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FXAK67 PAJK 011358
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
558 AM AKDT WED JUL 1 2015

.SHORT TERM...HIGH PRESSURE RIDGE OVER THE EASTERN AK GULF IS
TRACKING EASTWARD AND WILL MOVE OVER THE PANHANDLE TODAY AS A
DEVELOPING LOW MOVES INTO THE CENTRAL GULF. THIS LOW WILL TRACK
NORTHEASTWARD THROUGH WEDNESDAY NIGHT WITH THE CENTER NEARING CAPE
FAIRWEATHER. THE DRY CONDITIONS WITH PARTLY CLOUDY SKIES AND CALM
WINDS THIS MORNING WILL BE SHORT LIVED WITH THE ADVANCING LOW.
RAIN WILL HIT THE CENTRAL COASTAL PANHANDLE FIRST BY EARLY
AFTERNOON THE EXTEND EASTWARDS THROUGH THE EVENING AS THE FRONTAL
BOUNDARY ASSOCIATED WITH THE LOW MOVES INLAND. 6 HOUR QPF AMOUNTS
WILL BE HIGHEST OVER THE CENTRAL PANHANDLE WHERE STRONGEST LIFTING
MECHANISMS ARE LOCATED WITH VALUES UPWARDS OF A QUARTER OF AN INCH
OR MORE. AS THIS IS A FAIRLY FAST MOVING LOW THE RAIN LOOKS TO
MOVE IN AND OUT QUICKLY. WILL SEE RIVERS AND STREAMS SHOW RISES IN
RESPONSE TO THE RAINFALL BUT NONE ARE EXPECT TO NEAR BANKFULL.

UNSTABLE AIR MASS MOVING UNDER THE LOW CENTER WITH COLDER MID
LEVEL AIR MASS LOOKS TO HAVE POTENTIAL TO PRODUCE THUNDER STORMS
OVER THE OFFSHORE AND COASTAL WATERS TONIGHT. WHILE CAPE AND LI
INDEX VALUES ARE NOT VERY SIGNIFICANT SINCE THIS SYSTEM IS FAIRLY
ROBUST FOR THE SEASON HAVE PUT IN SLIGHT CHANCE OF THUNDER STORMS.

INCREASING WINDS WILL FOLLOW THE NORTHEASTERLY TRACK OF THE LOW
WITH GALES DEVELOPING NEAR THE CENTER TONIGHT OVER PKZ310 AND
PKZ043. EXPECTING SMALL CRAFT TO MAX SMALL CRAFT WINDS FOR THE
REST OF THE COASTAL WATERS BY TONIGHT. OVERLAND WINDS WILL BE
GENERALLY LIGHT THROUGH THE DAY THEN INCREASE AND SHIFT BY THIS
EVENING AND INTO THE OVERNIGHT HOURS. STRONGEST WINDS WILL BE
ALONG COASTAL AREAS SUCH AS ELFIN COVE AND SITKA. 850 MB WINDS ARE
JUST AROUND 35 KT TONIGHT AROUND THE LOW CENTER SO FOR NOW DO NOT
EXPECT STRONG WINDS TO DEVELOP BUT HIGHER GUSTS IN EXPOSED AREAS
ARE LIKELY.

MODELS ARE IN GENERAL AGREEMENT WITH SYNOPTIC PATTERN BUT STILL
HAD SOME DIFFERENCES WITH LOW POSITION AND STRENGTH. THE NAM MOVES
IN THE LOW THE FASTEST WITH GEM HAVING THE DEEPEST CENTER.
INHERITED FORECAST WAS A GOOD COMPROMISE BETWEEN THE GFS/ECMWF AND
FELT NAM WAS BIT MORE OF AN OUTLIER SO LEFT INHERITED GRIDS MOSTLY
AS IS. MOST MODELS HAD A SLIGHT INCREASE IN WINDS, JUST ENOUGH TO
ADD GALES TO THE MARINE FORECAST. OVERALL LITTLE CHANGE WAS DONE
TO THE FORECAST AS MOST FIELDS STILL LINED UP WITH NEW MODEL RUNS.
FORECAST CONFIDENCE IS ABOVE AVERAGE.

.LONG TERM...THE TREND IS FOR WARMER AND DRIER WEATHER TO RETURN
TO SE AK STARTING THIS WEEKEND AND LASTING THROUGH THE MIDDLE OF
NEXT WEEK. HOW FAST THE TRANSITION WILL OCCUR IS THE FORECAST
CHALLENGE. THERE ARE THE USUAL DISCREPANCIES IN MODEL SOLUTIONS
BUT WE WENT WITH A MOSTLY CLOUDY BUT MILD HOLIDAY WEEKEND WITH
LIGHT WIND. BY MON THROUGH WED NEXT WEEK SKY CONDITIONS MAY BE
CLEARER.

BACK TO THIS WEEK...THURS WILL BE AN ACTIVE WEATHER DAY PARTICULARLY
FOR THE NORTHERN PANHANDLE. A SMALL BUT DYNAMIC CYCLONE DEEPENING
OVER THE SE GULF OF AK TODAY WILL MOVE INLAND AROUND CAPE
FAIRWEATHER EARLY THUR. SEE MARINE DISCUSSION BELOW FOR IMPACTS. BY THUR
EVENING RAIN WILL BE CHANGING TO SHOWERS...POSSIBLY ACCOMPANIED
WITH LIGHTNING NEAR CROSS SOUND AND GLACIER BAY. AS THE LOW CENTER
CONTINUES QUICKLY THUR EVENING INTO CANADA...GALE FORCE S WINDS
WILL DEVELOP IN LYNN CANAL THEN DIMINISH AFTER MIDNIGHT.

FRI AND SAT WILL HAVE HIGH PRESSURE BUILD OVER THE PANHANDLE AT
THE SURFACE AND ALOFT. THE AIRMASS WILL STABLIZE SO RAIN CHANCE
DECREASES FRI AND WENT WITH RAIN FREE FORECAST FOR INDEPENDENCE
DAY. ONSHORE FLOW WILL LIKELY KEEP SKIES MOSTLY CLOUDY ACROSS
NORTHERN HALF OF PANHANDLE. THE PRESSURE RIDGE IS BUILDING N FROM
THE PAC NW WHERE IT HAS GENERATED QUITE WARM WEATHER RECENTLY.
THIS WARM AIR MASS WILL BUILD INTO SE AK FROM SAT INTO NEXT WEEK.
THE EC MODEL IS LESS ROBUST WITH THE WARMTH AND KEEPS DAY TIME
TEMPS IN THE 60S WHILE THE GFS MODEL PRODUCED HIGH TEMPS IN THE
70S TO NEAR 80 AT HYDER. I BLENDED EXISTING FORECASTS WITH A MIX
STATISTICAL OUTPUT FROM THE GFS FOR THIS WEATHER PATTERN WHICH
LED ME TO GO THE WARMER ROUTE THROUGH NEXT TUES.

&&

.MARINE...A VIGOROUS LOW FOR THE SEASON WILL MOVE NORTHEAST ACROSS
THE GULF OF ALASKA AND WILL TRACK INLAND SOUTH OF CAPE FAIRWEATHER
THURSDAY MORNING. SOUTHEAST WINDS ARE EXPECTED TO INCREASE TO 25
TO 35 KT FROM THE SOUTH WEDNESDAY EVENING. EAST WINDS OUT OF CROSS
SOUND WILL INCREASE WEDNESDAY NIGHT TO 25 TO 30 KT AS THE LOW
APPROACHES.

WINDS WILL SHIFT TO THE SOUTHWEST AND WEST AT SPEEDS 20 TO 25 KT
FOR THE OUTER COASTAL ZONES AND THROUGH CROSS SOUND LATE THURSDAY
MORNING AND AFTERNOON.

SEAS HEIGHTS OF 4 TO 10 FT WEDNESDAY EVENING WITH A LIGHT
SOUTHWEST SWELL WILL INCREASE UP TO 10 TO 12 FT THURSDAY EARLY
MORNING. THE SOUTHWEST SWELL WILL PERSIST INTO FRIDAY.

UNSTABLE AIR MASS MOVING IN WITH THE LOW HAS POTENTIAL FOR
PRODUCING THUNDERSTORMS OVER THE CAPE EDGECUMBE TO CAPE
FAIRWEATHER REGION STARTING WEDNESDAY NIGHT AND MOVING INLAND OVER
CROSS SOUND THURSDAY MORNING.

A MARINE WEATHER STATEMENT WAS ISSUED ON THIS EVENT.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...GALE WARNING FOR PKZ043.
         SMALL CRAFT ADVISORY FOR PKZ022-041-042-051.

&&

$$

PRB/TA

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