Small Craft Advisory 394, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE ANCHORAGE AK
418 PM AKDT FRI MAY 8 2015

.ANALYSIS AND UPPER LEVELS...
A TROUGH EXTENDING ALONG THE WEST COAST OF THE STATE AND DOWN
INTO THE NORTH PACIFIC CONTINUES TO BRING SOUTHERLY FLOW TO THE
SOUTHCENTRAL. THERE IS GOOD MOISTURE TRANSPORT WITH THIS FLOW
BRINGING RAIN TO AREAS ALL ALONG THE NORTH GULF COAST WITH SOME
SHOWERS MAKING IT FURTHER INLAND. HOWEVER...THE STRONGER WINDS
OVER THE MOUNTAINS ARE DOWNSLOPING OUT MUCH OF THE PRECIPITATION
ON THE LEE SIDE OF THE MOUNTAINS. THIS TROUGH IS BEING HELD IN
PLACE BY RIDGING THAT SITS OVER WESTERN CANADA AND ON THE WESTERN
SIDE OF THE TROUGH ANOTHER RIDGE IS OVER THE CENTRAL BERING. THE
BERING RIDGE IS WEAKER AND QUICKLY MOVING EAST AS IT WEAKENS.
BEHIND THE RIDGE A NORTH PACIFIC LOW IS MOVING TOWARDS THE
ALEUTIANS.

&&

.MODEL DISCUSSION...
THE MODELS ARE IN DECENT AGREEMENT WITH THE LOW IN THE GULF BUT
THEY ARE HAVING MORE ISSUES WITH THE WESTERN LOW NEAR THE
ALEUTIANS. AS THIS LOW TRACKS INTO THE BERING TONIGHT INTO
SATURDAY THE GEM AND EC MOVE IT QUICKLY INTO THE NORTHERN BERING
WHILE THE AMERICAN MODELS KEEP IT MORE IN THE CENTRAL BERING. WITH
THE BETTER RUN TO RUN CONSISTENCY OF THE EC AND GEM THE MORE
NORTHERN TRACK WAS PREFERRED.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
WITH THE FLOW ALOFT RETURNING TO A MORE SOUTHEASTERLY DIRECTION RAIN
SHADOW EFFECTS HAVE RETURNED TO THE STANDARD LOCATIONS IN THE LEE
OF THE CUGACH AND KENAI MOUNTAINS WITH PRECIPITATION IN THESE
AREAS LIMITED TO ISOLATED TO SCATTERED SHOWERS. ALONG THE GULF
COAST...ON THE WINDWARD SIDE OF THE MOUNTAINS RAIN CONTINUES TO
BE HEAVY AT TIMES. ONLY LOOKING AT MINIMAL CHANGES IN THIS PATTERN
THROUGH THE WEEKEND WITH ADDITIONAL FRONTAL WAVES ROTATING UP TO
THE NORTHERN GULF COAST LATE TONIGHT/EARLY SATURDAY
MORNING...SATURDAY AFTERNOON/EVENING AND ANOTHER ON SUNDAY.
OVERALL QPF AMOUNTS WILL GRADUALLY TAPER DOWN THROUGH THE WEEKEND
BUT IT WILL STILL REMAIN RATHER DAMP ALONG THE COAST.

SOUTHEASTERLIES WILL INCREASE EACH AFTERNOON AND EVENING THROUGH
THE GAPS AND PASSES THROUGH THE COASTAL MOUNTAINS SUCH AS
TURNAGAIN ARM...THE KNIK RIVER VALLEY AND THE COPPER RIVER AS A
SURFACE RIDGE STRENGTHENS ALONG THE COAST...OUT AHEAD OF THE GULF
LOW. FURTHER INLAND GAP WINDS WILL BE A POTENTIAL FIRE WEATHER
CONCERN WITH RELATIVE HUMIDITIES REMAINING LOWER IN THE COPPER
RIVER BASIN. WITH A RELATIVELY COOL AIR MASS AND SOME INCREASE IN
MOISTURE FROM THE COASTAL AIR MASS FILTERING INLAND...RHS ARE
EXPECTED TO REMAIN ABOVE RED FLAG CRITERIA FALLING TO A MINIMUM
AROUND 35 PERCENT BUT WITH THE STRONG WINDS EXPECTED THIS WILL
BEAR CONTINUED WATCHING.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
RIDGING JUST OFF THE SOUTHWEST COAST WILL MOVE NORTH TOWARD NORTON
SOUND TONIGHT...AND WILL COMBINE WITH THE LOW MOVING INTO THE
WESTERN GULF TO INCREASE THE OFFSHORE NORTHERLY FLOW. THIS WILL
SERVE TO PROGRESSIVELY DRY THE AREA OUT THROUGH EARLY SATURDAY
MORNING. DURING THE DAY ON SATURDAY...A STRENGTHENING SHORTWAVE
AND A DEFORMATION ZONE WILL DEVELOP AND BRING ANOTHER ROUND OF
RAIN AND SHOWERS TO EASTERN BRISTOL BAY AND THE KUSKOKWIM VALLEY.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
RAIN AND NEAR GALE-FORCE WINDS WILL IMPACT THE CENTRAL ALEUTIANS
TONIGHT AND THEN IMPACT THE PRIBILOFS AND EASTERN ALEUTIANS
SATURDAY AS THE LOW MOVES SWIFTLY NORTH THROUGH THE BERING. A NEW
LOW PRESSURE FORMS ALONG THE WEAKENING FRONT BY SUNDAY MORNING
SOUTHEAST OF DUTCH HARBOR BRINGING RAIN TO THE AKPEN AND EASTERN
BERING DURING THE DAY ON SUNDAY.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
THE CLOSED UPPER LEVEL LOW OVER THE SOUTHWESTERN GULF WILL REMAIN
ALMOST STATIONARY THROUGH TUESDAY BEFORE LOOSING SUPPORT AND
DISSIPATING. THE SURFACE LOW ASSOCIATED WITH THE UPPER LEVEL
FEATURE WILL PRODUCE WIDESPREAD RAIN ALONG THE GULF COAST...EXCEPT
FOR SOME SHOWERY PRECIPITATION FOR THE INLAND AREAS AND  DRIER
CONDITIONS ALONG THE CHUGACH AND WESTERN KENAI MOUNTAINS DUE TO
DOWNSLOPING THROUGH MONDAY. BY TUESDAY AN AMPLIFIED RIDGE OF HIGH
PRESSURE WILL BEGIN TO MOVE INTO THE SOUTHCENTRAL REGION FROM THE
WEST. BY THURSDAY THIS RIDGE WILL DEVELOP INTO AN UPPER LEVEL
CLOSED HIGH OVER THE INTERIOR. THERE WILL BE WARMER TEMPERATURES
WITH THIS RIDGE WITH DIURNAL SHOWERS IN THE AFTERNOON AND EVENING
ACCOMPANIED BY A THERMAL TROUGH FORMING IN THE INTERIOR AS WERE
HEADING INTO THE EARLY PART OF NEXT WEEK. THE MODELS WERE IN
DECENT AGREEMENT WITH THESE FEATURES AND FORECAST CONFIDENCE IS
ABOVE AVERAGE.

ON THE BERING SEA SIDE...THE STRONG ZONAL JET STREAM OVER THE WESTERN
TO CENTRAL ALEUTIANS CONTINUES THROUGH MONDAY BEFORE TRANSITIONING
TO A SOUTHERLY MERIDIONAL FLOW BY TUESDAY. THIS COINCIDES WITH AN
UPPER LEVEL CLOSED LOW MOVING INTO THE WESTERN ALEUTIANS. A GALE
FORCE LOW WILL BE REFLECTED AT THE SURFACE BY MONDAY BEFORE
BECOMING A BROAD AREA OF LOW PRESSURE OVER THE BERING SEA. THIS
WILL BRING WIDESPREAD RAIN WITH GUSTY WINDS THROUGH THE EARLY PART
OF NEXT WEEK BEFORE TRANSITIONING TO SHOWERY PRECIPITATION BY
MIDWEEK. DOWNSTREAM...AN AMPLIFIED RIDGE BUILDS THROUGH THE
EASTERN BERING/ALEUTIANS BY TUESDAY AND MOVES EASTWARD. THIS WILL
BRING WARMER TEMPERATURES THROUGH THURSDAY. THE MODELS CONTINUE
TO STRUGGLE WITH THE PLACEMENT/STRENGTH OF THIS NORTH PACIFIC LOW
APPROACHING THE WESTERN ALEUTIANS BY THE EARLY PART OF NEXT WEEK.
THE FORECAST CONFIDENCE REMAINS BELOW AVERAGE.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 173 174 AND 176.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...DK
SOUTHCENTRAL ALASKA...JR
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...CC
LONG TERM...PD