Gale Warning 860, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
400 PM AKST FRI DEC 20 2013

.ANALYSIS AND UPPER LEVELS...THE UPPER LEVEL PATTERN OVER THE STATE
TODAY HAS A RIDGE EXTENDING THROUGH THE GULF OF ALASKA NORTHWARD
THROUGH SOUTHCENTRAL AND INTO THE INTERIOR. AN UPPER LEVEL LOW CENTER
IS IN EASTERN RUSSIA WITH A TROUGH EXTENDING OUT OF IT ACROSS THE
BERING SEA INTO THE CENTRAL ALEUTIANS. THE JET STREAM RUNS AHEAD OF
THE TROUGH AND OVER THE RIDGE IN THE NORTHERN GULF OF ALASKA.
AT THE SURFACE THE HIGH PRESSURE IS CENTERED WELL SOUTH OF THE GULF
OF ALASKA WITH THE RIDGE EXTENDING NORTHWARD OVER THE COPPER RIVER
BASIN INTO THE EASTERN INTERIOR. THE LOW CENTER IN THE EASTERN BERING
SEA HAS ELONGATED AND DEVELOPED TWO DISTINCT CENTERS. THE STRONGER OF
THE TWO IS THE NORTHERN ONE NEAR THE KUSKOKWIM DELTA. THIS WILL
CONTINUE MOVING NORTHWARD AND SLOWLY WEAKEN THROUGH TOMORROW. THE LOW
TO THE SOUTH IS WEAKENING RAPIDLY AND MOVING EASTWARD SOUTH OF THE
ALASKA PENINSULA. THIS CENTER WILL DEVELOP AGAIN AS IT TAPS INTO THE
JET STREAM OVERNIGHT AND THEN MOVE INTO THE GULF OF ALASKA TOMORROW.

.MODEL DISCUSSION...MODEL INITIALIZATION HAS BEEN GOOD TODAY WITH ALL
MODELS LOCKED ON TO THE MAIN AND SECONDARY FEATURES. THE LOW
DEVELOPING SOUTH OF THE ALASKA PENINSULA WHICH WILL MOVE INTO THE
GULF TOMORROW IS STILL CAUSING DIFFICULTIES...BUT MORE WITH THE NAM
THAN THE OTHER MODELS. THE NAM WAS NOT USED MUCH PAST THE FIRST
PERIOD OF THE FORECAST AS IT DEFINITELY THE OUTLIER WITH NO
METEOROLOGICAL REASON TO SUGGEST IT SEES SOMETHING THE OTHER MODELS
DO NOT. OVERALL THE ECMWF MODEL WAS THE PREFERRED SOLUTION. THE GEM
MATCHES VERY CLOSELY TO IT AND THEY BOTH SEEM TO HANDLE THE LOW IN
THE ALEUTIANS EARLY NEXT WEEK BETTER THAN THE GFS DOES.

.SHORT TERM FORECAST...BIGGEST UNCERTAINTY IN THE SHORT TERM IS THE
WEATHER MOVING NORTHWARD THROUGH COOK INLET. THE ATMOSPHERE LOOKS
LIKE IT IS COLD ENOUGH THAT IT WILL REMAIN ALMOST ENTIRELY
SNOW...EXCEPT FOR THE SOUTHERN PART OF THE KENAI PENINSULA WHICH WILL
LIKELY WARM UP ENOUGH TO TURN TO RAIN. THERE MAY BE A AREA BETWEEN
THE SNOW AND RAIN WHERE THERE IS FREEZING RAIN ON THE KENAI
PENINSULA. THIS DOES NOT LOOK LIKE IT WOULD BE A VERY BIG AREA BUT IT
MAY BE THERE. FREEZING RAIN FARTHER NORTH INTO THE ANCHORAGE AREA OR
WESTERN SUSITNA VALLEY DOES NOT LOOK LIKELY BUT IT IS POSSIBLE AS
THIS FRONT SIS BRING A LOT OF LIQUID PRECIPITATION INTO SOUTHWEST
ALASKA OVERNIGHT AND INTO THE DAY TODAY.

SOUTHWEST ALASKA SHOULD BE MOSTLY DONE WITH THE FREEZING RAIN AS THE
FRONT MOVES INTO THE KUSKOKWIM DELTA TONIGHT AND CONTINUES TO TURN
REMAIN PRECIPITATION FROM RAIN TO SNOW. THE PLACE WITH GREATEST
CHANCE FOR CONTINUED FREEZING RAIN IS IN THE KUSKOKWIM VALLEY AS COLD
AIR IN THE VALLEY AREAS REMAIN BELOW FREEZING WITH WARM AIR ALOFT
PRODUCING RAIN. THE BRISTOL BAY REGION WILL LIKELY SEE A RAIN AND
SNOW MIX...WITHOUT THE FREEZING RAIN...UNTIL IT CLEARS OUT SOME ON
SUNDAY.

.LONG TERM FORECAST...
MODELS AND WPC GUIDANCE AGREE THAT THE NORTH PACIFIC LOW WILL CROSS
INTO THE BERING SEA BY TUESDAY AND DECAY ON THURSDAY. THE ASSOCIATED
WEATHER FRONT WILL CROSS INTO THE BERING AND SOUTHWEST ALASKA ON
TUESDAY. A SECOND LOW WILL MOVE TO THE CENTRAL ALEUTIANS THURSDAY
INTO FRI. THESE FEATURES WILL BRING WIND AND RAIN TO THE EASTERN HALF
OF THE ALEUTIANS THROUGH THE END OF THE WEEK...WITH SNOW SHOWERS TO
THE WESTERN HALF OF THE CHAIN. SNOW CHANGING TO RAIN CAN BE EXPECTED
OVER SOUTHWEST ALASKA DURING THIS TIME WITH THE POSSIBILITY OF SOME
MORE FREEZING RAIN.

SOUTHEAST OF THE AK RANGE WILL HAVE SOME SNOW SHOWERS LINGERING ON
MONDAY. ON TUESDAY THE REMNANTS OF THE BERING SEA FRONT WILL BEGIN TO
SPREAD RAIN ALONG THE NORTH GULF COAST WITH SOME SNOW CROSSING THE
CHUGACH MOUNTAINS. THERE IS A SLIGHT CHANCE FOR SOME AREAS OF
FREEZING RAIN IN SOUTH CENTRAL ALASKA TUESDAY DUE TO TEMPERATURES
ALOFT. HOWEVER AT THIS POINT IT LOOKS LIKE IT WILL BE MOSTLY SNOW
WITH FREEZING RAIN....WHILE POSSIBLE...UNLIKELY TO ACTUALLY HAPPEN.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 119 130 150 155 160 173 175 176 177 178 179 180.
         HEAVY FREEZING SPRAY 180 181 185.
FIRE WEATHER...NONE.

DEC 13