Small Craft Advisory 375, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM ADT SAT APR 21 2007

.MODEL DISCUSSION...
MODELS HAVE INITIALIZED MOISTURE FIELDS WELL AND POSITION OF THE LOW
SOUTH OF THE CENTRAL ALEUTIAN CHAIN. HOWEVER...MODELS UNCERTAINTY IS
HIGH WITH A SECOND LOW MOVING INTO THE WESTERN ALEUTIAN CHAIN SUNDAY
NIGHT. ALL MODELS AND ENSEMBLES HAVE A STRONG TENDENCY TOWARD A
SLOWER SOLUTION...BUT THEN AGAIN SOME ARE A BIT FASTER.

.UPPER LEVELS...
BIG PICTURE HAS AN ARCTIC LOW NORTH OF CENTRAL RUSSIA WITH A TROUGH
EXTENDING INTO THE WESTERN BERING. THE TROUGH IN THE BERING BECOMES
THE CLOSED LOW OVER THE EASTERN ALEUTIANS TOMORROW WITH A LARGE LOW
PARKED OVER EASTERN RUSSIA. THE CLOSED LOW OVER THE EASTERN ALEUTIANS
TO SLOWLY MOVE INTO THE GULF AND WEAKEN THROUGH THE WEEK AS THE LOW
IN MONGOLIA WEAKENS AS WELL. HOWEVER...A COLD CORE LOW DEVELOPS OVER
MONGOLIA BY THE END OF THE WEEK.

IN THE SMALLER PICTURE...CURRENTLY THERE IS A CLOSED LOW SOUTH OF THE
CENTRAL ALEUTIANS WITH A RIDGE OVER THE YUKON AND PANHANDLE. THE
CLOSED LOW TO PUSH INTO THE WESTERN GULF SHIFTING THE RIDGE EAST OF
THE PANHANDLE TOMORROW NIGHT. A SECONDARY LOW TO RIDE IN ON THE NEXT
JET STREAK MONDAY. THIS IS THE SYSTEM THAT IS UNCERTAIN ON THE DEPTH
AND SPEED. RIGHT NOW THE CURRENT MODELS HAVE SLOWED IT UP AND MADE IT
NOT AS DEEP AS PREVIOUS RUNS. STILL SOME UNCERTAINTY EXISTS AS SOME
MEMBERS OF THE ENSEMBLE VARY FROM THIS SOLUTION. AS TIME GOES ON
THOUGH...THE SOLUTIONS ARE VERY SIMILAR THROUGH THURSDAY. THE LOW IN
THE GULF WEAKENS OVER TIME AS THE NEW LOW BECOMES CLOSED TUESDAY AND
THEN SLOWLY WORKS INTO THE GULF BY THURSDAY WITH A RIDGE DEVELOPING
OVER THE BERING INTO FRIDAY. A SHORT WAVE TROUGH WILL RIDE DOWN THE
FRONT OF THE RIDGE INTO THE LARGE CLOSED LOW IN THE GULF THURSDAY AND
FRIDAY. BY SATURDAY...A NEW LOW WILL MOVE INTO PLAY OVER THE WESTERN
ALEUTIANS WITH THE LOW IN THE GULF CONTINUING.

.SURFACE WEST OF THE ALASKA RANGE...
A LARGE LOW PRESSURE SYSTEM SOUTH OF THE CENTRAL ALEUTIANS BRINGING
GALE FORCE WINDS AND PLENTY OF PRECIPITATION TO THE CENTRAL ALEUTIANS
INTO THE CENTRAL BERING SEA. A WEAKENING BOUNDARY OVER SOUTHWEST
ALASKA SPREADING SHOWERS AND SOME GUSTY CONDITIONS THERE TODAY. THIS
BOUNDARY TO DISSIPATE THIS EVENING AS THE LOW MOVES EAST. THE LOW
WILL BE WEAKENING AS IT MOVES EAST TOMORROW BUT NEAR GALE FORCE WINDS
AND SHOWERS WILL REMAIN OVER A LARGE PORTION OF THE BERING AND AKPEN
REGION THROUGH TOMORROW NIGHT. AS THE LOW TRANSITIONS INTO THE GULF
MONDAY...PRECIPITATION AND WINDS WILL BEGIN TO DROP. HOWEVER...WEAK
UPPER LEVEL DISTURBANCES AROUND THE LOW WILL PERIODICALLY BRING MORE
ORGANIZED PRECIPITATION OVER SOUTHWEST ALASKA INTO TUESDAY. IN THE
MEANTIME...A LOW WILL WORK SOUTH OF ADAK MONDAY NIGHT AND STAY SOUTH
OF THE CHAIN AS IT MOVE EAST TO 150 WEST BY THURSDAY MORNING.
PRECIPITATION WILL SPREAD ACROSS THE CENTRAL ALEUTIANS TUESDAY
AFTERNOON THEN TO THE APKEN BY WEDNESDAY AFTERNOON. GALE FORCE WINDS
WILL ACCOMPANY THIS SYSTEM TUESDAY INTO THURSDAY MORNING MAINLY ALONG
THE FRONT AND BEHIND THE LOW ITSELF. MOST PRECIPITATION WILL BE RAIN
IN NATURE FROM THE CENTRAL ALEUTIANS EAST. HIGH PRESSURE BUILDS OVER
THE WESTERN BERING THURSDAY AND SPREADS OVER THE ENTIRE BERING
FRIDAY. SHOWERS WILL REMAIN OVER THE MAINLAND AND AKPEN FROM THE LOW
IN THE GULF AND A UPPER LEVEL SHORT WAVE MOVING OUT OF THE NORTH
ACROSS THE EASTERN BERING THURSDAY NIGHT THROUGH FRIDAY.

.SURFACE EAST OF THE ALASKA RANGE...
CURRENTLY...THERE IS A WEAK BOUNDARY IN THE GULF WITH SHOWERS
REMAINING OVER KODIAK. SOME SMALL CRAFT WINDS REMAIN OVER THE AREA
WITH THIS BOUNDARY. WINDS TO PICK UP TO GALE FORCE TONIGHT...AS THE
LOW CURRENTLY SOUTH OF THE CENTRAL ALEUTIANS MOVES TO THE SOUTH OF
THE AKPEN. RAIN WILL SPREAD OVER THE WINDWARD SIDE OF THE KENAI
PENINSULA AS WELL. AS THE LOW MOVES INTO THE GULF TOMORROW
AFTERNOON...RAIN WILL SPREAD TO THE NORTHERN COAST AND PUSH THE HIGH
PRESSURE OUT OF THE EASTERN GULF WITH RAIN MAKING IT TO THE PANHANDLE
AS WELL. THE LOW WILL BASICALLY SIT AND SPIN IN THE WESTERN GULF
THROUGH TUESDAY AND WEAKEN THROUGH THE TIME FRAME AS WELL. THE LOW
WILL EVENTUALLY DISSIPATE TUESDAY NIGHT AS ANOTHER LOW SOUTH OF THE
EASTERN ALEUTIANS MOVES CLOSER. HOWEVER...THE REMNANT FRONTAL
BOUNDARY WILL REMAIN ALONG THE NORTHERN GULF COAST WITH PRECIPITATION
AND SMALL CRAFT ADVISORY WINDS. THE NEW LOW WILL MOVE EASTERLY SOUTH
OF THE GULF WEDNESDAY AFTERNOON WITH GALE FORCE WINDS AND RAIN
PICKING UP IN THE GULF. THE LOW WILL MOVE INTO THE CENTRAL GULF
THURSDAY AND START TO WEAKEN THROUGH FRIDAY. DUE TO THE WARM MOIST
SOUTHEAST FLOW THAT WILL PREVAIL OVER THE GULF THROUGH MUCH OF THIS
TIME FRAME...MOST ALL PRECIP WILL BE RAIN. IN ADDITION...MOST
PRECIPITATION WILL REMAIN ALONG THE COASTAL LOCATIONS. WE WILL ALSO
PICK UP THROUGH EAST WEST ORIENTED GAPS WITH EACH PROGRESSIVE FRONT.
THIS IS ESPECIALLY TRUE FOR TOMORROWS FRONT AS THE LOW WILL MOVE
FARTHER NORTH WHEN IT IS STRONGER THAN THE FRONT LATER IN THE WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 120 130 132 138 172
FIRE WEATHER...NONE

JN APR 07