Small Craft Advisory 714, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
404 PM AKDT FRI SEP 11 2015

.ANALYSIS AND UPPER LEVELS...
THERE IS AN UPPER LEVEL LOW OVER NORTHWEST ALASKA WITH A TROUGH
EXTENDING SOUTH THROUGH WESTERN ALASKA. A SMALL BUT FAIRLY POTENT
VORT-MAX IS CENTERED NEAR ANCHORAGE BRINGING UNSTABLE CONDITIONS
TO AREAS SURROUNDING COOK INLET AND PRINCE WILLIAM SOUND. ANOTHER
VORT-MAX IS LOCATED SOUTHWEST OF KODIAK ISLAND MOVING EAST INTO
THE GULF OF ALASKA. THERE IS A RIDGE OVER THE WESTERN BERING SEA
WITH NORTHWESTERLY FLOW OVER MOST OF THE BERING SEA AND ALEUTIANS.
THE ATMOSPHERE THROUGHOUT SOUTHERN ALASKA AND THE EASTERN BERING
IS STILL FAIRLY MOIST WITH PLENTY OF CLOUDS AND SHOWERS. WITH THE
MAIN TROUGH AXIS NEAR ANIAK...THE ATMOSPHERE IS QUITE COOL OVER
THE KUSKOKWIM DELTA AREA WITH 850 MB TEMPERATURES AROUND -5
DEGREES CELSIUS. WITH TEMPERATURES THIS COLD...THERE COULD BE
SOME SNOW MIXED IN WITH SOME OF THE SHOWERS.

&&

.MODEL DISCUSSION...
THE NUMERICAL MODELS ARE IN GOOD AGREEMENT FOR MOST OF THE SHORT
TERM PORTION OF THE FORECAST. THERE ARE A FEW MINOR DIFFERENCES IN
TIMING AND LOCATION OF SOME SMALL SCALE FEATURES...BUT THESE HAVE
LITTLE IMPACT OF THE FORECAST. THERE IS A BIT OF A DIFFERENCE IN A
LOW MOVING INTO THE NORTHERN BERING SUNDAY AFTERNOON (THE EXTRA-
TROPICAL REMNANTS OF FORMER TYPHOON KILO) WITH THE ECMWF FASTER
THAN THE OTHER MAJOR MODELS WITH THIS FEATURE. FORECAST CONFIDENCE
IS ABOVE NORMAL FOR THE AFTERNOON FORECAST.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE LOW OVER THE NORTHWEST PART OF THE STATE IS BRINGING SOUTHWEST
FLOW AND MULTIPLE SHORT WAVES THROUGH THE SOUTHCENTRAL. THIS IS
BRINGING RAIN SHOWERS THROUGHOUT THE AREA THAT ARE MORE INTENSE
WITH THE PASSAGE OF THE SHORT WAVES. THE LAST WILL PUSH THROUGH
SATURDAY AFTERNOON AND EVENING...MOVING FROM WEST TO EAST. THERE
WILL THEN BE A BRIEF BREAK FROM THE RAIN AS WEAK RIDGING MOVES IN
FROM THE WEST. BUT THE NEXT FRONT WILL MOVE IN ALSO FROM THE WEST
LATE ON SUNDAY BRINGING BACK MORE RAIN.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
SHOWERY WEATHER WILL DIMINISH FROM WEST TO EAST TONIGHT AS THE
UPPER LEVEL TROUGH MOVES EAST. ANOTHER DISTURBANCE WILL MOVE INTO
THE KUSKOKWIM DELTA SATURDAY MORNING AND SLOWLY SWEEP EAST DURING
THE DAY SATURDAY. THIS SYSTEM WILL SLOW DOWN...AND BEFORE IT CAN
EXIT SOUTHWEST ALASKA THE NEXT SYSTEM (THE EXTRA-TROPICAL
REMNANTS OF FORMER TYPHOON KILO) WILL RAPIDLY ARRIVE AT THE COAST
SUNDAY MORNING. IT WILL PUSH ACROSS SOUTHWEST ALASKA THROUGH THE
DAY. THIS SYSTEM WILL BRING A PRETTY GOOD PUNCH OF PRECIPITATION
AND WINDS...BUT NOT AN UNUSUAL AMOUNT FOR THIS TIME OF YEAR.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
FAIRLY BENIGN CONDITIONS FOR THIS TIME OF THE YEAR WILL ENCOMPASS
MOST OF THE BERING UNTIL SATURDAY NIGHT...WHEN WINDS WILL BEGIN TO
INCREASE AND RAIN BEGINS TO DEVELOP AND INTENSIFY OVER THE
NORTHERN AND WESTERN BERING AHEAD OF A STRONG DISTURBANCE WITH
DEEP TROPICAL MOISTURE ASSOCIATED WITH IT. THE LEADING FRONT WILL
BE OVER THE WESTERN BERING SATURDAY EVENING. AS IT MOVES EAST IT
WILL BECOME MORE POSITIVELY TILTED...WITH THE LEADING EDGE
STRETCHING FROM ABOUT NUNIVAK ISLAND THROUGH THE PRIBILOFS TO THE
RAT ISLANDS SUNDAY MORNING. BY SUNDAY AFTERNOON IT WILL BE PARALLEL
TO AND JUST NORTH OF THE ALASKA PENINSULA AND EASTERN/CENTRAL
ALEUTIANS.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
THE REMNANTS OF TYPHOON KILO WILL MOVE INTO THE NORTHERN BERING
SEA ON SUNDAY...BRINGING WIDESPREAD RAIN TO THE SOUTHERN MAINLAND
THROUGH MONDAY. WHILE THIS SYSTEM WILL BRING RAIN TO MOST
AREAS...IT SHOULD BE NOTABLY LIGHTER THAN RECENT STORMS THAT HAVE
AFFECTED THE GULF COAST AS THE FLOW ALOFT WILL GENERALLY BE
NORTHWESTERLY AND WILL NOT TAP INTO THE DEEP MOISTURE OVER THE
NORTH PACIFIC. GALE FORCE WINDS ARE STILL EXPECTED WITH THIS
SYSTEM FROM THE CENTRAL BERING TO THE SOUTHWEST COAST...BRINGING
INCREASED WAVE ACTION AND A POSSIBILITY FOR MINOR COASTAL EROSION
TO THE KUSKOKWIM DELTA COAST FROM LATE SUNDAY EVENING TO EARLY
MONDAY MORNING. HOWEVER...WITH TIDES GENERALLY AT A LOW POINT IN
THE TIDAL CYCLE...COASTAL FLOODING IS NOT EXPECTED. AFTER THIS
SYSTEM CROSSES THE AKPEN INTO THE GULF ON TUESDAY...AN ARCTIC
TROUGH OVER THE BROOKS RANGE WILL SLOWLY DESCEND INTO THE MAINLAND
THROUGH THE MIDDLE OF NEXT WEEK...KEEPING CYCLONIC FLOW AND ACTIVE
WEATHER FOR MUCH OF THE AREA THROUGH THE MIDDLE OF NEXT WEEK.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 130.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...BL
SOUTHCENTRAL ALASKA...DK
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...BL
LONG TERM...DEK