Gale Warning 226, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
426 PM AKST FRI MAR 11 2016

.ANALYSIS AND UPPER LEVELS...
A LARGE LOW REMAINS SOUTH OF THE ALASKA PENINSULA WITH THE
ASSOCIATED FRONT HAVING PASSED THROUGH SOUTHERN KODIAK ISLAND AND
IS PUSHING INLAND ALONG THE NORTH GULF COAST. THE JET IS RUNNING
SOUTH SOUTHEAST TO NORTH NORTHWEST FROM THE GULF INTO PRINCE
WILLIAM SOUND PUMPING MOISTURE AND CLOUDS INTO THE REGION. ACROSS
THE COASTAL MOUNTAINS THE LOW LEVEL AIR IS QUITE DRY AND THUS NOT
MUCH IF ANY PRECIPITATION HAS BEEN OBSERVED ON THE LEE SIDE OF THE
MOUNTAINS. BEHIND THE FRONT COLD ADVECTION AND UNSTABLE AIR HAD
PRODUCED SOME ISOLATED THUNDERSTORMS ON THE SOUTHERN SIDE OF
KODIAK ISLAND THIS MORNING. BEHIND THIS LOW IN THE NORTHWEST
QUADRANT A DEFORMING TRAILING TROUGH IS SHIFTING JUST WEST OF THE
PRIBILOF ISLAND AND EXTENDS THROUGH UNALASKA. SNOW AND OR SNOW
SHOWERS HAVE BEEN PREVALENT TODAY UNDER THIS DEFORMATION ZONE.

&&

.MODEL DISCUSSION...
MODELS ARE GENERALLY IN GOOD AGREEMENT WITH THE SYNOPTIC PATTERN
HEADING THROUGH THE WEEKEND INTO EARLY NEXT WEEK. OVERALL THE
MODELS HANDLE THE AREAS OF PRECIPITATION ALONG THE COAST AND
REFLECT THE EXPECTED CROSS BARRIER DOWN SLOPE DRY REGIONS ON THE
LEE SIDE OF THE COASTAL MOUNTAINS THROUGH THE WEEKEND. THE MODELS
ARE IN AGREEMENT WITH RESPECT TO MOVING THE LOW EAST ACROSS THE
GULF AND DRAGGING THE TRAILING TROUGH AND LOW TO THE WEST OF THE
LOW SOUTH ACROSS THE ALEUTIANS AND ALASKA PENINSULA BY TUE. NO
MAJOR CHANGES WERE NEEDED FOR THE SHORT TERM.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
A POCKET OF UNSTABLE AIR IS CURRENTLY MOVING OVER THE SOUTHCENTRAL
AIDING IN SHOWER DEVELOPMENT. MOST OF THIS ACTIVITY IS CONFINED TO
THE NORTH GULF COAST AS UPSLOPING EASTERLY FLOW IMPINGES ON THE
MOUNTAINS. THESE SHOWERS WILL CONTINUE TO AFFECT THE WESTERN
PRINCE WILLIAM SOUND AREA TONIGHT AS WELL AS AROUND KACHEMAK BAY.
SHOWERS WILL END TOMORROW MORNING AS WEAK HIGH PRESSURE SETS UP
OVER THE AREA. AFTER TONIGHT...EXPECT A GENERAL CLEARING TREND IN
ALL AREAS...THE LACK OF RIDGING ALOFT AND DRY LOW LEVELS MAKE FOG
A NON-THREAT IN THIS SCENARIO. WINDS WILL DROP OFF TO LIGHT AND
VARIABLE IN MOST AREAS WITH A CONTINUATION OF ABOVE NORMAL
TEMPERATURES FOR MID-MARCH.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
DRY OFFSHORE FLOW HAS BECOME THE DOMINANT FEATURE OVER THE
SOUTHCENTRAL MAINLAND...AND WILL PERSIST THROUGH MUCH OF THE
WEEKEND. THE ONLY POSSIBILITY FOR SNOW OVER THE MAINLAND WOULD BE
CAUSED BY A WEAK UPPER LEVEL WAVE TRAVERSING THROUGH THE BRISTOL
BAY AND LOWER KUSKOKWIM VALLEY EARLY THIS EVENING...THEN LIFTING
NORTHWESTWARD OVER THE KUSKOKWIM DELTA COAST LATER SATURDAY
MORNING. HOWEVER...BEING IN A DRIER OFFSHORE FLOW REGIME...VERY
LIGHT (IF ANY) SNOWFALL IS EXPECTED OVER THESE AREAS AS THE UPPER
LEVEL WAVE PASSES OVER THROUGH TOMORROW MORNING. UPSLOPE SHOWERS
ARE EXPECTED ALONG NORTH PACIFIC/GULF OF ALASKA SIDE OF THE ALASKA
PENINSULA AND ALEUTIAN RANGE BUT WILL LIKELY NOT MAKE IT BEYOND
THE MOUNTAINS AS STRONG CROSS BARRIER FLOW IS EATING UP MUCH OF
THE MOISTURE. FOG COULD LOCALLY BE AN ISSUE FOR AREAS THAT SEE
PERIODS OF CALM WIND BUT IT IS LIKELY THAT THE GRADIENT WILL
REMAIN STRONG ENOUGH TO INHIBIT FOG DEVELOPMENT.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
GUSTY NORTH TO NORTHWESTERLY FLOW WILL PERSIST OVER MUCH OF THE
CENTRAL AND EASTERN BERING/ALEUTIANS THROUGH SATURDAY NIGHT...
ENDING WITH A WEAK LOW DEVELOPING OVER THE EASTERN BERING EARLY
SUNDAY MORNING. THE MAIN FOCUS OF THE FORECAST REMAINS ON A
FRONTAL BAND PARKING OVER DUTCH HARBOR AND NEAR THE PRIBILOF
ISLANDS THROUGH SUNDAY...ENHANCING PRECIPITATION CHANCES AND
POTENTIALLY BRING SOME SNOW ACCUMULATION OVER THESE AREAS. THE
EASTERN ALEUTIANS BEST CHANCE OF ACCUMULATING SNOW WILL BE THROUGH
SATURDAY AFTERNOON...WITH THE PRIBILOF ISLANDS SEEING THEIR BEST
CHANCE OF ACCUMULATING SNOW ON SUNDAY AS A SECOND WAVE TRACKS
THROUGH THE EASTERN BERING AND ALEUTIANS. A WEAK LOW WILL DEVELOP
NORTH OF SHEMYA ON SATURDAY BUT MODELS CONTINUE TO STRUGGLING ON
WHETHER IT CLOSES OFF OR REMAINS A WEAKER TROUGH. REGARDLESS...
INCREASED PRECIPITATION CHANCES AND SMALL CRAFT WINDS WILL BE
ASSOCIATED WITH THIS FEATURE BEFORE IT GETS RE-ABSORBED INTO THE
MEAN FLOW ON SUNDAY.

&&

.LONG TERM FORECAST (DAYS 3 THROUGH 7...MON THROUGH FRI)...
THIS PERIOD WILL START RELATIVELY QUIET WITH THE TAIL END OF THE
HIGH PRESSURE OVER SOUTHERN AK AND WEAK LOW PRESSURE OVER THE
SOUTHERN GULF. FOR THE WEST...ANOTHER WEAK LOW NORTH OF THE
EASTERN ALEUTIANS WILL CONTINUE TO FILL. THE CYCLONIC FLOW AROUND
THIS LOW WILL KEEP SNOW SHOWERS ACTIVE FROM THE CENTRAL TO THE
WESTERN ALEUTIANS.

AS WE MOVE TOWARD THE MIDDLE OF NEXT WEEK...A PATTERN SHIFT WILL
BE UPON US. HOWEVER...HOW MUCH OF THAT PATTERN SHIFT WILL AFFECT
MAINLAND ALASKA REMAINS TO BE SEEN. THE JET OVER THE GULF/NORTH
PACIFIC WILL EFFECTIVELY "BUCKLE" SOUTH NEAR 155W. THIS WILL
CREATE MERIDIONAL FLOW...THE LIKES OF WHICH WE HAVE NOT SEEN FOR
QUITE SOME TIME. THIS IS CAUSING FITS IN THE MODELS WITH A VARIETY
OF SOLUTIONS WITH LOW POSITIONS RANGING FROM THE NORTH PACIFIC TO
THE PANHANDLE. IT DOES LOOK LIKE A BETTER CHANCE FOR SOME ACTIVE
WEATHER TO MAKE IT INTO SOUTHERN AND SOUTHEAST AK BY THE END OF
PERIOD...BUT FEW CHANGES WERE MADE TO THE FORECAST TODAY BASED ON
MODEL DISPARITY.

OUT WEST...THERE IS MUCH BETTER AGREEMENT THAT FOR THE FIRST TIME
IN A LONG TIME...A FAIRLY STRONG LOW IN THE UPPER 970 MB-RANGE
WILL SWING A FRONT INTO THE WESTERN ALEUTIANS. THIS LOOKS MUCH
MORE LIKE A TYPICAL "TRANSITION"-SEASON PATTERN. THIS SYSTEM WILL
FINALLY BRING A CHANGE FROM THE NORTHERLY WINDS AND BRING AN END
TO THE COLD AIR ADVECTION SHOWERS.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING 155 170 171 172.
 HEAVY FRZ SPRAY 185.

&&

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