Winter Weather Advisory 2, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
527 AM AKST FRI JAN 8 2016

.ANALYSIS AND UPPER LEVELS...

EARLY THIS MORNING WV SATELLITE IMAGERY SHOWS A CLOSED UPPER LOW
IN THE NORTH PACIFIC BEGINNING TO TAKE A TURN TOWARD KODIAK ISLAND.
THIS SYSTEM IS PUMPING ABUNDANT MOISTURE ACROSS THE SOUTHWEST
BETWEEN THE PARENT LOW NEAR KAMCHATKA AND RIDGING OVER CENTRAL ALASKA.
HIGH LEVEL CLOUDS ARE SPREADING NORTH OVER THE KENAI TO THE NORTHERN
INLET AND INTO THE SUSITNA VALLEY. AT THE SURFACE...RIDGING IS
BUILDING TOWARD SOUTHCENTRAL WHILE A LOW IS PUSHING A WARM FRONT
INTO THE SOUTHERN GULF. MAINLY DRY CONDITIONS ACROSS THE MAINLAND
WITH A FEW SHOWERS ACROSS THE SOUTHWEST AND ALONG A WEAK BOUNDARY
IN THE CENTRAL GULF. SKIES CLEARED OVERNIGHT ACROSS SOUTHCENTRAL
ALLOWING TEMPERATURES TO DROP INTO THE TEENS WITH BELOW ZERO
TEMPERATURES ACROSS THE COPPER RIVER VALLEY. TEMPERATURE TRENDS
ACROSS THE SOUTHWEST REMAINED NEARLY STEADY OVERNIGHT WITH A FEW
LOCATIONS SLIGHTLY WARMING ACROSS BRISTOL BAY. OUT WEST ACROSS THE
BERING...A SHARP DIVIDING LINE IS SITUATED IN THE CENTRAL BERING
WITH A SATURATED AIR MASS ACROSS THE EAST WITH TEMPERATURES IN THE
LOW TO MID 30S AND COLDER DRIER CONDITIONS ALONG THE WEST.

&&

.MODEL DISCUSSION...
MODELS ARE GENERALLY IN GOOD AGREEMENT WITH THE SYNOPTIC PATTERN
THROUGH SATURDAY NIGHT. HOWEVER THE SYSTEMS DEVELOPING IN THE
NORTH PACIFIC ARE LOCATED IN A LARGELY DATA VOID AREA SO
SIGNIFICANT CHANGES WERE MADE...MAINLY ACROSS THE SOUTHWEST AND
BERING. THE MAIN FORECAST CHALLENGE INTO THE WEEKEND IS THE
DEVELOPING NORTH PACIFIC SYSTEM THAT IS EXPECTED TO BRING GUSTY
WINDS AND PRECIPITATION ALONG A FRONT. THE GFS AND ECMWF WERE THE
FAVORED MODEL ACROSS THE SOUTHERN MAINLAND AN SURROUNDING WATERS
WITH USE OF THE NAM FOR LOCAL EDITS THROUGH TONIGHT.

&&

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

A DEVELOPING LOW SOUTH OF THE GULF MOVES NW TO SOUTH OF THE AK
PEN LATE TONIGHT THEN INTO BRISTOL BAY SAT AFTERNOON. ITS
ASSOCIATED FRONTAL TROUGH MOVES TO THE NORTH GULF COAST EARLY
SAT THEN MOVES INLAND AND WEAKENS SAT AFTERNOON/NIGHT.
EXPECT GALE TO STORM FORCE WINDS WITH AND AHEAD OF FRONT AS IT
MOVES NORTH. BRISK/STRONG GAP FLOWS WILL ALSO BE EVIDENT IN THE
FAVORED LOCALS (TURNAGAIN ARM PORTAGE VALLEY MAT VALLEY) WITH
WINDS PEAKING ON SAT PRIOR TO FRONTAL PASSAGE. SOUTH WINDS WILL
THEN DEVELOP ACROSS THE COPPER RIVER BASIN LATE SAT
AFTERNOON/EVENING.

PRECIPITATION WILL BE MAINLY CONFINED TO THE COASTS WITH RAIN THE
DOMINATE TYPE...BECOMING MIXED INLAND KENAI AND HIGHER ELEVATIONS
ALONG THE COAST. CURRENT THOUGHT IS THAT PRECIPITATION AMOUNTS
WILL BE FAIRLY LIGHT ALONG THE NORTH GULF COAST THROUGH EARLY SAT
THEN WILL INCREASE AS THE 850 MB FLOW VEERS TO THE SOUTH. THOMPSON
PASS WILL LIKELY SEE INCREASED SNOW RATES AT THAT POINT BUT VALUES
SHOULD STAY WELL BELOW ADVISORY LEVELS. STRONG CROSS BARRIER FLOW
ACROSS THE CHUGACH RANGE/KENAI MOUNTAINS WILL KEEP AREAS TO THE
LEE GENERALLY ON THE DRY SIDE.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
AN APPROACHING LOW PRESSURE SYSTEM SOUTH OF THE ALASKA PENINSULA
WILL BE THE FOCUS FOR ACTIVE WEATHER FOR THE NEXT COUPLE DAYS. A
STALLED FRONTAL BOUNDARY OUT AHEAD OF THIS SYSTEM JUST OFF THE
SOUTHWEST COAST WILL BRING SOME SNOW EARLY TODAY...MAINLY FOR THE
KUSKOKWIM DELTA COAST. THE STRONG EASTERLY FLOW DEVELOPING WITH
THIS SYSTEM WILL KEEP MOST OF THE MAINLAND ON THE DRY SIDE ALONG
WITH WARMER THAN AVERAGE TEMPERATURES. AS THE OCCLUDED FRONT
ASSOCIATED WITH THIS SYSTEM MOVES OVERHEAD THE GREATER BRISTOL BAY
AREA THIS EVENING...CHANCES FOR RAIN INCREASE...HOWEVER ANY RAIN
WILL BE LIGHT GIVEN THE STRONG CROSS BARRIER FLOW THAT REMAINS IN
PLACE. AS THE WHOLE UPPER TROUGH LIFTS NORTHWARD SATURDAY EVENING
AREAS OF RAIN AND SNOW WILL LINGER WITH THE BEST CHANCE FOR
PRECIPITATION BEING ALONG THE UPSLOPE AREAS OF WOOD RIVER
MOUNTAINS. EXPECT ABOVE AVERAGE TEMPERATURES AND GUSTY EASTERLY
WINDS. A NEARLY IDENTICAL SYSTEM MOVES ACROSS THE ALASKA PENINSULA
LATE SATURDAY NIGHT.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
A FRONTAL BOUNDARY DRAPED OVER THE EASTERN BERING SEA IS THE FOCUS
FOR RAIN AND SNOW AS AN APPROACHING LOW PRESSURE SYSTEM FEEDS
MOISTURE INTO IT FROM THE SOUTHEAST. SNOW WILL TURN TO RAIN TODAY
OVER THE ALASKA PENINSULA THEN BECOME MORE SHOWERY FOR THAT AREA.
AS THE FRONTAL BOUNDARY APPROACHES THE PRIBILOF ISLANDS TONIGHT
WINDS WILL INCREASE...BRINGING A THREAT FOR BLOWING SNOW. THE
DIVISION BETWEEN WARM AIR TO THE EAST AND COLD AIR TO THE WEST
WILL BE VERY CLOSE TO THE PRIBILOFS...HOWEVER CURRENT GUIDANCE
SUGGESTS THEY WILL STAY JUST ON THE COLD SIDE OF THE BOUNDARY.
GIVEN THIS SCENARIO...WINDS OF 25 TO 35 MPH WITH HIGHER
GUSTS...AND FALLING/BLOWING SNOW APPEAR LIKELY. TEMPERATURES WILL
REMAIN PRETTY CLOSE TO FREEZING AND THERE IS NO SNOW COVER TO AID
IN ADDITIONAL BLOWING SNOW. TAKING THOSE FACETS INTO CONSIDERATION
THIS SHIFT OPTED TO ISSUE A WINTER WEATHER ADVISORY FOR BLOWING
SNOW AS OPPOSED TO A BLIZZARD WATCH AT THIS POINT. HOWEVER...SOME
UNCERTAINTY STILL EXISTS DUE TO THE AREA'S CLOSE PROXIMITY TO THE
FRONT.

&&

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

ON SUNDAY ANOTHER ELONGATED AND COMPLEX LOW MOVES NORTH FROM THE
NORTH PACIFIC TOWARD THE ALASKA PENINSULA. THIS SYSTEM WILL BRING
GALES FROM THE ALASKA SOUTHWEST ALASKA COASTAL WATERS EAST THROUGH
THE GULF OF ALASKA...WITH STORM-FORCE WINDS THROUGH SHELIKOF
STRAIT. THIS SYSTEM WILL STALL...WEAKEN...AND ELONGATE IN THIS
REGION THROUGH THE MIDDLE OF NEXT WEEK WHILE A SERIES OF FRONTAL
SYSTEMS MOVE NORTH THROUGH THE GULF TO THE GULF COAST.

THE RESULTANT IMPACTS WILL BE WET AND SNOWY CONDITIONS FROM EAST
TO SOUTHEAST FLOW UPSLOPING AGAINST THE MOUNTAIN RANGES ALONG THE
COASTS...WITH MUCH LESSER AMOUNTS ON THE LEE SIDES IN THE MUCH
MORE POPULATED AREAS...WHERE DOWNSLOPE DRYING WILL BE PREVALENT.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...BLOWING SNOW ADVISORY 195.
MARINE...GALE 125 136 139 141 150 155 160 165 170 171 172 179 180.

&&

SYNOPSIS AND MODEL DISCUSSION...KH
SOUTHCENTRAL ALASKA...RMC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MTL
LONG TERM...CC

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ANCHORAGE AK
1218 PM AKST FRI JAN 8 2016

AKZ121-092100-
WESTERN KENAI PENINSULA-
INCLUDING THE CITIES OF...KENAI...SOLDOTNA...HOMER...
COOPER LANDING
1218 PM AKST FRI JAN 8 2016

...MINOR FLOODING ON THE ANCHOR RIVER NEAR ANCHOR POINT VILLAGE...

AS OF FRIDAY MORNING AN ICE JAM REMAINS IN PLACE ALONG THE ANCHOR
RIVER DOWNSTREAM OF THE OLD STERLING HIGHWAY BRIDGE. PORTIONS OF
CUFFEL DITTON ROAD AND THE HISTORIC ANCHOR POINT VILLAGE WILL
CONTINUE TO SEE SOME WATER MOVING THROUGH THE AREA UNTIL THE ICE
IN THE RIVER MOVES DOWNSTREAM.

THIS STATEMENT WILL BE UPDATED IF NECESSARY.