Small Craft Advisory 445, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM ADT SAT MAY 13 2006

.DISCUSSION...
OVERALL WEATHER PICTURE IS EASILY OBSERVED ON SATELLITE THIS MORNING.
DEEP UPPER LEVEL TROUGHS OVER NORTHEAST SIBERIA AND THE GULF OF
ALASKA...AND STRONG RIDGES OVER NORTHWEST CANADA AND A SLIGHTLY
POSITIVELY TILTED RIDGE AROUND 165W LONGITUDE. MOST OF MAINLAND
ALASKA IS SQUEEZED IN THE MIDDLE OF ALL THE ACTION. A DECENTLY DRY
WEEKEND IS IN STORE FOR SOUTH CENTRAL AS THE CANADIAN RIDGE BUILDS
WEST INTO ALASKA. AN INVERTED TROUGH CURRENTLY OVER BRITISH COLUMBIA
AND ALBERTA WILL BRING PRECIP INTO THE COPPER RIVER VALLEY AND PRINCE
WILLIAM SOUND LATER SUNDAY AND MONDAY. CURRENTLY FAVOR THE GFS
SOLUTION WHICH IS A LITTLE LESS BULLISH ON PRECIP AND DOES NOT BRING
THE TROUGH AS FAR WEST AS THE ETA.

FURTHER WEST...A VERY SLOW MOVING WARM FRONT IS BRINGING SOME SNOW
TO THE KUSKOKWIM DELTA THIS MORNING...AND THAT COULD LAST INTO THE
AFTERNOON. THE WARM FRONT WILL STALL LATER TODAY AS THE CANADIAN
RIDGE BUILDS INTO ALASKA. THE TRAILING COLD/OCCLUDED FRONT WILL
REACH THE WEST COAST SUNDAY MORNING...BUT THE UPPER LEVEL JET
DYNAMICS BY THIS TIME ARE DIVING SOUTH AND WILL SPLIT THE FRONT WITH
MOST OF THE ENERGY DIVING SOUTH ACROSS THE AKPEN SUNDAY AFTERNOON.
THE LEFT OVER FRONT DISSIPATES SUNDAY NIGHT AS ALL UPPER LEVEL
SUPPORT IS LONG GONE.

THE WEATHER PICTURE NEXT WEEK FROM TUESDAY ON IS A STORY OF WEAK
UPPER LEVEL FLOW OVER ALASKA WHICH IS CAUSING ALL SORTS OF GRIEF
FOR THE STRUGGLING NUMERICAL MODELS. THE VARIOUS OPERATIONAL RUNS
AND ENSEMBLES AGREE THAT TEMPERATURES WILL GENERALLY BE ABOVE NORMAL
EXCEPT ALONG THE WEST COAST AND ALEUTIANS AS 500 MB HEIGHTS OVER
THE HIGHER LATITUDES OF NORTH AMERICA WILL BE HIGH IN A NEGATIVE
PHASE OF THE ARCTIC OSCILLATION. HOWEVER...THE PRECIPITATION PICTURE
IS NOT SO CLEAR AS THE TWO UPPER LOWS OVER THE BERING SEA AND GULF
OF ALASKA SPIN WEAK DISTURBANCES THROUGH THE FRINGES OF THE RIDGE.
SO HAVE INTRODUCED SOME MORE SHOWERS INTO THE EXTENDED THAN WAS IN
YESTERDAYS FORECAST.

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

LUDWIG MAY 06