Small Craft Advisory 353, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
200 PM AKDT THU MAY 19 2011

.ANALYSIS AND UPPER LEVELS...NO SIGNIFICANT CHANGES FROM THE VERY
STABLE SYNOPTIC PATTERN CONSISTING OF A LONGWAVE TROUGH OVER THE
BERING SEA AND A HIGH AMPLITUDE RIDGE OVER WESTERN CANADA. A SOUTH TO
NORTH ORIENTED JET IS BRINGING ABUNDANT MOISTURE BETWEEN THESE TWO
MAIN FEATURES. NUMEROUS LOWS ARE EMBEDDED WITHIN THE LARGE SCALE
CYCLONIC CIRCULATION OVER THE BERING SEA AND NORTHERN PACIFIC
REGION...THE STRONGEST ONE CURRENTLY LOCATED SOUTH OF THE EASTERN
ALEUTIANS WITH GALE FORCE WINDS IS AFFECTING THE COASTAL WATERS IN
THE REGION.

.MODEL DISCUSSION...MODELS IN EXCELLENT AGREEMENT THROUGH THE SHORT
TERM. TIMING DIFFERENCES REGARDING THE SIGNIFICANT SHORT WAVE TO MOVE
INLAND FRIDAY APPEAR TO HAVE BEEN RESOLVED. ONLY MINOR DIFFERENCES
WITH THE LOW SOUTH OF THE EASTERN ALEUTIANS AS IT BEGINS TO WEAKEN
AND DRIFT EAST OVER THE NEXT COUPLE OF DAYS. THE AFTERNOON FORECAST
PACKAGE WILL REFLECT MINOR CHANGES CONSISTENT WITH THE LATEST RUN OF
THE GFS.

.SHORT TERM FORECAST...
.SOUTHCENTRAL...AN OCCLUDED FRONT IS MOVING UP ALONG THE NORTH GULF
COAST THIS AFTERNOON BRINGING GALE FORCE WINDS AND ABUNDANT MOISTURE
TO THE REGION. THE INCREASED CLOUD COVERAGE HAS HELPED KEEP
TEMPERATURES A BIT LOWER TODAY...ELIMINATING THE NEED FOR ANY FIRE
WEATHER WARNINGS. THE FRONT WILL SLOWLY WEAKEN THROUGH TOMORROW AS
SURFACE HIGH PRESSURE BUILDS BACK ALONG THE COAST. THE FEATURE THAT
WE WILL BE WATCHING CLOSELY IS A STRONG SHORTWAVE THAT WILL MOVE
INLAND FRIDAY MORNING. THE AIR BEHIND THIS SHORTWAVE IS MUCH
DRIER...SO EXPECTING PARTLY CLOUDY SKIES TO RESUME FRIDAY AFTERNOON
ALONG WITH BREEZY CONDITIONS. THE COMBINATION OF DRIER WEATHER AND
INCREASED WINDS WILL RESULT IN SOME FIRE WEATHER
CONCERNS...ESPECIALLY FOR THE COPPER RIVER BASIN AND MATANUSKA
VALLEY.

THERE IS ALSO AN OUTSIDE CHANCE OF SEEING OUR FIRST LIGHTNING STRIKES
TOMORROW AFTERNOON ALONG THE ALASKA RANGE. THE SHORTWAVE WILL BE
NEARING THE ALASKA RANGE IN THE AFTERNOON DURING MAXIMUM HEATING. THE
INCREASED INSTABILITY COULD LEAD TO AN ISOLATED THUNDERSTORM IN THIS
AREA...BUT THE HIGHER POTENTIAL WILL BE OUT WEST OVER THE MIDDLE AND
UPPER KUSKOKWIM VALLEY.

HIGH PRESSURE STRENGTHENS THROUGH THE WEEKEND LEADING TO PLEASANT
WEATHER ACROSS SOUTHCENTRAL. WARMER TEMPERATURES WILL ALSO BE ON THE
INCREASE ALONG WITH AFTERNOON INSTABILITY SO EXPECTING SCATTERED
SHOWERS TO DEVELOP EACH AFTERNOON THROUGH EARLY NEXT WEEK.

.SOUTHWEST MAINLAND AND ALEUTIANS...VERY SIMILAR WEATHER FOR THE
SOUTHWEST MAINLAND WITH SHOWERS DEVELOPING IN THE AFTERNOON AND
EVENING ALONG WITH LOCALLY BREEZY CONDITIONS. THE AFOREMENTIONED
SHORTWAVE MOVES INLAND FRIDAY...FURTHER ENHANCING THE SHOWER ACTIVITY
AND AS MENTIONED BEFORE AN OUTSIDE CHANCE OF THUNDERSTORMS OVER THE
KUSKOKWIM VALLEY.

FURTHER WEST...THE LOW SOUTH OF THE CHAIN WILL WEAKEN AS IT DRIFTS
EAST. THIS WILL LEAD TO WINDS SHIFTING FROM THE EAST TO THE NORTH AS
AN AREA OF HIGH PRESSURE BUILDS OVER THE WESTERN BERING SEA FRIDAY.
ANOTHER NORTH PACIFIC LOW WILL DEVELOP SOUTH OF THE CHAIN AND FOLLOW
A SIMILAR PATH AS THE PREVIOUS LOWS THROUGH EARLY NEXT WEEK.

.AER/ALU...WATCH/WARNING SUMMARY
PUBLIC...NONE
MARINE...120 125 129 170 171 172
FIRE WEATHER...FIRE WEATHER WARNING 111 141

AB MAY 11