Small Craft Advisory 546, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
211 PM AKDT THU JUL 17 2014

.ANALYSIS AND UPPER LEVELS...
THE UPPER LEVEL PATTERN HAS SLOWLY BEEN EVOLVING OVER THE PAST FEW
DAYS AND WILL CONTINUE TO FLUCTUATE INTO THE WEEKEND AS CHANGES
WILL BE NOTED. SATELLITE ANALYSIS THIS AFTERNOON HIGHLIGHTS A
WEAKENING RIDGE ACROSS MUCH OF THE MAINLAND IN ALASKA...AS IT
SLOWLY TRANSITIONS EAST AND INTO CANADA. NORTHEAST OF THE BERING
STRAIT IS A STACKED LOW THAT WILL CONTINUE TO SPIN AND SLOWLY
DRIFT TO THE NORTHEAST. ROUNDING THE SOUTHERN PERIPHERY OF THE
AFOREMENTIONED LOW IS A STRENGTHENING SHORTWAVE AND DIGGING
TROUGH...RIGHT ON THE NOSE OF A JET THAT WILL MOVE ACROSS WESTERN
ALASKA. FARTHER SOUTH ALONG THE ALEUTIAN CHAIN AND SOUTHERN GULF
ARE A SERIES OF WEAK LOWS WILL STAY SOUTH OF THE FORECAST AREA AND
MOVE INTO THE SOUTHEASTERN PANHANDLE.

&&

.MODEL DISCUSSION...

IN THE SHORT TERM /OUT TO 42 HOURS/ GUIDANCE IS IN GOOD AGREEMENT
WITH THE NORMAL TIMING/STRENGTH ISSUES WITH SMALL SCALE FEATURES STILL
PRESENT AT THE SURFACE. THE SAME CAN BE SAID IN THE UPPER LEVELS
WHERE THE DISTINCT DIFFERENCES THAT HAVE BEEN NOTED OVER THE
PREVIOUS DAYS HAVE SINCE RESOLVED ITSELF. FORECAST CONFIDENCE IS
NEAR NORMAL FOR THIS FORECAST PACKAGE. THE GFS AND ECMWF WERE
FAVORED IN THE SHORT TERM FOR THE WESTERN PACKAGE AND THE NAM
MIXED WITH A LITTLE OF THE GEM ACROSS FOR THE EAST.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...
FAIRLY BENIGN WEATHER WILL CONTINUE THROUGH TOMORROW EVENING
ACROSS MUCH OF THE AREA. THE SUBTROPICAL JET THAT HAS BEEN THE
FOCUS FOR THE LOWS SOUTH OF THE ALASKAN MAINLAND WILL CONTINUE TO
SHIFT THOSE SYSTEMS EAST AND INTO PAJK/S FORECAST AREA. WEAK FLOW
ALOFT...AIDED BY THE RIDGING...COUPLED WITH MOISTURE STILL
PRESENT...MEANS THAT THERE WILL BE THE CONTINUED CHANCE FOR
AFTERNOON MOUNTAIN SHOWERS. ANY SHOWERS THAT DO DEVELOP ARE
EXPECTED TO REMAIN OVER THE HIGHER TERRAIN AND NOT WORK INTO THE
POPULATED AREAS.

OUTSIDE OF MOUNTAIN SHOWER ACTIVITY... THE BIGGEST FOCUS ON
SENSIBLE WEATHER WILL BE THE FIRST IN A SERIES OF TROUGHS TO MOVE
INTO THE AREA LATE TOMORROW NIGHT AND INTO THE WEEKEND. SHOWER
ACTIVITY WILL INCREASE LATE TOMORROW NIGHT AND INTO THE WEEKEND AS
ACTIVITY IS SLATED TO BECOME WIDESPREAD. INCREASED CLOUD COVER WITH
RAIN INCREASING WILL LEAD TO COOLER THAN NORMAL TEMPERATURES
THROUGH SATURDAY... WITH A REBOUND EXPECTED INTO THE EXTENDED.

SOUTHWEST ALASKA...
THE PATTERN TRANSITION IS UNDERWAY ACROSS THE Y-K DELTA AS WINDS
HAVE BEGUN TO SLOWLY VEER AND WILL EVENTUALLY BECOME NORTHERLY
BEFORE THE NEXT FRONT MOVES THROUGH TOMORROW. SHOWERS WILL
DIMINISH FOR A SHORT PERIOD LATE TOMORROW NIGHT AND INTO SATURDAY
MORNING FROM WEST TO EAST. THE STRENGTHENING NORTHWESTERLY FLOW
ALOFT WILL REINFORCE CONSIDERABLE CLOUDINESS ACROSS MUCH OF THE
AREA THROUGH THE WEEKEND. THE SECOND SYSTEM WILL SCRAPE THE Y-K
DELTA BUT LEAVE THE MAJORITY OF BRISTOL BAY UNTOUCHED.

BERING SEA/ALEUTIANS...
HIGH PRESSURE ACROSS THE ALEUTIANS WILL CONTINUE TO WEAKEN AND
SLIDE WEST THROUGH TOMORROW...THUS ALLOWING A FRONT TO SLIDE SOUTH
ACROSS THE EASTERN ALEUTIANS. THIS FRONT WILL WEAKEN TOMORROW
EVENING AS IT MOVES ACROSS THE AKPEN AND HIGH PRESSURE WILL AGAIN
REBUILD. CLOUD COVER WILL PERSIST AS HIGH PRESSURE REBUILDS.

&&

.LONG TERM FORECAST...
THE EXTENDED TERM (DAYS 4-8) WILL BEGIN WITH GUSTY OUTFLOW WINDS
ALONG THE NORTHERN GULF COAST AS AN UNSEASONABLY STRONG UPPER TROUGH
DIGS INTO THE EASTERN GULF OF ALASKA FROM THE NORTHWEST AND
DEVELOPS INTO A CLOSED UPPER LOW. A MUCH WARMER DAY IS IN STORE
FOR MONDAY AS THIS SYSTEM DEPARTS TO THE SOUTHEAST AND UPPER
RIDGING BUILDS IN FROM THE WEST. HOWEVER...THE WARMER TEMPERATURES
WILL BE SHORT LIVED AS UPPER TROUGHING RETURNS TO THE MAINLAND FOR
TUESDAY AND WEDNESDAY AND ANOTHER CLOSED UPPER LOW SKIRTS THE
ALEUTIAN CHAIN AND THEN MOVES INTO THE GULF...BRINGING AN
INCREASED CHANCE OF RAIN TO MUCH OF THE STATE AS TEMPERATURES
RETURN TO AROUND NORMAL BY THE MIDDLE OF NEXT WEEK.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.
&&

SHEA/CB JUL 14