Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 011334
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
534 AM AKDT FRI AUG 1 2014

.ANALYSIS AND UPPER LEVELS...THE PATTERN CONTINUES TO BE DOMINATED
BY THE MASSIVE OMEGA BLOCK WHICH STRETCHES FROM THE KAMCHATKA
PENINSULA TO THE PANHANDLE OF ALASKA. THE RIDGE AXIS BASICALLY
STRADDLES LONGITUDE 172W-173W WITH ANCHOR LOWS UPSTREAM AND
DOWNSTREAM. THIS BLOCKING PATTERN IS KEEPING ANY SORT OF JET AWAY
FROM THE MAINLAND WITH JUST TWO WEAK FINGERS OF 70KTS AT ~28K FT
ALONG THE PERIPHERY OF THE RIDGE. A 75KT FINGER IS ALSO STARTING
TO APPEAR ALONG THE EAST SIDE OF THE EASTERN-MOST CUT-OFF LOW.
THIS WILL SERVE TO PUSH THIS LOW EVER SO SLOWLY NORTHWARD AND
CREATE THE CHANGE IN THE PATTERN THAT WE WILL ADDRESS IN THIS
DISCUSSION.


&&

.MODEL DISCUSSION...MODELS REMAIN IN VERY GOOD AGREEMENT THROUGH
SATURDAY AFTERNOON LEADING TO ABOVE AVERAGE CONFIDENCE IN THE
FORECAST. BEYOND THAT... SOME DISCREPANCIES EMERGE WITH THE
HANDLING OF THE CUT-OFF LOW IN THE GULF AND HOW FAST IT MOVES
NORTHWARD. THE GFS HAS BEEN THE OUTLIER BEING THE FASTEST AND THE
STRONGEST WITH THIS FEATURE...SO IT WAS MORE OR LESS RULED OUT FOR
THIS FORECAST PACKAGE. THE RUN TO RUN CONSISTENCY OF THE EC AND
THE GEM REGIONAL SHOWED LITTLE CHANGE SO THEY WERE HEAVILY
UTILIZED.


&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...COASTAL RIDGING CONTINUES TO CREATE A STABLE
ATMOSPHERE ACROSS THE AREA. THIS IS LEADING TO ANOTHER MORNING OF
LOW STRATUS AROUND THE ANCHORAGE BOWL AND SOME PATCHY FOG STARTING
TO CREEP THROUGH KACHEMAK BAY. BOTH OF THESE FEATURES SHOULD YIELD
QUICKLY TO ANOTHER PARTLY CLOUDY DAY WITH SEASONAL TEMPERATURES.
THE EXCEPTION TO THIS WILL BE UP TOWARDS THE SUSITINA
VALLEY/COPPER RIVER BASIN WHERE A WEAK WAVE WILL PUSH UP AGAINST
THE ALASKA/TALKEETNA RANGE AND HELP TO BRING INCREASING RAIN
CHANCES THIS AFTERNOON. AT THIS TIME...IT STILL LOOKS LIKE THE
ALASKA RANGE WILL KEEP THIS SYSTEM FROM MAKING IT ANY FURTHER
SOUTH...SO MOST AREAS WILL JUST SEE AN INCREASE IN MID AND UPPER
LEVEL CLOUDS.

FOR THE WEEKEND...THE CLOSED LOW IN THE GULF WILL FINALLY START TO
MAKE SLOW PROGRESS NORTHWARD. RAIN WILL BE LIKELY FOR KODIAK
SATURDAY NIGHT AND THEN SPREAD TOWARDS THE GULF COAST SUNDAY
MORNING. WE WILL INTRODUCE A CHANCE OF RAIN FOR THE ANCHORAGE AREA
DURING THE DAY SUNDAY. AS THIS LOW DRAWS CLOSER TO THE COAST...IT
WILL WORK IN CONJUNCTION WITH THE COASTAL RIDGE TO INCREASE THE SE
TO NW GRADIENT ACROSS THE AREA. THEREFORE...EXPECT TYPICAL AREAS
LIKE THE TURNAGAIN ARM AND THE MAT VALLEY TO SEE AN UPTICK IN
WINDS. BUT AS THE FRONT IS ALREADY STARTING TO FALL APART BY THE
TIME IT REACHES THE AREA...DON`T ANTICIPATE ANYTHING BEYOND RUN-
OF-THE-MILL WINDS AND PRECIPITATION.

SOUTHWEST ALASKA...THE WAVE CURRENTLY SLIDING DOWN THE EASTERN
SIDE OF THE BERING RIDGE IS BRINGING WIDESPREAD PRECIPITATION AND
LOW CEILINGS FROM THE YK-DELTA TOWARDS THE AHKLUN MOUNTAINS. THIS
SYSTEM WILL FOLLOW THE "PATH OF LEAST RESISTANCE" TOWARDS THE
SOUTHWEST BETWEEN THE RIDGE AND THE CLOSED LOW IN THE GULF. IT
WILL LEAVE JUST SOME SHOWERS IN ITS WAKE FOR SATURDAY. BY SUNDAY
THE LOW IN THE GULF WILL HAVE MIGRATED FAR ENOUGH NORTHWARD THAT
IT WILL SPREAD SOME COOLING TEMPERATURES ALOFT. AMPLE SUNSHINE
SUNDAY MORNING SHOULD LEAD TO A RATHER UNSTABLE
ATMOSPHERE...ESPECIALLY ALONG THE AK RANGE...BY SUNDAY AFTERNOON.
FOR NOW WE WENT WITH SHOWERS IN THE FORECAST...BUT UNLESS THERE IS
A SIGNIFICANT CHANGE IN THE MODELS...THERE COULD BE A DECENT
CHANCE OF THUNDERSTORMS ALONG THE MOUNTAINS.

BERING SEA/ALEUTIANS...FOG AND STRATUS IS THE STORY. SUBSIDENCE
UNDER THE RIDGING IS KEEPING MOISTURE TRAPPED AT THE SURFACE FOR
MOST OF THE BERING IN THIS PATTERN AND THIS WILL CONTINUE AT LEAST
THROUGH THE WEEKEND. THE WEAK DISTURBANCE MOVING THROUGH THE
SOUTHWEST WILL HELP TO BREAK THINGS UP WITH SOME RAIN AND
NORTHERLY FLOW FOR THE EASTERN ALEUTIANS LATER TODAY AND INTO
SATURDAY. BY EARLY NEXT WEEK...THE RIDGE WILL SLOWLY START TO
WEAKEN...BUT THE OVERALL PATTERN WILL NOT CHANGE TOO MUCH.


&&

.LONG TERM FORECAST...THE OMEGA BLOCK OVER THE BERING SEA WILL
START TO WEAKEN THROUGH THE EARLY PART OF NEXT WEEK. STRATUS AND
FOG WILL PERSIST OVER THE BERING WITH RELATIVELY LIGHT WINDS FOR
MOST AREAS THROUGH MONDAY. AN UPPER LEVEL WEAK SHORTWAVE TROUGH
WILL DROP DOWN FROM THE UPPER KUSKOKWIM VALLEY INTO THE SOUTHWEST
ALASKA REGION BY MONDAY. THIS WILL BRING INCREASED CLOUDS AND
SHOWERS THROUGHOUT THE AREA. THE UPPER LEVEL LOW WILL CONTINUE TO
MEANDER THROUGH THE SOUTHWESTERN GULF OF ALASKA MONDAY. AN
INVERTED TROUGH ASSOCIATED WITH THIS LOW WILL EXTEND THROUGH THE
ALASKA PENINSULA AND THROUGH THE ALASKA RANGE. THIS WILL BRING
NORTHEASTERLY WINDS AND INCREASED CLOUD COVER WITH RAIN ALONG THE
COASTLINE AND SPREADING INLAND THROUGH THE EARLY PART OF NEXT
WEEK. MODELS ARE IN SURPRISINGLY GOOD AGREEMENT FOR THE MIDDLE TO
END OF NEXT WEEK SHOWING ENERGY FROM ASIA JOINING INTO THE WESTERN
ANCHOR LOW OVER THE BERING. THIS LOW THEN TRIES TO MERGE WITH THE
ANCHOR LOW OVER THE GULF WHILE THE UPPER LEVEL RIDGING DRIFTS OVER
THE NORTHERN PORTION OF THE STATE. THIS COULD BECOME YET ANOTHER
BLOCKING PATTERN BY WEEK`S END WHICH WOULD RESULT IN MOST ACTIVE
WEATHER STAYING AWAY FROM THE MAINLAND WITH JUST LIGHT WINDS AND
DIURNAL SHOWERS.


&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.
&&

$$

MSO/PD AUG 14


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