Small Craft Advisory 526, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
159 PM AKDT TUE JUL 8 2014

.ANALYSIS AND UPPER LEVELS...
THE DOMINANT LONG WAVE TROUGH OVER ALASKA WILL STEER THE WEATHER
FOR THE FORESEEABLE FUTURE. AT THE JET STREAM LEVEL...TWO DISTINCT
LOW PRESSURE CENTERS ARE SHAPING THE SENSIBLE WEATHER BELOW. THE
EASTERNMOST SYSTEM IS OVER THE GULF OF ALASKA WHILE THE MORE
DOMINANT LOW IS OVER THE SOUTHERN BERING SEA. A THIRD LOW OVER THE
NORTH PACIFIC IS IN THE PROCESS OF MERGING WITH THE BERING SEA
LOW AND ASSOCIATED UPPER LEVEL TROUGH.

A HEALTHY VORTICITY MAXIMUM IS RESPONSIBLE FOR THE CONVECTION OVER
BRISTOL BAY WHILE CONVECTION OVER THE COPPER RIVER BASIN AND
EASTERN PRINCE WILLIAM SOUND DEVELOPED FROM THE UPPER LOW
PINWHEELING EASTWARD WITH A WEAKENING SHORTWAVE AND SHEARED WAVE
OF VORTICITY.

FLOODING CONCERNS CONTINUE ALONG THE MATANUSKA RIVER AS A RESULT
OF RECENT RAINFALL...AND WARMER WEATHER EXPERIENCED OVER THE
WEEKEND.

&&

.MODEL DISCUSSION...
MODEL CHOICES THIS DAY INCLUDE THE NAM FOR THE FIRST 48 HOURS OVER
SOUTHCENTRAL...WHILE THE WESTERN SOLUTION IS HANDLED BETTER BY A
BLEND OF THE EC AND GFS. HOWEVER..AS TIME MARCHES ON TOWARD THE
NEXT ALASKA WEATHER EVENT... MOST MODELS ARE CONVERGING ON A
COLLECTIVE SOLUTION OF SETTING JET LEVEL PHASING TO A STUNNING
RAINY PATTERN FOR SOUTHCENTRAL BY LATE WEDNESDAY INTO THURSDAY.
THE NORTH PACIFIC VORT MAX WILL BE ASSIMILATED INTO THE BERING SEA
TROUGH BY EARLY WEDNESDAY...AND ROTATING NORTHWARD TOWARD KODIAK
ISLAND THURSDAY MORNING. UNDERNEATH THE MAIN UPPER LOW CENTER...
CONDITIONS WILL REMAIN UNSETTLED OVER THE YUKON-KUSKOKWIM DELTA/ALASKA
PENINSULA.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
A QUICK GLANCE AT MOISTURE FIELDS OVER WESTERN ALASKA TELLS THE
STORY OF WHAT APPEARS TO BE A LATE SUMMER PATTERN REARING ITS
SOGGY HEAD IN MIDSEASON. WITH HEALTHY WEST-SOUTHWESTERLY FLOW
AROUND THE UPPER LOW IN THE BERING AND LOW LEVEL FLOW THAT BACKS
TO A SOUTHERLY DIRECTION WITH TIME...THERE SHOULD BE NO IMPEDIMENT
TO CONNECTING LIFT AND STORM ENERGY WITH AMPLE PACIFIC MOISTURE BY
LATE WEDNESDAY. THE FIRST WAVE OF THE RAINFEST SHOULD MOVE ONTO
KODIAK ISLAND AFTER 0Z THURSDAY (WEDNESDAY AFTERNOON).

AS THE SHORTWAVE MOVES TOWARD THE KENAI PENINSULA...WINDS WILL
COME UP IN THE NORTHERN GULF...BARRENS AND SHELIKOF BY LATE
THURSDAY MORNING. SOLID GALES WILL BE LIKELY BY THURSDAY
AFTERNOON.

SEVERAL INCHES OF RAIN ARE LIKELY OVER PRINCE WILLIAM SOUND TO
HOMER...AND KODIAK ISLAND...CONTINUING INTO THE LATE WEEK.

SOUTHWEST ALASKA...
UNDERNEATH THE PARENT UPPER LOW IN THE BERING...SEVERAL SURFACE
WAVES OF LOW PRESSURE WILL DEVELOP IN THE LEE OF THE WESTERN
ALASKA RANGE AND TRACK WESTWARD. EXPECT REDUCED VISIBILITY AND
CEILINGS FOR AVIATION INTERESTS PERIODICALLY THROUGH THE MID TO
LATE WEEK.

WINDS WILL COME UP THURSDAY AFTERNOON INTO THURSDAY EVENING FROM
THE NORTHWEST WITH GUSTY CONDITIONS MAINLY SOUTH OF CAPE NEWENHAM
WITH THE STRONGEST WINDS THROUGH BAYS AND PASSES. A MORE
SUSTAINED NORTHERLY FLOW WILL RUN DOWN THE YK COAST HEADING INTO
THE WEEKEND.

BERING SEA/ALEUTIANS...
ON THE WEST SIDE OF THE UPPER LEVEL LOW...A TROUGH OF LOW
PRESSURE DEVELOPS AT THE SURFACE BRINGING WINDS UP FOR A BRIEF
TIME IN THE CENTRAL AND EASTERN CHAIN. SHOWERS WILL ACCOMPANY THIS
DISTURBANCE...BUT NOTHING ON THE ORDER OF WHAT IS TO BE
EXPERIENCED FARTHER EAST. FARTHER SOUTH IN THE NORTH PACIFIC...A
SURFACE RIDGE WILL WORK TOWARD FLATTENING THE SURFACE PATTERN INTO
A ZONE FLOW FOR THE CENTRAL AND WESTERN CHAIN BY THE END OF THE
WEEK.

&&

.LONG TERM FORECAST...
A LARGE SPRAWLING TROUGH WILL REMAIN ACROSS SOUTHCENTRAL
FRIDAY...WITH A WELL DEFINED ATMOSPHERIC RIVER DIRECTED AT
SOUTHCENTRAL. HEAVY RAIN WILL BE IMPACTING THE COAST...WITH
PERIODS OF LIGHTER RAIN ACROSS MUCH OF THE INTERIOR AS DEEP
MOISTURE POURS OVER THE LOWER COASTAL RANGES. MORE SHOWERY
CONDITIONS WILL DEVELOP FRIDAY AFTERNOON AS A DRYSLOT ALOFT MOVES
OVERHEAD. THE UPPER TROUGH...HOWEVER...WILL REMAIN OVER THE
REGION THROUGH SUNDAY...WITH PERIODS OF SHOWERS IMPACTING
SOUTHCENTRAL...WITH PERIODS OF RAIN ALONG THE COAST.

&&

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

DJS / BL / AHSENMACHER JUL 14