Heavy Freezing Spray Warning 41, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
515 AM AKST FRI MAR 4 2016

.ANALYSIS AND UPPER LEVELS...

AN INCREDIBLY BENIGN PATTERN WEATHER-WISE HAS SET UP OVER SOUTHERN
MAINLAND ALASKA THIS MORNING. DESPITE AN UPPER LOW PASSING JUST
WEST OF THE SPINE OF THE ALASKA RANGE MOVING
SOUTHWESTWARD...THE INGREDIENT LACKING FOR SIGNIFICANT WEATHER IS
MOISTURE. ANCHORAGES 00Z SOUNDING WAS ONE OF THE DRIEST THAT HAS
BEEN SEEN IN QUITE SOME TIME. BROAD SURFACE RIDGING CENTERED ALONG
THE SOUTHWEST ALASKA COAST IS KEEPING EVERYWHERE BUT THE MOUNTAINS
OF THE COPPER RIVER BASIN AND THE ALEUTIANS NEARLY CLOUD-FREE. AS
A RESULT...MUCH OF SOUTHCENTRAL AND SOUTHWEST ALASKA HAVE DROPPED
INTO THE 20S...WITH TEENS IN THE USUAL COLD SPOTS.

THE ONLY FEATURES OF ANY CONSEQUENCE ARE A WEAK SHORTWAVE MOVING
WESTWARD ACROSS THE ALEUTIANS...WHICH IS ONLY CAUSING INCREASED
CLOUDINESS WITH GENERALLY LITTLE IN THE WAY OF PRECIPITATION...AND
SOMEWHAT BREEZY CONDITIONS IN PARTS OF SOUTHWEST ALASKA. A TIGHT
PRESSURE GRADIENT BETWEEN THE SURFACE RIDGING NORTH AND WEST OF
THE AREA AND A BROAD LOW SOUTH OF THE ALASKA PENINSULA...COUPLED
WITH DRAINAGE FLOW AS TEMPERATURES DROP OVERNIGHT UNDER CRYSTAL
CLEAR SKIES ARE THE REASONS FOR THE HIGHER WINDS...BUT ONCE
AGAIN...ARE NOT CAUSING SIGNIFICANT IMPACTS.

&&

.MODEL DISCUSSION...

WITH THE BENIGN WEATHER PATTERN AND FEW...IF ANY...FEATURES THAT
CAN CAUSE DISAGREEMENT BETWEEN THE MODELS...ALL OF THEM REMAIN IN
EXCELLENT AGREEMENT. AS A RESULT...FORECAST CONFIDENCE REMAINS
HIGH.

&&

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

A PATTERN CHANGE IS BEGINNING THAT WILL BRING MORE MOISTURE TO
SOUTH CENTRAL ALASKA. AN UPPER LEVEL LOW CENTERED SOUTH OF THE
GULF WILL SPIN A SERIES OF WEATHER SYSTEMS INTO THE AREA FROM THE
SOUTHEAST OVER THE NEXT COUPLE OF DAYS AS THE RIDGE THAT HAS BEEN
PROTECTING SOUTHERN ALASKA MOVES NORTH. THE FIRST SYSTEM WILL
MOVE ACROSS THE KENAI PENINSULA TODAY THEN CURVE SOUTHWEST TO
KODIAK ISLAND. THIS SYSTEM IS RATHER WEAK AND DOES NOT HAVE A
CLOSED SURFACE LOW ASSOCIATED WITH IT...JUST A FRONT OR INVERTED
TROUGH. THE NEXT SYSTEM WILL BE STRONGER AND HAVE A CLOSED SURFACE
LOW WITH GALE FORCE WINDS. THIS LOW WILL RACE INTO THE NORTHERN
GULF TONIGHT AND REACH THE KENAI PENINSULA SATURDAY MORNING...THEN
WEAKEN. THE THIRD SYSTEM WILL BE FAIRLY WEAK AND ARRIVE AT THE
GULF COAST SATURDAY NIGHT.

&&

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

THE UPPER LEVEL LOW ACROSS THE CENTRAL INTERIOR WILL DIVE SOUTH
TODAY PUSHING A COLDER AIR MASS ACROSS THE SOUTHWEST AND ALASKA
PENINSULA. NORTHERLY FLOW WILL INCREASE THROUGH THE DAY WITH THE
HIGHEST GUSTS EXPECTED ALONG THE KUSKOKWIM DELTA COAST AND ALONG
THE ALASKA PENINSULA. LOW LEVEL MOISTURE ALSO ADVECTS IN FROM THE
NORTH WHICH WILL BRING FLURRIES ACROSS THE KUSKOKWIM AND INCREASING
CLOUDS. BRISTOL BAY WILL BE THE EXCEPTION FOR TODAY...STAYING
UNDER MOSTLY CLEAR SKIES THROUGH THE AFTERNOON. HOWEVER...THIS
CHANGES TONIGHT WITH A WEAK FRONT MOVING IN FROM THE WESTERN GULF.
ISOLATED TO SCATTERED SNOW SHOWERS WILL DEVELOP ALONG THE
ALEUTIAN RANGE THIS EVENING WITH A SLOW WESTWARD PUSH THROUGH THE
WEEKEND. PRECIPITATION CONTINUES THROUGH THE WEEKEND FOR BRISTOL
BAY AS SEVERAL UPPER LEVEL WAVES MOVE IN FROM THE GULF. A WARMER
PACIFIC AIR MASS BEGINS WORKS BACK ACROSS THE ALEUTIAN RANGE ON
SUNDAY WHICH CHANGES PRECIPITATION OVER TO RAIN FOR A SHORT PERIOD
ALONG THE MOUNTAINS DURING THE AFTERNOON.

&&

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

COLD NORTHERLY FLOW RETURNS ACROSS THE BERING AND ALEUTIANS AS THE
COLD FRONT CURRENTLY ACROSS THE NORTHERN BERING MOVES SOUTH THROUGH
THE ALEUTIAN CHAIN. GALE FORCE WINDS CAN BE EXPECTED ALONG THE
NORTHERN AND EASTERN BERING WITH SMALL CRAFT WINDS ELSEWHERE.
THERE IS SOME UNCERTAINTY IN THE PRESSURE GRADIENT ACROSS THE
ALASKA PENINSULA AND EASTERN BERING AND THEREFORE SHOULD BE
MONITORED THROUGH THE WEEKEND FOR HIGHER WINDS THAN CURRENTLY
EXPECTED. PRECIPITATION ALONG THE FRONT WILL BRING LIGHT SNOW
THROUGH TONIGHT FOR THE EASTERN HALF OF THE BERING...WITH
SCATTERED RAIN AND SNOW SHOWERS ACROSS THE WESTERN AREAS CHANGING
TO ALL SNOW BY EARLY SATURDAY MORNING. SCATTERED TO NUMEROUS SNOW
SHOWERS CONTINUE THROUGH THE WEEKEND AS LOW PRESSURE BECOMES
DOMINANT ACROSS THE EASTERN BERING.

&&

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

THE LARGE SCALE GENERAL PATTERN REMAINS SIMILAR THROUGH THE LONG
TERM. BY SATURDAY NIGHT THE COLD UPPER LEVEL TROUGH SHIFTS WEST
TO BE CENTERED OFFSHORE OF THE WEST COAST OF ALASKA EXTENDING OVER
BRISTOL BAY...THE EASTERN BERING AND ACROSS THE BERING STRAIT. AT
THE SURFACE COLD NORTHERLY WINDS WILL CONTINUE TO BRING SNOW
SHOWERS TO THE BERING. MEANWHILE THE UPPER LEVEL RIDGE OVER
WESTERN CANADA WILL STRENGTHEN AND BUILD INTO INTERIOR ALASKA. A
SERIES OF WEAKENING LOWS BEING SPUN OFF OF THE LARGE UPPER LEVEL
LOW SOUTH OF THE GULF OF ALASKA WILL ROTATE ACROSS THE GULF
TRACKING IN FROM THE SOUTHEAST. WHILE THERE REMAINS A FAIR BIT OF
UNCERTAINTY REGARDING THE TIMING AND DEPTH OF THE INDIVIDUAL WAVES
IT LOOKS LIKELY THAT THE IMPACTS OF THESE SYSTEMS WILL REMAIN
CONFINED TO COASTAL REGIONS.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE
MARINE...GALE WARNING 119 180 185
 		 HEAVY FREEZING SPRAY 160 179 180 181 185

&&

SYNOPSIS AND MODEL DISCUSSION...JW
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KH
LONG TERM...JR