Small Craft Advisory 603, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT THU AUG 25 2011

.MODEL DISCUSSION...
MODEL INITIALIZATIONS LOOK REASONABLE THIS MORNING. UPPER LEVEL
PATTERN IS SIMILAR ON ALL MODELS THRU SUN...HOWEVER THERE ARE SOME
DIFFERENCES ON HANDLING OF SURFACE FEATURES. THE NAM AND GFS LOOK
REASONABLE WITH STRONG SURFACE CENTER APPROACHING THE GULF TODAY. THE
ECMWF FORECAST APPEARS TO BE TOO FAR NORTH AND EAST...BUT THE IDEAL
OF A DEEPER PRESSURE SEEMS REASONABLE. A STRONG EASTERLY JET CARRIES
NEXT LOW CENTER RAPIDLY EAST ACROSS THE ALEUTIANS OVER THE NEXT 24-36
HRS. TIMING LIKELY TO BE AN ISSUE...HOWEVER WILL LEAN TOWARD A
GFS/ECMWF BLEND.

.ANALYSIS AND UPPER LEVELS...
.500 MB...PROGRESSIVE PATTERN CONTINUES. A LOW NEAR THE GULF OF
ANADYR/EASTERN RUSSIA ACTS AS A FOCAL POINT FOR WAVES MOVING ACROSS
THE BERING SEA/ALEUTIANS TO THE GULF OF AK. CURRENT CENTER SOUTH OF
THE GULF OF AK...ASSOCIATED WITH A DEVELOPING SURFACE LOW... WEAKENS
AS IT MOVES INTO THE NORTH GULF FRI AFTERNOON. THIS CENTER THEN
ROTATES WEST TOWARD BRISTOL BAY AND FURTHER WEAKENS SAT MORNING. A
WAVE OVER THE WESTERN ALEUTIANS MOVES TO THE EASTERN BERING SEA WITH
A CENTER FORMING SOUTH OF THE EASTERN ALEUTIANS FRI MORNING. THIS
CENTER WEAKENS AS IT MOVES TO THE GULF OF AK SAT AFTERNOON/NIGHT. A
RIDGE BUILDS OVER THE EASTERN BERING SEA/ALEUTIANS SAT AND SHIFTS TO
NEAR SW AK SAT NIGHT/SUN AS SHORT WAVES MOVE WESTWARD ACROSS THE
BERING SEA.

.SHORT TERM FORECAST...
EAST OF THE ALASKA RANGE...SAT IMAGERY SHOWS AN IMPRESSIVE LOOKING
LOW APPROACHING THE SOUTHERN GULF OF AK. BUOY AND SHIP DATA AROUND
12Z INDICATED THAT THE PRESSURE WAS IN THE 970'S. AFTERNOON
OBSERVATIONS WOULD INDICATE THE LOWS PRESSURE  IN THE UPPER 970S TO
LOWER 980S. THIS CENTER SHOULD BOTTOM OUT THIS AFTERNOON...THEN
SLOWLY WEAKEN AS IT BECOMES STACKED WITH UPPER CENTER. LOW WILL
BECOME NEARLY STATIONARY OVER THE GULF FRI...THEN ROTATE WEST AND
WEAKEN SAT AS A TRIPLE POINT LOW MOVES TO THE SOUTHERN GULF. THE
WEATHER FRONT ASSOCIATED WITH GULF GULF CENTER MOVES TO THE NORTH
GULF TONIGHT...THEN WEAKENS AS IT MOVES INLAND FRI. GALES AHEAD OF
THE FRONT AND WITH THE TRAILING LOW WILL TAPER OFF THROUGH FRI. THE
BRUNT OF THE RAIN WILL OCCUR OVER THE GULF COAST AND EAST
EXPOSURES...WITH SHOWERS INLAND. A TRIPLE POINT MOVING IN FROM THE
WEST SAT WILL BRING ANOTHER ROUND OF WINDY CONDITIONS AND RENEWED
RAINS TO THE GULF COASTS.

WEST OF THE ALASKA RANGE...RAIN FOR THE MOST PART HAS TAPPER OFF OVER
THE SW MAINLAND. WEAK RIDING TONIGHT WILL BRING AREAS OF STRATUS AND
FOG. A STRENGTHENING THERMAL TROUGH LIKELY TO KEEP SHOWERS OVER THE
INTERIOR SW AK INTO THE WEEKEND. A RIDGE BUILDING OVER THE EASTERN
BERING SEA SAT WILL LIKELY CREATE LOW STRATUS AND FOG ISSUES FOR THE
COASTS.
UNSETTLED WEATHER WITH AREAS OF RAIN OR SHOWERS ARE EXPECTED ACROSS
THE ALEUTIANS INTO THE WEEKEND AS A SERIES OF WAVE MOVE EASTWARD. THE
MORE SIGNIFICANT OF THE WAVES NEAR CENTRAL ALEUTIANS WILL BRING GALES
AND STRONG WINDS AS IT MOVES TO SOUTH OF UNALASKA FRI AFTERNOON.

.LONG TERM FORECAST...
THE LONG TERM WEATHER PATTERN SHOWS SIGNS OF A POTENTIAL CHANGE
BEGINNING EARLY NEXT WEEK. WHILE THERE REMAINS SIGNIFICANT MODEL
DISAGREEMENT...THE TREND SEEMS TO BE THAT THE PERSISTENT BERING SEA
TROUGH WILL WEAKEN AS RIDGING CURRENTLY OVER WESTERN NORTH AMERICA
RETROGRADES SLIGHTLY WESTWARD. THIS MAY SET THE STAGE FOR MORE ZONAL
FLOW ACROSS THE AOR...BRINGING A POSSIBLE REPRIEVE FROM THE STRONG
EARLY-FALL STORMS OF LATE...AND INSTEAD BRINGING A RETURN OF A BIT
MORE SUNSHINE AND NEAR-NORMAL TEMPERATURES TO MAINLAND ALASKA.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 120 150 155 170 171 172.
FIRE WEATHER...NONE.

RMC AUG 11