Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 172137
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
137 PM AKDT FRI OCT 17 2014

.ANALYSIS AND UPPER LEVELS...

UPPER LEVELS...
CURRENT WATER VAPOR SATELLITE IMAGERY SHOWS A NEGATIVELY TILTED
TROUGH EXTENDING SE FROM THE WESTERN INTERIOR ACROSS THE BARREN
ISLANDS. MID AND HIGH LEVEL MOISTURE STREAMING TO THE NW IS
EVIDENT WITH THIS FEATURE. THE BROADENING UPPER LEVEL LOW WAS
POSITIONED SOUTH OF THE AK PEN WITH ANOTHER LOW NEAR THE SW
ALASKA COAST. AN AMPLIFYING RIDGE WAS EVIDENT ACROSS THE WESTERN
BERING SEA WITH MOISTURE ASSOCIATED WITH A SURFACE FRONT MOVING
TOWARD THE WEST ALEUTIANS AND KAMCHATKA PEN.

THE TROUGH CONTINUES TO DIG OVER THE GULF/NE PACIFIC THROUGH
TONIGHT AS AN AMPLIFYING RIDGE OVER THE BERING SEA PUSHES COLD
AIR SOUTH. THE LOW NEAR THE SW ALASKA COAST BECOMES THE PIVOT
POINT AS WAVES MOVES ACROSS THE NORTH PACIFIC. THE TROUGH OVER
THE NE PACIFIC LIFTS N AND E AS THE BERING SEA RIDGE WEAKENS
ALLOWING A STRONG WAVE TO PROGRESS EASTWARD ACROSS THE NORTH
PACIFIC.

SURFACE...
A WESTWARD MOVING LOW OVER THE NE GULF GENERATED AN EASTERLY
COASTAL JET OF AROUND 35 KT. SHOWERS ASSOCIATED THIS LOW WERE
MOVING WEST ACROSS PRINCE WILLIAM SOUND. RAIN ASSOCIATED WITH AN
UPPER TROUGH WAS EVIDENT FROM THE SOUTHERN SUSITNA VALLEY TO THE
KENAI PEN THIS MORNING. THE RAIN THIS AFTERNOON HAS SHIFTED MORE
TOWARD THE SOUTHERN KENAI/WESTERN COOK INLET.
OUT WEST...STRONG AND GUSTY NORTHERLY WINDS WITH COLD ADVECTION
WAS EVIDENT ACROSS THE CENTRAL AND EASTERN ALEUTIANS. THE EXTENT
OF THE COLD ADVECTION OVER THE NORTH PACIFIC IS EVIDENCED BY THE
PRESENCE OF OPEN CELL CU WELL SOUTH OF THE ALEUTIANS. SHOWERS WERE
ALSO PRESENT OVER MUCH OF ALEUTIANS AND AK PEN AS WELL WAS BRISTOL
BAY.

&&

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT WITH THE OVERALL SYNOPTIC PATTERN
THROUGH SUNDAY NIGHT.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
SHOWERS/RAIN ACROSS THE KENAI PEN WILL TAPER OFF SOME THROUGH
TONIGHT. THE THREAT OF SHOWERS WILL CONTINUE THROUGH THE WEEKEND
WAS WAVES PIVOT AROUND THE UPPER CENTER ANCHORED NEAR SW ALASKA.
INCREASED CHANGES OF STEADY PRECIPITATION DEVELOP ALONG THE
COASTS...KENAI PEN/ANCHORAGE BOWL...SUN NIGHT AND MON MORNING AS
THE LOW COMPLEX OVER THE NE PACIFIC MOVES TO NEAR THE EASTERN
KENAI PEN. AT THIS TIME 850 MB TEMPS AND THICKNESS VALUES WOULD
SUPPORT RAIN ALONG THE COASTS AND POSSIBLY MIXED WEST OF THE
CHUGACH.

SOUTHWEST ALASKA... THE SOUTHWESTERN MAINLAND WILL SEE SCATTERED
RAIN AND SNOW ACTIVITY THROUGH THE WEEKEND AS A TROUGH OF LOW
PRESSURE PERSISTS. A COOLER AIR MASS MOVES IN SATURDAY NIGHT WHICH
CHANGES PRECIPITATION TO PRIMARILY ALL SNOW FOR SUNDAY. STRONG
GUSTY NORTHERLY WINDS ACROSS ACROSS THE AK PEN TONIGHT AND
CONTINUE INTO SUN BEFORE WEAKENING.

BERING SEA/ALEUTIANS...
GUSTY WINDS ACROSS THE EASTERN GULF/ALEUTIANS WILL CONTINUE
THROUGH SATURDAY MORNING AND THEN TAPER OFF AS THE SURFACE LOW
MOVES EAST. LIGHT RAIN AND SNOW SHOWERS WILL CONTINUE ALONG A
WEAK WAVE THAT PUSHES EAST ACROSS THE BERING INTO SATURDAY
MORNING. ANOTHER FRONT WILL MOVE INTO THE WESTERN ALEUTIANS LATE
TONIGHT AND SLOWLY PUSH A FRONT INTO THE CENTRAL BERING AND
EASTERN ALEUTIANS BY SUNDAY MORNING. RAIN AND GUSTY WINDS DEVELOP
ALONG THE FRONT WITH SOUTH TO EAST ALONG THE BOUNDARY AS IT
STRETCHES SLOWLY TOWARD THE WEST COAST.


&&

.LONG TERM FORECAST...
WHILE THERE REMAINS MODEL DISAGREEMENT WITH LOW LOCATION NEAR THE
GULF INTO THE MIDDLE OF NEXT WEEK...THE GENERAL LONG TERM FORECAST
PATTERN REMAINS UNCHANGED SINCE YESTERDAY. AFTER THE NEXT GULF LOW
DISSIPATES OVER THE GULF COAST ON MONDAY...THE LONGWAVE TROUGH
CURRENTLY OVER THE EASTERN BERING WILL SLOWLY MIGRATE INTO THE
SOUTHERN GULF BY MID WEEK. THIS SETUP WILL KEEP A SERIES OF GULF
LOWS CONFINED TO THE SOUTHERN GULF OR NORTH PACIFIC...AND THE
MODELS ARE TRENDING FURTHER TO THE SOUTH. AS LONG AS THIS TREND
CONTINUES...THE CHANCES OF PRECIPITATION AND GAP WINDS WILL ALSO
DIMINISH...INCLUDING FOR THE GULF COAST. OUT WEST...RIDGING OVER
THE WESTERN BERING WILL MOVE TO THE WEST COAST BY MID WEEK...THEN
SPREAD OVER THE MAINLAND LATE NEXT WEEK. THIS WILL CAUSE GUSTY
NORTHERLY FLOW AND SHOWERS TO DEVELOP OVER THE EASTERN BERING AND
ALEUTIANS UNTIL WEDNESDAY...WHEN RIDGING WILL APPROACH THE AREA.

&&


AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 155 165 170 171 172 173 174.
FIRE WEATHER...NONE.


$$

RMC/DEK OCT 14



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