Heavy Freezing Spray Warning 68, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
449 PM AKDT SAT MAR 26 2016

.ANALYSIS AND UPPER LEVELS...
A RELATIVELY DYNAMIC PATTERN IS IN PLACE ACROSS SOUTHERN ALASKA
TODAY. CURRENTLY A BROAD TROUGH DIGS SOUTHEASTWARD FROM THE
MAINLAND INTO THE GULF OF ALASKA. FURTHER EAST...A RIDGE IS
BUILDING IN ACROSS THE CENTRAL AND EASTERN BERING. A MUCH BETTER
DEVELOPED LOW IS CURRENTLY CENTERED SOUTH OF SHEMYA. AN UPPER
LEVEL JET THAT LIES ALONG THE EAST BORDER OF THIS LOW AND THE WEST
PERIPHERY OF THE RIDGE IS EXPECTED TO INTENSIFY DRAMATICALLY IN
THE SHORT TERM...AND HELP TO DRIVE A BURST OF MUCH WARMER...AND
SATURATED AIR TOWARD THE MAINLAND.

AT THE SURFACE...A WELL DEVELOPED FRONT TAPPING INTO SUBTROPICAL
MOISTURE IS BRINGING RAIN AND SNOW TO THE WESTERN AND CENTRAL
ALEUTIANS AS IT SLOWLY DRIFTS NORTHEAST TOWARD THE PRIBILOF
ISLANDS.

&&

.MODEL DISCUSSION...
IN GENERAL MODELS ARE IN GOOD AGREEMENT IN CAPTURING SYNOPTIC
FEATURES AS A DRAMATIC RIDGE BUILDS INTO THE GULF OF ALASKA. THERE
IS SOME DISCREPANCY IN HOW MUCH WARM AIR ADVECTION WILL OCCUR NEAR
THE PRIBILOFS AS A FRONT APPROACHES SUNDAY. CURRENTLY THE GFS
FAVORS WARMER TEMPERATURES WHICH COULD LIMIT SNOWFALL AND BLOWING
SNOW BUT IS CURRENTLY THE LEAST LIKELY CHOICE. GENERALLY A BLEND
OF THE NAM AND ECMWF WAS FAVORED.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
THE MAJORITY OF THE PRECIPITATION IN THE AREA HAS PUSHED OFF EAST
AS THE UPPER TROUGH CONTINUES ITS EASTERLY TRACK. RIDGING IS
BUILDING IN BEHIND THE TROUGH ALLOWING FOR MORE CLEARING AROUND
SOUTHCENTRAL. SUNDAY MORNING A FRONT WILL MOVE IN OVER KODIAK AND
QUICKLY MAKE ITS WAY TO THE KENAI PENINSULA BY SUNDAY AFTERNOON.
THIS FRONT IS AIDED BY A STRONG JET AND IS BRINGING UP A LARGE
AMOUNT OF MOISTURE AND WARM AIR. THE SETUP WILL LEAD TO WIDESPREAD
RAIN AROUND SOUTHCENTRAL WITH THE HEAVIEST AMOUNTS MONDAY AND
MONDAY NIGHT.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 3)...
SOUTHWEST ALASKA WILL STAY IN A WET PATTERN THROUGH TUESDAY AS
A SHORTWAVE TROUGH MOVES THROUGH THE NORTHERN HALF OF THE REGION
TONIGHT AND A FRONT ASSOCIATED WITH STRONG LOW CURRENTLY SOUTH OF
SHEMYA BEGINS TO IMPACT THE AREA ON SUNDAY. A TRIPLE POINT LOW IS
EXPECTED TO FORM ALONG THE FRONT SOUTHEAST OF THE PRIBILOF ISLANDS
ON SUNDAY MORNING AND WILL MOVE INTO THE KUSKOKWIM DELTA ON
TUESDAY MORNING.

TONIGHT...SNOW WILL BEGIN TO CLEAR OVER THE KUSKOKWIM DELTA AS
THE BACKSIDE OF THE TROUGH MOVES EASTWARD...OTHERWISE KEEPING SNOW
OVER THE MIDDLE KUSKOKWIM VALLEY AND SCATTERED RAIN AND SNOW
SHOWERS FROM DILLINGHAM EAST. TEMPERATURES WILL DECREASE OVERNIGHT
TONIGHT OVER THE KUSKOKWIM DELTA AS NORTHERLY FLOW DEVELOPS OVER
THE AREA. AS THE TRIPLE POINT LOW APPROACHES THE REGION...WINDS
WILL INCREASE OVER THE KUSKOKWIM DELTA TOMORROW AFTERNOON. SNOW
AND BLOWING SNOW ARE EXPECTED TO DEVELOP TOMORROW EVENING AS THE
FRONT MOVES ASHORE...REDUCING VISIBILITY TO BELOW ONE HALF MILE
AT TIMES...THUS A BLOWING SNOW ADVISORY HAS BEEN ISSUED FOR SUNDAY
NIGHT INTO MONDAY MORNING WHEN THE GRADIENT WILL RELAX AS THE LOW
MOVES INLAND.

ON TUESDAY...THE REGION WILL STAY SOMEWHAT SHOWERY IN THE WAKE OF
THE LOW WITH SCATTERED RAIN AND SNOW SHOWERS.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 3)...
THE DOMINATE WEATHER FEATURE OF THE FORECAST WILL CONTINUE TO BE
THE STRONG LOW SOUTH OF SHEMYA AND THE ASSOCIATED FRONT CURRENTLY
PUSHING NORTHWARD INTO THE REGION. GALE TO STORM FORCE WINDS ARE
EXPECTED TO CONTINUE THROUGH MONDAY NIGHT AS THE FRONT MOVES
NORTHWARD. A TRIPLE POINT LOW IS EXPECTED TO FORM ALONG THE FRONT
SOUTHEAST OF THE PRIBILOF ISLANDS ON SUNDAY MORNING AND MOVE
NORTHEAST INTO THE KUSKOKWIM DELTA BY TUESDAY MORNING.

WIDESPREAD SNOW IS EXPECTED ALONG THE FRONT. THIS...COMBINED WITH
THE STRONGER WINDS...IS EXPECTED TO BRING BLIZZARD CONDITIONS TO
THE PRIBILOF ISLANDS STARTING SUNDAY MORNING AND CONTINUING INTO
MONDAY MORNING AS THE TRIPLE POINT LOW MOVES TO THE EAST OF THE
ISLANDS. AS THE LOW MOVES INTO THE KUSKOKWIM DELTA...THE ISLANDS
WILL REMAIN IN NORTHEASTERLY FLOW WITH SNOW SHOWERS THROUGH THE
REMAINING PORTION OF THE SHORT TERM.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
IN THE LONG TERM AN ACTIVE PATTERN PERSISTS WITH A DRAMATIC RIDGE
CONTINUING TO BUILD ACROSS THE EAST GULF OF ALASKA. THE UPPER
LEVEL JET ALONG THE WESTERN PERIPHERY OF THIS RIDGE IS EXPECTED TO
CONTINUE TO FUNNEL MOISTURE FROM THE PACIFIC TOWARDS THE ALASKA
PENINSULA AND SOUTHCENTRAL MAINLAND. MODELS ARE IN GENERALLY GOOD
AGREEMENT FOR THE LONG TERM...WITH CONSISTENCY BETWEEN ENSEMBLE
MEMBERS. TODAY...MODELS ARE TRENDING TOWARD LESS PRECIPITATION IN
TYPICALLY DOWNSLOPED REGIONS IN SOUTHCENTRAL...AS A TIGHTER
PRESSURE GRADIENT IS ANTICIPATED FROM PRINCE WILLIAM SOUND TO
ANCHORAGE. BUT OVERALL...THE DYNAMIC PATTERN CHANGE OCCURRING IN
THE SHORT TERM WILL CONTINUE INTO THE LONG TERM...WITH COPIOUS
AMOUNTS OF MOISTURE SURGING TOWARDS THE GULF COAST AND WIDESPREAD
ABOVE AVERAGE TEMPERATURES.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...BLIZZARD WARNING 195. WINTER WEATHER ADVISORY 155.
MARINE...GALE WARNING 170 171 173 175 177 178 179 180 181.

&

SYNOPSIS AND MODEL DISCUSSION...EN
SOUTHCENTRAL ALASKA...DWK
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...RF
LONG TERM...EN