Small Craft Advisory 350, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
500 PM AKDT WED MAY 18 2011

.MODEL DISCUSSION...IN THE SHORT TERM THE MODELS ARE IN GOOD
AGREEMENT...GOING WITH THE NAM FOR ITS ABILITY TO CAPTURE LOCAL
EFFECTS BETTER. IN THE MID TERM THE EC IS BRINGING THE NEW NORTH
PACIFIC LOW INTO THE EASTERN BERING WHILE THE NAM AND GFS KEEP IT
MORE TO THE SOUTH AND THIS DIFFERENCE CONTINUES IN THE LONG TERM WITH
THE GFS AND EC. THE OVERALL TRACK OF THE EC SEEMS TO BE MORE
CONSISTENT AND WE ARE TRENDING TO THAT AS WE MOVE INTO THE LONG TERM.

.UPPER LEVELS...A BROAD LONGWAVE TROUGH WITH EMBEDDED LOWS OVER THE
BERING REMAINS THE DOMINATE FEATURE FOR THE REGION. NEW LOWS CONTINUE
TO FORM IN THIS LONGWAVE TROUGH AND KEEP THE PATTERN FOR THE WEST AND
INTO THE GULF ACTIVE. THE MAIN PART OF THE JET IS SOUTH OF THE
ALEUTIANS AND IS GUIDING THE LOW THAT SITS SOUTH OF THE ALASKA
PENINSULA TO THE EAST. ANOTHER LOW IN THE CENTRAL BERING IS STARTING
TO WEAKEN AND BECOME STATIONARY. TO THE SOUTH OF THIS LOW IN THE
NORTH PACIFIC A NEW DEEP LOW IS FORMING THAT WILL BE PUSHED EAST BY
THE JET SKIRTING ALONG JUST TO THE SOUTH OF THE ALEUTIANS. RIDGING
FROM WESTERN CANADA BUILDS WEST ACROSS THE CENTRAL MAINLAND FRI NIGHT
AND SAT WITH THE PASSAGE OF A NORTHWARD MOVING SHORT WAVE.

.AT THE SURFACE...FRONTS AND TROUGHS ASSOCIATED WITH THE VARIOUS LOWS
IN THE WEST WILL BE IMPACTS FOR AREAS ALL ALONG THE ALEUTIANS AND
INTO SOUTHWEST ALASKA SIMILAR TO THE PATTERN OVER THE LAST SEVERAL
DAYS. THE FRONT FROM THE LOW SOUTH OF THE ALASKA PENINSULA WILL MOVE
ACROSS THE GULF TONIGHT AND BECOME A FACTOR FOR THE GULF COAST AND
SOUTHCENTRAL INTO THE WEEKEND. AHEAD OF THIS FRONT A RIDGE OF HIGH
PRESSURE SITS JUST TO THE NORTH OF THE GULF COAST EXTENDING INTO THE
SOUTHCENTRAL.

.SHORT TERM FORECAST...FOR THE EAST...WITH THE FRONT MOVING THROUGH
FOLLOWED BY CONSTANT EASTERLY FLOW KODIAK WILL SEE RAIN FOR THE NEXT
SEVERAL DAYS. AS THE FRONT MOVES INTO THE NORTHERN GULF AND
EVENTUALLY TO THE COAST AREAS IN THE PRINCE WILLIAM SOUND WILL SEE
RAIN SHOWERS. THIS FRONT WILL ALSO BRING RAIN SHOWERS TO AREAS IN THE
SOUTHCENTRAL AS THERE IS A DEEP LAYER OF MOISTURE ASSOCIATED WITH IT.
DIURNAL CHANGES COMBINED WITH THE RIDGING NEAR THE GULF COAST BRINGS
GAP WINDS TO AREAS AROUND THE SOUTHCENTRAL...ESPECIALLY ALONG
TURNAGAIN ARM...PORTAGE VALLEY...AND THE KNIK VALLEY.

.FOR THE WEST...THE MULTIPLE FRONTS AND TROUGHS THAT ARE MOVING
THROUGH THE ALEUTIANS ARE BRINGING WITH THEM RAIN SHOWERS FOR THE
NEXT SEVERAL DAYS. THE DEEP LOW SOUTH OF SHEMYA IS PRODUCING STRONGER
WINDS AND GALES THAT WILL BE AN IMPACT FOR AREAS ALONG THE ALEUTIANS
AS THIS SYSTEM MOVES CLOSER AND THEN PROGRESSES EAST. A CONSISTENT
PATTERN IN THE CENTRAL BERING CONTINUES TO BRING LOW STRATUS AND FOG
TO SAINT PAUL ISLAND. THE PATTERN OF RAIN SHOWERS REMAINS FOR
SOUTHWEST ALASKA WITH SOUTHEASTERLY FLOW THAT WILL BE THE NORM FOR
THE AREA INTO THE WEEKEND.

.LONG TERM FORECAST...THE GENERAL PATTERN OF UPPER LEVEL TROUGHING
ACROSS THE BERING THAT IS BRINGING AN ACTIVE PATTERN OF LOWS TO THE
REGION AS WELL AS THE RIDGING ACROSS THE INTERIOR WILL PERSIST OVER
THE NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...120 170 171 172
FIRE WEATHER...RED FLAG WARNING 111 141

*** MAY 11