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000
FXAK68 PAFC 202134
AFDAFC

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
130 PM AKDT MON MAY 20 2013

.ANALYSIS AND UPPER LEVELS...
THE AXIS OF A BROAD LONGWAVE TROUGH ACROSS THE REGION HAS SHIFTED
WESTWARD AND IS NOW LOCATED OVER THE BERING SEA. THIS IS ALLOWING A
NORTH PACIFIC RIDGE TO CONTROL THE WEATHER OVER MUCH OF THE
MAINLAND...WHERE ABUNDANT SUNSHINE AND MODERATING TEMPERATURES ARE
THE GENERAL RULE. THE MOST ACTIVE WEATHER ACROSS THE REGION IS
UNDOUBTEDLY A 993 MB LOW CENTERED NEAR ADAK WITH AN ASSOCIATED STRONG
GALE-FORCE FRONT MOVING THROUGH THE ALASKA PENINSULA. A MIXTURE OF
RAIN AND SNOW HAS MOVED INTO THE COASTAL AREAS OF THE KUSKOKWIM DELTA
AND WESTERN CAPES OF THE BRISTOL BAY ZONE...WITH ALL RAIN FURTHER
SOUTH ALONG THE ALASKA PENINSULA AND EASTERN ALEUTIANS. RAIN BECOMES
MORE SHOWERY OVER THE CENTRAL AND WESTERN ALEUTIANS AS SHOWERS ROTATE
AROUND THE LOW CENTER. WINDS UPWARD OF 65 MPH HAVE BEEN OBSERVED
THROUGH THE CHANNELED TERRAIN OF THE ALASKA PENINSULA...WHICH IS A
SIGNIFICANT DEPARTURE FROM THE TRANQUIL WEATHER OF RECENT WEEKS.

.MODEL DISCUSSION...
MODELS CONTINUE TO BE IN ABOVE AVERAGE SYNOPTIC AGREEMENT THROUGH
NEXT WEEKEND. ALL THE MODELS SEEM TO BE SLIGHTLY TOO SLOW WITH THE
NORTHWARD PROGRESS OF THE CURRENT BERING LOW...WITH THE ECMWF GIVEN A
SLIGHT EDGE OVER THE OTHER MODELS IN THIS RESPECT. OVERALL...THE
LONGWAVE TROUGH WILL REMAIN OVER THE BERING SEA...WHICH WILL KEEP
MOST OF THE MAINLAND UNDER GENERALLY HIGHER PRESSURES WITH GRADUALLY
WARMING TEMPERATURES. THE LOW CURRENTLY AFFECTING THE ALEUTIANS WILL
STALL AND WEAKEN IN THE CENTRAL BERING SEA THROUGH MIDWEEK...BEFORE
ANOTHER PACIFIC LOW MOVES INTO THE SOUTHERN BERING BY NEXT WEEKEND.
THIS WILL KEEP MOST OF THE ACTIVE WEATHER WEST OF THE MAINLAND THIS
WEEK.

.SHORT TERM FORECAST...
SOUTHCENTRAL...HIGH CLOUDS ASSOCIATED WITH A LEADING SHORTWAVE FROM
THE BERING STORM ARE MOVING INTO THE AREA FROM THE SOUTHWEST. THIS IS
HAPPENING AS THE UPPER LEVEL RIDGE DRIFTS SLOWLY EASTWARD. DESPITE
THE INCREASING CLOUDS...RAIN IS ONLY EXPECTED TO MAKE IT AS FAR EAST
AS KODIAK ISLAND THIS EVENING...AS THE BERING LOW BEGINS TO RE-CURVE
WESTWARD INTO THE LONGWAVE TROUGH. UPPER LEVEL CLOUDS SHOULD HAVE
ENOUGH BREAKS TO ALLOW SEA BREEZES TO DEVELOP AGAIN TOMORROW AROUND
COOK INLET AND PRINCE WILLIAM SOUND. EACH DAY THIS WEEK SHOULD BE
WARMER THAN THE PREVIOUS...WITH TEMPERATURES AT OR ABOVE NORMAL BY
THE END OF THE WEEK. HOWEVER...EVEN THOUGH WARMING TEMPERATURES WILL
GRADUALLY DESTABILIZE THE LOWER ATMOSPHERE...LITTLE MORE THAN DIURNAL
MIDLEVEL CLOUDINESS IS EXPECTED AT MOST LOCATIONS.

SOUTHWEST...STRONG WINDS AND STEADY PRECIP WILL STAY MOSTLY CONFINED
TO THE COASTLINE AS THE FRONT STALLS AND WEAKENS THROUGH MIDWEEK.
TEMPERATURES WILL SLOWLY MODERATE BACK TOWARD MORE SEASONABLE
TEMPERATURES...BUT CONTINUED ONSHORE FLOW WILL KEEP THE RISK OF LOW
CLOUDS/MARINE STRATUS AROUND COASTAL AREAS THROUGH THE END OF THE
WEEK.

BERING SEA AND ALEUTIANS...STRONG WINDS CURRENTLY AFFECTING THE
EASTERN HALF OF THE REGION WILL GRADUALLY DIMINISH AS THE FRONT FALLS
APART AND WEAKENS BY TUESDAY AFTERNOON. WARMING TEMPERATURES AND SOME
AREAS OF SUNSHINE MAY MOVE THROUGH MIDWEEK AS A SHORTWAVE RIDGE
BUILDS IN FROM THE SOUTH. BY LATE THURSDAY NIGHT ANOTHER LOW MOVES
INTO THE CENTRAL ALEUTIANS AND FOLLOWS A FAMILIAR TRACK NORTHWARD
INTO THE BERING SEA.

.LONG TERM FORECAST...
LONG RANGE MODELS ARE SUGGESTING THAT THE BERING SEA LONGWAVE TROUGH
WILL REMAIN ENTRENCHED THROUGH EARLY NEXT WEEK. THIS WILL LIKELY
RESULT IN A PROLONGED PERIOD OF NEAR OR ABOVE-AVERAGE TEMPERATURES
AND SUNNY SKIES SPREADING ACROSS MUCH OF THE SOUTHERN MAINLAND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 155 160 165 170 180
FIRE WEATHER...NONE

DIXON MAY 13