Weather Service Report


520 
FXAK67 PAJK 242246
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JUNEAU AK
246 PM AKDT SUN MAY 24 2015

.SHORT TERM...MAIN STORY TODAY IS THE EXTENSIVE MARINE LAYER
ACROSS THE GULF AND PANHANDLE. MARINE LAYER CLOUDS INFILTRATED ALL
OF THE PANHANDLE OVERNIGHT. EXCEPT FOR SOME PATCHY FOG HERE AND
THERE IT MOSTLY TOOK THE FORM OF LOW STRATUS. SATELLITE IMAGES
AROUND NOON REVEAL THAT THE CLOUDS ARE STARTING TO BURN OFF OVER
CHATHAM STRAIT, BARANOF ISLAND, CHICHAGOF ISLAND, AND SOUTHERN
PRINCE OF WALES ISLAND WITH THE HOLES WIDENING AS THE DAY GOES ON.
THE PERSISTENT CLOUDS TODAY WILL NEGATE ANY THUNDERSTORM TODAY AS
THERE WILL NOT BE ENOUGH DAY TIME HEATING TO GET TEMPS HIGH ENOUGH
TO INITIALIZE ANY CONVENTION.

HOWEVER FAR THE MARINE LAYER CLOUDS RETREAT TODAY, THEY WILL JUST
REFORM TONIGHT. SLIGHT LOW LEVEL ONSHORE FLOW IS STILL ONGOING SO
MOST AREAS OF THE PANHANDLE SHOULD AGAIN SEE LOW TO MID LEVEL
CLOUDS DEVELOP OVERNIGHT. ANY FOG SHOULD STILL BE RELEGATED TO THE
OUTER COAST AND SOUTHERN PANHANDLE TONIGHT BUT VISIBILITY
REDUCTION IS NOT EXPECTED TO BE SIGNIFICANT. THE MARINE CLOUDS
SHOULD AGAIN BURN OFF TOMORROW.

THE NEXT STORY IS THE WEAKENING TROUGH THAT IS IN THE CENTRAL GULF
RIGHT NOW. THIS TROUGH WILL BRING RAIN TO THE GULF AND NORTHERN
GULF COAST, INCLUDING YAKUTAT, TONIGHT AND TOMORROW. IT WILL NOT
GET MUCH FARTHER EAST AS IT WILL BE FIGHTING AGAINST THE SURFACE
RIDGE OVER THE EASTERN GULF AND THE UPPER LEVEL RIDGE OVER THE
PANHANDLE AND WESTERN CANADA. ALL THE RAIN WILL BE LIMITED TO CAPE
FAIRWEATHER AND WESTWARD WITH QPF AMOUNTS OF AROUND A QUARTER INCH
OR LESS. THE REST OF THE PANHANDLE MAY SEE SOME MID TO HIGH LEVEL
CLOUDS STREAM OVERHEAD ON MON FROM THIS SYSTEM BUT THAT WILL BE
ABOUT IT. WITH THESE UPPER LEVEL CLOUDS AND THE LINGERING MARINE
LAYER CLOUDS STILL AROUND TOMORROW, HIGH TEMPERATURES WILL AGAIN
BE IN THE 60S. THIS WILL NOT BE HIGH ENOUGH FOR ANY CONVECTION
TOMORROW EITHER. SO PRECIP CHANCES FOR THE MAIN PANHANDLE ARE LOW
WITH ALL T-STORM ACTIVITY EXPECTED TO STAY IN CANADA.

SHORT RANGE MODELS WERE IN GOOD AGREEMENT AGAIN TODAY. SO MAIN
CHANGES TODAY WERE LOCAL CHANGES FOR MARINE LAYER AND SEA BREEZE
EFFECTS. NAM CONTINUES TO BE THE MAIN GUIDANCE FOR THE NEXT 24
HOURS.

.LONG TERM...EXTENDED FORECAST WILL BE DOMINATED BY BUILDING HIGH
PRESSURE RIDGE OVER THE AK GULF WHICH WILL KEEP SURFACE FEATURES
TO THE WEST OR SOUTH OF THE REGION. HOWEVER UNLIKE THE PREVIOUS
WEEKS BLOCKING HIGH WHICH EXTENDED THROUGH TO UPPER LEVELS THERE
IS A 500 MB CLOSED LOW TRACKING TOWARDS THE NORTHERN PANHANDLE MID
WEEK. OVERALL THE REGION WILL BE ON THE WARM AND DRY SIDE COMPARED
TO CLIMATE NORMAL WITH THAT WAVE MOVING CLOUD COVER NOT EXPECTING
AS MANY RECORD HIGHS AND POTENTIAL FOR LIGHT RAIN MAY BREAK THE
DRY STREAK AT LEAST FOR THE NORTHERN AND CENTRAL PANHANDLE.

 SHORT WAVE CROSSING OVER THE NORTHERN AK GULF WILL HAVE
DISSIPATED BY MONDAY NIGHT. HIGH PRESSURE WILL BUILD OVER THE GULF
AT THE SAME TIME WITH MARINE LAYER FORMATION EXPECTED. INLAND
SKIES SHOULD SEE SOME CLEARING ON MONDAY NIGHT BUT THEN A RETURN
TO MORE CLOUD COVER. MODELS ARE STARTING TO FALL MORE INLINE WITH
THE 500 BM SHORT WAVE FORMING OVER KODIAK AROUND THE TRIPLE POINT
OF A FRONT EXTENDING FROM A BERING SEA LOW ON MONDAY. THE WAVE
WILL TRACK ACROSS THE AK GULF AND MOVING OVER THE PANHANDLE BY
WEDNESDAY. WHILE THERE IS BETTER CONSENSUS ON THE STRENGTH OF THE
UPPER LEVEL CLOSED LOW AT THIS TIME POSITION OF THE LOW STILL NOT
NAILED DOWN. GFS MOVES IT FURTHER SOUTH WHILE ECMWF/GEM HAVE THE
LOW CENTER MOTE OVER THE CENTRAL TO NORTHERN PANHANDLE. MODELS
THEN TRACK THE LOW TO THE SOUTHEAST OVER BRITISH COLUMBIA BY THE
WEEKEND. WHILE THERE IS NO SURFACE LOW ASSOCIATED WITH THE UPPER
LEVEL FEATURE THE CHANCE OF PRECIPITATION IN ADDITION TO INCREASED
CLOUD COVER IS EXPECTED. KEEPING POPS AS CHANCE OR LOWER MAINLY
OVER THE NORTHERN REGIONS. QPF VALUES ARE LOW, A FEW HUNDREDTHS OF
AN INCH, SO WENT WITH LIGHT RAIN WORDING. AS THE WAVE MOVE INTO
B.C. DRIER WEATHER IN STORE FOR THE END OF THE WEEK, JUST IN TIME
FOR ANOTHER POTENTIAL WAVE DROPPING INTO THE NORTHERN GULF FROM
THE AK INTERIOR, BUT HIGH UNCERTAINTY BY THAT TIME.

WINDS OVER THE COASTAL WATERS ON THE LESS SIDE OF THE RIDGE WILL
BE NORTHWESTERLY PICKING UP TO 20 TO 25 KT OVER THE SOUTHERN
REGIONS. SHOULD SEE ANOTHER TIP JET FORM NEAR CAPE DECISION WITH
WINDS NEARING SMALL CRAFT LEVELS FOR CROSS SOUND AND ICY STRAIT.
WINDS WILL HAVE A DIURNAL PATTERN BUT NOT AS MUCH AS WE ARE SEEING
CURRENTLY DUE TO DECREASED THERMAL GRADIENT. OVERLAND WINDS STILL
HAVE SOME SEA BREEZE DEVELOPMENT ON THOSE CLEARER DAYS BUT MOSTLY
DRIVEN BY NORTHERLY PRESSURE GRADIENT.

GOOD INITIALIZATION WITH THE NAM/ECMWF WHICH WERE USED TO UPDATE
GRIDS THROUGH DAY 4, ALTHOUGH BY DAY 3 INHERITED GRIDS WERE SO
CLOSE TO ECMWF CHANGES WERE MINOR. FOR REMAINDER OF EXTENDED
FORECAST USED NEW WPC WHICH WAS MOSTLY ENSEMBLE ECMWF, CHANGES FOR
THIS TIME WERE MINOR AS WELL. BIGGEST CHANGE WAS TO INCREASE POPS
IN TUESDAY NIGHT INTO WEDNESDAY JUST ENOUGH FOR CHANCE OF RAIN TO
BE MENTIONED. FORECAST CONFIDENCE IS AVERAGE.

&&

.FIRE WEATHER...FUELS CONTINUE TO BE VERY DRY WITH THE CONTINUING
LACK OF ANY SIGNIFICANT RAINFALL. MIN RH VALUES HAVE IMPROVED OVER
THE LAST 24 HOURS WITH THE INFILTRATION OF THE MARINE LAYER
FURTHER INLAND OVERNIGHT SO NO RED FLAG CONDITIONS ARE EXPECTED
FOR THE NEXT FEW DAYS. HOWEVER THE CONTINUING LACK OF ANY
SIGNIFICANT RAINFALL WILL MEAN VEGETATION WILL REMAIN VERY
SUSCEPTIBLE TO FIRE. PEOPLE ARE ENCOURAGED TO CONTINUE TO USE
CAUTION WITH ANY OPEN AIR FIRES FOR THE NEXT SEVERAL DAYS.

&&

.HYDROLOGY...THE RECENT WARM WEATHER OVER THE LAST SEVERAL DAYS
HAS CAUSED THE LARGER GLACIER AND SNOW MELT FED RIVERS TO RISE. NO
FLOODING IS EXPECTED, BUT THE TAIYA RIVER HAS RISEN TO NEAR
BANKFULL STAGE LAST NIGHT AND THE NIGHT BEFORE. COOLER WEATHER
FROM INCREASED CLOUD COVER WILL SLOW MELTING AND ALLOW RIVER
LEVELS TO FLATTEN OUT OR DECREASE OVER THE NEXT FEW DAYS.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...SMALL CRAFT ADVISORY FOR PKZ012. 

&&

$$

EAL/PRB

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