Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 222143
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
143 PM AKDT WED OCT 22 2014

.ANALYSIS AND UPPER LEVELS...

500MB...A BROAD LOW COMPLEX WITH SEVERAL CENTERS WERE EVIDENT
OVER THE GULF AND NE PACIFIC. A HIGH AMPLITUDE RIDGE WAS PRESENT
OVER THE EASTERN BERING SEA WITH A TROUGH JUST EAST OF THE
KAMCHATKA PENINSULA. THE GULF LOW COMPLEX WILL CONTINUE TO SLOWLY
WEAKEN AND DRIFT SE THROUGH FRI. A TROUGH MOVING ACROSS EASTERN
RUSSIA/BERING SEA FLATTENS THE RIDGE AND SHOVES IT EAST AS IT
MOVES OVER THE CENTRAL MAINLAND FRI MORNING. AS A RESULT...NEARLY
ZONAL WESTERLY FLOW SETS UP OVER THE THE BERING SEA. THIS WILL
ALLOW UPPER WAVES AND ASSOCIATED FRONTAL TROUGHS TO PROGRESS
EASTWARD ACROSS THE BERING AND BRING UNSETTLED WEATHER TO THE
REGION.

NEAR SURFACE...THE MAIN LOW CENTER OVER THE GULF CONTINUES TO MOVE
WSW AND SLOWLY WEAKEN. ITS ASSOCIATED FRONTAL BOUNDARY OVER THE
NORTHERN GULF PRODUCED SOME SHOWERS ON ITS LEADING EDGE. WITH THE
EXCEPTION OF STRATUS AND FOG OVER THE COPPER RIVER
BASIN...SOUTHCENTRAL WAS RELATIVELY CLEAR. OUTFLOW WINDS WERE
EVIDENT ALONG THE NORTH GULF COAST WITH BRISK WINDS ACROSS THE
MARINE ZONES. OUT WEST...COLD NORTHERLY FLOW CONTINUED OVER THE
EASTERN BERING AND WESTERN AK PEN AND STREAMED SOUTH INTO THE
NORTH PACIFIC. A FRONTAL TROUGH MOVING OVER THE WESTERN BERING
SEA SET UP BRISK SOUTHERLY FLOW OVER THE WESTERN ALEUTIANS.

&&

.MODEL DISCUSSION...
THE NUMERICAL MODELS ARE IN GENERALLY GOOD AGREEMENT IN THE SHORT
TERM. TIMING OF THE FIRST FRONTAL TROUGH CROSSING THE BERING SEA
TONIGHT AND THU IS SIMILAR ON ALL THE MODELS. SOME TIMING ISSUES
ARISE WITH THE NEXT COUPLE OF FRONTS WHICH TYPICALLY OCCURS UNDER
STRONG ZONAL FLOW IN THE UPPER LEVELS.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
QUIET WEATHER WILL PREVAIL ACROSS MOST OF SOUTHCENTRAL ALASKA AS
DRY OFFSHORE FLOW PERSISTS THROUGH TONIGHT. THE LACK OF A STRONG
PUSH OF DRY AIR INTO THE COPPER BASIN WILL LIKELY KEEP SOME DEGREE
OF LOW LEVEL CLOUDS AND PATCHY FOG IN THE BASIN...BUT MOST OTHER
LOCATIONS WILL STAY DRY AND LARGELY CLEAR. SOME RAIN SHOWERS
WILL IMPACT THE NORTH GULF COAST AND PRINCE WILLIAM SOUND THIS
EVENING AND TONIGHT. A FRONT MOVING IN FROM THE WEST WILL SPREAD
CLOUDS WITH A CHANCE OF SNOW INLAND FRI AND SAT WITH A MIX
ELSEWHERE. AT THIS TIME...IT LOOKS AS THOUGH MOST OF THE
PRECIPITATION WITH THIS FEATURE WILL FALL WEST OF THE ALASKA
RANGE. OUTFLOW WINDS WILL DIMINISH ACROSS THE NORTH GULF
OVERNIGHT... THOUGH THE EASTERN KENAI AND WESTERN COASTAL MARINE
AREAS WILL CONTINUE TO SEE BRISK W TO NW WINDS.

SOUTHWEST ALASKA...
LARGELY QUIET WEATHER WILL PREVAIL AS THE PRESSURE GRADIENT
BECOMES OFFSHORE/OUTFLOW ACROSS THE REGION. NORTHERLY WINDS WILL
BECOME GUSTY TODAY...ESPECIALLY ACROSS THE BRISTOL BAY COAST AND
THROUGH GAPS IN THE ALASKA RANGE. A FRONT WILL PROGRESS WEST TO
EAST THURSDAY MORNING THROUGH FRIDAY MORNING...BRINGING RAIN AND
SNOW TO THE COASTS AND MEASURABLE SNOW TO THE KUSKOKWIM VALLEY.
THERE IS ALSO A POSSIBILITY OF POCKETS OF LIGHT FREEZING RAIN IN
THE INTERIOR BRISTOL BAY ZONE LATER THU.

BERING SEA/ALEUTIANS...
NORTHERLY WINDS AND SHOWERS WILL RAPIDLY DIMINISH TODAY AS WEAK
HIGH PRESSURE BUILDS IN OVER THE CENTRAL AND EASTERN BERING. A
FAST MOVING FRONT WILL TRACK INTO THE WESTERN ALEUTIANS AND WILL
SPREAD TO THE EASTERN BERING BY THURSDAY NIGHT.

&&

.LONG TERM FORECAST...

MODELS CONTINUE TO STRUGGLE IN THE EXTENDED...AT LEAST PARTIALLY
DUE TO NO SATELLITE DATA BEING INGESTED. AGREED WITH WPC
ASSESSMENT THAT THE PREVIOUS FORECAST SHOULD ONLY BE MODIFIED
SLIGHTLY BY VARIOUS ENSEMBLE RUNS FOR NOW.

THE CURRENT SOLUTION BRINGS A WEAK TROUGH INTO THE NORTHEAST GULF
OF AK LATE SUN THAT PERSISTS INTO MIDWEEK WITH SPOTTY
PRECIPITATION AT BEST FOR MOST OF SOUTHCENTRAL AND THE GULF COAST.

A FRONT FROM A LOW OVER EASTERN RUSSIA WILL MOVE ACROSS THE BERING
ON TUE...AND A SECOND LOW OVER THE NORTHERN BERING WILL BRING A
SECOND FRONT TO THE WESTERN AK COAST ON THU. TIMING AND STRENGTH
OF BOTH OF THESE SYSTEMS IS STILL UNCERTAIN...BUT SMALL CRAFT TO
GALES ARE POSSIBLE ALONG WITH RAIN MIXING WITH SNOW THROUGH THE
MIDDLE OF NEXT WEEK.

SOUTHWEST AK WILL BE DRY UNTIL RAIN AND SNOW SHOWERS ARRIVE WITH
THE INITIAL FRONT TUE AND THE SECOND FRONT THU.

&&

AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE 150 155 170 172 185.
FIRE WEATHER...NONE.

&&

$$

RMC/DS OCT 14



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