Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 161355
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
555 AM AKDT TUE SEP 16 2014

.ANALYSIS AND UPPER LEVELS...
A BROAD UPPER LOW IS CENTERED OVER THE BERING NEAR THE PRIBILOF
ISLANDS. THIS LOW IS MOVING A SHORTWAVE INTO THE SOUTHERN MAINLAND
AND HAS PRODUCED A FEW LIGHTENING STRIKES ALONG THE NORTHEAST
GULF. ALONG THE BASE OF THE LOW...A SHORT WAVE IS MOVING A NORTH
TO SOUTH ORIENTED FRONT WHICH STRETCHES JUST SOUTH OF NUNIVAK
ISLAND TO THE EASTERN ALASKA PENINSULA.

&&

.MODEL DISCUSSION...
MODELS REMAIN IN GOOD AGREEMENT WITH THE OVERALL SYNOPTIC PATTERN
THROUGH WEDNESDAY NIGHT AND THEN BEGIN TO DIVERGE IN SOLUTIONS.
THE MAIN CHALLENGE IS THE TIMING AND TRACK OF THE BERING FRONT
THAT MOVES INTO GULF ON WEDNESDAY. MODELS MERGE TWO EASTWARD
TRACKING SURFACE LOWS...FROM THE BERING AND THE NORTH
PACIFIC...INTO ONE BROAD CENTER EARLY THURSDAY MORNING IN THE
SOUTHERN GULF. THIS LOW PUSHES A FRONT INTO THE AHEAD OF IT
BRINGING ANOTHER ROUND OF PRECIPITATION AND GUSTY WINDS ACROSS THE
GULF AND COASTAL AREAS WITH RAIN SPREADING INLAND ACROSS
SOUTHCENTRAL WEDNESDAY AND THURSDAY. THE GREATEST UNCERTAINTY IS
HOW THE SURFACE LOW MEANDERS ACROSS THE GULF THROUGH FRIDAY.
MODELS ARE CURRENTLY PROJECTING THE LOW TO STAY IN THE GULF WITH A
WESTWARD REGRESSION THURSDAY NIGHT. RAIN AND GUSTY WINDS WILL NEED
ADJUSTMENTS AS MODEL SOLUTIONS GET A BETTER RESOLUTION OF THIS
DEVELOPING SYSTEM.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
ISOLATED THUNDERSTORMS ALONG THE NORTHEASTERN GULF WILL COME TO AN
END LATER THIS MORNING AS THE UPPER WAVE MOVES INLAND. RAIN
ACTIVITY WILL BE HEAVIEST ACROSS THE SUSITNA VALLEY...NORTHERN
GULF COAST AND UPSLOPE AREAS OF THE COPPER RIVER VALLEY. THE NEXT
FRONT MOVES INTO THE WESTERN GULF TUESDAY NIGHT AND TRACKS QUICKLY
INTO THE NORTHERN GULF WEDNESDAY AFTERNOON. SOUTHCENTRAL WILL SEE
MEASURABLE RAINFALL WITH THIS FRONT...WITH THE MOST APPRECIABLE
AMOUNTS ALONG THE GULF COASTAL AREAS AND THE SUSITNA VALLEY. GUSTY
GALE FORCE WINDS INCREASE ACROSS THE GULF WATERS AS THE FRONT
MOVES THROUGH WITH A CHANGE OF WIND DIRECTION AS THE LOW MEANDERS
AROUND THE GULF THROUGH FRIDAY.


SOUTHWEST ALASKA...
RAIN AND GUSTY WINDS WILL TAPER OFF ALONG THE ALASKA PENINSULA
LATER TODAY AS THE BERING FRONT MOVES INTO THE SOUTHWESTERN
MAINLAND LATER THIS AFTERNOON. RAIN SPREADS INTO BRISTOL BAY THIS
AFTERNOON ALONG WITH AN INCREASE IN EASTERLY WINDS ALONG THE
FRONT. THE KUSKOKWIM VALLEY AND DELTA WILL SEE INCREASE RAIN
CHANCES TONIGHT WITH THE GREATEST RAINFALL EXPECTED ACROSS THE
WESTERN ALASKA RANGE. A GENERAL NORTHERLY WIND PATTERN SETS UP
ACROSS THE SOUTHWEST BEHIND THE FRONT WITH ISOLATED TO SCATTERED
SHOWERS REMAINING IN THE FORECAST FOR THE SOUTHWEST AND ALASKA
PENINSULA AS LOW PRESSURE STALLS IN THE GULF BRINGING WRAP AROUND
PRECIPITATION THROUGH THE END OF THE WEEK.


BERING SEA/ALEUTIANS...
NORTH TO NORTHWEST WINDS RETURN ACROSS THE BERING AND ALEUTIANS AS
LOW PRESSURE SHIFTS ITS CENTER INTO THE GULF OF ALASKA. A SHOWERY
PATTERN WITH PATCHY FOG REMAINS OVER THE FORECAST AREA AS WEAK
WAVES MOVE AROUND THE BACKSIDE OF THE LOW. COOLER TEMPERATURES
ACROSS THE BERING WILL WARM SLIGHTLY ON FRIDAY ACROSS THE WESTERN
BERING AS RIDGING BUILDS IN BEHIND THE LOW.

&&

.LONG TERM FORECAST...
THE LONGWAVE PATTERN WILL STAY OVER THE GULF OF ALASKA THROUGH THE
WEEKEND WITH RIDGING BUILDING INTO BERING. THE RIDGE WILL BE SHORT
LIVED AS LOW PRESSURE FROM EASTERN RUSSIAN AND THE ARCTIC QUICKLY
BREAK IT DOWN BY MONDAY. LOW PRESSURE REMAINS THE DOMINANT PATTERN
THROUGH THE BEGINNING OF NEXT WEEK KEEPING A WETTER THAN NORMAL
PATTERN ACROSS THE SOUTHERN MAINLAND AND SURROUNDINGS WATERS.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALES 119 120 130 131 132.
FIRE WEATHER...NONE.

&&

$$

KH SEP 14


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