Small Craft Advisory 87, NWS Anchorage, AK

AREA FORECAST DISCUSSION
SOUTHCENTRAL AND SOUTHWEST ALASKA
200 PM AKST SUN JAN 25 2009

.MODEL DISCUSSION...
MODELS CONTINUE TO HAVE PROBLEMS HANDLING THE NORTH PACIFIC LOW
MOVING INTO THE GULF OF ALASKA TONIGHT THROUGH MONDAY. STILL THINK
THERE WILL BE TWO INDIVIDUAL LOW CENTERS...WITH THE SECONDARY LOW
DEVELOPING TONIGHT BECOMING THE DOMINANT LOW. MODELS ARE ALSO HAVING
PROBLEMS RESOLVING THE COMPLEX OF LOWS BEGINNING TO AFFECT THE
ALEUTIANS. ACCORDINGLY...FORECASTS THROUGH 36 HOURS WERE CONSTRUCTED
USING A COMPROMISE OF THE NAM/GFS/UKMET SOLUTIONS WITH MAINLY MINOR
TWEAKS. MINIMAL CHANGES WERE ALSO MADE TO THE EXISTING FORECAST
BEYOND 36 HOURS.

.ANALYSIS AND UPPER LEVELS...
THE UPPER LEVEL RIDGE OVER THE GULF OF ALASKA AND EASTERN
MAINLAND...AND THE LONG WAVE TROUGH OVER THE BERING SEA AND CENTRAL
ALEUTIANS CONTINUE TO BREAK DOWN. AS THESE FEATURES DEAMPLIFY...FLOW
WILL BECOME NEARLY ZONAL ACROSS THE AREA BY TUESDAY. ELSEWHERE A 125
KT JET EXTENDS FROM THE GULF OF ALASKA THROUGH THE ALASKA
PANHANDLE...AND A 165 KT JET IS LOCATED SOUTHWEST OF THE EASTERN
ALEUTIANS.

AT THE SURFACE...AN OLD FRONTAL BOUNDARY EXTENDS ACROSS THE NORTHERN
GULF COAST. A 1018 MB LOW IS LOCATED NEAR 54N 144W. A DEVELOPING LOW
IS EVIDENT ON SATELLITE IMAGERY NEAR 50N 156W. A 1012 MB LOW OVER
SAINT MATTHEW ISLAND IS DISSIPATING WHILE REMAINING STATIONARY.
ANOTHER LOW IS WEST OF ATTU AT 1004 MB.

.SHORT TERM FORECAST...

.SOUTHCENTRAL...
SCATTERED SNOW SHOWERS WILL PERSIST ALONG COASTAL AREAS AND THE
COPPER RIVER BASIN THROUGH TONIGHT...BUT WILL COME TO AN END AS THE
FRONTAL BOUNDARY DISSIPATES BY TOMORROW MORNING. ELSEWHERE ACROSS
SOUTHCENTRAL EXPECT PARTLY TO MOSTLY CLOUDY SKIES TO PREVAIL THROUGH
TUESDAY. THE AFOREMENTIONED 1018 MB LOW WILL DISSIPATE AS THE NEW LOW
NEAR 50N 156W BECOMES DOMINANT. THIS LOW IS EXPECTED TO MOVE INTO THE
NORTHEASTERN GULF BY MONDAY MORNING. AS THE LOW MOVES INTO THE GULF
GUSTY GAP WINDS WILL BE DEVELOPING FOR PLACES LIKE
SEWARD...WHITTIER...THOMPSON PASS...AND THE COPPER RIVER DELTA. THE
LOW IS EXPECTED TO REMAIN FAR ENOUGH SOUTH AND EAST TO KEEP THE
THREAT OF PRECIPITATION ACROSS SOUTHCENTRAL TO A MINIMUM.

.SOUTHWEST...
SCATTERED SNOW SHOWERS AND LIGHT WINDS WILL CONTINUE ACROSS SOUTHWEST
ALASKA THROUGH TUESDAY. SNOW THAT HAS BEEN MORE WIDESPREAD IN THE
KUSKOKWIM VALLEY AND DELTA TODAY WILL BECOME SCATTERED IN NATURE
THROUGH TONIGHT. AS THE LOW CURRENTLY NEAR ATTU APPROACHES THE ALASKA
PENINSULA ON TUESDAY EXPECT MAJORITY OF EFFECTS TO BE FELT ALONG THE
PENINSULA...WITH SNOW AND RAIN BECOMING WIDESPREAD BY TUESDAY NIGHT.

.BERING SEA AND ALEUTIANS...
PRECIPITATION ASSOCIATED WITH THE LOW NEAR ATTU WILL CONTINUE TO
SPREAD EASTWARD OVER THE NEXT SEVERAL DAYS. RAIN WILL MIX WITH SNOW
IN THE WESTERN ALEUTIANS TONIGHT AS WARM AIR IS PULLED
NORTHWARD...BUT SHOULD REMAIN ALL SNOW IN THE PRIBILOFS. SNOW AND
RAIN WILL BECOME MORE WIDESPREAD OVER THE CENTRAL AND EASTERN
ALEUTIANS TOMORROW INTO TUESDAY AS THE LOW NEARS. AS THE LOW DEPARTS
TO THE EAST EXPECT GUSTY NORTHERLY AND EASTERLY FLOW TO
DEVELOP...WITH SCATTERED SNOW SHOWERS PERSISTING.

.LONG TERM FORECAST...
UPPER LEVEL ZONAL FLOW WILL STEER THE LOW NEAR ATTU EASTWARD INTO THE
GULF OF ALASKA BY THE END OF THE WEEK. AMPLE MOISTURE AND GALE FORCE
WINDS WILL ACCOMPANY THIS LOW AS IT MOVES ACROSS THE ALEUTIANS AND
ALASKA PENINSULA. MODELS CONTINUE TO SUGGEST THAT COLDER AIR MAY
FILTER INTO THE REGION ON THE BACKSIDE OF THIS LOW BY THE END OF THE
WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...GALE 120 175 176
FIRE WEATHER...NONE

NRH JAN 09