Heavy Freezing Spray Warning 92, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
1140 AM AKST FRI MAR 11 2011

.ANALYSIS AND UPPER LEVELS...A STRONG BLOCKING HIGH REMAINS FIRMLY
ENTRENCHED OVER THE BERING STRAIT. OTHER THAN SOME VERY LOCALIZED
GAP WINDS IN SOUTHCENTRAL CONDITIONS ARE VERY CALM ACROSS THE
MAINLAND. DOWN OVER THE GULF THERE ARE A FEW WEAK UPPER LEVEL
WAVES PRODUCING AREAS OF SNOW SHOWERS. THE MOST ACTIVE WEATHER
IS ALONG THE CENTRAL ALEUTIANS WITH A 970S MB LOW JUST TO THE
SOUTH. THIS LOW WAS TRACKING NORTHEASTWARD BUT HAS NOW STALLED
DUE TO THE RIDGE TO THE NORTH. EXPECT EASTWARD MOTION TO BEGIN
SOON AS LOW GETS CAUGHT IN THE WESTERLY FLOW OF UPPER JET JUST
TO THE SOUTH.

.MODEL DISCUSSION...MODELS ARE IN GOOD AGREEMENT THROUGH THE NEXT
FEW DAYS WITH QUIET CONDITIONS EXPECTED ACROSS ALL OF ALASKA.

.SHORT TERM FORECAST...THE BLOCKING HIGH WILL RETROGRADE WESTWARD
A BIT OVER THE NEXT FEW DAYS AS SHORT-WAVES DROP DOWN OUT OF THE
ARCTIC ALONG ITS EAST SIDE. THE MORE NOTEWORTHY ASPECT OF THIS
IS THAT THESE SHORT-WAVES COMING FROM THE NORTH WILL INTERACT
WITH ENERGY OVER THE GULF TO LOWER HEIGHTS OVER THE BERING
SEA...LIKELY FORMING AN UPPER LOW IN THE EASTERN BERING ON MONDAY.
THIS IS THE FIRST STEP IN WHAT WILL BE A MAJOR PATTERN SHIFT
AT WEEK'S END.

WEAK LOW LEVEL COLD AIR ADVECTION WILL ACCOMPANY THE FIRST SHORT-WAVE
AS IT MOVES THROUGH SOUTHCENTRAL LATE TONIGHT INTO SATURDAY MORNING
RESULTING IN A TIGHTENING OF THE SURFACE PRESSURE GRADIENT AND AN
INCREASE IN GAP WINDS ONCE AGAIN. DON'T EXPECT THESE WINDS TO BE
AS STRONG AS THE PAST FEW DAYS...BUT SOME WIND WILL PERSIST THROUGH
THE WEEKEND. MEANWHILE...DOWN OVER THE GULF EXPECT SNOW SHOWERS TO
MOVE BACK TO KODIAK ISLAND AND PRODUCE SOME LIGHT ACCUMULATION.
HEIGHTS WILL RISE OVER THE BERING TONIGHT AND HELP TO PUSH THE LOW
ALONG THE ALEUTIANS OFF TO THE SOUTH. THE NEXT MAJOR PACIFIC STORM
WILL THEN TRACK MUCH FURTHER SOUTH OF THE ALEUTIANS...SO THAT ONLY
IMPACTS WILL BE A BIT OF WIND AND A FEW SHOWERS ALONG THE PERIPHERY
OF THE STORM SATURDAY NIGHT AND SUNDAY.

.LONG TERM FORECAST...LOWER PRESSURE OVER THE BERING WILL ALLOW
THE NEXT SYSTEM MOVING OUT OF ASIA TO TRACK FURTHER NORTH ALONG
THE ALEUTIANS IN THE TUESDAY/WEDNESDAY TIME FRAME. AT THE SAME
TIME MODELS SHOW BLOCKING HIGH OVER THE BERING STRAIT BEGINNING
TO WEAKEN...ALTHOUGH THIS WEAKENING IS SLOWER IN LATEST MODELS
THAN IT HAS BEEN. ALTHOUGH DETAILS ARE IN QUESTION DUE TO
POOR-RUN-TO-RUN CONSISTENCY MODELS CONTINUE TO DEPICT A MUCH
STRONGER SYSTEM MOVING INTO THE BERING SEA DURING THE SECOND
HALF OF THE WEEK. THEN...ASSUMING THE RIDGE CONTINUES TO WEAKEN...
THIS SYSTEM WILL BRING PRECIPITATION TO MAINLAND ALASKA LATE IN
THE WEEK AND INTO THE WEEKEND.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE WARNING 170 172 175.
FIRE WEATHER...NONE.

SEB MAR 11