Gale Warning 743, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
210 PM AKDT WED OCT 19 2011

.ANALYSIS AND UPPER LEVELS...TODAY IS A TRANSITIONAL DAY AS THE
REMNANTS OF ONE SYSTEM FINALLY DEPART THE DOMAIN AND ANOTHER
INTENSIFIES SOUTH OF THE ALASKA PENINSULA. A SHORTWAVE RIDGE WITH A
SE TO NW AXIS BETWEEN THE TWO SYSTEMS IS CURRENTLY OVER THE SOUTHERN
ALASKA RANGE UP THROUGH THE KUSKOKWIM VALLEY. FAIR WEATHER CAN BE
FOUND UNDER THIS RIDGE WHILE SHOWERS STILL LINGER OVER THE EASTERN
HALF OF THE DOMAIN. THE DEVELOPING LOW SOUTH OF THE ALASKA PENINSULA
IS BRINGING WIDESPREAD RAIN FROM THE EASTERN ALEUTIANS NORTH TO THE
KUSKOKWIM DELTA. THE ANCHOR LOW FOR THIS NEW DEVELOPING SYSTEM IS
POSITIONED BACK OVER THE WESTERN BERING SEA...AND WILL SLOWLY DIVE
SOUTHEAST ACROSS THE ALEUTIANS THROUGH THE END OF THE WEEK.

.MODEL DISCUSSION...
MODELS ARE LOOKING A BIT DIFFERENT TODAY...BUT SEEM TO BE COMING INTO
AGREEMENT WITH ONE ANOTHER. THE NAM/ECMWF HAVE HAD THE BEST RUN TO
RUN CONSISTENCY AND SUGGEST A STRONGER LOW WITH A SLIGHTLY SLOWER
TRACK TOWARD THE AKPEN OVERNIGHT. THIS CHANGE WILL EFFECT THE WINDS
AROUND THE AKPEN AND BRISTOL ZONES. LATER IN THE WEEK...THE MODELS
ARE HAVING A DIFFICULT TIME PINNING DOWN THE TIMING OF SOME VERY FAST
MOVING SHORTWAVES EMBEDDED IN THE CYCLONIC CIRCULATION. AGAIN...THE
NAM AND ECMWF HAVE SHOWN THE BEST RUN TO RUN CONSISTENCY SO WE WILL
BE NUDGING TOWARD THESE LATEST SOLUTIONS WITH THE AFTERNOON PACKAGE.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...THE REMNANTS OF THE UPPER TROF OVER
SOUTHCENTRAL HAVE HAD A BIGGER IMPACT ON THE WEATHER THAN
ANTICIPATED. ENOUGH INSTABILITY AND MOISTURE HAS LINGERED IN THE
REGION FOR SHOWERS TO DEVELOP OVERNIGHT AND THROUGH THIS
AFTERNOON...MAINLY AROUND PRINCE WILLIAM SOUND BUT A FEW STRAY
SHOWERS MADE IT FROM EAGLE RIVER UP TO PALMER. A FEW MORE FLURRIES
ARE POSSIBLE THIS AFTERNOON BEFORE THE REMNANTS MOVE INLAND AND THE
RIDGE BRIEFLY BUILDS FROM THE WEST.

GALE FORCE WINDS MOVE INTO THE WESTERN GULF OVERNIGHT AS THE
DEVELOPING LOW STALLS JUST SOUTH OF THE ALASKA PENINSULA. THIS FRONT
EVENTUALLY APPROACHES THE NORTH GULF COAST THURSDAY NIGHT AND FRIDAY
MORNING...WITH MOST PRECIPITATION FALLING AROUND PRINCE WILLIAM
SOUND. THE SOUTHERN TRACK OF THE LOW COUPLED WITH THE WEAKENING FRONT
WILL KEEP GAP WINDS WELL BELOW WARNING CRITERIA FOR THIS STORM.

SOUTHWEST ALASKA...LINGERING FOG UNDER THE UPPER LEVEL RIDGE WAS VERY
SLOW TO BURN OFF THIS MORNING AND EARLY AFTERNOON NEAR DILLINGHAM AND
UP THE NUSHAGAK RIVER. OTHERWISE A VERY NICE FALL DAY ACROSS THE
SOUTHWEST INTERIOR. EASTERLY WINDS WILL INCREASE THIS AFTERNOON AS
THE LOW RAPIDLY DEEPENS SOUTH OF THE AKPEN. A DEFORMATION ZONE
CONNECTING THE DEVELOPING LOW TO THE ANCHOR LOW WILL STAY JUST OFF
THE COAST OVERNIGHT SO PRECIPITATION SHOULD BE LIMITED TO THE
IMMEDIATE COASTLINE. EASTERLY GAP WINDS WILL BE THE MAIN WEATHER
STORY FOR THIS AREA AS THE LOW STALLS NEAR SAND POINT AT 970 MB. THE
WINDS WILL CONTINUE THROUGH FRIDAY AND THEN SLOWLY DIMINISH BY THE
WEEKEND AS THE FLOW BECOMES MORE ZONAL ACROSS THE ENTIRE DOMAIN.

ALEUTIAN/BERING SEA...
THE MOST SIGNIFICANT CHANGE TO THE FORECAST IN THE SHORT TERM WILL BE
INCREASING WINDS TO STORM FORCE JUST SOUTH OF THE ALASKA PENINSULA.
STORM FORCE GUSTS ARE POSSIBLE ACROSS BRISTOL BAY AS WELL.

WIDESPREAD RAIN WILL FINALLY GIVE WAY TO WEAK COLD AIR ADVECTION AND
RAIN OR SNOW SHOWERS THROUGH THE WEEKEND. THE RIDGE THAT WAS
ANTICIPATED TO BUILD ACROSS THE BERING SEA IS LOOKING MUCH MORE FLAT
THESE LAST FEW MODEL RUNS...SO CONTINUED WEAK TEMPERATURE ADVECTION
AND CONSEQUENTLY WEAK LOWS DEVELOPING AND TRAVERSING ACROSS THE
REGION.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...STORM WARNING 132 138 150
         GALE WARNING 120 130 140 155 160 165 175 180 185
FIRE WEATHER...NONE.

AB OCT 11