Heavy Freezing Spray Warning 166, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT SAT MAR 31 2012

.MODEL DISCUSSION...MODEL INITIALIZATIONS LOOK REASONABLE. THEY ARE
NOW STARTING TO CONVERGE ON A COMMON POSITION WITH A LOW APPROACHING
THE WESTERN ALEUTIANS MON. THE GFS/ECMWF BOTH PLACE THE CENTER NEAR
THE CENTRAL ALEUTIANS TUE AFTERNOON. THIS IS QUITE THE DEPARTURE FROM
THE PREVIOUS RUNS OF THE GFS WHICH DROVE THE CENTER WELL INTO THE
BERING SEA. THE MODELS ARE STILL DIFFERING ON THE CENTRAL PRESSURE
WITH THE ECMWF BEEN THE DEEPEST. THE ECMWF HAS BEEN THE MOST
CONSISTENT WITH THIS FEATURE...SO WILL BLEND HEAVILY TOWARD THIS
MODEL FOR THE AFTERNOON FORECAST PACKAGE. IN THE EAST...MODELS ARE IN
GOOD AGREEMENT OVER THE MAINLAND AND HAVE SIMILAR TIMING OF THE
EASTERLY WAVE MOVING WEST ACROSS SOUTHCENTRAL TONIGHT/SUN. BIG
DIFFERENCES OCCUR BETWEEN THE GFS/ECMWF WITH STRONG LOW MOVING TOWARD
THE QUEEN CHARLOTTE ISLANDS ON TUE. WILL ONCE AGAIN LEAN TOWARD THE
MORE CONSISTENT ECMWF SOLUTION WITH THIS FEATURE.

.ANALYSIS AND UPPER LEVELS...
.500MB...A BROAD CUT-OFF LOW WITH SEVERAL SMALL WAVES ROTATING AROUND
ITS CORE IS EVIDENT OVER THE GULF OF ALASKA. WEAK RIDING EXTENDS
ACROSS THE NORTHERN MAINLAND. A WEAK TROUGH EXTENDS FROM THE EASTERN
BERING SEA TO OVER EASTERN RUSSIA. STRONG WESTERLY FLOW EXTENDS
ACROSS MUCH OF THE NORTH PACIFIC FROM JAPAN TO SOUTH OF THE
ALEUTIANS.

.SURFACE...A MIXTURE OF RAIN AND SNOW SHOWERS EXTENDS ACROSS
SOUTHCENTRAL ALASKA. WEAK RIDGING ALONG THE NORTH GULF COAST AND WEAK
TROUGHING OVER COOK INLET IS PRODUCING GUSTY WINDS FROM PORTAGE
VALLEY TO OVER WESTERN TURNAGAIN ARM THIS AFTERNOON. CLOUDY
CONDITIONS ARE EVIDENT OVER THE MAINLAND WITH SOME LIGHT SNOW AND FOG
OVER THE BRISTOL BAY REGION. BRISK AND GUSTY NORTHERLY FLOW OVER THE
EASTERN BERING SEA IS PRODUCING SNOW SHOWERS ACROSS THE EAST
ALEUTIANS AND AK PEN. A WEAK FRONTAL TROUGH IS EVIDENT OVER THE
WESTERN ALEUTIANS AND IS PRODUCING GUSTY EAST WINDS AND SNOW.

.SHORT TERM FORECAST...

.SOUTHCENTRAL ALASKA...WEAK COLD ADVECTION AND AN EASTERLY WAVE
MOVING WEST FROM THE COPPER RIVER BASIN TONIGHT WILL BRING SOME
SNOW/SNOW SHOWERS. THE WAVE IS EXPECTED TO MOVE WEST OF THE COPPER
RIVER BASIN AROUND MIDNIGHT AND WEAKEN AS IT SPLITS SUN WITH SOME OF
THE ENERGY MOVING INTO WESTERN MAINLAND AND WESTERN GULF. SNOW
AMOUNTS WITH THIS SYSTEM LOOK RELATIVELY LIGHT...EXCEPT FOR UPSLOPE
AREAS OVER THE WESTERN COPPER RIVER BASIN. SHOULD SEE DRIER
CONDITIONS MOVE IN DURING THE DAY SUN AS THE WAVE EXITS THE AREA. A
SECONDARY WAVE MOVES OUT OF WESTERN CANADA TO OVER THE COPPER RIVER
BASIN/NORTHERN GULF ON MON AND PROBABLY WILL BRING RENEWED SHOWER
ACTIVITY.

SOUTHWEST...
SNOW SHOWERS...ESPECIALLY OVER BRISTOL BAY...WILL TAPER OFF THROUGH
THIS EVENING. WEAK RIDGING MOVES OVER THE REGION TONIGHT...SO EXPECT
AREAS OF FOG TO DEVELOP. STRATUS AND FOG SUN MORNING WILL GIVE WAY TO
A LITTLE CLEARLY WITH NORTHERLY WINDS AND SOME ISOLATED SNOW SHOWERS.

BRISK NORTHERLY FLOW AND SNOW SHOWERS WILL PERSIST OVER THE AK PEN
THROUGH SUN.

ALEUTIANS/BERING...
NORTHWEST FLOW WILL CONTINUE OVER THE EASTERN HALF OF THE BERING
RESULTING IN COLD ADVECTION SNOW SHOWERS FROM THE PRIBILOFS DOWN
ACROSS THE ALASKA PENINSULA.

.LONG TERM FORECAST...
BY MID WEEK AN UPPER BERING RIDGE MOVES TOWARD THE SOUTHWEST AND
BUILDS IN OVER MAINLAND TROUGH THE REST OF THE WEEK. EXPECT DRY
CONDITIONS OVER THE STATE WELL INTO THE WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 176.
FIRE WEATHER...NONE.

RMC MAR 12