Small Craft Advisory 662, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM ADT WED AUG 15 2007

.ANALYSIS...
UPPER LEVEL LOW OVER THE LOWER KENAI PENINSULA WITH A RIDGE OVER THE
EASTERN BERING. FARTHER WEST...A LARGE LOW NEAR 50N 160E. THE MAJOR
ASSOCIATED SURFACE LOWS ARE POSITIONED UNDERNEATH THE UPPER LEVEL
LOWS. IN ADDITION...A LOW IS DEVELOPING ALONG THE FRONT IN THE
WESTERN BERING WITH A SUPPORTIVE UPPER LEVEL JET/SHORT WAVE TROUGH.
THIS IS ADDING SOME WINDS TO THE CENTRAL AND WESTERN BERING. THE LOW
NEAR THE KENAI IN COMBINATION WITH HIGH PRESSURE OVER THE EASTERN
BERING CREATING A DECENT PRESSURE GRADIENT OVER THE APKEN/EASTERN
ALEUTIANS. SOME GUSTY WINDS WILL BE EXPECTED THEIR THROUGH THIS
EVENING BEFORE THE HIGH MOVES FARTHER EAST AND THE KENAI LOW WEAKENS
FURTHER. HOWEVER...THE LOW DEVELOPING NEAR ATKA WILL DEEPEN THIS
EVENING AS IT CROSSES THE CHAIN. THIS WILL INCREASE THE WINDS OVER
THE CENTRAL AND EASTERN BERING.

.MODEL DISCUSSION AND UPPER LEVELS...
MODELS LOOK AS THOUGH THEY INITIALIZED WELL THIS MORNING. IN THE
SHORT TERM...EURO MODELS VERSUS NORTH AMERICAN MODELS IS THE FORECAST
SOLUTION OF THE DAY. ALL MODELS DRIFT THE LOW IN THE KENAI TO THE
WESTERN GULF OVER THE NEXT 48 HOURS. THIS WOULD MEAN A DRYING PERIOD
FOR SOUTH CENTRAL. THE DIFFERENCE DEVELOPS AFTER THIS PERIOD. THE
EURO MODELS AND PREV RUN OF THE GFS THEN LIFT THE LOW BACK TO THE
BERING LOW ACROSS THE AKPEN FRIDAY/SATURDAY. THE CURRENT
GFS...NAM...GFS ENSEMBLES...ALONG WITH THE CANADIAN AND THEIR
ENSEMBLES PUSH THE LOW TO THE SOUTHEAST OVER THE GULF TO HOOK UP WITH
THE CURRENT LOW NEAR 45N 135W. IN THE MEANTIME...ALL MODELS HAVE THE
UPPER LOW NEAR 50N 160E TO MOVE INTO THE BERING NEAR ADAK FRIDAY
NIGHT THEN INTO THE EASTERN BERING FOR THE EURO MODELS AND ALL OTHER
WILL KEEP THE LOW IN THE CENTRAL BERING THROUGH MONDAY. AFTER THIS
PERIOD THE LOW WILL BEGIN TO SWING SOUTHEAST ACROSS THE ALEUTIANS
NEAR UNALASKA WEDNESDAY. OVERALL...THE EURO MODEL SOLUTION WOULD KEEP
SOUTH CENTRAL OPEN TO MORE CLOUDINESS AND CHANCE OF SHOWERS WITH THE
FARTHER EAST BERING LOW AND THE KENAI LOW MOVING NORTH AND EAST
FRIDAY AND SATURDAY. THE NORTH AMERICAN MODEL SOLUTION WOULD MEAN AN
EXTENDED DRYING PERIOD FOR SOUTH CENTRAL ALASKA.

FOR THE RECORD...WILL GO WITH THE NORTH AMERICAN MODELS SINCE THE
CANADIAN HAS BEEN QUITE CONSISTENT WITH ITS MEMBERS AND THE PREVIOUS
GFS ENSEMBLE MEAN AGREES AS WELL DESPITE THE 00Z GFS OPERATIONAL RUN.

.SHORT TERM FORECAST...
BERING/ALEUTIANS...
A DEVELOPING LOW NEAR ATKA TO MOVE NORTH ACROSS THE CHAIN THIS
EVENING AND DEEPEN TO 985 MB IN THE NORTHERN BERING THURSDAY
AFTERNOON. THE ASSOCIATED FRONT WITH A SUPPORTIVE SHORT WAVE TROUGH
WILL PUSH INTO THE CENTRAL BERING TONIGHT AND INTO THE EASTERN BERING
THURSDAY. THE FRONT WILL WEAKEN FRIDAY AS IT HITS THE STRONG HIGH
PRESSURE OVER THE MAINLAND. LITTLE PRECIP TO MAKE ITS WAY PAST THE
COAST. THE WINDS WITH THIS LOW INCREASE AS IT DEEPENS TO THE NORTH
THURSDAY. THE NORTHERN BERING LOW TO DISSIPATE AS IT MOVES OVER THE
CHUKOTSK PENINSULA FRIDAY. THE WESTERN BERING IS SWINGING EAST AT
THIS TIME TO ATKA THURSDAY NIGHT AND INTO THE WESTERN BERING FRIDAY
AND SETTLE INTO THE CENTRAL BERING SATURDAY. THE ASSOCIATED FRONT
WITH THIS LOW TO MOVE INTO THE CENTRAL BERING FRIDAY WITH STRONG
UPPER LEVEL SUPPORT AND IT MOVES TO THE EASTERN BERING FRIDAY NIGHT
INTO SATURDAY. WINDS TO BE STRONG WITH THIS SYSTEM AS WELL FRIDAY
THROUGH SATURDAY.

SOUTHWEST ALASKA...
HIGH PRESSURE MOVING OVER WESTERN ALASKA TONIGHT. SHOWERS ASSOCIATED
WITH THE LOW NEAR THE KENAI PENINSULA TO END AS THE LOW PULLS INTO
THE GULF AND THE HIGH IS ALLOWED INLAND. HIGH PRESSURE WITH WARMING
AND DRYING TO DOMINATE WESTERN ALASKA THROUGH FRIDAY AFTER THIS
EVENING. A FRONT TO MOVE TO THE COAST LATE FRIDAY WITH MODERATE WINDS
AND SOME PRECIP JUST ALONG THE COAST. THE HIGH PRESSURE WILL NOT
ALLOW THIS TO MOVE FARTHER INLAND. A STRONGER FRONT TO MOVE IN
SATURDAY WITH THE LARGE UPPER LOW AND WEAKEN OVER TIME THROUGH THE
WEEKEND.

SOUTH CENTRAL...
WEAK SURFACE LOW UNDER UPPER LOW OVER THE KENAI PENINSULA. THE UPPER
LOW MOVES INTO THE WESTERN GULF WITH THE SURFACE LOW DISSIPATING OVER
THE NEXT DAY. THE SHOWERS WILL THEN BE ON THE DOWNSWING THROUGH THE
NEXT 24 HOURS. SOME SHOWERS TO REMAIN AROUND THE COAST THROUGH
TOMORROW...BUT A DRYING TREND TO MOVE IN TOMORROW AFTERNOON THROUGH
THE WEEKEND.

.LONG TERM FORECAST...
A DEEP UPPER TROUGH WILL STAY OVER THE BERING AND ALEUTIAN CHAIN WITH
A RIDGE ESTABLISHING ITSELF OVER THE MAINLAND IN A BLOCKING PATTERN
FOR LATE THIS WEEKEND THROUGH EARLY NEXT WEEK. THIS WILL KEEP SYSTEMS
CONFINED TO THE BERING AND KEEP MOST OF THE MAINLAND IN A CALM
WEATHER PATTERN. THE FLOW OPENS UP FOR SOUTH CENTRAL EARLY NEXT WEEK
FOR MORE CLOUDINESS AND POSSIBLE SHOWERS. SHOWERS AND MODERATE TO
STRONG WINDS OVER THE BERING AND ALEUTIANS THROUGH MID NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 185
FIRE WEATHER...NONE

JN AUG 07