Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 121411
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
611 AM AKDT FRI SEP 12 2014

.ANALYSIS AND UPPER LEVELS...
AN UPPER LEVEL RIDGE IS POSITIONED OVER THE SOUTHEASTERN ALASKA
REGION AND BECOMING NEGATIVELY TILTED EXTENDING THROUGH KOTZEBUE
SOUND. A STRONG CLOSED UPPER LEVEL LOW IS LOCATED JUST WEST OF THE
PRIBILOF ISLANDS. THE SATELLITE IMAGERY SHOWS THE 976 MB SURFACE LOW
LOCATED JUST EAST OF SAINT PAUL. THE SATELLITE IMAGERY HAS A
LARGE SWATH OF MOISTURE OVER THE EASTERN ALEUTIANS SPREADING
THROUGH THE EASTERN BERING SEA NORTHWARD INTO THE BERING STRAIT.
THE 300 MB DEPICTS A SOUTHEASTERLY 95 KNOT MERIDIONAL JET STREAK
OVER THE EASTERN BERING SEA AND A NORTHWESTERLY 120 KNOT
MERIDIONAL JET STREAK SOUTH OF THE WESTERN/CENTRAL ALEUTIANS.

&&

.MODEL DISCUSSION...
THE MODELS ARE IN GOOD AGREEMENT WITH THE MERGING OF THE EXTRA-
TROPICAL SYSTEM AND THE LOW PRESSURE SYSTEM IN THE BERING SEA. THE
MODELS HAVE THIS STRONG LOW ON EAST SIDE OF SAINT PAUL AND THEN
PINWHEELS THE LOW AROUND THE PRIBILOF ISLANDS THROUGH THE WEEKEND.
BY SATURDAY THE LOW WILL BRING STORM FORCE WINDS TO THE CENTRAL
BERING SEA BEFORE SPREADING INTO THE CENTRAL ALEUTIANS. THE
NORTHERN GULF HAS A FRONTAL BOUNDARY MOVING THROUGH THE REGION
WITH A GALE FORCE BARRIER JET THROUGH THE LATE MORNING TODAY. THE
GFS/EC WERE THE MODELS OF CHOICE OVER THE BERING SEA AND SOUTHWEST
ALASKA REGION. THE NAM WAS THE PREFERRED MODEL FOR SOUTHCENTRAL
ALASKA AND THE GULF. THE FORECAST CONFIDENCE IS GOOD HEADING INTO
THE WEEKEND.

&&

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...
THE HIGH WIND WARNING FOR THE TURNAGAIN ARM AND HIGHER ELEVATIONS
REMAINS IN EFFECT AND IS UPDATED TO INCLUDE THE LOWER HILLSIDE
AND EAST ANCHORAGE. THE WINDS HAVE ALREADY INCREASED ALONG THE
TURNAGAIN EARLY THIS MORNING. THE WINDS WILL INCREASE THROUGH THE
AFTERNOON AND REMAIN STEADY THROUGH LATE TONIGHT. THE WINDS WILL
TAPER DOWN BELOW HIGH WIND CRITERIA BY EARLY SATURDAY MORNING.
THE ANCHORAGE BOWL WILL HAVE PERIODS OF LIGHT RAIN GOING INTO THE
WEEKEND. THE EASTERN KENAI PENINSULA AND NORTH GULF COAST WILL
RECEIVE SIGNIFICANT AMOUNTS OF PRECIPITATION WITH THE FRONTAL
BOUNDARY MOVING THROUGH THE AREA TODAY.

SOUTHWEST ALASKA... THE FRONTAL BOUNDARY IS LOCATED ALONG THE
SOUTHWEST ALASKA COASTLINE BRINGING STORM FORCE WINDS THROUGH THE
LATE AFTERNOON BEFORE DIMINISHING AS THE FRONT MOVES NORTH. THIS
WILL BRING WIDESPREAD CLOUDS AND RAIN TO THE SOUTHWEST REGION
BEFORE TAPERING OFF TO SCATTERED SHOWERS HEADING INTO THE WEEKEND.
THE WINDS ALONG THE COASTLINE WILL INCREASE TO GALE FORCE BY
SATURDAY AGAIN AS ANOTHER FRONT MOVES INTO THE SOUTHWEST ALASKA
REGION.

BERING SEA/ALEUTIANS...
THE DOMINANT LOW PRESSURE REMAINS ACROSS THE BERING SEA THROUGH
THE WEEKEND. ON THE BACKSIDE OF THE LOW PRESSURE SYSTEM THERE
WILL BE CLEARING OF SKIES. THIS WILL ALLOW FOR INCREASED
INSTABILITY PRODUCING A SLIGHT CHANCE FOR ISOLATED THUNDERSTORMS
THROUGH THE CENTRAL ALUETIANS. BY EARLY SATURDAY MORNING THE LOW
PRESSURE SYSTEM WILL BE LOCATED JUST SOUTH OF THE PRIBILOF
ISLANDS. THIS WILL BRING STORM FORCE WINDS TO THE CENTRAL BERING
SEA AND THE CENTRAL ALEUTIANS.

&&

.LONG TERM FORECAST...
THE MAIN FOCUS IN THE EXTENDED TERM CONTINUES TO BE ON THE
EVOLUTION OF THE BERING SEA LOW AS IT TRACKS EASTWARD EARLY NEXT
WEEK. MODELS BEGIN TO DIVERGE BY LATE SUNDAY BUT HAVE ALSO
REMAINED FAIRLY CONSISTENT IN THEIR RESPECTIVE SOLUTIONS OVER THE
PAST 24 HOURS...WITH THE EC BRINGING THE LOW INLAND OVER THE
SOUTHWEST MAINLAND AND THE GFS TAKING IT ALONG THE ALASKA
PENINSULA AND THEN INTO THE FAR SOUTHWESTERN GULF. PREFER THE EC
SOLUTION FOR NOW AS THE GEM AND NAM HAVE BOTH TRENDED THAT
DIRECTION IN THE PAST FEW RUNS. REGARDLESS OF THE ULTIMATE TRACK
OF THE LOW...THE SOUTHERN MAINLAND LOOKS TO REMAIN IN A CLOUDY AND
WET PATTERN THROUGH MUCH OF NEXT WEEK AS A STOUT UPPER LEVEL RIDGE
OVER THE WEST COAST OF NORTH AMERICA KEEPS MOIST SOUTHERLY FLOW
FOCUSED ALONG THE NORTHERN GULF COAST. RAIN AND GUSTY WINDS WILL
ALSO PERSIST OVER THE EASTERN HALF OF THE BERING IN THE VICINITY
OF THE LOW...WITH A MORE SHOWERY REGIME FARTHER WEST IN NORTHERLY
FLOW ON THE BACKSIDE OF THE SYSTEM.

&&

AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...HIGH WIND WARNING 101 187.
         FLOOD ADVISORY 181.
MARINE...STORM WARNING 170 173 174 175 176 185 411 413.
         GALE WARNING 119 120 125 130 131 132 150 155 160 165 171
                      172 177 178 179 180 181 351 352 412 414.
FIRE WEATHER...NONE.

$$




PLD/CB SEP 14


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