Small Craft Advisory 681, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM ADT WED AUG 22 2007

.ANALYSIS...
LARGE UPPER LOW CONSOLIDATING OVER THE EASTERN BERING WITH A COUPLE
SURFACE LOWS IN THE MIX AS WELL. A LOW IS DEVELOPING IN THE SOUTHERN
GULF THIS AFTERNOON ON THE FRONT SIDE OF THE LARGE UPPER LOW IN THE
EASTERN BERING. STRONG JET WITH THIS DEVELOPING LOW AND A GOOD
TROPICAL MOISTURE TAP AS WELL. THE CURRENT FLOW OVER WESTERN AND
SOUTH CENTRAL ALASKA IS SOUTHERLY WITH PLENTY OF MOISTURE COVERING
THESE AREAS. WINDS ARE NOT THAT STRONG CURRENTLY...BUT THE LOW IN THE
SOUTHERN GULF TO DEEPEN OVERNIGHT AND INCREASE THE WINDS TO GALE
FORCE ACROSS THE GULF. THIS STRONG SURFACE AND UPPER LEVEL FEATURE
WILL DRAG THE UPPER LOW INTO THE GULF THURSDAY. HIGH PRESSURE BUILDS
OVER THE WESTERN BERING INTO THE CENTRAL BERING THROUGH TONIGHT. A
STRONG FRONT WILL APPROACH THE WESTERN ALEUTIANS LATE TONIGHT WITH
GALE FORCE WINDS.

.MODEL DISCUSSION AND UPPER LEVELS...
MODELS INITIALIZED OK. EURO AND NCEP MODELS AND HAVE CONSOLIDATED ON
THE GULF LOW PROGRESSION THROUGH SATURDAY. THE UNCERTAINTY ONCE AGAIN
FOLLOWS WITH THE SPEED OF THE SECOND LOW COMING ACROSS THE BERING SEA
FRIDAY THROUGH SUNDAY. THIS SECOND LOW WILL MOVE ALL OTHER FEATURES
ALONG AND PUSH THE ALASKA REGION INTO A MORE AMPLIFIED PATTERN.

THE UPPER LEVEL LOW OVER THE EASTERN BERING HAS A STRONG SHORT WAVE
TROUGH ON THE FRONT SIDE JUST SOUTH OF THE AKPEN MOVING INTO THE
GULF. THIS FEATURE IS ALSO ASSOCIATED WITH A STRONG JET. A SURFACE
LOW WILL DEEPEN IN THE GULF FROM THIS FEATURE AS WELL. THE WAVE WILL
HELP SWING THE BERING LOW INTO THE GULF. THE GULF LOW WILL SIT AND
FILL THROUGH FRIDAY OVER THE GULF. MEANWHILE A LARGE UPPER LOW MOVES
INTO THE WESTERN BERING. THE RIDGE IN BETWEEN THE TWO LOWS WILL ERODE
MAKING A VERY ZONAL PATTERN WITH A MODERATE TO STRONG JET FROM ASIA
THROUGH TO THE PACIFIC NORTHWEST. THEREFORE...THE UNCERTAINTY COMES
IN ON THE SPEED OF THE NEXT LOW. THE NEW LOW WILL EVENTUALLY RIDE TO
THE CENTRAL BERING SATURDAY PUSHING THE GULF LOW TO THE PANHANDLE.
THE LOW WILL CROSS INTO THE NORTHERN PACIFIC SOUTH OF THE AKPEN
SUNDAY AND SLOWLY MOVE TO JUST SOUTH OF THE GULF MID NEXT WEEK. A
RIDGE WILL BUILD OVER THE BERING BEHIND THE LOW FROM SUNDAY TO MID
NEXT WEEK.

.SHORT TERM FORECAST...
ALEUTIANS AND BERING...
THE WEAK LARGE LOW OVER THE EASTERN BERING CREATING SOME SHOWERS
THROUGHOUT THE AREA WILL MOVE INTO THE GULF TOMORROW WITH SHOWERS
DIMINISHING FROM THE WEST STARTING TONIGHT. WINDS ON THE BACK SIDE OF
THIS LOW COMBINED WITH THE HIGH PRESSURE IN CENTRAL BERING WILL GET
SMALL CRAFT ADVISORY WINDS FOR A BIT TONIGHT AND TOMORROW. HIGH
PRESSURE OVER THE WESTERN BERING WILL BE REPLACED WITH A STRONG FRONT
MOVING ACROSS THE AREA STARTING TONIGHT FROM A LOW NEAR KAMCHATKA.
THE FRONT WILL PROCEED TO THE CENTRAL BERING BY FRIDAY MORNING BUT
WEAKENING THE ENTIRE TIME. GALE FORCE WINDS WILL ACCOMPANY THE FRONT
HOWEVER TONIGHT AND TOMORROW. THE EVENTUALLY MOVES INTO THE CENTRAL
BERING SATURDAY WITH SHOWERS PUSHED OUT OF EASTERN BERING FRIDAY BUT
RETURNING BY FRIDAY NIGHT AND REMAINING THROUGH SATURDAY. THE PRECIP
WILL END OVER THE WESTERN ALEUTIANS AT THIS TIME.

WESTERN ALASKA...
THE LARGE LOW OVER THE EASTERN BERING SPREADING SHOWERS OVER THE
ENTIRE AREA. SHOWERS WILL DIMINISH FROM THE WEST STARTING TONIGHT AS
THE LOW PULLS OFF TO THE GULF. ENOUGH RESIDUAL MOISTURE AND
INSTABILITY WILL BE AROUND FOR SHOWERS THROUGH SATURDAY. ON THE
FRINGES WHERE SUN BREAKS ARE EXPECTED...THUNDERSTORMS COULD DEVELOP
ESPECIALLY OVER ELEVATED TERRAIN.

SOUTH CENTRAL...
LOW IN THE EASTERN BERING CONTINUING MOIST SOUTHERLY FLOW FOR SHOWERS
OVER THE AREA THROUGH TONIGHT. A LOW DEEPENING IN THE GULF TONIGHT
WILL INCREASE THE WINDS ACROSS THE GULF TO GALE FORCE LATE TONIGHT
THROUGH TOMORROW. THE LOW WILL WEAKEN AS IT BECOMES STACKED UNDER THE
UPPER LOW TOMORROW. THE LOW WILL CONTINUE TO WEAKEN THROUGH FRIDAY IN
THE SAME POSITION OF THE NORTHERN GULF. RAIN WILL BE PREVALENT ALONG
THE COAST THROUGH FRIDAY. SHOWERS WILL BECOME MORE SCATTERED FRIDAY
FARTHER INLAND AS MOST OF THE PRECIP WILL BE CLOSE TO THE LOW WHEN IT
WEAKENS. THE LOW WILL PULL OFF SATURDAY WITH PRECIP WANING EVERYWHERE
AND SKIES BECOMING MUCH LESS CLOUDY.

.LONG TERM FORECAST...
LARGE STACKED LOW OVER THE CENTRAL BERING SATURDAY WILL SLOWLY DRIFT
SOUTHEAST THROUGH SUNDAY AND INTO THE GULF BY MONDAY. SHOWERS WILL
SURROUND THE LOW WITH LIGHT TO MODERATE WINDS. HIGH PRESSURE MOVES IN
BEHIND THE LOW WITH ANOTHER FRONT ENCROACHING ON THE WESTERN
ALEUTIANS MID WEEK.

THE GULF LOW LEAVES THE AREA SATURDAY WITH PRECIPITATION ON THE WANE.
SOME INSTABILITY AND MOISTURE WILL REMAIN OVER SOUTH CENTRAL FOR
SHOWERS OVER THE MOUNTAINS WITH A SLIGHT CHANCE OF THUNDERSTORMS.
THIS IS OVER BY SUNDAY AS THE AIR MASS DRIES OUT SUFFICIENTLY. THE
NEXT LOW TO ENTER THE GULF AREA SUNDAY NIGHT/MONDAY WITH INCREASING
WINDS AND PRECIP FOR KODIAK AND THE SOUTHERN GULF THROUGH MID NEXT
WEEK.

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

JN AUG 07