Small Craft Advisory 363, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 AM AKDT TUE MAY 24 2011

.MODEL DISCUSSION...MODELS IN GOOD AGREEMENT THROUGH THE SHORT
TERM...GFS OUTLIER IN MID AND LONG RANGE. NAM PREFERRED THROUGH FIRST
84 HOURS FOR DETAIL.

.SURFACE ANALYSIS AND SHORT TERM FORECAST...

SURFACE RIDGE OVER EASTERN GULF OF ALASKA AND ALONG NORTH GULF COAST
REMAINS NEARLY STATIONARY THROUGH WEDNESDAY NIGHT BUT GRADUALLY
WEAKENS. PRESSURE GRADIENT ALONG THE GULF COAST NEITHER RELAXES NOR
STRENGTHENS TODAY. GUSTY SOUTHEAST WINDS 20 TO 35 MPH THROUGH TONIGHT
CHANNELED AREAS OF PRINCE WILLIAM SOUND...KENAI PENINSULA...AND
TALKEETNA MOUNTAINS.

MANY AREAS OF SOUTHCENTRAL ARE EXPECTED TO BE DRY OR WINDY
TODAY...BUT ONLY THE MAT VALLEY SHOULD EXPERIENCE BOTH LOW RH AND
STRONG WIND. RED FLAG WARNING FOR THE MATANUSKA VALLEY THIS AFTERNOON
AND EVENING WHERE RELATIVE HUMIDITIES ARE EXPECTED ONCE AGAIN TO DROP
BELOW THE 30 PERCENT THRESHOLD AND EASTERLY GUSTS TO 25 MPH ARE
EXPECTED OUT OF THE KNIK RIVER VALLEY.

OLD FRONTAL BOUNDARY EXTENDING ACROSS SOUTHWEST ALASKA AND KODIAK
ISLAND CONTINUING TO SPREAD LIGHT RAIN OR SHOWERS ACROSS THESE
REGIONS. FRONT BREAKS DOWN BY THIS EVENING AND PRECIPITATION SHOULD
BRIEFLY ABATE...BUT NEXT SYSTEM IS MOVING IN QUICKLY FROM THE WEST
AND RAIN WILL REDEVELOP BY MORNING.

A 983 MB LOW NEAR ADAK TRACKS EASTWARD ALONG THE ALEUTIAN CHAIN TODAY
AND TONIGHT THEN WEAKENS SLIGHTLY TO 994 MB AS IT DIPS SOUTH OF THE
CHAIN WEDNESDAY MORNING. ASSOCIATED OCCLUDED FRONT PRESENTLY EXTENDS
IN AN ARC ACROSS THE SOUTHERN BERING SEA AND THEN CUTS SOUTHWARD
THROUGH THE EASTERN ALEUTIANS. THE FRONT WILL PRESS EASTWARD TODAY
AND PASS OVER KODIAK ISLAND AND THE BRISTOL BAY REGION LATE TONIGHT.
PLENTY OF RAIN AND A NARROW BAND OF GALE FORCE WINDS ALONG AND AHEAD
OF THE FRONT. BEHIND THE FRONT...STEADY RAIN WILL GIVE WAY TO
SCATTERED SHOWERS AND EAST SOUTHEAST WINDS WILL SHIFT TO WEST
NORTHWEST.

.UPPER LEVELS AND EXTENDED FORECAST...

UPPER LOW CENTER OVER THE CENTRAL ALEUTIANS MOVES TO JUST SOUTHWEST
OF KODIAK ISLAND ON THURSDAY...FOLLOWING A SIMILAR TRACK TO
ASSOCIATED SURFACE FEATURE. BUT WHILE SURFACE LOW WEAKENS AND DRIFTS
OFF TO THE SOUTHEAST...UPPER FEATURES RECONSOLIDATES OVER THE CENTRAL
ALEUTIANS ON SUNDAY. MODELS DISAGREE ON PLACEMENT BUT NEW SURFACE LOW
EXPECTED TO DEVELOP JUST SOUTH OF ALEUTIAN CHAIN TOWARDS THE END OF
THE WEEKEND.

EASTERLY ONSHORE FLOW...BOTH SURFACE AND ALOFT...WILL PERSIST ACROSS
KODIAK...KEEPING THE ISLAND SHROUDED IN RAIN THROUGH THROUGH THURSDAY
AND POSSIBLY THROUGH THE WEEKEND AS WELL.

UPPER LEVEL HIGH OVER WESTERN CANADA REMAINS NEARLY STATIONARY
THROUGH THE WEEKEND WITH RIDGING OVER NORTHERN AND INTERIOR ALASKA
GRADUALLY STRENGTHENING. THIS RIDGE WILL HELP HOLD ANY STEADY RAINS
OFFSHORE THROUGH THE SUNDAY...BUT CONVECTIVE SHOWERS STILL POSSIBLE
IN THE AFTERNOON AND EVENING HOURS ESPECIALLY OVER THE CHUGACH AND
KENAI MOUNTAINS.

INCREASINGLY WARM AND DRY OVER THE SOUTHERN MAINLAND AS THE WEEK
PROGRESSES. AFTERNOON AND EVENING MAX TEMPS EXCEEDING 70 DEGREES IN
SOME INLAND AREAS ON THURSDAY AND FRIDAY. THANKFULLY LITTLE IN THE
WAY OF WIND EXPECTED DURING THIS TIME FRAME SO FIRE WEATHER NOT A
MAJOR CONCERN AS THE MEMORIAL DAY WEEKEND APPROACHES.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE.
MARINE...GALE 132 138 150 160
FIRE WEATHER...RED FLAG STRONG WIND 111.

ASB MAY 11