Small Craft Advisory 674, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
115 PM ADT SAT AUG 18 2007

.ANALYSIS AND UPPER LEVELS...IN THE UPPER LEVELS THERE IS A RIDGE
FROM THE SOUTHERN YUKON ACROSS INTERIOR ALASKA TO THE CHUKCHI SEA.
A COUPLE CLOSED LOWS DOMINATE THE BERING REGION WITH ONE OVERHEAD
OF DUTCH HARBOR AND ANOTHER OVER THE KAMCHATKA PENINSULA. A NEARLY
ZONAL UPPER JET EXTENDS EASTWARD ALONG 47N SOUTH OF THE ALEUTIANS
AND THEN CURVES NORTHEASTWARD AROUND THE EAST SIDE OF THE UPPER LOW.
THERE IS GOOD UPPER DIVERGENCE IN THIS AREA. SATELLITE IMAGERY
SHOWS THIS AREA (INCLUDING KODIAK ISLAND AND THE WESTERN GULF) IS
EXPERIENCING THE BEST LIFT. KODIAK IS OBSERVING MODERATE TO HEAVY
RAIN AND RADAR IMAGERY SHOWS STEADY RAIN FROM KODIAK ISLAND TO
BRISTOL BAY. AT THE SURFACE THERE IS A LOW JUST NORTHWEST OF THE
EASTERN ALEUTIANS UPPER CENTER. A TIGHT GRADIENT ON THE BACK SIDE
OF THIS LOW COMPLEX IS PRODUCING NORTHWESTERLY GALES OVER THE
CENTRAL ALEUTIANS. THERE ARE ALSO GALES FROM THE KODIAK ISLAND
WATERS TO BRISTOL BAY...AHEAD OF AN OCCLUDED FRONT. A SURFACE
RIDGE EXTENDS FROM THE EASTERN GULF TO SOUTHCENTRAL ALASKA.

.MODEL DISCUSSION...MODELS INITIALIZED WELL AND ARE IN VERY GOOD
AGREEMENT THROUGH TUESDAY. WITH FAIRLY GOOD RUN-TO-RUN CONSISTENCY,
THERE IS ABOVE AVERAGE CONFIDENCE IN THIS SOLUTION.

.SHORT TERM FORECAST...
SOUTHCENTRAL...AS THE FRONT MOVES ACROSS KODIAK ISLAND TONIGHT THE
GRADIENT WILL TIGHTEN AHEAD OF THE FRONT ALONG THE NORTH GULF COAST.
THIS WILL RESULT IN EASTERLY GAP WINDS AND DOWNSLOPING. THERE DOES
APPEAR TO BE ENOUGH LIFT ALOFT TO PRODUCE AT LEAST A FEW SPRINKLES
ON THE LEE SIDE OF THE MOUNTAINS TONIGHT THROUGH MONDAY. GOOD
DYNAMICS AND MOISTURE FETCH WILL CONTINUE TO PRODUCE MODERATE TO
HEAVY RAIN AHEAD OF THE FRONT TONIGHT AND SUNDAY...PARTICULARLY FOR
WESTERN PRINCE WILLIAM SOUND AND THE WEST SIDE OF COOK INLET. INLAND
WILL REMAIN DRY (BUT CLOUDY) UNTIL TUESDAY WHEN AN UPPER TROUGH AXIS
MOVES NORTHWARD ACROSS THE SOUTHERN MAINLAND. THIS WILL RESULT IN
SHOWERS ACROSS THE REGION.

SOUTHWEST ALASKA/AKPENN...MODELS INDICATE A SECONDARY SURFACE LOW
WILL FORM THIS AFTERNOON JUST SOUTH OF THE SOUTHERN TIP OF THE AKPENN

IN RESPONSE TO A SHORT-WAVE ROTATING AROUND THE UPPER CENTER. A NEW
UPPER CENTER THEN FORMS OVER THIS AND BECOMES THE DOMINANT CENTER
AND TRACKS BACK NORTHWARD TO BRISTOL BAY LATE SUNDAY AND WESTWARD
INTO THE BERING MONDAY. THE END RESULT WILL BE PERIODS OF RAIN FOR
BRISTOL BAY AND THE KUSKOKWIM DELTA WITH DIMINISHING PRECIP AS YOU
HEAD INLAND TO THE KUSKOKWIM VALLEY.

BERING SEA/ALEUTIANS...THE KAMCHATKA LOW WILL TRACK EASTWARD TO THE
CENTRAL BERING MONDAY AND MERGE WITH THE LOW COMING FROM THE EAST
TO FORM A SINGLE LOW CENTERED NEAR THE PRIBILOF ISLANDS ON TUESDAY.

ASIDE FROM NORTHWESTERLY GALES OVER THE CENTRAL ALEUTIANS TONIGHT
PRESSURE GRADIENT WILL REMAIN LOOSE. SO JUST THE NORMAL CLOUDS AND
AREAS OF RAIN FOR THE NEXT FEW DAYS.

.LONG TERM FORECAST...MEDIUM RANGE MODELS INDICATE A PROGRESSIVE
PATTERN AS WE HEAD THROUGH THE EXTENDED FORECAST PERIOD...WITH
BERING LOW MOVING INTO GULF AND CONTINUING ON TO SOUTHEAST ALASKA
WHILE A NEW CLOSED LOW MOVES INTO THE BERING. THIS WOULD MEAN A
SHOWERY MID WEEK FOR THE SOUTHERN MAINLAND FOLLOWED BY IMPROVING
CONDITIONS AS WE HEAD TO THE WEEKEND....WHILE THE BERING WOULD DRY
OUT MID WEEK AND THEN NEXT STORM WOULD MOVE IN LATE IN THE WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALES 130 172.
FIRE WEATHER...NONE.

SEB AUG 07