Small Craft Advisory 432, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT THU JUN 23 2011

.ANALYSIS AND UPPER LEVELS...
BROAD TROUGH OVER THE BERING SEA AND WESTERN INTERIOR IS STILL THE
MAIN WEATHER MAKER ACROSS THE STATE. HIGH PRESSURE IS TRYING TO NOSE
ACROSS THE ALASKA BORDER FROM THE NORTHERN YUKON TERRITORY. SEVERAL
EASTERLY WAVES CONTINUE TO CAUSE FORECAST CHALLENGES FOR SOUTHCENTRAL
ALASKA...THE CURRENT IS LOCATED JUST NORTH OF THE ALASKA RANGE NEAR
THE TANANA RIVER VALLEY. THE NEXT EASTERLY WAVE IS ORGANIZING ITSELF
OVER THE PANHANDLE AND WILL FOLLOW A SIMILAR PATH ALONG THE NORTHEAST
GULF COAST TOWARD SOUTHCENTRAL.

.MODEL DISCUSSION...SOME MINOR ISSUES WITH THE MODELS THIS MORNING.
ALL MODELS ARE NOW POINTING TOWARD A MUCH STRONGER LOW DEVELOPING
SOUTH OF THE WESTERN ALEUTIANS. WHILE THE PATH OF THE LOW IS VERY
SIMILAR...THE GFS IS 10 MB STRONGER THAN ALL OTHER OPTIONS. WE WILL
CONTINUE FAVORING THE NAM/ECMWF SOLUTION WHICH HAS BEEN MUCH MORE
CONSISTENT. LIKEWISE IN THE EAST...THE WAVE MOVING OUT OF THE
PANHANDLE TOWARD THE NORTHEAST GULF COULD LEAD TO SOME CHANGES IN THE
ONGOING FORECAST. THE NAM CONTINUES TO BE THE MOST AGGRESSIVE WHILE
THE GFS SPREAD VERY LITTLE IF ANY MOISTURE OVER THE REGION. LEANING
TOWARD THE WET NAM AT THIS TIME BUT WILL CONTINUE JUST ADVERTISING A
CHANCE FOR THE INTERIOR AND LIKELY POPS ALONG THE COAST.

.SHORT TERM FORECAST...
ACTIVE WEATHER PATTERN CONTINUES WITH MANY CHALLENGES TO THE FORECAST
THIS AFTERNOON. THE AFOREMENTIONED SHORTWAVE JUST NORTH OF THE ALASKA
RANGE WILL CONTINUE TO MOVE TO THE NORTHWEST THIS AFTERNOON. WEAK
RIDGING OVER THE KENAI PENINSULA UP TO THE SUSITNA VALLEY SHOULD
PROVIDE FAIR WEATHER FOR THESE AREAS TODAY. LOTS OF QUESTIONS THEN
COME UP REGARDING POTENTIAL FOR CONVECTION FRIDAY AFTERNOON AS ALL
CONVECTIVE PARAMETERS LOOK VERY FAVORABLE FOR THUNDERSTORMS. THE
AIRMASS WILL WARM FRIDAY BEHIND THE DEPARTING SHORTWAVE INCREASING
THE MIDLEVEL LAPS RATES. ASSUMING SKIES START OUT MOSTLY
CLEAR...SHOULD SEE PLENTY OF SURFACE HEATING WHICH WILL LEAD TO
NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS FROM THE COPPER RIVER
BASIN OVER TO THE SUSITNA VALLEY. AT THIS TIME...BELIEVE THE
TALKEETNA MOUNTAINS WILL BE THE SOUTHERN MOST EXTENT OF THE
CONVECTIVE POTENTIAL...BUT CAN NOT RULE OUT THE STRAY SHOWER OVER THE
CHUGACH RANGE.

THE PANHANDLE SHORTWAVE THEN APPROACHES THE NORTHEAST GULF COAST LATE
FRIDAY NIGHT INTO SATURDAY MORNING. WHILE THE NAM HAS BACKED OFF
SUBSTANTIALLY FROM PREVIOUS RUNS SPREADING RAIN THROUGHOUT
SOUTHCENTRAL...IT IS STILL INDICATING EXTENSIVE CLOUD COVER AND
NUMEROUS SHOWERS BY SATURDAY AFTERNOON. THUNDERSTORMS POTENTIAL
REMAINS NORTH IN THE SAME AREAS...FROM THE COPPER RIVER BASIN TO THE
SUSITNA VALLEY.

BY THE MIDDLE OF THE WEEKEND...THE THERMAL TROUGH IS ENTRENCHED OVER
THE REGION CENTERED JUST NORTH OF THE ALASKA RANGE. TEMPERATURES WILL
BE NEAR OR JUST ABOVE AVERAGE THROUGH EARLY NEXT WEEK WITH PARTLY
CLOUDY SKIES AND AFTERNOON SHOWERS CONTINUING.

.SOUTHWEST...MAIN AREA OF LOW PRESSURE HAS MOVED NORTH TOWARD THE
SEWARD PENINSULA WHILE ANOTHER UNDERCUTS THE ALASKA PENINSULA. THE
COAST CONTINUES TO SEE ABUNDANT MOISTURE WHILE THE INTERIOR IS AT
LEAST STARTING OUT MOSTLY CLEAR BEFORE AFTERNOON SHOWERS DEVELOP.
CONVECTIVE POTENTIAL...ESPECIALLY ALONG THE LOWER KUSKOKWIM
VALLEY...INCREASES EACH DAY AS THE THERMAL TROUGH STRENGTHENS JUST
NORTH OF THE ALASKA RANGE.

FURTHER WEST...A SIGNIFICANT STORM WILL BE DEVELOPING SOUTH OF THE
ALEUTIAN RANGE FRIDAY NIGHT...SPREADING AT LEAST GALE FORCE WINDS
ACROSS THE ISLANDS. WE WILL BE BUMPING WINDS UP ALONG THE ASSOCIATED
FRONTAL BOUNDARY BECAUSE THE INCREASED CONFIDENCE IN THE STRENGTH OF
THE LOW. IT REACHES ITS MAXIMUM STRENGTH SATURDAY EVENING AS IT
CROSSES THE ALEUTIAN CHAIN INTO THE WESTERN BERING SEA...WHERE IT
WILL SLOWLY FILL THROUGH EARLY NEXT WEEK.

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

AB JUN 11