Snow Advisory 18, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM ADT THU APR 24 2008

.MODEL DISCUSSION...
DECENT MODEL AGREEMENT IN THE SHORT TERM CONSIDERING THE COMPLEXITY
OF THE PATTERN. GLOBAL MODELS BEGIN TO HAVE MINOR DIFFERENCES IN THE
GULF BY AROUND 84 HOURS...THEN GENERAL PATTERN DISAGREEMENTS AFTER
ABOUT 144 HOURS.

.ANALYSIS AND UPPER LEVELS...
RIDGE RUNNING GENERALLY NORTH TO SOUTH ACROSS ALASKA...WITH THE AXIS
THIS MORNING RUNNING FROM ABOUT KODIAK TO BARTER ISLAND. DEEP POLAR
LOW CENTERED JUST WEST OF THE BERING STRAIT. OTHER LOWS NEARBY
INCLUDE ONE SOUTH OF THE GULF OF ALASKA...AND ANOTHER CENTERED NEAR
THE GREAT SLAVE LAKE IN CANADA. STRONG POLAR JET RACING OFF SOUTHERN
SIBERIA AND ACROSS THE BERING SEA. THE JET ARRIVES INTO WESTERN
ALASKA NEAR BETHEL...THEN VEERS NORTHWARD TOWARD BARROW. SUBTROPICAL
JET IS WELL SOUTH OF THE AREA AND WILL NOT COME INTO PLAY IN THE
FORECAST UNTIL SATURDAY...AND EVEN THEN NOT DIRECTLY.

.SHORT TERM FORECAST...
WEATHER ALREADY DETERIORATING OVER SOUTHWEST ALASKA AS THE BERING
STRAIT LOW MOVES EASTWARD. LAST FINE DAY OVER SOUTH CENTRAL AS THE
RIDGE GETS SQUASHED DOWN. FLOW ALOFT BECOMES PROGRESSIVELY STRONGER
SOUTHWESTERLY THROUGH TONIGHT AS THE POLAR JET SLAMS INTO THE STATE.
ON FRIDAY THE EASTWARD PROGRESS OF THE LOW STALLS AS THE RIDGE
FINALLY MAKES A STAND ALONG THE CANADIAN WEST COAST. SOME OF THE
ENERGY WILL THEN DIVE SOUTH INTO THE GULF...AND SOME NORTH TOWARD
THE YUKON. BY LATE SATURDAY A MAJOR LOW WILL BE SPINNING UP IN THE
GULF AS THE COLD AIR FROM THE POLAR JET COMBINES WITH THE WARM AND
WET AIR FROM THE LOW SOUTH OF GULF...THAT BY THIS TIME WILL BE
MOVING NORTH. AT THIS TIME SOME MOISTURE FROM THE SUBTROPICAL JET
WILL MOVE INTO SOUTH CENTRAL ALASKA...BUT THE BULK OF THE ENERGY IS
DESTINED FOR THE PANHANDLE.

.LONG TERM FORECAST...
ON SUNDAY AND MONDAY THE GULF LOW WILL BECOME THE DOMINANT WEATHER
FEATURE...WITH THE BERING STRAIT LOW SLOWLY RECEDING NORTHWARD. THE
GULF LOW WILL SLOWLY MOVE EAST NEXT WEEK (HOW SLOWLY IS WHERE THE
MODELS ARE HAVING MAJOR DIFFERENCES). THIS WILL LEAVE SOUTHERN
ALASKA IN A COL WITH GRADUALLY DRYING WEATHER.

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

LUDWIG APR 08