Small Craft Advisory 408, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
500 PM ADT FRI MAY 4 2007

.MODEL DISCUSSION...
BOTH UKMET AND GFS ARE MOVING THE NEXT LOW PRESSURE SYSTEM
APPROACHING THE GULF OF ALASKA A LITTLE FASTER AND KEEPS IT A LITTLE
STRONGER THAN THE NAM MODEL. GFS HAS BEEN A LITTLE ERRATIC OVER THE
FEW RUNS, BUT APPEARS TO HAVE SETTLED DOWN. OTHERWISE, THE MODELS ARE
IN GOOD AGREEMENT OVER MAINLAND ALASKA AND THE BERING SEA.

.ANALYSIS AND UPPER LEVELS...
THE 500 MB PATTERN SHOWS AN UPPER LOW OVER THE WESTERN GULF WITH A
TROUGH EXTENDED TO THE SOUTHWEST INTO THE NORTH PACIFIC. A WEAK SHORT
WAVE OVER THE WRANGELL MOUNTAINS IS CONTINUING TO DRIFT WEST INTO THE
COPPER RIVER BASIN. LIGHT RAIN HAS FALLEN MOSTLY OVER THE EASTERN
THIRD OF THE BASIN, BUT WILL SLOWLY MOVE WEST THROUGH TONIGHT.

AT SURFACE...A THERMAL TROUGH REMAINS OVER THE CENTRAL AND SOUTHWEST
INTERIOR. INCREASED CLOUD COVER SHOULD SUPPRESSED SHOWERS OVER THE
BASIN TODAY. SOUTHWEST REMAIN FAIRLY UNSTABLE TODAY. SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED TO DEVELOP IN THE
LATE AFTERNOON THROUGH EVENING.

.SHORT TERM FORECAST...
SOUTHCENTRAL ALASKA...THE UPPER VORT OVER THE EASTERN COPPER RIVER
BASIN WILL SPREAD INTO THE INTO THE CENTRAL INTERIOR TONIGHT THEN
WILL WEAKEN THROUGH SATURDAY NIGHT. THE AREA OF RAIN WILL SPREAD WEST
INTO THE CENTRAL COPPER RIVER BASIN TONIGHT THEN DIMINISH SATURDAY.
SCATTERED SHOWERS WILL DEVELOP ALONG THE ALASKA RANGE TODAY BUT ARE
LESS LIKELY SATURDAY AND SUNDAY AS THE AIR MASS BECOMES MORE STABLE.

SOUTHWEST ALASKA...THE AIRMASS OVER THE KUSKOKWIM VALLEY AND THE
BRISTOL BAY ZONE REMAINS FAIRLY UNSTABLE TODAY. COOLER AIR AT 850 MB
WILL SPREAD INTO THE ARE FROM BERING SEA SATURDAY AND SUNDAY WILL
REDUCE CONVECTION OVER THE NEXT TWO DAYS.

BERING SEA...AREA OF HIGH PRESSURE SOUTH OF THE WESTERN ALEUTIANS
WILL SLOWLY DRIFT EAST THROUGH SUNDAY. A WEAK WARM FRONT OVER THE
CENTRAL BERING AND CENTRAL ALEUTIANS WILL MOVE INTO THE EASTERN
BERING SATURDAY THEN DISSIPATE SATURDAY NIGHT. AREAS OF RAIN AND SNOW
ASSOCIATED WITH THE FRONT WILL PERSIST OVER THE EASTERN BERING
THROUGH SATURDAY NIGHT.

.LONG TERM FORECAST...
BERING SEA...
RIDGE OVER THE BERING SEA WILL FLATTEN MONDAY AND MONDAY NIGHT AS A
SHORT WAVE TROUGH MOVES THROUGH THE BERING. A STRONG LOW NEAR THE TIP
OF THE KAMCHATKA PENINSULA MONDAY NIGHT WILL MOVE INTO THE BERING SEA
WEDNESDAY. MORE WIND AND RAIN WILL MOVE INTO THE BERING BY THE MIDDLE
OF NEXT WEEK.

SOUTHWEST ALASKA...
CONDITIONS OVER SOUTHWEST ALASKA WILL REMAIN FAIRLY STABLE WITH
LITTLE TO NO SHOWERS MONDAY. AN UPPER SHORT WAVE MOVING INTO THE AREA
TUESDAY WILL BRING SOME RAIN AND SNOW.

SOUTHCENTRAL ALASKA...
THE THERMAL TROUGH WILL REFORM OVER THE INTERIOR SECTION MONDAY AND
REMAIN THROUGH WEDNESDAY.

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

NM MAY 07