251  
FXAK67 PAJK 172234  
AFDAJK  
 
SOUTHEAST ALASKA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE JUNEAU AK  
234 PM AKDT THU SEP 17 2020  
   
SHORT TERM
 
A RELATIVELY NARROW FRONT LIES ACROSS THE CENTRAL  
GULF WITH CLOUDS SEEN ON SATELLITE BETWEEN PWS AND MT.  
FAIRWEATHER. S-SE WINDS WITH GUSTS TO GALE FORCE HAVE BEEN  
OBSERVED SO FAR AT THE CAPE SUCKLING BUOY AND EXPECT THE BARRIER  
JET TO CONTINUE IN THAT REGION THROUGH MOST OF THE NIGHT. VERY  
LIGHT RAIN HAS BEEN FALLING IN YAKUTAT ALL DAY OUT OF A FAIRLY  
HIGH CLOUD DECK, AROUND 7KFT. EXPECT THE RAINFALL RATES/AMOUNTS TO  
INCREASE THROUGH THE EVENING AS THE FRONT SLOWLY MOVES EASTWARD  
SINCE UPWIND AREAS OF VALDEZ AND CORDOVA HAVE BEEN REPORTING  
MODERATE RAIN ALL DAY.  
 
EXPECT RAIN TO REACH THE SITKA TO JUNEAU AREAS BY EARLY FRIDAY  
MORNING, THEN CONTINUE E-SE THROUGH THE AFTERNOON. THE FRONT LOOKS  
TO WEAKEN AS IT CROSSES THE REGION, SO AMOUNTS WILL BECOME LIGHTER  
OR EVEN SHADOWED BY THE TIME IT REACHES THE SOUTHERN INNER  
CHANNELS. THE WEAKENING TREND APPLIES TO WINDS AS WELL, SO THE  
WIND SPEED FORECAST HAS BEEN DECREASED.  
 
SATELLITE IMAGERY SHOWS A SHARP BACK EDGE TO THE FRONT SO SOME  
SUN IS POSSIBLE POST-FRONT FRIDAY AFTERNOON/EVENING ACROSS THE  
NORTH. CAA BEHIND THE FRONT WILL CHANGE THE RAIN TO SHOWERS AND  
SWLY ONSHORE FLOW FRIDAY NIGHT THROUGH SATURDAY WILL KEEP THE  
POTENTIAL FOR ISOLATED/SCATTERED SHOWERS IN THE FORECAST. A  
POSITIVELY TILTED RIDGE PUSHING IN OVER THE GULF BETWEEN SYSTEMS  
WILL ALLOW FOR SOME SUNNY BREAKS ON SATURDAY. THIS IS ESPECIALLY  
TRUE FOR THE SOUTHERN INNER CHANNELS SATURDAY AFTERNOON AS THERE  
WILL BE NWLY FLOW ON THE LEE SIDE OF THE RIDGE. GENERALLY THE  
PRESSURE GRADIENT WITH THE BRIEF RIDGE LOOKS WEAK, SO WINDS WERE  
DECREASED WITH THAT AS WELL. THEN SATURDAY NIGHT, A LOW MOVING  
INTO THE CENTRAL GULF WILL INCREASE THE THREAT OF SHOWERS AGAIN AS  
FRONTAL BANDS MOVE INTO THE NORTHERN GULF COAST.  
   
LONG TERM.../SATURDAY THROUGH THURSDAY NIGHT/
 
AS OF WEDNESDAY  
EVENING. A LOW WILL BE LOCATED SOUTH OF KODIAK AND A SURFACE  
RIDGE WILL EXTEND FROM THE EASTERN GULF NE ACROSS THE PANHANDLE  
AND INTO CANADA AT THE START OF THIS LONG RANGE FORECAST PERIOD.  
THE LOW WILL MOVE SLOWLY TO THE EAST AND DISPLACE THE RIDGE SOUTH  
AND EAST ON SUNDAY, THEN BEGIN TO WEAKEN AND DISSIPATE MONDAY  
EVENING. AT THAT TIME, A MUCH STRONGER LOW WILL BE LOCATED SOUTH  
OF THE PENINSULA AND HEADED EAST. THIS LOW WILL FILL THE GULF WITH  
A CIRCULATION THAT EXTENDS AS FAR NORTH AS THE CENTRAL INTERIOR  
AND AS FAR SOUTH AS CALIFORNIA. IT WILL BEGIN WEAKENING WEDNESDAY  
EVENING, ONLY TO BE REPLACED BY ANOTHER LOW SLIGHTLY LESS INTENSE  
AND A BIT FARTHER SOUTH IN THE GULF BY THE END OF THIS FORECAST  
PERIOD FRIDAY MORNING.  
 
EACH OF THESE LOWS WILL PUSH A FRONT ACROSS THE GULF WITH  
INTENSITIES COMMENSURATE TO THE STRENGTH OF THE PARENT LOWS. THE  
SECOND FRONT IS LOOKING MORE AND MORE LIKELY TO FEATURE HEAVY RAIN  
FOR ALL OF SOUTHEAST ALASKA ON WEDNESDAY. THIS SECOND FRONT WILL  
ALSO PRODUCE A GALE FORCE WINDS OVER THE EASTERN GULF AND SMALL  
CRAFT WINDS OVER MANY OF THE INNER CHANNELS. THIS SECTION OF THE  
LONG RANGE FORECAST GOT THE MOST ATTENTION TONIGHT WITH MOST OF  
THE WORK DONE TO INCREASE MARINE WINDS. MODEL AGREEMENT THIS FAR  
OUT INTO THE FUTURE IS NOT VERY GOOD AND SOME OF THE LONG RANGE  
MODELS ARE SUGGESTING STORM FORCE WINDS. FOR NOW, WIND GRIDS OVER  
THE EASTERN GULF HAVE BEEN INCREASED TO MARGINAL GALE STRENGTH. IF  
MODEL SOLUTIONS CONVERGE, STRONGER WINDS WILL BE NECESSARY AND  
STRONG WINDS ON THE OUTER COAST WILL BECOME LIKELY TUESDAY GOING  
INTO WEDNESDAY.  
 

 
   
AJK WATCHES/WARNINGS/ADVISORIES
 
 
PUBLIC...NONE.  
MARINE...GALE WARNING FOR PKZ052.  
SMALL CRAFT ADVISORY FOR PKZ022-043-051-053.  
 

 
 

 
 
FERRIN/FRITSCH  
 
VISIT US AT HTTP://WWW.WEATHER.GOV/JUNEAU  
 
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