Small Craft Advisory 623, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM ADT THU AUG 2 2007

.ANALYSIS...
A LARGE LOW COMPLEX EXISTS IN THE BERING WITH A RIDGE OVER THE
NORTHERN AND EASTERN GULF. A FRONT IS DRAPED ACROSS SOUTHWEST ALASKA
INTO THE KENAI PENINSULA AND KODIAK ISLAND. THE RIDGE ALONG THE
NORTHERN GULF COAST CREATING SOME MODERATE WINDS THROUGH EAST WEST
ORIENTED GAPS. IN ADDITION...AREAS NEAR THE FRONT HAVE SMALL CRAFT
LEVEL WINDS. ANOTHER LOW IS DEVELOPING SOUTH OF ADAK AS EXPECTED WITH
YET ANOTHER LOW CENTER SOUTH OF SHEMYA.

.MODEL DISCUSSION...
ONCE AGAIN THE EURO MODELS AND GFS INITIALIZED A BIT BETTER. UPPER
LEVELS IN GOOD AGREEMENT THROUGH MID NEXT WEEK. THE DIFFERENCES
REMAIN IN THE DETAILS OF THE SURFACE FEATURES. THE STRENGTH AND SPEED
OF THE EURO MODELS COMPARED TO THE GFS ARE A LITTLE OFF BUT SAME
GENERAL PROGRESSION. THE BIGGEST DIFFERENCE IS THE BRISTOL BAY LOW
FOR FRIDAY. MODELS A LITTLE OFF ON THE JET POSITION OUT NEAR 50N 165W
THIS MORNING. THE MODELS ALL TEND TO HAVE IT A BIT FARTHER SOUTH. HOW
THAT WILL PLAY WITH THE POSITION OF THE LOW ON FRIDAY IN BRISTOL BAY
IS THE CONCERN. FOR EXAMPLE...THE UKMET IS 10 MB DEEPER THAN THE GFS.
THROWING OUT ALL CONCERN FOR THE NAM BEYOND 12 HOURS SINCE JET
STRUCTURE TAKES ON DIFFERENT AND LESS REALISTIC CHARACTERS THAN OTHER
MODELS.

.UPPER LEVELS...
LARGE UPPER LEVEL LOW OVER THE BERING WITH A RIDGE OVER MUCH OF THE
GULF IS EXPECTED THROUGH SATURDAY. THE LOW TO LIFT ACROSS THE EASTERN
BERING SUNDAY AS A TROUGH AND THEN ACROSS THE MAINLAND MONDAY AND
TUESDAY. IN THE MEANTIME...A LOW DEVELOPS OVER KAMCHATKA SUNDAY AND
GRADUALLY PUSHES NEAR SHEMYA TUESDAY AND INTO THE CENTRAL BERING BY
THURSDAY. THE RESULT WILL BE A RIDGE OVER THE WESTERN BERING SUNDAY
THEN THE EASTERN BERING MONDAY AND MOVING OVER THE MAINLAND TUESDAY
AND WEDNESDAY.

.SHORT TERM FORECAST...
SOUTH CENTRAL.
FRONT MOVING UP THE KENAI PENINSULA THIS EVENING AND EXITING KODIAK
ISLAND. RIDGE ALONG THE COAST WITH A SOUTHEAST FLOW ALOFT PROVIDING
MODERATE WINDS ALONG THE COAST AND THROUGH EAST WEST ORIENTED GAPS.
THESE CONDITIONS THROUGH THE GAPS WILL PERSIST THROUGH TOMORROW. THE
FRONT WILL WEAKEN AS IT MOVES INLAND TONIGHT. SHOWERS WILL TAPER TO
SCATTERED SHOWERS BY MORNING. A LOW MOVES INTO BRISTOL BAY TOMORROW
WITH RAIN SPREADING TO KODIAK TOMORROW AFTERNOON AND THEN INLAND
OVERNIGHT FRIDAY. THIS WILL BE A WARM RAIN WITH GOOD JET SUPPORT.
RAIN COULD BE HEAVY AT TIMES. THE GAP WINDS TO LESSEN AS WELL DUE TO
LOW PRESSURE WEAKENING THE RIDGE ALONG THE COAST. PLENTY OF PRECIP TO
REMAIN SATURDAY INTO SUNDAY WITH MOIST SOUTHWEST FLOW CONTINUING.
THIS IS DUE TO ANOTHER LOW MOVING TO THE KUSKOKWIM DELTA.

SOUTHWEST.
FRONT OVER SOUTHWEST ALASKA WITH SHOWERS OVER MUCH OF THE AREA. THE
FRONT WEAKENS TONIGHT WITH SHOWERS DIMINISHING AS WELL. COVERAGE AND
INTENSITY OF PRECIP TO PICK UP FRIDAY AFTERNOON AND EVENING AS A LOW
ENTERS BRISTOL BAY. GOOD JET SUPPORT FOR THIS FEATURE...SO WILL
EXPECT HEAVIER AMOUNTS OF PRECIP THROUGH SATURDAY MORNING. ANOTHER
LOW TO MOVE INTO THE EASTERN BERING SATURDAY EVENING WITH RAIN AGAIN
PICKING UP WITH AN EVEN STRONGER JET. THIS LOW TO LIFT INLAND SUNDAY
ACROSS KUSKOKWIM DELTA INTO THE YUKON DELTA. PRECIP TO REMAIN THROUGH
SUNDAY. WINDS WILL BE NEAR SMALL CRAFT FOR EACH OF THESE SYSTEMS.

BERING SEA/ALEUTIAN.
AN UNORGANIZED LOW WORKING SOUTH OF THE WESTERN CHAIN THIS AFTERNOON
WITH PRECIP OVER THE WESTERN AND WEST CENTRAL ALEUTIANS. WINDS ARE
RATHER WEAK WITH THIS SYSTEM. THIS WILL DEVELOP INTO A CLOSED LOW
NEAR DUTCH FRIDAY AFTERNOON BEFORE MOVING INTO BRISTOL BAY. GOOD
PRECIP AND WINDS TO REACH THE EASTERN ALEUTIANS AND AKPEN FRIDAY AND
ENDING FROM THE WEST FRIDAY EVENING. A STRONG LOW TO MOVE TO THE
CENTRAL ALEUTIANS SATURDAY WITH GREAT JET SUPPORT. WINDS WILL
POSSIBLY REACH GALE FORCE WITH MODERATE TO POSSIBLE HEAVY PRECIP AS
IT CROSSES THE CHAIN SATURDAY AFTERNOON. THE LOW WILL MOVE TO
KUSKOKWIM BAY SATURDAY NIGHT. A RIDGE OF HIGH PRESSURE MOVES TO THE
WESTERN ALEUTIANS SATURDAY NIGHT AS WELL.

.LONG TERM FORECAST...
BY MONDAY...SHOWERS WILL BE PREVALENT OVER THE MAINLAND WITH THE
UPPER LEVEL TROUGH SITUATED THERE. A LOW NEAR SHEMYA WILL SPREAD
PRECIP INTO THE CENTRAL BERING WITH A STRONG GALE FORCE FRONT IN THE
WESTERN BERING. HIGH PRESSURE WILL BE IN BETWEEN. THE FRONT WILL
WEAKEN AS IT PUSHES ACROSS THE BERING TUESDAY THEN TO THE WEST COAST
WEDNESDAY. THE LOW WILL BEGIN TO FILL AS WELL. HIGH PRESSURE WILL
MOVE OVER THE MAINLAND TUESDAY NIGHT ENDING THE SCATTERED SHOWERS.
THE LOW WILL BECOME A BROAD TROUGH OVER THE ENTIRE BERING BY THURSDAY
WITH A MOIST SOUTHWEST FLOW RETURNING TO SOUTH CENTRAL ALASKA.

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

JN AUG 07