIGHT UNDER THE UPPER LEVEL RIDGE.
FLOW EVENTUALLY BECOMES NORTHEASTERLY BY FRIDAY AFTERNOON. THIS
SHOULD HELP USHER IN THE WARMER AND DRIER AIR FROM THE
INTERIOR...UNTIL THE MID AND UPPER LEVEL CLOUDS ARRIVE LATER IN THE
WEEKEND FROM THE APPROACHING FRONT. PRECIPITATION OVER THE WEEKEND
ASSOCIATED WITH THE FRONTAL BOUNDARY WILL NOT BE WIDESPREAD AS MUCH
OF THE ENERGY WILL REMAIN OVER THE GULF OF ALASKA.

.BERING SEA/ALEUTIANS...VERY BENIGN WEATHER OUT WEST WITH LIGHT
NORTHERLY FLOW PERSISTING. HIGH PRESSURE BUILDS OVER THE WESTERN
BERING THROUGH THE WEEKEND WITH STRATUS AND A FEW SHOWERS LINGERING
ALONG THE ALASKA PENINSULA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 132 150 155 170
         HEAVY FREEZING SPRAY 412
FIRE WEATHER...NONE.

AB APR 12