Brisk Wind Advisory 16, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
100 PM AKST SAT FEB 13 2010

.ANALYSIS AND UPPER LEVELS...
A LARGE MERIDIONAL UPPER LEVEL RIDGE CENTERED OVER THE WESTERN
CANADIAN PLAINS CURVES WESTWARD ACROSS SOUTH CENTRAL ALASKA. A FIXED
UPPER LEVEL TROUGH COVERS MUCH OF THE BERING AND THE ALEUTIANS. A
CUTOFF LOW RINGED BY MULTIPLE WEAK SHORTWAVES RESIDES AT THE CREST OF
THE TROUGH OVER THE SOUTHERN GULF OF ALASKA. AT THE SURFACE...THE
REMNANTS OF A LOW PRESSURE SYSTEM THAT TRACKED ACROSS THE AKPEN LAST
NIGHT ARE MOVING OUT OF BRISTOL BAY AND SPREADING CLOUDS AND ISOLATED
SNOW SHOWERS ACROSS THE PRIBILOF ISLANDS AND COASTAL REGIONS OF
SOUTHWEST ALASKA. A 953 MB LOW TRAINING ALONG A SIMILAR PATH AS ITS
PREDECESSOR IS ENTERING THE SOUTHERN GULF THIS AFTERNOON...WITH THE
TRIPLE POINT RIDING OUT AHEAD OF THE SYSTEM AND SPREADING RAIN ACROSS
THE SOUTHERN PANHANDLE.

.MODEL DISCUSSION...
MODELS ARE IN GOOD AGREEMENT THROUGH THE WEEKEND WITH THE TRACK AND
STRENGTH OF THE CURRENT SYSTEM ROTATING INTO THE GULF. TRACK
DISCREPANCIES BEGIN TO EMERGE BY TOMORROW EVENING AS THE SYSTEM NEARS
KODIAK ISLAND...WITH THE ECMWF THE MOST AGGRESSIVE WITH THE SPEED OF
THE LOW. NEVERTHELESS..ALL OF THE SOLUTIONS AGREE THAT THE LOW WILL
SIGNIFICANTLY WEAKEN OR POSSIBLY TROUGH OUT AS IT MOVES ONSHORE ON
MONDAY AFTERNOON. THE GFS AND ECMWF HAVE COME INTO AGREEMENT OUT
THROUGH TUESDAY NIGHT ON THE TRACK OF A WEAKER LOW THAT MOVES INTO
THE NORTHERN GULF ON THE HEALS OF THIS WEEKEND'S STORM. THE NAM
SOLUTION FOR THE CENTER OF THE LOW LAGS A GOOD SIX TO TEN HOURS
BEHIND THE OTHER MODELS. THE MESSY MODEL SITUATION OUT IN THE WEST
HAS CHANGED LITTLE SINCE YESTERDAY. WHILE THE MODELS ARE AT LEAST
PREDICTING THE DEVELOPMENT OF SIMILAR FEATURES...THE SOLUTIONS FAIL
TO AGREE ON ALMOST ALL FACETS OF THESE SYSTEMS. A SLIGHT NUDGE
TOWARDS THE ECMWF WAS MADE WITH THIS FORECAST PACKAGE OUT WEST...BUT
WITH SUCH LOW MODEL CONFIDENCE THE FORECAST REMAINS ESSENTIALLY A
BLEND OF MANY MODELS. LITTLE CHANGES WERE MADE IN THE FORECAST OUT IN
THE EAST.

.SHORT TERM FORECAST...

.SOUTHCENTRAL...WEATHER ACROSS SOUTH CENTRAL ALASKA WILL REMAIN CALM
TODAY AS RIDGING BUILDS OUT AHEAD OF THE NEXT SYSTEM MOVING NORTH
INTO THE GULF. SHOWERS RIDING OUT AHEAD OF THE FRONT ARE ALREADY
MAKING THEIR WAY TOWARDS PRINCE WILLIAM SOUND AS SEEN ON THE
MIDDLETON ISLAND RADAR. PRECIPITATION WILL SPREAD ACROSS THE COAST
TONIGHT AS THE LOW TRACKS CLOSER TO THE MAINLAND. THE ASSOCIATED
IMPACTS ACROSS SOUTH CENTRAL WILL BE SIMILAR TO PREVIOUS LOWS. THUS
EXPECT A WIDE SWATH OF PRECIPITATION ACROSS THE NORTHERN GULF
BEGINNING ON SUNDAY...WITH THE BULK OF THE PRECIPITATION OCCURRING ON
THE UPSLOPE SIDES OF COASTAL MOUNTAIN RANGES. GUSTY WINDS CAN ALSO BE
EXPECTED ALONG TURNAGAIN ARM AND OTHER PASSES. THE LOW WEAKENS ON
MONDAY AS IT MOVES INLAND...BUT A NEW LOW WILL QUICKLY TAKE ITS PLACE
AND HELP PRECIPITATION LINGER ALONG THE COAST THROUGH MIDWEEK.

.SOUTHWEST...THE KING SALMON AND BETHEL RADARS DEPICT A NARROW SWATH
OF SNOW SHOWERS WORKING THEIR WAY NORTHWARD ALONG THE COAST OF
SOUTHWEST ALASKA...WHICH ARE ASSOCIATED WITH THE DISSIPATING LOW
MOVING NORTHWEST OUT OF BRISTOL BAY. THESE SHOWERS DIMINISH BY THIS
EVENING AS THE RESIDUAL SHORTWAVE MOVES FURTHER FROM THE COAST.
CONDITIONS SHOULD DRY OUT FOR THE LATTER HALF OF THE WEEKEND...BUT
CLOUDS AND LIGHT SHOWERS CREEP INTO THE FORECAST EARLY NEXT WEEK AS
THE REMNANTS OF THE NEXT GULF LOW MOVE ACROSS THE REGION LATE ON
MONDAY.

.ALEUTIANS...CLOUDS AND SHOWERS FROM THE BRISTOL BAY LOW ARE
SPREADING ACROSS THE SOUTHEASTERN BERING SEA AND THE EASTERN
ALEUTIANS. THESE WILL BE SHORT LIVED WITH THE WAVE LIFTING OUT OF THE
AREA AND WEAKENING. A SERIES OF MID-LEVEL SHORTWAVES SPREAD LIGHT
SHOWERS ACROSS THE ISLAND CHAIN THROUGH EARLY NEXT WEEK BEFORE THE
NEXT BIG SYSTEM MOVES INTO THE ISLAND CHAIN ON WEDNESDAY. WHILE THE
MODELS ARE IN AGREEMENT OVER THE DEVELOPMENT OF THIS SYSTEM...TIMING
AND POSITION DIFFERENCES INCREASE THE UNCERTAINTY IN THE FORECAST.

.LONG TERM FORECAST...
WHILE THE POSITION OF THE UPPER LEVEL RIDGE FLUCTUATES THROUGHOUT THE
WEEK...IT WILL GENERALLY RETROGRADE SLOWLY WESTWARD. BY NEXT WEEKEND
THE LONG RANGE MODELS DEPICT A STRONG BLOCKING RIDGE OVER EASTERN
ALASKA. WITH THE RIDGE REMAINING MORE OR LESS EAST OF THE
STATE...CLOCKWISE FLOW AROUND IT WILL CONTINUE TO ADVECT WARM GULF
AIR ACROSS THE MAINLAND. THUS EXPECT UNSEASONABLY WARM TEMPERATURES
TO PERSIST FOR THE FORESEEABLE FUTURE. IN A NUTSHELLL...EXPECT A
PERSISTENT WEATHER PATTERN ACROSS THE MAINLAND FOR AT LEAST THE NEXT
SEVEN TO TEN DAYS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING...125 130 132.
         STORM WARNING...120.
FIRE WEATHER...NONE.

KS FEB 10