Small Craft Advisory 451, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT SAT JUN 1 2013

.ANALYSIS AND UPPER LEVELS...
THERE IS AN UPPER LEVEL HIGH OVER CENTRAL ALASKA AND AN UPPER LOW
SOUTH OF THE ALEUTIANS. THERE IS A BAROCLINIC ZONE/FRONT BETWEEN
THESE TWO SYSTEMS DRAPED FROM ABOUT NUNIVAK ISLAND TO YAKUTAT.
UNDERNEATH THE UPPER HIGH THERE IS A THERMAL TROUGH AT THE SURFACE.

.MODEL DISCUSSION...
THE GFS AND ECMWF ARE IN RATHER GOOD AGREEMENT UP UNTIL JUST BEFORE
84 HOURS WHEN THEY BEGIN TO DIVERGE ON SURFACE FEATURES...WITH THE
ECMWF BRINGING A SURFACE LOW FROM THE GULF INLAND A LITTLE FASTER
THAN THE GFS. THE NAM BEGINS TO DIVERGE AFTER 36 HOURS...AND AS AN
OUTLIER IT WAS LITTLE USED IN THE THE FORECAST.

.SHORT TERM FORECAST...
AS THE RIDGE OVER CENTRAL ALASKA MOVES NORTH AND THE LOW SOUTH OF
THE ALEUTIANS MOVES TO THE NORTHEAST TONIGHT AND SUNDAY...THE
NUNIVAK-TO-YAKUTAT FRONT WILL CROSS SOUTHERN ALASKA. THIS WILL BRING
A GOOD CHANCE OF RAIN TO MOST OF THE AREA. AS THE UPPER LOW MOVES
INTO THE GULF SUNDAY NIGHT/MONDAY ANOTHER FRONT WILL MOVE TO THE
GULF COAST. THERE WILL BE CHANCES OF RAIN INLAND...BUT MOST OF THE
PRECIPITATION WILL BE ALONG THE GULF COAST. THE UPPER LOW WILL THEN
SETTLE IN NORTHERN GULF KEEPING PLENTY OF CLOUDS AND SOME SHOWERS
OVER SOUTHERN ALASKA THROUGH TUESDAY.

THE CENTRAL ALASKA RIDGE IS STILL KEEPING WARM AND UNSTABLE AIR FOR
AREAS FURTHER INLAND. THIS IS PROVIDING SOME INSTABILITY...WITH
THUNDERSTORMS POSSIBLE THIS AFTERNOON AND EVENING FROM THE LOWER
KUSKOKWIM VALLEY EASTWARD ALONG THE ALASKA RANGE AND INTO THE
WRANGLE MOUNTAINS. AS THE RIDGE MOVES NORTH ON SUNDAY...THUNDERSTORM
CHANCES WILL BE CONFINED TO THE ALASKA RANGE IN THE NORTHERN COPPER
RIVER BASIN. BY MONDAY COOLER AND MORE STABLE AIR WILL HAVE PUSHED
ACROSS ALL OF SOUTHERN ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...FLOOD WATCH 145.
MARINE...NONE.
FIRE WEATHER...NONE.

LUDWIG JUN 13