Small Craft Advisory 259, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
154 PM AKDT FRI MAR 28 2014

.ANALYSIS AND UPPER LEVELS...
AT THE SURFACE HIGH PRESSURE REMAINS OVER THE MAINLAND NORTH OF
THE ALASKA RANGE WITH A MODERATE LOW IN THE NORTHWEST BERING SEA
AND ANOTHER LOW SOUTH OF THE GULF OF ALASKA. THE LOW PRESSURE
ALOFT THAT IS SUPPORTING THE TWO LOWS EXTENDS FROM A CENTER OVER
THE RUSSIAN FAR EAST WITH A TROUGH CONNECTING TO THE UPPER LOW
SOUTH OF THE GULF OF ALASKA. IN THIS TROUGH A WEAK UPPER CENTER IS
NEAR KODIAK ISLAND WHILE ANOTHER WEAK UPPER CENTER HAS FORMED OVER
THE ILIAMNA AREA. THE OCCLUDED FRONT FROM THE BERING SEA LOW IS
CURRENTLY MOVING THROUGH THE PRIBILOF ISLANDS AND STALLING AND
SHEARING APART AS IT HITS HIGH PRESSURE OVER WESTERN ALASKA.
BEHIND THIS FRONT IS THE COLD ADVECTION AND MODERATE INSTABILITY
THAT IS SUPPORTING THE SHOWERY ACTIVITY.

&&

.MODEL DISCUSSION...
THE MODELS ARE IN EXCELLENT AGREEMENT THROUGH THE WEEKEND FOR THE
MAJOR SYNOPTIC FEATURES. THE MAIN THEME IS THE DISSIPATION OF THE
LOW AND FRONT IMPACTING THE BERING SEA AS THE NEXT STORM MOVES
INTO THE PICTURE FROM THE NORTH PACIFIC WITH A RIDGE BUILDING IN
ADVANCE OF IT. THE LOW AT THE SURFACE AND ALOFT SOUTH OF THE GULF
OF ALASKA BASICALLY PERSISTS AND EVENTUALLY IS MOVING SOUTHEAST BY
SUN EVENING. THE MODELS HAVE ADEQUATELY CAPTURED THE WEAK UPPER
LEVEL LOWS NEAR KODIAK TO THE ILIAMNA AREA AND CONTINUE TO HAVE
THIS FEATURE WEAKEN TO AN OPEN TROUGH THAT WILL EXTEND FROM
NORTHWEST ALASKA INTO THE COOK INLET REGION BY SUN. THE RIDGE
DEVELOPS IN ADVANCE OF THE NEXT INCOMING STORM AND THIS WILL
SUPPORT INCREASED NORTH TO NORTHWEST FLOW ACROSS THE SOUTH CENTRAL
REGION. THIS WILL RESULT IN INCREASED GAP WINDS OUT OF THE ALASKA
RANGE AND CHUGACH MOUNTAINS.

THE INCOMING NORTH PACIFIC STORM WILL BE ACCOMPANIED WITH MODERATE
WARM ADVECTION WITH THE FRONTAL BOUNDARY THAT SHOULD HELP TO HOLD
THE STRONGER GUSTS DOWN ACROSS THE ALEUTIANS TO ALASKA PENINSULA.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
EXPECT A QUIET MOSTLY SUNNY WEEKEND ACROSS THE SOUTH CENTRAL
REGION WITH A MODERATE INCREASE IN THE GAP WIND FLOW SUNDAY AS THE
RIDGE OF HIGH PRESSURE BUILDS INTO WESTERN ALASKA. WEAK
INSTABILITY ALONG THE NORTHERN GULF OF ALASKA WILL SUPPORT SOME
SCATTERED SHOWER ACTIVITY ALONG THE OUTER COASTAL AREAS THAT MAY
AT TIMES SPREAD INTO THE SOUTH PORTIONS OF WESTERN PRINCE WILLIAM
SOUND.

SOUTHWEST ALASKA...
THE BROAD WEAK UPPER TROUGH OVER WESTERN ALASKA WILL RESULT IN
SOME BRIEF PERIODS OF CLOUDS THOUGH FOR THE MOST PART THE AREA
SHOULD SEE MORE SUNNY CONDITIONS. SOME FOG ISSUES ARE EXPECTED
AGAIN SAT MORNING ALONG THE KUSKOKWIM DELTA COAST ALTHOUGH THIS
SHOULD HAVE MINIMAL IMPACT. THE RIDGE BUILDING IN SUNDAY RESULTING
IN CLEAR OVERNIGHT CONDITIONS WITH SIGNIFICANT RADIATIONAL COOLING
THUS FOG WILL LIKELY BE AN ISSUE SUNDAY NIGHT INTO MONDAY.

BERING SEA/ALEUTIANS...
THE WEAK FRONT IS DISSIPATING IN THE EASTERN BERING SEA. RAIN AND
SNOW ALONG THIS FRONT WILL TAPER OFF WITH A RAPID TRANSITION TO
THE POST FRONTAL SHOWERY REGIME. THE SHOWERY REGIME IS ALREADY
PREVALENT ALONG THE ALEUTIANS. THE INCOMING STORM WILL PUSH A
FRONT TO THE CENTRAL TO EASTERN ALEUTIANS SUNDAY. THE CURRENT
MODEL SOLUTION IS ADVERTISING STRONGER PREFRONTAL WIND THAN
PREVIOUS SOLUTIONS THOUGH WE STILL EXPECT THIS TO REMAIN IN THE
STORM FORCE RANGE AND DO NOT ANTICIPATE A HIGH WIND EVENT. THE
STRONG WARM ADVECTION IS EXPECTED TO PROVIDE ENOUGH STABILITY TO
KEEP WIND GUSTS DOWN.

&&

.LONG TERM FORECAST...
THE STRONG WEST WILL SET UP BY THE MIDDLE OF NEXT WEEK SUPPORTING
THE MOVEMENT OF NORTH PACIFIC AND ALEUTIAN LOWS INTO THE GULF OF
ALASKA. OVERALL THIS SHOULD RESULT IN WETTER AND CLOUDIER
CONDITIONS ALONG THE GULF COAST REGIONS THAT COULD POSSIBLY PUSH
FURTHER INLAND INTO THE COPPER RIVER BASIN AND SUSITNA VALLEY
LATE NEXT WEEK INTO NEXT WEEKEND.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

SAM MAR 14