Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 182150
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
150 PM AKDT SAT OCT 18 2014

.ANALYSIS AND UPPER LEVELS...
A LARGE BROAD UPPER LEVEL TROUGH PERSISTS FROM THE ARCTIC THROUGH
THE BERING STRAIT TO A CLOSED UPPER LOW OVER THE GULF OF ALASKA.
THIS UPPER LOW IS SUPPORTING A LARGE STRONG SURFACE LOW IN THE
SOUTHERN GULF OF ALASKA. A FRONT EXTENDS IN AN ARC TO THE EAST TO
THE SOUTHERN PANHANDLE. AROUND THE BACK SIDE OF THIS LOW IS STRONG
NORTHERLY FLOW. IN THIS NORTHERLY FLOW SATELLITE IMAGERY SHOWS
SHOWERY CONDITIONS IN THE COLD ADVECTION AS EVIDENCED BY THE OPEN
CELL CUMULUS. THIS IS BRINGING SHOWERS TO THE PRIBILOFS TO THE
EASTERN ALEUTIANS AND ALASKA PENINSULA. TO THE WEST OF THIS IS A
WEAK RIDGE OF HIGH PRESSURE. A WEAK LOW IS JUST EAST OF THE
SOUTHERN KAMCHATKA PENINSULA PUSHING A FRONT ACROSS THE WESTERN
ALEUTIANS.

&&

.MODEL DISCUSSION...
THE MODELS REMAIN IN GOOD AGREEMENT THROUGH MONDAY MORNING. BY MON
EVENING DIFFERENCES SHOW UP WITH RESPECT TO THE LOW MOVING SOUTH
OF THE GULF OF ALASKA...THOUGH THIS WILL NOT HAVE ANY SIGNIFICANT
IMPACT TO THE FORECAST SOLUTIONS FOR THE GULF COAST AREAS. THE
MODELS ARE IN GOOD AGREEMENT BRINGING THE LOW SOUTH OF THE GULF
TO THE NORTH GULF COAST PUSHING THE LOW INLAND NEAR SEWARD MON
AFTERNOON. THE ASSOCIATED FRONT PUSHES TO THE NORTH GULF COAST BY
SUN MORNING BRINGING WITH IT WARM AIR ALOFT. AROUND THE NORTHWEST
SIDE OF THIS LOW COLD AIR WILL REMAIN IN PLACE OVER SOUTHWESTERN
ALASKA. FURTHER TO THE WEST IS THE LOW AND ASSOCIATED FRONT
IMPACTING THE WESTERN ALEUTIANS. THIS LOW WILL TRACK EAST AS WILL
THE ASSOCIATED FRONT PUSHING WARM AIR ACROSS THE ALEUTIANS. A LOW
FORMS ALONG THE FRONT NEAT SEGUAM ISLAND TONIGHT THAT WILL TRACK
EAST SOUTHEAST TO SOUTH OF THE GULF OF ALASKA.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
THE UPPER LEVEL TROUGH IS MAINTAINING THE THREAT OF SHOWERS OVER
THE SOUTH CENTRAL REGION AND NORTH GULF COAST THROUGH THIS
EVENING. AS THE LOW AND FRONT MOVE IN ALONG THE NORTH GULF COAST
THROUGH MON AFTERNOON RAIN CAN BE EXPECTED ALONG THE COASTAL SIDE
OF THE CHUGACH MOUNTAINS. THE FLOW ALOFT WILL BE SOUTHEASTERLY
RESULTING IN THE TYPICAL PRECIPITATION SHADOW ALONG THE WEST SIDE
OF THE CHUGACH MOUNTAINS. THEREFORE WE WILL MAINTAIN THE CHANCE OF
PRECIPITATION FOR THE NORTHERN COOK INLET REGION TO THE MATANUSKA
VALLEY. PRECIPITATION WILL BE IN THE FORM OF RAIN AT THE LOWER
ELEVATION WHILE THE THE HIGHER ELEVATIONS OF THE CHUGACH WILL
LIKELY SEE SNOW ABOVE 3000 FEET. COLD AIR WILL REMAIN TRAPPED OVER
THE COPPER RIVER BASIN AND ANY PRECIPITATION WILL FALL AS
SNOW...THOUGH THE CHANCES REMAIN LOW AT THIS TIME.

SOUTHWEST ALASKA...
THE COLDER AIR REMAINS OVER SOUTHWEST ALASKA UNDER THE UPPER LEVEL
TROUGH. THIS TROUGH IS SQUEEZING OUT SOME LIGHT SNOW OVER THE
KUSKOKWIM DELTA. SCATTERED SNOW SHOWERS ARE EXPECTED TO PERSIST
ACROSS SOUTHWEST ALASKA UNDER THE UPPER LEVEL TROUGH THROUGH MON.
OVER THE BRISTOL BAY REGION THE SURFACE TEMPERATURES AND LOW LEVEL
AIR IS SLIGHTLY WARMER...THUS ANY SNOW SHOWERS WILL BE MIXED WITH
RAIN THROUGH THIS EVENING AND AGAIN SUN AFTERNOON. THE STRONGER
GUSTY NORTH WINDS WILL PERSIST ALONG THE BERING SEAS COAST TO
BRISTOL BAY AND THE EASTERN ALASKA PENINSULA THROUGH THE
BEGINNING OF NEXT WEEK AS A TIGHT PRESSURE GRADIENT PERSISTS.

BERING SEA/ALEUTIANS...
THE FRONT MOVING ACROSS THE ALEUTIANS IS NOT PARTICULARLY STRONG
BY ALEUTIANS STANDARDS...SMALL CRAFT TO MINIMAL GALE FORCE WIND...AND
THE MAIN IMPACT WILL BE CLOUDS AND PRECIPITATION. AS THE LOW MOVES
EAST THEN SOUTH THROUGH MON THE WIND FLOW WILL BECOME NORTHERLY
AND OVERALL CONDITIONS WILL BECOME DRIER FOR THE BEGINNING OF THE
WEEK.

&&

.LONG TERM FORECAST...

IT IS NOW LIKELY THAT A NORTH PACIFIC LOW EARLY NEXT WEEK WILL
STRUGGLE TO REACH AS FAR NORTH AS THE EXTREME SOUTHERN GULF.
BECAUSE OF THIS CONFIDENCE IS INCREASING THAT THE SOUTHERN
MAINLAND WILL SEE A CLEARING...DRYING...AND COOLING TREND STARTING
ON TUESDAY THAT WILL CONTINUE FOR A MAJORITY OF THE UPCOMING
WEEK. THIS SYSTEM WILL ALSO DRAG DOWN SOME OF THE COLDEST AIR OF
THE SEASON BY LATE IN THE WEEK...POSSIBLY DIPPING BELOW ZERO IN
THE COPPER RIVER BASIN AND NORTHERN SUSITNA VALLEY.

OUT WEST LITTLE HAS CHANGED IN THE LONG TERM FORECAST. GUSTY
NORTHWESTERLY WINDS AND SHOWERS WILL BEGIN TO DIMINISH ON
WEDNESDAY IN ADVANCE OF RIDGING THAT WILL EVENTUALLY SPREAD ONTO
THE SOUTHERN MAINLAND. BY LATE IN THE WEEK...A FRONT ASSOCIATED
WITH A KAMCHATKA WILL BRING THE NEXT ROUND OF RAIN AND WINDS TO
THE WESTERN BERING AND ALUETIANS.

&&

AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 155 165 170 172 178 411 414.
FIRE WEATHER...NONE.

$$

SAM/DEK OCT 14


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