Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 271710 CCA
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
505 AM AKDT SAT SEP 27 2014

.ANALYSIS AND UPPER LEVELS...
AN AMPLIFIED PATTERN RESIDES OVER ALASKA DEFINED BY OCCLUDED LOWS ON
EITHER SIDE OF A RIDGE THAT SITS OVER THE CENTRAL ALEUTIANS AND
CENTRAL BERING SEA. THE LOW ON THE EASTERN SIDE IS NOW SOUTH OF
KODIAK ISLAND AND IS SLOWLY FILLING. HOWEVER...IT IS STILL BRINGING
WINDY CONDITIONS TO THE ALASKA PENINSULA AND THE FRONT ASSOCIATED
WITH THIS LOW IS BRINGING RAIN TO THE NORTHERN GULF COAST. THE LOW
OUT WEST IS SOUTH OF THE ALEUTIANS BUT IS STILL CLOSE ENOUGH TO
BRING RAIN AND WINDS TO THE WESTERN ISLANDS.

&&

.MODEL DISCUSSION...
MODELS IN THE SHORT AND MID TERMS ARE IN PRETTY GOOD AGREEMENT
WITH THE 00Z RUNS AND ARE ONLY HAVING SLIGHT PRESSURE DIFFERENCES
AROUND 2 MB. THIS RESULTS IN OVERALL CONFIDENCE FOR THE SHORT AND
MID TERMS BEING ABOVE AVERAGE. IN THE LONG TERM THINGS START OUT
FINE BUT THE MODELS STRUGGLE WITH A LOW APPROACHING THE GULF ON
THURSDAY. THE EC PUSHES THE LOW OVER THE PANHANDLE WHILE THE GFS
IS DEEPER AND BRINGS THE LOW INTO THE GULF.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
A FRONT OVER THE NORTHERN GULF IS MAKING ITS WAY OVER THE
COASTLINE AND IS STARTING TO BRING RAIN TO THOSE AREAS. SOME OF
THIS RAIN MAY SQUEEZE ITS WAY THROUGH THE MOUNTAINS AND INTO MORE
INLAND AREAS OF THE SOUTHCENTRAL. THE PRESSURE GRADIENT DUE TO THE
LOW TO THE SOUTH WILL KEEP WINDS OUT OF THE NORTH THROUGH THE
WEEKEND. THE NEXT IMPACT WILL BE THE TROUGH MOVING IN FROM THE
NORTH MONDAY. THIS TROUGH WILL BRING COLDER AIR AND MORE
PRECIPITATION WITH IT.

SOUTHWEST ALASKA...
NORTHERLY WINDS WILL CONTINUE OVER THE SOUTHWEST AS THE LOW SOUTH
OF THE ALASKA PENINSULA WEAKENS AND DRIFTS EAST. RIDGING WILL
ALSO BE MOVING IN OVER THE SOUTHWEST THROUGHOUT THE DAY WHICH WILL
CLEAR OUT THE SKIES. AS THE RIDGE MOVES OFF TO THE SOUTH SUNDAY AN
UPPER LEVEL TROUGH WILL DROP DOWN FROM THE NORTH BRINGING
PRECIPITATION BACK TO THE AREA.

BERING SEA/ALEUTIANS...
THE LOW SOUTH OF THE ALASKA PENINSULA WILL BRING STRONGER WINDS
FOR THE PENINSULA THROUGHOUT THE DAY AND INTO SUNDAY. HIGH
PRESSURE WILL THEN MOVE OVER THE EASTERN ALEUTIANS AND ALASKA
PENINSULA DROPPING THE WINDS AND CLEARING OUT THE SKIES. OUT WEST
THE OTHER LOW WILL TRACK EAST AS IT REMAINS SOUTH OF THE
ALEUTIANS. AS IT GETS NEAR THE CENTRAL ALEUTIANS ON SUNDAY IT
WILL CHANGE COURSE AND START HEADING SOUTH. AS IT PASSES THE
WESTERN AND CENTRAL ALEUTIANS IT WILL BRING WINDS AND RAIN TO THE
AREAS.

&&

.LONG TERM FORECAST...
ALASKA WILL BE UNDER THE INFLUENCE OF A DRY AND COLD OUTFLOW WIND
PATTERN ON TUESDAY...WITH MODERATELY STRONG CHANNELED GAP WINDS
CONTINUING THROUGH TUESDAY BEFORE DIMINISHING WEDNESDAY. A
GENERALLY DRY NORTHWEST FLOW PATTERN ALOFT WILL CONTINUE OVER THE
MAINLAND AS A HIGHLY AMPLIFIED RIDGE ALOFT BUILDS OVER THE BERING
SEA...KEEPING THE STORM TRACK ALONG THE WESTERN PERIPHERY OF THE
BERING...AND SOUTH ACROSS THE NORTH PACIFIC. THE GFS...ECMWF...AND
ECMWF ENSEMBLE ALL DEPICT A SIMILAR LARGE SCALE PATTERN EVOLUTION
HEADING INTO THE WEEKEND WITH AN ARCTIC TROUGH DEEPENING OVER THE
MAINLAND OF ALASKA. THIS WOULD SUPPORT THE POTENTIAL FOR THE
COLDEST AIR OF THE SEASON...AND A CONTINUATION OF A DRY OFFSHORE
FLOW PATTERN. HOWEVER...SOME UNCERTAINTY BUILDS BY FRIDAY AS A
NORTH PACIFIC LOW...WHICH MAY INCLUDE THE REMNANTS OF TS
KAMMURI...MOVES INTO THE GULF OF ALASKA.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING...130 132 150 176 178
FIRE WEATHER...NONE. &&

$$

SEP 14



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