Heavy Freezing Spray Warning 64, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
409 PM AKDT SUN MAR 20 2016

.ANALYSIS AND UPPER LEVELS...
THE CLOSED UPPER LOW HAS MOVED INTO BRISTOL BAY WITH THE OVERALL
FLOW NOW SOUTHEAST INTO THE SOUTHERN MAINLAND. THE SURFACE LOW IS
BACKING ACROSS THE BARREN ISLANDS AND SHELIKOF STRAIT WITH THE
WARM FRONT EXTENDING NORTH ALONG THE KENAI AND CHUGACH MOUNTAINS
DELINEATING THE RAIN SNOW LINE. MODERATE CROSS BARRIER FLOW IS
LIMITING THE PRECIPITATION ON THE LEE SIDE OF THE CHUGACH
MOUNTAINS. WARM ADVECTION IS PUSHING ACROSS THE MOUNTAINS AND
BRINGING A WARM LAYER ALOFT INTO THE COOK INLET REGION THAT MAY
RESULT IN SOME ISOLATED POCKETS OF FREEZING RAIN. THE TRAILING COLD
FRONT EXTENDS FROM THE SURFACE LOW SOUTH AND SOUTHWEST. AROUND THE
WEST SIDE OF THIS LOW STRONG NORTHERLY FLOW AND COLD ADVECTION IS
GENERATING THE TYPICAL SHOWERS ALONG THE BERING SIDE OF THE ALASKA
PENINSULA AND ALEUTIANS.

&&

.MODEL DISCUSSION...
THE MODELS CONTINUE TO BE IN GOOD AGREEMENT. THE CHALLENGE IS THE
RESOLUTION OF THE AREAS OF PRECIPITATION AND QPF. THE HIGHER
RESOLUTION MODELS WERE ONCE AGAIN PREFERRED FOR THE QPF AND THE
DIFFERENT SOLUTIONS ARE EVIDENT IN THE BRISTOL BAY REGION WHERE
THE CROSS BARRIER FLOW AND LEE SIDE PRECIPITATION SHADOW IS BETTER
DEPICTED. THE MODELS DIFFER SLIGHTLY ON THE EXTENT OF THE WARM
ADVECTION AND THE RAIN SNOW LINE. THE NAM WAS THE PREFERRED MODEL
OF CHOICE DUE TO ITS HIGHER RESOLUTION.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
A WAVE MOVING WEST ACROSS THE GULF TONIGHT WILL CONTINUE RAIN AND
SNOW ACROSS THE GULF AND WILL BRING INCREASED CHANCES OF
PRECIPITATION WEST OF THE KENAI/CHUGACH MOUNTAINS. NORTHERLY FLOW
WILL LIKELY KEEP TEMPS FROM THE NORTHERN KENAI TO MAT VALLEY
HOVERING IN THE UPPER 20S TO MID 30S OVERNIGHT. THAT SAID...THE
APPROACHING WAVE WILL BRING MIXED PRECIPITATION TYPES IN THE
AFOREMENTIONED AREAS AS THE SOUTHEAST CROSS BARRIER FLOW WEAKENS.
MAINLAND AREAS WILL SEE SOME CLEARING ON MON WITH THE PASSAGE OF
THE WAVE TONIGHT...THOUGH THE COPPER RIVER BASIN WILL LIKELY SEE
SOME PATCHY FOG DURING THE NIGHT AND MORNING HOURS. ON MON AND
TUE...THE FLOW BECOMES MORE EASTERLY AS A DEVELOPING NORTH PACIFIC
LOW AND ASSOCIATED FRONT MOVE NORTH INTO THE GULF. SOME GALES ARE
EXPECTED WITH THIS FRONT. PRECIPITATION WILL LIKELY BE CONFINED TO
THE COASTAL AREAS. TEMPERATURES ARE EXPECTED TO RETURN TO NORMAL
OR ABOVE NORMAL ACROSS THE MAINLAND MON AND TUE.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
SNOW IS RETURNING TO THE MAINLAND AS A FRONT PUSHES OVERHEAD FROM
THE GULF OF ALASKA. THIS FRONT WILL BEGIN TO TAPER THE BELOW
AVERAGE TEMPERATURES THAT TEMPORARILY GRIPPED THE AREA.
TEMPERATURES WILL STAY STEADY OR RISE OVERNIGHT AS THE FRONT
PUSHES WESTWARD TOWARD THE KUSKOKWIM DELTA. THE FRONT WILL
SOMEWHAT LOSE A LITTLE OF ITS PUNCH OVERNIGHT...HOWEVER BEHIND IT
A WARMER AIR MASS AND AN UPPER LEVEL DISTURBANCE WILL FOLLOW. LIGHT
SNOW WILL CONTINUE OVER BRISTOL BAY THROUGH THE NIGHT TONIGHT AND
TAPER OFF TOWARD MORNING MONDAY. LATE MONDAY MORNING A TROUGH WILL
PUSH IN FROM THE GULF BRINGING IN EVEN WARMER AIR AND RAIN AS
WELL. FROM HERE THE BRISTOL BAY AREA WILL BE UNDER A TYPICAL
EASTERLY DOWNSLOPE REGIME WITH RAIN AND SNOW FROM DILLINGHAM WEST.
THIS DISTURBANCE WILL MOVE OVER THE KUSKOKWIM DELTA RETURNING BOTH
PRECIPITATION AND WARMER TEMPERATURES TO THAT AREA. INTO
TUESDAY...THE ABOVE AVERAGE WARMTH WILL STICK AROUND UNDER MOSTLY
CLOUDY CONDITIONS.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
THE NEXT COUPLE DAY WILL BE CHARACTERIZED BY CLOUDY SKIES AND
MODERATE NORTHERLY WINDS OVER THE WHOLE BERING SEA. THE EASTERN
HALF WILL EXPERIENCE PRETTY CONSTANT SNOW SHOWERS...WITH THE
HEAVIEST SHOWERS ALONG THE ALASKA PENINSULA. LATE MONDAY INTO
TUESDAY A DISTURBANCE WILL SWING INTO THE EASTERN BERING AND BRING
SOME STEADIER SNOW FROM DUTCH HARBOR TO THE PRIBILOF ISLANDS.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7)...
WET AND WARM WEATHER WILL CONTINUE ALONG THE GULF COAST INTO THE
LATER HALF OF NEXT WEEK...AS AN UPPER LEVEL TROUGH CENTERED OVER
THE EASTERN BERING/ALEUTIANS BRINGS A SERIES OF NORTH PACIFIC LOWS
INTO THE GULF THROUGH THE END OF THE WEEK. THESE SYSTEMS WILL
HOWEVER PRIMARILY IMPACT COASTAL AREAS AS RIDGING OVER THE
INTERIOR WILL HELP BRING PARTLY TO MOSTLY CLOUDY SKIES...BUT
OTHERWISE DRY CONDITIONS TO MUCH OF SOUTHCENTRAL. THE BERING SEA
ON THE OTHER HAND WILL ONCE AGAIN BE UNDER PREVAILING NORTH TO
NORTHWESTERLY FLOW AND COLD AIR ADVECTION SHOWERS THROUGH MID
WEEK. BY LATER THIS UPCOMING WEEK...MODEL AGREEMENT BEGINS TO
BREAK DOWN WITH THE EXACT DETAILS OF INDIVIDUAL SYSTEMS...HOWEVER
THEY ARE IN GENERALLY GOOD AGREEMENT SYNOPTICALLY THAT AN UPPER
LEVEL TROUGH WILL SET UP OVER THE BERING WITH RIDGING OVER THE
PANHANDLE. THIS MAY ALLOW FOR A DISTURBANCE WITH ASSOCIATED FRONT
TO MOVE INLAND AND BRING A CHANCE OF RAIN OR SNOW TO INLAND AREAS
TOWARD THE WEEKEND...THOUGH TEMPERATURES ARE LIKELY TO REMAIN
ABOVE NORMAL FOR LATE MARCH.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING 130.
 HEAVY FRZ SPRAY 179 180 185.

&&

SYNOPSIS AND MODEL DISCUSSION...SA
SOUTHCENTRAL ALASKA...RC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML
LONG TERM...CC