Gale Warning 356, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
130 PM AKDT FRI APR 16 2010

.ANALYSIS AND UPPER LEVELS...
A WEAK UPPER LEVEL RIDGE EXTENDS OUT OF BRITISH COLUMBIA AND ACROSS
EASTERN AND NORTHERN ALASKA WHILE A BROAD TROUGH WITH AN EMBEDDED LOW
ENCOMPASSES THE BERING SEA. A 180 KT JET TRAVELS ALONG THE 50 N
PARALLEL BEFORE DIVING INTO THE CENTRAL PACIFIC SOUTH OF KODIAK. AT
THE SURFACE...A 980 MB COMPLEX LOW PRESSURE CENTER WHICH IS
EXHIBITING CHARACTERISTICS OF A BARBELL LOW IS CENTERED ACROSS THE
NORTH BERING SEA. AN OCCLUDED FRONT ASSOCIATED WITH THIS LOW IS
INSTIGATING WIDESPREAD SNOW ACROSS SOUTHWESTERN ALASKA. SOUTH TO
SOUTHEASTERLY WINDS OUT AHEAD OF THIS FRONT ARE SPREADING CLOUDS AND
SNOW SHOWERS OVER UPSLOPED REGIONS OF THE NORTH GULF COAST...SUCH AS
WESTERN COOK INLET...THE SOUTHERN AND EASTERN KENAI PENINSULA...AND
PRINCE WILLIAM SOUND.

.MODEL DISCUSSION...
SYNOPTICALLY SPEAKING ALL MODELS INITIALIZED WELL THIS
MORNING...THOUGH THERE IS SOME CONFUSION AS TO THE EXACT STRUCTURE OF
THE COMPLEX LOW IN THE BERING SEA. BUT OVERALL...CONSIDERING THE
REMOTE LOCATION OF THE LOW...ONE CANT EXPECT A MUCH BETTER SOLUTION.
AS WAS THE CASE YESTERDAY...MODELS DIFFER SUBSTANTIALLY ON THE
DEVELOPMENT OF A NEW TRIPLE POINT LOW SOUTH OF THE GULF THIS
AFTERNOON INTO TONIGHT...THOUGH THE NAM AND GFS HAVE COME INTO BETTER
AGREEMENT WHILE THE ECMWF IS WEAKER AND FURTHER NORTH WITH THIS LOW.
THIS DISCREPANCY CONTINUES THROUGH THE LIFE OF THE LOW UP UNTIL IT
DISSIPATES ON WEDNESDAY. WITH THE ECMWF BEING THE OUTLIER...THE
FORECAST USED A BLEND OF THE NAM AND GFS THROUGHOUT THE FORECAST
PERIOD.

.SHORT TERM FORECAST...
A TRIPLE POINT LOW DEVELOPS 700 MILES SOUTH OF KODIAK TONIGHT AND
EARLY TOMORROW MORNING AND SLOWLY WRAPS INTO THE GULF OVER THE COURSE
OF THE WEEKEND. MULTIPLE FRONTAL BANDS WILL SPREAD NUMEROUS RAIN AND
SNOW SHOWERS ACROSS THE GULF COAST THROUGHOUT THE WEEKEND. PREVAILING
SOUTHEASTERLY WINDS WILL ENHANCE PRECIPITATION ALONG FAVORABLE
MOUNTAIN UPSLOPE REGIONS...INCLUDING SOUTHWESTERN COOK INLET...THE
EASTERN KENAI PENINSULA...AND PRINCE WILLIAM SOUND. WHILE THE
ANCHORAGE BOWL REMAINS DOWNSLOPED FOR THE EVENT...WIDESPREAD CLOUDS
AND ISOLATED SHOWERS ARE EXPECTED THROUGH THE WEEKEND. GUSTY GAP
WINDS THROUGH TURNAGAIN ARM AND OTHER MOUNTAIN PASSES ARE POSSIBLE
WITH THE INCREASING PRESSURE GRADIENT OVER SOUTH CENTRAL ALASKA.

SNOW SHOWERS PERSIST ACROSS SOUTHWESTERN ALASKA TODAY AND TONIGHT AS
THE DETERIORATING FRONTAL SYSTEM CURRENTLY OVERHEAD STALLS AND
EVENTUALLY WRAPS NORTH INTO ITS PARENT LOW. SHORTWAVES TRACKING NORTH
AND WEST AROUND THE NEW GULF LOW WILL REINITIATE SNOW SHOWERS OVER
SOUTHWESTERN ALASKA ON SUNDAY. COLD AND WET WEATHER PERSISTS OVER THE
ALEUTIANS THIS WEEKEND AS A RESULT OF NORTHERLY WINDS ON THE BACKSIDE
OF THE BERING LOW.

.LONG TERM FORECAST...
LOOK FOR A WET BUT SLIGHTLY WARMER WEATHER PATTERN ACROSS SOUTH
CENTRAL ALASKA THROUGH THE END OF NEXT WEEK DUE TO A SERIES OF LOWS
INHABITING THE NORTH GULF. THE PRESENCE OF THESE LOWS WILL MAINTAIN A
PRESSURE GRADIENT OVER SOUTH CENTRAL ALASKA AND KEEP LOCALLY STRONG
WINDS A POSSIBILITY THROUGH THE WEEK. A NEW LOW PASSES SOUTH OF THE
ALEUTIANS AND SPREADS RAIN AND SNOW OVER THE ISLAND CHAIN DURING THE
EARLY PART OF NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING...120 125 130 172 175.
FIRE WEATHER...NONE.

KS APR 10