Small Craft Advisory 874, NWS Anchorage, AK

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

.ANALYSIS AND UPPER LEVELS...
THE BERING SEA AND SOUTHWEST ALASKA REMAIN IN GENERAL WEST TO
SOUTHWESTERLY FLOW AROUND A LARGE UPPER LEVEL LOW CENTERED JUST TO
THE WEST OF THE BERING STRAIT. THE LATEST LOW PRESSURE WAVE MOVING
THROUGH THIS FLOW IN THE WESTERN BERING IS CURRENTLY AROUND 58N
AND 173E AND SWINGING UP TO THE EAST NORTHEAST. THE NEXT INCOMING
LOW PRESSURE SYSTEM IS BEGINNING TO SPIN UP WELL SOUTHWEST OF THE
WESTERN ALEUTIAN WITH THE SUPPORT OF A RATHER STRONG JET STREAM.

FURTHER EAST A STRONG FRONTAL SYSTEM IS SWEEPING UP THROUGH THE
WESTERN GULF COASTAL WATERS THIS MORNING. WHILE THIS CENTRAL LOW
IS NOT ALL THAT DEEP IT IS A RATHER COMPACT SYSTEM WITH A VERY TIGHT
PRESSURE GRADIENT ALONG THE BACK SIDE OF THE LOW...THEREFORE
EXPECTING TO SEE WINDS RAPIDLY SHIFTING TO WEST TO NORTHWEST
STORMS IMMEDIATELY AFTER THE PASSAGE OF THE SURFACE LOW.
PRECIPITATION WISE THE SYSTEM IS LARGER CURRENTLY SPREADING LIGHT
SNOW AS FAR NORTH AS THE MATANUSKA AND SOUTHERN SUSITNA VALLEYS.

&&

.MODEL DISCUSSION...
SYNOPTIC MODEL AGREEMENT REMAINS VERY GOOD FOR BOTH THE SURFACE
LOW SWEEPING THROUGH THE WESTERN GULF THIS MORNING AND THE STRONG
LOW TRACKING UP INTO THE CENTRAL ALEUTIANS WEDNESDAY. NAM WAS
PREFERRED IN THE EASTERN DOMAIN FOR ITS HIGHER RESOLUTION AND GFS
OUT WEST FOR ITS CONSISTENT TRACK OF THE BIG MIDWEEK LOW. BY
THU...THIS AFORE MENTIONED BIG LOW CROSSES INTO THE GULF NEAR
KODIAK. MODELS CONTINUE TO BE NEARLY IN LOCK-STEP WITH THIS
LOW...EVEN AS IT TRACKS ALONG THE ALEUTIAN CHAIN AND ACROSS THE
ALASKA PENINSULA. THE LONE EXCEPTION TO THIS CONSENSUS WAS THE
NAM. IT TRACKS THE LOW SOUTH OF THE KODIAK ISLAND AND WAS
DISCARDED AS AN OUTLIER.

&&

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

A LOW PRESSURE SYSTEM CURRENTLY CENTERED OVER KODIAK ISLAND IS
BRINGING WIDESPREAD PRECIPITATION ACROSS THE SOUTHCENTRAL
MAINLAND THIS MORNING. WHILE SNOWFALL IS GENERALLY LIGHT ACROSS
PORTIONS OF THE ANCHORAGE BOWL AND WESTERN KENAI...IT IS EXPECTED
TO CONTINUE INTO THE MORNING HOURS AS THIS LOW DRIFTS WESTWARD
INTO THE GULF OF ALASKA. IN ADDITION...PRESSURE GRADIENTS ARE NOT
FAVORABLE FOR SIGNIFICANT DOWNSLOPING ACROSS MAINLAND
SOUTHCENTRAL. AS A RESULT...UP TO ONE OR TWO INCHES OF SNOW ARE
EXPECTED TO ACCUMULATE BEFORE THE AFTERNOON FROM THE KENAI
PENINSULA TO THE ANCHORAGE BOWL. MEANWHILE...IN SOUTHERN AND
EASTERN PORTIONS OF THE KENAI PENINSULA...TEMPERATURES ARE JUST
WARM ENOUGH THIS MORNING FOR RAIN TO BE FALLING INSTEAD OF SNOW.
BY THIS AFTERNOON...TEMPERATURES ARE EXPECTED TO BE WARM ENOUGH
FOR A RAIN AND SNOW MIX AS SHOWERS TAPER ACROSS MOST OF
SOUTHCENTRAL.

MEANWHILE...THIS LOW IS ALREADY BRINGING GUSTY NORTHWEST WINDS TO
KODIAK ISLAND...WHICH ARE EXPECTED TO DIMINISH AS THE LOW DRIFTS
INTO THE GULF THIS AFTERNOON. GENERALLY DRY CONDITIONS ARE
EXPECTED ACROSS SOUTHCENTRAL THIS EVENING INTO WEDNESDAY...BEFORE
THE NEXT FRONTAL SYSTEM MOVES INTO THE GULF WEDNESDAY NIGHT. &&

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

AS LOW PRESSURE CROSSES INTO THE EASTERN GULF OF AK...A FEW RAIN
AND SNOW SHOWERS WILL PERSIST OVER SW AK TODAY. AS THE NEXT FRONT
MOVES ACROSS THE BERING AND REACHES THE WEST COAST...SOME RAIN AND
SNOW WILL CAN BE EXPECTED TONIGHT ALONG THE COAST. THIS WILL THEN
MOVE INLAND ON WED. THE FRONT ASSOCIATED WITH THE MAJOR BERING
LOW WILL THEN BRING MORE PRECIPITATION TO THE SOUTHWEST WED NIGHT.
WARMER AIR WITH THE FEATURE WILL KEEP MOST OF THE PRECIPITATION AS
RAIN.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...

A FRONT MOVING ACROSS THE EASTERN BERING TODAY WILL BRING SOME
RAIN TO THE PRIBILOFS AND EASTERN PORTIONS OF THE CHAIN THROUGH
TONIGHT. THE NEXT MAJOR LOW WILL BRING AT LEAST STRONG WINDS TO
MOST OF THE CHAIN TUE NIGHT THROUGH WED NIGHT. AS THE LOW MOVES
EAST...THE WESTERN FLANK WILL EXPERIENCE THE STRONGEST
WINDS...POSSIBLY REACHING HIGH WIND CRITERIA FROM JUST WEST OF
ADAK TO EAST OF ATKA WED AND WED NIGHT. MOST OF THE ALEUTIANS WILL
EXPERIENCE PLENTY OF RAIN WITH THIS SYSTEM AS WELL.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...THU THROUGH MON)...

THE LONG TERM FORECAST IS LARGELY DOMINATED BY A DEEP AREA OF LOW
PRESSURE OVER THE EASTERN ALEUTIANS. BY THURSDAY EVENING...THE
LOW WILL BE ON A WEAKENING TREND AS IT PUSHES FROM DUTCH HARBOR
TOWARD KODIAK ISLAND. ALTHOUGH THE LOW WILL BE WEAKENING...STRONG
NORTHWESTERLY WINDS WILL BE OBSERVED ACROSS THE ALEUTIAN CHAIN AS
COLD AIR ADVECTION WILL ALLOW FOR STRONGER WINDS TO MIX DOWN TO
THE SURFACE. IN ADDITION...A WEAK ISALLOBARIC COMPONENT WILL BE
DEVELOPING OVER THE CENTRAL ALEUTIANS IN RESPONSE TO WEAK SHORT
WAVE RIDGING DEVELOPING BEHIND THE SFC LOW. THIS WILL LEAD TO
WIDESPREAD WIND GUSTS OF 60 TO 70 MPH WITH POTENTIALLY STRONGER
GUSTS THROUGH NORTHWEST ORIENTED GAPS. SEAS WILL ALSO BE A
CONCERN AS THE LOW SKIRTS ACROSS THE ALEUTIANS. WAVE HEIGHTS OF 25
TO 35 FT WILL BE SEEN ON THE PACIFIC SIDE OF THE ALEUTIANS WHILE
THE SOUTHERN BERING SEA COULD SEE SEAS OF 20 TO 30 FT. SOME OF THE
GUSTY SOUTHEAST WINDS SHOULD ALSO MAKE IT INTO THE SOUTHWEST
MAINLAND AS WE GO THROUGH THE DAY ON THU. WIDESPREAD GUSTS TO 40
MPH LOOK VERY POSSIBLE WITH SOME STRONGER WINDS PUSHING THROUGH
THE GAPS ALONG THE ALEUTIAN RANGE.

PRECIPITATION TYPE WITH THIS SYSTEM LOOKS PRETTY SIMPLE AS A STOUT
WARM FRONT SLAMS INTO SOUTHWEST ALASKA LATE WEDNESDAY INTO
THURSDAY. 850 MB TEMPERATURES WILL QUICKLY WARM TO 0 TO -2 DEGREES
CELSIUS AND PRECIPITATION WILL FALL AS RAIN. HOWEVER...A FEW
LOCATIONS NEAR THE ALASKA RANGE AND THE LOWER KUSKOKWIM VALLEY MAY
HOLD ONTO COLD AIR LONG ENOUGH TO SUPPORT SNOW BEFORE EVENTUALLY
CHANGING OVER TO RAIN. THE SAME CAN BE SAID FOR SOUTHCENTRAL WHERE
PRECIPITATION ON THURSDAY AND FRIDAY COULD START AS SNOW BUT
SHOULD TURN OVER TO RAIN WITH WARMING 850 MB TEMPERATURES.
EVENTUALLY COLDER AIR WILL BEGIN FILTERING IN BEHIND THE LOW AND
GRADUALLY CHANGE PRECIP FROM RAIN TO SNOW STARTING ACROSS
SOUTHWEST ALASKA ON FRIDAY AND SOUTHCENTRAL ALASKA ON SATURDAY.
DOWNSLOPING CONDITIONS WILL NEED TO BE MONITORED ON THE LEE SIDE
OF THE ALEUTIAN RANGE AND CHUGACH MOUNTAINS WITH A STOUT LOW LEVEL
JET PASSING ACROSS THE MOUNTAINS.

ATTENTION WILL THEN TURN BACK TO THE BERING SEA AS ANOTHER NEAR
GALE FORCE FRONT WILL PUSH ACROSS THE BERING SEA ON SUNDAY AS A
DEVELOPING AREA OF LOW PRESSURE PUSHES OFF OF KAMCHATKA. MODELS
ARE IN A BIT OF DISAGREEMENT WITH TIMING AT THIS TIME BUT IT IS
ALSO 7 DAYS OUT. REGARDLESS...THE UPPER LEVEL PATTERN CONTINUES TO
FAVOR AN ACTIVE PATTERN AND NO PATTERN CHANGE APPEARS IN SIGHT AT
THIS TIME.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WATCH 187.
MARINE...STORM WARNING 130 131 132 174 175 176 177 178.
	GALE WARNING 119 120 125 136 137 138 139 150 155 165 170 172 173
                 179.

&&

SYNOPSIS AND MODEL DISCUSSION...JR
SOUTHCENTRAL ALASKA...EN
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DS
LONG TERM...MC/MSO

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1058 AM AKST TUE NOV 03 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1057 AM     SNOW             2 N CLAM GULCH          60.25N 151.40W
11/03/2015  M5.2 INCH                           AK   PUBLIC

            SNOW TOTAL STARTING THE NIGHT OF 11/2

&&

JPW