Area Forecast Discussion
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FXAK67 PAJK 140032 CCA
AFDAJK

SOUTHEAST ALASKA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE JUNEAU AK
415 PM AKDT SUN JUL 13 2014

.SHORT TERM...SATELLITE IMAGERY THIS AFTERNOON SHOWING THE
STALLED WEATHER FRONT THAT HAS BEEN PRODUCING AMPLE RAIN OVER THE
CENTRAL AND NORTHERN PANHANDLE STARTING TO MOVE NORTHWARD. AS A
HIGH PRESSURE RIDGE BUILDS OVER THE AK GULF THE FRONT WILL WEAKEN
TONIGHT WITH PRECIP DIMINISHING FROM SOUTH TO NORTH WITH A SLIGHT
SHIFT TO THE EAST LATE TONIGHT INTO MONDAY. THE WAVES ALONG THE
FRONT WILL STILL BRING IN QPF AMOUNTS NEARING A HALF INCH FROM
THIS AFTERNOON TO EVENING BUT WILL SEE A RAPID DROP OFF LATER
TONIGHT. SPORADIC RAINFALL WILL CONTINUE TOMORROW FOR THE
NORTHERN AREAS AND THOUGH MODEL SOUNDINGS ARE BORDER LINE WITH
STABLE OR CONVECTIVE ENVIRONMENT GOING WITH SHOWER TERMINOLOGY.
WHILE THE NORTHERN AND CENTRAL REGIONS HAVE BEEN UNDER LOW CLOUDY
SKIES WITH FOG AND RAIN THE SOUTHERN PANHANDLE HAS SEEN AMPLE
SUNSHINE. THE SOUTHERN REGIONS WILL SEE SOME INCREASED CLOUDS TO
NIGHT AS THE FRONT SHIFTS TO THE EAST AS IT PULLS NORTH.
TEMPERATURES FOR POINTS NORTH OF FREDERICK SOUND WERE IN TO UPPER
50S TO LOW 60S WHILE POINTS SOUTH REACHED TO UPPER 70S TO LOW
80S. FOR MONDAY THE SOUTH WILL BE SLIGHTLY COOLER DUE TO THE
INCREASED CLOUD COVER EARLY IN THE MORNING WHILE THE NORTH WILL
SEE TEMPS IN THE MID 60S DUE TO THE DIMINISHING RAINFALL. WINDS
WERE GENERALLY LIGHT DUE TO THE WEAK GRADIENT. NORTHWESTERLY
WINDS WILL PICK UP FOR THE CENTRAL AND SOUTHERN PANHANDLE AS THE
RIDGE BUILDS THROUGH MONDAY.

 MODELS IN FAIR AGREEMENT AND SHOW ONLY MINOR VARIATIONS BETWEEN
EARLIER AND CURRENT RUNS. KEPT WITH AN ECMWF/GEM BLEND WITH ONLY
COSMETIC CHANGES TO THE FORECAST GRIDS. MAIN CONCERN WILL BE
TIMING OF PRECIP ENDING THIS EVENING AND HOW FAR EAST OVER THE
SOUTHERN PANHANDLE THE CLOUD COVER WILL MOVE. THIS IN TURN WILL
EFFECT TOMORROWS HIGH TEMPERATURES.

 &&

 .AVIATION...LOW CEILINGS, AREAS OF FOG, AND RESTRICTED
VISIBILITIES IMPACTED AVIATION OPERATIONS TODAY AND TONIGHT OVER
A MAJORITY OF THE PANHANDLE. THE ONLY AREAS THAT ARE NOT EXPECTED
TO BE TROUBLE SPOTS TODAY ARE PETERSBURG, WRANGELL, AND
KETCHIKAN. LOW CLOUDS AND FOG OVER THE REGION WILL DISSIPATE AND
LIFT LATE TONIGHT INTO MONDAY MORNING AS THE FRONT EXITS THE
REGION. WINDS ALOFT STILL FAIRLY LIGHT, SO NO TURBULENCE IS
EXPECTED IN CLOUD OR ON TOP.

 &&

 .HYDROLOGY...RAINFALL FROM THE WEATHER FRONT BROKE SEVERAL
ONE-DAY RECORDS ACROSS THE NORTHERN AND CENTRAL PANHANDLE AND
RESULTED IN RISES IN LOCAL RIVERS AND STEAMS. THE TAIYA RIVER
ROSE JUST ABOVE MINOR FLOOD STAGE OF 16.5 FEET SATURDAY NIGHT AND
IS HOLDING STEADY THIS AFTERNOON. A FLOOD ADVISORY WAS ISSUED
UNTIL MON MORNING FOR THE TAIYA. OTHER RIVERS TO THE NORTH SUCH
AS THE CHILKAT ROSE BUT STILL REMAINED BELOW FLOOD STAGE. NEAR
JUNEAU SMALL STREAMS SUCH AS MONTANA AND JORDAN CREEK RESPONDED
QUICKLY TO THE RAINFALL SHOWING RAPID WATER LEVEL FLUCTUATIONS,
BUT NEITHER REACHED MINOR FLOOD STAGE. LARGER WATER BODIES SUCH AS
THE MENDENHALL LAKE AND RIVER WERE SLOWER TO RESPOND TO THE
MULTIPLE DAY RAINFALL AND SHOWED A SLOWER BUT STEADY RISE.
MENDENHALL LAKE IS CURRENTLY AT MINOR FLOOD STAGE AND IS EXPECTED
TO CREST AT ABOUT 9.2 FEET LATER THIS EVENING. A FLOOD ADVISORY
FOR THE LAKE HAS BEEN ISSUED UNTIL 5 AM TOMRROW MORNING. BOTH
THESE WATER BODIES SHOULD CREST THIS AFTERNOON THE DROP AS RAIN
EXITS THE AREA.

 &&

 .LONG TERM...DRYING TREND IN THE WORKS FOR MID WEEK BEFORE MORE
RAIN TAKES AIM AT THE PANHANDLE FOR LATE WEEK. MID RANGE MODELS
ARE IN GOOD AGREEMENT ON A RIDGE SETTING UP SHOP OVER THE GULF BY
TUES WITH NW WINDS BLOWING THROUGH MUCH OF THE GULF AND
PANHANDLE. LITTLE IN THE WAY OF RAIN IS EXPECTED BUT THE MARINE
LAYER WILL BE MAKING A RETURN BY TUE NIGHT. IT WILL MAINLY AFFECT
THE GULF AND OUTER COAST TUE NIGHT BUT SHOULD START TO SPREAD
INLAND IN THE NORTHERN INNER CHANNELS WED NIGHT. THE DAILY
RETREAT AND ADVANCE OF THE MARINE LAYER SHOULD CONTINUE THROUGH
THU AT LEAST WITH MORE AREA COVERED BY CLOUDS EACH SUCCESSIVE
NIGHT.

 THU INTO FRI BECOMES RATHER DIFFICULT AS MODELS STRUGGLE WITH
THE NEXT SYSTEM THAT COMES INTO THE GULF. MAIN PROBLEMS SEEM TO
BE WITH HOW THE RIDGE OVER THE GULF WILL AFFECT THE STORM AND
WHAT THE UPPER LEVEL FLOW PATTERN IS LIKE. GFS IS THE OBVIOUS
OUTLIER AS IT KEEPS A MORE W TO E UPPER FLOW PATTERN THAT BLASTS
THE SURFACE LOW RIGHT THROUGH THE RIDGE INTO THE SOUTHERN
PANHANDLE BY EARLY FRI. NO OTHER MODEL DOES THIS. ALL THE REST
FEATURE A LOW THAT IS AROUND 10 MB DEEPER WITH A TRACK THAT SENDS
IT UP OVER KODIAK ISLAND AND THE KENAI PENINSULA EARLY FRI. WITH
HOW SYSTEMS USUALLY REACT UPON FIGHTING A RIDGE I AM MORE ABLE TO
BELIEVE THE RE-CURVE TRACK OVER KODIAK THEN I AM THE CANNON BLAST
THROUGH THE RIDGE THAT THE GFS IS TAKING SO USED MAINLY ECMWF AND
WPC GUIDANCE FOR THE THU THROUGH FRI NIGHT PERIOD. OVERALL THIS
IS NOT MUCH DIFFERENT FROM THE PREVIOUS FORECAST BUT RECENT
MODELS HAVE ALSO SPEAD UP THE LOW COMPARED TO PREVIOUS RUNS. THIS
HAS RESULTED IN MOVING UP THE TIME FOR WHEN THE FRONT WILL REACH
THE PANHANDLE LATE WEEK AND BROUGHT UP THE WINDS TO 20 KT IN THE
GULF AS THE FRONT MOVES THROUGH IN THE CURRENT FORECAST PACKAGE.

 INTO NEXT WEEKEND, OVERALL FLOW SWITCHES TO SW ACROSS MUCH OF
THE GULF. OUTER COASTAL AREAS WILL LIKELY BE BREEZY AND COOL WITH
THE WIND OFF THE WATER. ALSO WITH ALL THAT ONSHORE FLOW, NEXT
WEEKEND LOOKS TO REMAIN DAMP AND CLOUDY AS WELL.


.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...AREAL FLOOD ADVISORY UNTIL 9 AM AKDT MONDAY MORNING FOR
AKZ018.
AREAL FLOOD ADVISORY UNTIL 5 AM AKDT MONDAY MORNING FOR AKZ025.
MARINE...NONE.

&&

$$

PRB/EAL









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