Gale Warning 544, NWS Anchorage, AK

SOUTHCENTRAL AND SOUTHWEST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ANCHORAGE AK
114 PM AKDT FRI SEP 26 2014

.ANALYSIS AND UPPER LEVELS...SATELLITE IMAGERY SHOWS A PICTURESQUE
CONCENTRIC LOW SOUTH OF THE ALASKA PENINSULA WITH THE OCCLUSION
WRAPPED MULTIPLE TIMES AROUND THE CENTER. THIS STORM PRODUCED
HEAVY RAIN AND STRONG WINDS ALONG THE EASTERN ALEUTIANS AND SOUTHERN
ALASKA PENINSULA LAST NIGHT THROUGH THIS MORNING...BUT THE WORST
CONDITIONS ARE COMING TO AN END AND EXPECT SLOW IMPROVEMENT AS THE
LOW TRACKS SLOWLY EASTWARD TODAY. THE OCCLUDED FRONT OUT AHEAD OF
THE LOW IS LIFTING VERY SLOWLY NORTHWARD INTO THE SOUTHWESTERN
GULF...WITH VERY LITTLE PUSH BEHIND IT. DOWNSTREAM OF THIS SYSTEM
A SHORT-WAVE TROUGH OVER THE EASTERN GULF IS LIFTING NORTHWARD WITH
SOME HIGH CLOUDS JUST BEGINNING TO MOVE INTO THE FAR SOUTHEASTERN
CORNER OF THE COPPER RIVER BASIN (SOUTHEAST OF MCCARTHY).
OTHERWISE...IT IS ANOTHER DRY AND QUIET DAY OVER THE SOUTHERN
MAINLAND OF ALASKA. A STRONG RIDGE IS ALSO PROVIDING BENIGN
CONDITIONS ACROSS MUCH OF THE BERING SEA AND WESTERN TO CENTRAL
ALEUTIANS. UPSTREAM OF THIS RIDGE A DEEPENING LOW SOUTH OF THE
KAMCHATKA PENINSULA IS TRACKING EAST-SOUTHEASTWARD. ON THIS TRACK
THE STORM WILL PASS WELL SOUTH OF THE ALEUTIANS...BUT WILL BE
LARGE ENOUGH TO PROVIDE SOME IMPACT ON THE NORTHERN PERIPHERY.

&&

.MODEL DISCUSSION...THERE CONTINUE TO BE MINOR DIFFERENCES WITH
WEAK FEATURES CROSSING THE GULF OUT AHEAD OF THE MAIN LOW. THIS
WILL AFFECT SOME OF THE DETAILS OF PRECIP AND WINDS...BUT NOTHING
OF HIGH IMPACT. THE ONE NOTABLE DIFFERENCE FROM YESTERDAY IS THAT
THE SHORT-WAVE OVER THE EASTERN GULF IS HEADED DUE NORTH RATHER
THAN CURVING WESTWARD...SO LESS MOISTURE FROM THIS WILL BE PULLED
INTO SOUTHCENTRAL. OUT WEST ALL OF THE MODELS HAVE TRENDED A BIT
FARTHER NORTH WITH TRACK OF LOW SOUTH OF THE KAMCHATKA PENINSULA...
SO EXPECT GALE FORCE WINDS TO MAKE IT INTO THE COASTAL WATERS
SOUTH OF THE WESTERN TO CENTRAL ALEUTIANS. WITH ARCTIC TROUGH
DIGGING SOUTHWARD ACROSS MAINLAND ALASKA SUNDAY NIGHT AND MONDAY
ALL MODELS HAVE BOUGHT OFF ON THE MORE AMPLIFIED SOLUTION OF THE
GFS FROM YESTERDAY...WHICH MEANS A WIDESPREAD STRONG WIND EVENT
IS LIKELY FOR COASTAL SOUTHCENTRAL.

OVERALL FORECAST CONFIDENCE IS ABOVE AVERAGE THROUGH THE NEXT FEW
DAYS.

&&

.SHORT TERM FORECAST...

SOUTHCENTRAL ALASKA...THE VARIOUS FRONTS AND SHORT-WAVES MOVING
ACROSS THE GULF OUT AHEAD OF THE MAIN LOW WILL BE ON THE WEAK
SIDE. THEY WILL ALSO BE WEAKENING AS THEY PROGRESS NORTH AND WEST
AND RUN INTO THE RIDGE BUILDING EASTWARD ACROSS THE BERING SEA
INTO SOUTHWEST ALASKA. THUS...AS IS CURRENTLY ADVERTISED EXPECT
THE BULK OF PRECIP TO FALL ALONG THE GULF COAST WITH JUST A CHANCE
OF A SOME LIGHT PRECIP MAKING IT OVER THE COASTAL RANGE. THE ONE
EXCEPTION IS THE SOUTHEASTERN COPPER RIVER BASIN. AS SHORT-WAVE
LIFT NORTHWARD CROSS THIS REGION EXPECT SOME AREAS OF LIGHT
PRECIP. CONDITIONS WILL DRY OUT OVER MUCH OF SOUTHCENTRAL SUNDAY
AS THE SYSTEM PULLS EASTWARD AND A SHORT-WAVE RIDGE BUILDS IN. ALL
MODELS SHOW SOME INDICATION OF ANOTHER SHORT-WAVE MOVING NORTHWARD
INTO THE EASTERN COPPER BASIN...SO LIGHT RAIN WILL LIKELY HOLD ON
THERE.

THE BIG STORY FOLLOWING THIS SYSTEM WILL BE AN ARCTIC TROUGH
DIGGING SOUTHWARD ACROSS MAINLAND ALASKA SUNDAY NIGHT THROUGH
MONDAY. CONFIDENCE IS GROWING THAT THIS WILL PRODUCE SIGNIFICANT
GAP WINDS ACROSS SOUTHCENTRAL AND BRING WITH IT THE COLDEST AIR
MASS OF THE SEASON THUS FAR. THERE IS A CHANCE OF PRECIP RIGHT OUT
AHEAD OF THE TROUGH...BUT BASED ON ITS RAPID MOVEMENT AND LACK OF
MOISTURE EXPECT MOST AREAS WILL STAY DRY. IT DOES LOOK LIKE AN
UPPER LEVEL LOW WILL FORM AS THIS TROUGH DIGS INTO THE
GULF...WHICH MEANS THERE WILL BE A MUCH BETTER CHANCE OF PRECIP
FOR AREAS EAST OF THIS CENTER EARLY NEXT WEEK. MOST LIKELY THIS
WILL BE OVER THE EASTERN HALF OF SOUTHCENTRAL.

SOUTHWEST ALASKA...DRY CONDITIONS WILL CONTINUE TO PREVAIL ACROSS
THE SOUTHWEST MAINLAND. THE ONLY SHOT OF PRECIP WILL BE WITH PASSAGE
OF THE ARCTIC TROUGH SUNDAY AFTERNOON THROUGH SUNDAY NIGHT...BUT
ANYTHING THAT FALLS WILL BE BRIEF AND LIGHT. THE COLDEST AIR WILL
BE SHUNTED FURTHER EAST AS TROUGH CONTINUES TO DIG SOUTHEASTWARD.
THUS...EXPECT TEMPERATURES TO REMAIN NEAR SEASONAL NORMS.

BERING SEA/ALEUTIANS...WINDS WILL BE SLOW TO DIMINISH TONIGHT
ALONG THE EASTERN ALEUTIANS AND SOUTHERN ALASKA PENINSULA WITH
A FAIRLY STRONG RIDGE BUILDING IN BEHIND THE EXITING LOW. THE
FOCUS WILL THEN SHIFT OUT WEST AS A DEEP LOW PASSES SOUTH OF THE
ALEUTIANS. WITH A FURTHER NORTHWARD TRACK (AS MENTIONED ABOVE)
EXPECT A LITTLE MORE RAIN AND WIND TO MAKE IT TO THE ALEUTIANS
THAN ORIGINALLY THOUGHT. STILL THIS WILL BE A QUICK SHOT SATURDAY
WITH THE SYSTEM DROPPING BACK SOUTHWARD ON SUNDAY. A RIDGE WILL
BUILD OVER THE HEART OF THE BERING SUNDAY AND DOMINATE THROUGH AT
LEAST THE EARLY PART OF NEXT WEEK RESULTING IN EXTREMELY QUIET
CONDITIONS ACROSS THE REGION.

&&

.LONG TERM FORECAST (TUE SEP 30TH - FRI OCT 3)...

ALASKA WILL BE UNDER THE INFLUENCE OF A DRY AND COLD OUTFLOW WIND
PATTERN ON TUESDAY...WITH MODERATELY STRONG CHANNELED GAP WINDS
CONTINUING THROUGH TUESDAY BEFORE DIMINISHING WEDNESDAY. A
GENERALLY DRY NORTHWEST FLOW PATTERN ALOFT WILL CONTINUE OVER THE
MAINLAND AS A HIGHLY AMPLIFIED RIDGE ALOFT BUILDS OVER THE BERING
SEA...KEEPING THE STORM TRACK ALONG THE WESTERN PERIPHERY OF THE
BERING...AND SOUTH ACROSS THE NORTH PACIFIC. THE GFS...ECMWF...AND
ECMWF ENSEMBLE ALL DEPICT A SIMILAR LARGE SCALE PATTERN EVOLUTION
HEADING INTO THE WEEKEND WITH AN ARCTIC TROUGH DEEPENING OVER THE
MAINLAND OF ALASKA. THIS WOULD SUPPORT THE POTENTIAL FOR THE
COLDEST AIR OF THE SEASON...AND A CONTINUATION OF A DRY OFFSHORE
FLOW PATTERN. HOWEVER...SOME UNCERTAINTY BUILDS BY FRIDAY AS A
NORTH PACIFIC LOW...WHICH MAY INCLUDE THE REMNANTS OF TS
KAMMURI...MOVES INTO THE GULF OF ALASKA.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING...132 138 150 155 172 177 178.
FIRE WEATHER...NONE.

&&

SEB/JA SEP 14