Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 261413
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
513 AM AKST FRI DEC 26 2014

.ANALYSIS AND UPPER LEVELS...
AN UPPER LEVEL TROUGH IS POSITIONED EAST OF THE BERING STRAIT
EXTENDING SOUTHWARD THROUGH SOUTHWEST ALASKA THROUGH KODIAK ISLAND
INTO THE NORTH PACIFIC THIS MORNING. WHILE THE SOUTHWEST AND
SOUTHCENTRAL ALASKA REGIONS HAVE WEAK SHORTWAVES MOVING THROUGH
THE REGIONS. THE EASTERN ALEUTIANS HAS AN UPPER LEVEL RIDGE OF
HIGH PRESSURE EXTENDING NORTHWARD THROUGH THE PRIBILOF ISLANDS
INTO SAINT MATTHEW ISLAND REGION. THE WESTERN ALEUTIANS HAS AN
UPPER LEVEL CLOSED LOW JUST NORTH OF SHEMYA. THIS IS REFLECTED AT
THE SURFACE WITH A STORM FORCE LOW NEAR SHEMYA. THE SATELLITE
IMAGERY IS SHOWING A LARGE COMMA CLOUD OF MOISTURE THROUGH THE
WESTERN TO EASTERN ALEUTIANS SPILLING OVER INTO THE BERING SEA.
THE FRONTAL BOUNDARY ASSOCIATED WITH THE LOW PRESSURE SYSTEM IS
LOCATED JUST WEST OF NIKOLSKI THIS MORNING WITH A STRONG 160 KNOT
SOUTH TO NORTH MERIDIONAL JET STREAK THROUGH THE SAME AREA
TRACKING INTO THE EASTERN BERING SEA. THE ASCAT SCATTEROMETER
WINDS THIS MORNING ARE SHOWING GALE FORCE WINDS THROUGH THE
AFOREMENTIONED REGION.


&&

.MODEL DISCUSSION...
THE MODELS ARE IN GOOD AGREEMENT WITH THE REMNANTS OF THE
OCCLUDED LOW THAT HAS BECOME ALMOST STATIONARY JUST NORTH OF
SHEMYA BEFORE GRADUALLY MOVING TOWARD THE KAMCHATKA PENINSULA. THE
NEXT NORTH PACIFIC LOW WILL TRACK TOWARDS THE CENTRAL ALEUTIANS BY
SUNDAY AFTERNOON. THE MODELS ARE STRUGGLING WITH THE POSITION AND
STRENGTH OF THE AFOREMENTIONED SYNOPTIC FEATURES. THERE IS A WEAK
TROUGH OVER SOUTHWEST ALASKA WITH A RIDGE OF HIGH PRESSURE
UPSTREAM OVER THE EASTERN ALEUTIANS EXTENDING SOUTHWARD TO THE
NORTH PACIFIC HIGH NEAR 48N 160W. THIS HIGH PRESSURE WILL MOVE
INTO THE GULF OF ALASKA THROUGH THE WEEKEND. THE FORECAST
CONFIDENCE REMAINS AVERAGE THROUGH SATURDAY AND BEGINS TO WEAKEN
WITH THE UNCERTAINTY OF THE NORTH PACIFIC LOW TRACKING TOWARDS THE
CENTRAL ALEUTIANS.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (DAYS 1 AND 2)...
THERE IS AN UPPER LEVEL WEAK SHORTWAVE THAT WILL CONTINUE TO PUSH
THROUGH THE SOUTHWEST ALASKA REGION THIS MORNING. THIS WILL BRING
A BRIEF ROUND OF SNOW SHOWERS TO THE REGION BEFORE TAPERING OFF
WITH A RIDGE OF HIGH PRESSURE MOVING INTO THE AREA THROUGH
TONIGHT. THIS WILL RESULT IN ONSHORE FLOW WITH SOUTHERLY FLOW
WHICH WILL INCREASE THE TEMPERATURES HEADING INTO THE WEEKEND WITH
AREAS OF MARINE LAYER STRATUS AND FOG MOVING INLAND WITH THE
CONTINUED SOUTHERLY FLOW.


&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (DAYS 1 AND 2)...
THE OCCLUDED NORTH PACIFIC LOW OVER THE WESTERN ALEUTIANS WILL
BRING A LARGE SWATH OF GUSTY STORM WINDS TO THE WESTERN AND
CENTRAL BERING SEA. THE ASSOCIATED WEATHER FRONT WITH THIS SYSTEM
WILL BE LOCATED NEAR UNALASKA THIS MORNING EXTENDING INTO THE
EASTERN BERING SEA. THIS WILL RESULT IN GALE FORCE WINDS THROUGH
THE EASTERN BERING SEA AND EASTERLY STORM FORCE WINDS THROUGH
SAINT MATTHEW REGION. BY SATURDAY EVENING A NORTH PACIFIC LOW WILL
TRACK TOWARD THE CENTRAL ALEUTIANS. THIS WILL BRING ANOTHER ROUND
OF RAIN AND GUSTY WINDS TO THE ALEUTIANS BEFORE SPILLING OVER INTO
THE BERING SEA. THE TEMPERATURES WILL REMAIN ABOVE FREEZING WITH
THE WARM SOUTHERLY FLOW THROUGH THE WEEKEND.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (DAYS 1 AND 2)...
SCATTERED SHOWERS LINGER IN THE AREA WITH THE SOUTHWESTERLY FLOW.
THEN THIS AFTERNOON A SHORTWAVE MOVES THROUGH THE AREA FROM THE
NORTHWEST. IT WILL KICK UP MORE SNOW SHOWERS AROUND THE ANCHORAGE
BOWL UP INTO THE SUSITNA VALLEY INTO EARLY THIS EVENING...WITH THE
MOST ACTIVITY ALONG THE MOUNTAINS. THEN STRONG RIDGING WILL PUSH
IN FROM THE WEST CLEARING OUT THE SKIES FOR SATURDAY.

&&

.LONG TERM FORECAST (SUNDAY THROUGH THURSDAY)...

ON SUNDAY AND MONDAY...AN AMPLIFIED UPPER LEVEL RIDGE OVER
EASTERN ALASKA WILL BRING STRONG SOUTHERLY FLOW AND UNSEASONABLY
WARM TEMPERATURES TO SOUTHCENTRAL ALASKA. A LOW PRESSURE SYSTEM
SOUTH OF THE ALEUTIANS WILL TAP INTO AN ATMOSPHERIC RIVER WITH
AMPLE SUBTROPICAL MOISTURE MONDAY RESULTING IN PLENTY OF
PRECIPITATION TO AREAS OF SOUTHWEST ALASKA IN THE EARLY WEEK. THE
BAND OF PRECIPITATION WILL MOVE INTO SOUTHCENTRAL ALASKA MONDAY
NIGHT INTO TUESDAY. AREAS ON THE GULF COAST WILL SEE HEAVY AT
TIMES PRECIPITATION FROM THIS MOISTURE PLUME WHICH...GIVEN THE
WARMING DUE TO THE STRONG SOUTHERLY FLOW...SHOULD FALL MAINLY AS
RAIN. AREAS FARTHER INLAND SHOULD SEE SOME MIXED PRECIPITATION
THROUGH THE MIDDLE OF THE WEEK. AS THE LOW PRESSURE SYSTEM MOVES
NORTHWARD OVER THE BERING SEA...THE PRESSURE GRADIENT BETWEEN THE
AFOREMENTIONED SYSTEM AND THE HIGH PRESSURE ASSOCIATED WITH THE
UPPER LEVEL RIDGE FARTHER EAST WILL STRENGTHEN. THIS WILL CREATE
SOME STRONGER GAP WINDS TO THE TURNAGAIN ARM AND OTHER FAVORED
GAPS. TROUGHING MOVING IN FROM THE BERING SEA WILL PUSH THE RIDGE
OVER MAINLAND ALASKA EASTWARD...BRINGING A RETURN TO MORE ZONAL
FLOW AND DRIER CONDITIONS OVER SOUTHCENTRAL ALASKA WEDNESDAY INTO
THURSDAY. A RIDGE WILL PROGRESS QUICKLY EASTWARD FROM SOUTHWEST
ALASKA WEDNESDAY BEFORE STALLING AND AMPLIFYING OVER THE MAINLAND
TOWARDS THE END OF THE WEEK.



&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 150 155 165 170 172 175 177 179 180 181.
         STORM 173 174 176 178 185.
         HEAVY FREEZING SPRAY 185.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...PD
SOUTHCENTRAL ALASKA...DK
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PD
LONG TERM...RD


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