Small Craft Advisory 353, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 AM ADT SUN APR 15 2007

.ANALYSIS AND UPPER LEVELS...

LARGE UPPER LEVEL PLANETARY TROUGH PERSISTS FROM CHINA TO THE CENTRAL
GULF OF ALASKA THIS MORNING. EMBEDDED WITHIN THE TROUGH ARE CUT-OFF
LOWS WELL SOUTH OF COLD BAY AND WEST OF KAMCHATKA...WITH A WEAK RIDGE
SOUTH OF THE ALEUTIAN CHAIN AND STRONGER ONE OVER SE AK. AT THE
SURFACE A TRIPLE POINT LOW IS DEVELOPING EAST OF KODIAK FROM A LARGE
LOW SOUTH OF COLD BAY. ANOTHER NORTH PACIFIC LOW IS LINED UP TO
APPROACH THE WESTERN ALEUTIANS.

.MODEL DISCUSSION...

MODELS AGAIN ARE IN VERY GOOD AGREEMENT WITH THE KODIAK AND COLD BAY
LOWS ULTIMATELY SPINNING AROUND EACH OTHER IN THE GULF LATER TODAY
THROUGH EARLY TUE AND THEN MOVING INTO VANCOUVER ISLAND TUE
AFTERNOON. THE MODELS BEGIN TO DIVERGE WITH THE NEXT LOW COMING
TOWARD THE ALEUTIANS. WENT WITH THE GFS SINCE THIS ACTUALLY SPLITS
THE LOW NORTH AND SOUTH OF THE AKPEN TOWARD MIDWEEK. YET ANOTHER
LOW...WHICH IS THE THIRD MAIN LOW IN THIS SERIES..SEEMS TO BE HEADING
SOUTH OF THE ALEUTIANS THROUGH THE END OF THE WEEK ALTHOUGH
UNCERTAINTY IS INCREASING RAPIDLY. THE TRAJECTORY OF THE FOURTH LOW
FROM THE SAME SOURCE REGION WILL BECOME CLEAR WITH SUBSEQUENT MODEL
RUNS.

.SHORT TERM FORECAST...

IN BERING...THE FIRST LOW WILL BRING SMALL CRAFT WIND AND SHOWERS TO
THE EASTERN ALEUTIANS TODAY BEFORE MOVING EAST TONIGHT,. THE NEXT LOW
WILL TRACK ALONG THE CHAIN TONIGHT AND TUE AND SPLIT NORTH AND SOUTH
OF THE AKPEN TUE THROUGH WED. THIS WILL BRING SHOWERS AND SMALL CRAFT
AND GALES TO THE ENTIRE AREA THROUGH WED NIGHT. THE THIRD LOW WILL
AGAIN TRACK SOUTH OF THE BERING WED THROUGH THE END OF THE WEEK WITH
ACTIVITY LIMITED PRIMARILY TO THE ALEUTIANS THROUGH THIS PERIOD.

OVER SOUTHWEST AK...SOME RAIN AND SNOW SHOWERS WILL AFFECT THE AREA
AS THE COLD BAY LOW MOVES INTO THE GULF THROUGH TONIGHT. DRYING WILL
OCCUR MON. AS THE LOW SPLITS AROUND THE AKPEN IT WILL INCREASE
COASTAL WIND TUE WITH SNOW RAPIDLY CHANGING TO RAIN INLAND. SOUTHEAST
FLOW ALOFT WILL KEEP PRECIPITATION FAIRLY SHOWERY TUE AND THEN MORE
STRATIFORM WED AS THE LOW MOVES OVERHEAD. THE LOW BECOMES A TROUGH
AND GRADUALLY DISSIPATES THROUGH THE END OF THE WEEK WITH DIMINISHING
SHOWER ACTIVITY.

SOUTH AND EAST OF THE AK RANGE...PRECIPITATION WILL BE MAINLY LIMITED
TO THE NORTH GULF COAST AS THE LOWS MOVE AROUND EACH OTHER THROUGH
MON. A MIX OF RAIN AND SNOW IS EXPECTED...WITH MORE SNOW AT HIGHER
ELEVATIONS OF THE KENAI AND CHUGACH MOUNTAINS. DRYING WILL OCCUR MON
NIGHT AND TUE. THE AKPEN SPLITTING LOW WILL AGAIN BRING A ROUND OF
RAIN WITH SOME SNOW TO KODIAK ISLAND AND THE SOUTHEAST FACING KENAI
MOUNTAINS THROUGH THU. SOME SHOWERS MAY REACH INLAND AREAS THU.

.LONG TERM FORECAST...

THE UNCERTAINTY OF STORM TRACKS MEANS THE WEEKEND WILL BE A TOUGH
CALL...ALTHOUGH THE THIRD LOW MAY TAKE ITS PLACE IN THE GULF FOR MORE
COASTAL PRECIPITATION. IF THIS COMES TO PASS THE ALEUTIANS WILL BE
UNDER HIGH PRESSURE FOR MUCH OF THE WEEKEND...WHILE SW AK WILL HAVE A
FEW MORE SHOWERS.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALES 120 130 138 170 172 175 176
FIRE WEATHER...NONE

DS APR 07