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FXAK67 PAJK 272306
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
306 PM AKDT MON JUL 27 2015

.SHORT TERM...STEADY RAIN IS FALLING ACROSS SOUTHEAST ALASKA THIS
AFTERNOON AS A SURFACE WAVE APPROACHES MOVES INTO THE NORTHEAST
GULF THIS AFTERNOON. PRECIPITABLE WATER VALUES WITH THIS FEATURE
ARE BETWEEN 1.1 TO 1.2 INCHES. THIS HAS RESULTED IN RAINFALL
BEING OCCASIONALLY HEAVY AT TIMES ALONG THE OUTER COAST. ACROSS
THE REST OF THE CWA, AMOUNTS HAVE BEEN BETWEEN FIVE HUNDREDTHS AND
A TENTH AN HOUR. EXPECT STEADY RAIN TO CONTINUE THROUGH MUCH OF
THE NIGHT AS THE WEAK WAVES MOVES INLAND OVER THE NORTHERN GULF
COAST. AS IT DOES SO, PRESSURE RISES WILL RESULT IN CONTINUED
GUSTY WINDS TONIGHT AND INTO TUESDAY. EXPECT SMALL CRAFT WINDS TO
PERSIST IN NORTHERN LYNN CANAL WITH 15-20 KTS ACROSS THE REMAINDER
OF THE INNER CHANNELS. LAND AREAS WILL BE IN THE 10 TO 20 MPH
RANGE WITH SOME LOCALLY HIGHER GUSTS IN EXPOSED LOCATIONS.

RAIN COVERAGE AND INTENSITY WILL DECREASE ON TUESDAY BEHIND THE
WAVE. HOWEVER, CONTINUED ONSHORE FLOW WILL RESULT IN LIKELY TO
CATEGORICAL POPS ACROSS MOST OF THE AREA. BROAD UPPER LEVEL LOW
WILL BE DROPPING INTO THE CENTRAL AND EASTERN GULF BUT THE COLD
POOL ASSOCIATED WITH IT IS ONLY AROUND -20 TO -22 C AT 500 MB. DID
HAVE SOME THOUGHT TO CHANGING PRECIPITATION TO SHOWERS INSTEAD OF
RAIN BUT WANTED TO KEEP CONTINUITY OF PREVIOUS SHIFT AND AFTER
COORDINATING WITH LONG TERMER OPTED TO JUST LEFT AS RAIN. DIURNAL
RANGE IN TEMPERATURES WILL BE A FEW DEGREES MORE ON TUESDAY BUT
HIGHS WILL STILL ONLY BE AROUND 60 DEGREES IN MOST LOCATIONS.

USED THE 12Z NAM FOR UPDATES TO THE FORECAST THROUGH THE SHORT
TERM FORECAST PERIOD. MAIN CHANGES WERE TO INCREASE WINDS ACROSS
MANY OF THE INNER CHANNELS TONIGHT. FORECASTER CONFIDENCE IS
ABOVE AVERAGE.


.LONG TERM...MOST OF THE LONG RANGE REMAINS DAMP AS AN UPPER LEVEL
TROUGH REMAINS PLANTED OVER MOST OF ALASKA. THOUGH THERE IS SOME
HOPE OF DRIER WEATHER TOWARD LATE WEEKEND AND EARLY NEXT WEEK.
OVERALL PATTERN DOES NOT CHANGE ALL THAT MUCH AS A BROAD UPPER
TROUGH WITH A NORTH/SOUTH AXIS AROUND 150 W SITS IN PLACE THROUGH
AT LEAST THE EARLY WEEKEND. UPSTREAM A WESTERN US RIDGE IS PUSHING
THE MAIN FLOW NORTHWARD RESULTING IN SW FLOW AT MOST LEVELS OVER
THE PANHANDLE. SOME CHANGE IN THE PATTERN FROM THE PREVIOUS
FORECAST FOR LATE WEEKEND INTO EARLY NEXT WEEK. LONG RANGE MODELS
ARE STARTING TO SUGGEST THAT SOME OF THE ENERGY THAT IS DESCENDING
THROUGH THE BERING SEA DEEPENS THE TROUGH OVER ALASKA AND CAUSES A
RIDGE TO BUILD OVER THE PANHANDLE. IF THIS TREND HOLDS, A DRIER
FORECAST MAY BE IN THE WORKS FOR THAT PERIOD.

AT THE SURFACE, THE MAIN CONCERN IS THE CONTINUING RAIN THROUGH
LATE WEEK. THE SW FLOW AT MOST LEVELS IS HELPING THIS ALONG.
HOWEVER, THERE ARE NO ORGANIZED SYSTEMS EMBEDDED IN THE FLOW FOR
MOST OF THE PERIOD. SO THE MAIN DRIVING INFLUENCE FOR THE PRECIP
IS ONSHORE FLOW BEING LIFTED BY THE TERRAIN. HIGHEST RAINFALL
AMOUNTS WILL BE NEAR HIGHER TERRAIN AS A RESULT. OVERALL NO
SIGNIFICANT AREAS OF WIND OR RAIN ARE EXPECTED.

INTO LATE WEEK AND NEXT WEEKEND, A WEAK WAVE WILL SHOW UP AND MOVE
THROUGH THE SOUTHERN PANHANDLE THU INTO FRI. MOST OF THE RAIN WILL
BE CONFINED TO THE SOUTHERN PANHANDLE WHILE THE NORTHERN PANHANDLE
MAY START TO DRY OUT WITH LOCALIZED EASTERLY FLOW TO THE NORTH OF
THE WAVE. HOWEVER, CONFIDENCE IS LOW DUE TO TIMING ISSUES BUT NOT
AS LOW AS IT WAS YESTERDAY AS LONG RANGE MODELS SEEM TO BE
REACHING AN AGREEMENT.

THE LOW CONFIDENCE CONTINUES THROUGH THE WEEKEND AND INTO NEXT
WEEK. THE GENERAL TREND FROM THE LONG RANGE MODELS ARE TURNING
MORE AND MORE DRY AS SUCCESSIVE MODEL RUNS COME IN TODAY. THE
CHANGE IN THE UPPER LEVELS OF A RIDGE STARTING TO DEVELOP OVER THE
PANHANDLE IS THE MAIN DRIVER. IF THIS TREND CONTINUES TO HOLD, THE
WEEKEND THROUGH MID NEXT WEEK MAY END UP BEING DRY AS THE RIDGE
HOLDS OFF MOST SYSTEMS WELL WEST OF THE PANHANDLE. AS SUCH DECIDED
TO START A DOWNWARD TREND ON POPS TO SLIGHT CHANCE FOR SAT AND
BEYOND. STILL KEPT MOSTLY CLOUDY CONDITIONS AS ONSHORE FLOW COULD
LEAVE SOME MARINE CLOUDS LINGERING.

&&

.HYDROLOGY...THERE ARE INDICATIONS OF ANOTHER GLACIAL DAM RELEASE
ON MENDENHALL LAKE WHICH BEGAN ON SUNDAY EVENING. THE LAKE HAS
RISEN JUST OVER A FOOT SINCE THEN AND IS CURRENTLY AT 6.1 FEET. IT
IS NOT KNOWN EXACTLY HOW MUCH WATER IS IN THE BASIN BUT WE DO NOT
EXPECT THE LAKE TO REACH ACTION STAGE OF 8 FEET. ADDITIONALLY,
STEADY RAIN IN THE SKAGWAY AREA HAS LED TO RISING WATER LEVELS ON
THE TAIYA RIVER. THE LATEST WATER LEVEL IS 15.8 FEET WHICH IS JUST
BELOW THE ACTION STAGE OF 16.0 FEET. CURRENT FORECASTS INDICATE
THE RIVER WILL CREST LATER THIS EVENING AT 16.1 FEET WHICH IS JUST
ABOVE BANKFULL. THIS WILL CONTINUE TO BE MONITORED OVER THE
REMAINDER OF THE NIGHT.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012-031-033-034-036-041>043.

&&

$$

TPS/EAL

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