575  
FXAK67 PAJK 122153  
AFDAJK  
 
SOUTHEAST ALASKA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE JUNEAU AK  
153 PM AKDT SUN JUL 12 2020  
   
SHORT TERM
 
RIDGE OF HIGH PRESSURE MOVED ONSHORE AND IS EXPECTED  
TO STALL ALONG THE COASTAL RANGE SUNDAY NIGHT. SCATTERED RAIN  
SHOWERS, MAINLY UNDER A WAVE RIDING NORTH OVER THE RIDGE, WILL  
DIMINISH THROUGH THE EVENING, JUST IN TIME FOR ANOTHER SYSTEM TO  
MOVE IN WITH MORE RAIN. FOR NOW KEPT FOG OUT OF THE FORECAST DUE  
TO EXPECTATION OF LINGERING CLOUD COVER, HOWEVER WITH THE  
DIMINISHING SHOWERS AND A FEW BREAKS COULD SEE MORE RADIATIONAL  
FOG DEVELOPMENT TONIGHT. AN EASTWARD TRACKING LOW SOUTH OF THE  
ALEUTIANS WILL JOIN AND BE INVIGORATED BY AN UPPER LEVEL LOW  
MOVING FROM NEAR NORTON SOUND SOUTH TOWARDS KODIAK ISLAND. THE  
SURFACE LOW WILL DEEPEN TO NEAR 1000 MB AS IT MOVES INTO THE  
NORTHERN GULF. THE RAIN ASSOCIATED WITH THIS LOW/FRONT WILL  
SPREAD INTO THE AREA MONDAY AND MONDAY NIGHT. A SECOND WAVE IS  
EXPECTED TO DEVELOP ON THE TRAILING COLD FRONT AND THEN MOVE TO  
THE SOUTHERN HALF OF THE PANHANDLE BY TUESDAY. THE SURFACE LOW  
WILL BEGIN TO WEAKEN AND DISSIPATE TUESDAY NIGHT. STILL SOME  
TIMING DIFFERENCES ON THE FRONT, WITH NAM BEING THE FASTEST  
SOLUTION.  
 
ATMOSPHERIC RIVER WILL CLIP THE SOUTHERN PORTION OF THE PANHANDLE  
WITH THE SECOND WAVE. LONG FETCH OF MOISTURE FROM CONNECTION TO  
THE MID TROPICS ADVANCING ACROSS THE NORTH PACIFIC WILL BRING IN  
PERIODS OF HEAVY RAIN. THE FORECAST RAINFALL NUMBERS HAVE SO FAR  
REMAINED THE SAME WITH ROUGHLY 1.0 TO 2.5 INCHES INTO TUESDAY  
NIGHT.  
 
LYNN CANAL WINDS BUMPED TO SMALL CRAFT SUNDAY EVENING. COASTAL  
WATER WINDS UNDER THE ADVANCING FRONT WILL INCREASE TO 30 TO 35  
KT, POSSIBLY 40 KT BY MONDAY EVENING. STRONGEST WINDS WILL BE  
OVER THE NE GULF. SOUTHERN INNER CHANNEL WINDS WILL INCREASE WITH  
THE SECOND WAVE BY EARLY TUESDAY MORNING.  
 
WITH THE TIMING DIFFERENCES IN THE FRONT LIMITED FORECAST  
CHANGES. DID INCREASE WINDS WITH SOME GFS/GEM AND NUDGED POP TO  
SREF FOR BIT MOVE COVERAGE. ABOVE AVERAGE CONFIDENCE IN THE  
RAIN/BREEZY FORECAST BUT STILL LOWER CONFIDENCE ON EXACT TIMING.  
   
LONG TERM
 
/TUESDAY THROUGH NEXT SATURDAY/ AS OF 8PM SATURDAY.  
BY TUESDAY MORNING THE FRONT DISCUSSED IN THE SHORT TERM PERIOD  
SHOULD BE CAUSING WIDESPREAD RAIN OVER MAJORITY OF THE PANHANDLE.  
THIS PORTION OF THE FORECAST HAS THE HIGHEST CONFIDENCE IN A  
WET/CLOUDY DAY. DESPITE MODELS HAVING DIFFERENT TIMING/PLACEMENT  
OF THE PARENT LOW ALL WEEK, THEY AGREE THAT MOST OF THE DAY WILL  
SEE RAIN. THE DIFFERENCES IN LOW PLACEMENT STILL HAVE AN AFFECT  
ON WIND DIRECTIONS HOWEVER. IF THE LOW IS A BIT FURTHER SOUTH,  
THEN WINDS THROUGH SOME OF THE NORTHERN INNER CHANNELS WILL TURN  
OUT OF THE NORTH. HAVE INCREASED WIND SPEEDS WITH THE FRONT TO  
25KT IN A LARGER SWATH AND OUT OF CROSS SOUND AND UP CLARENCE  
STRAIT. GUSTY WINDS ARE ALSO LIKELY IN PLACES LIKE KETCHIKAN AND  
PORTIONS OF POW.  
 
THE LOW WILL WEAKEN TO A TROUGH LATE TUESDAY NIGHT OR WEDNESDAY  
MORNING, BUT MODELS DIFFER ON WHETHER THAT WILL BE OVER THE GULF OR  
IF IT WILL CONTINUE EAST OVER THE SOUTH/CENTRAL PANHANDLE. EITHER  
WAY, EXPECT RAIN TO BECOME MORE INTERMITTENT ON WEDNESDAY THAN  
TUESDAY. BEYOND WEDNESDAY IS LESS CERTAIN. THE ECMWF HAS  
CONSISTENTLY SHOWN A RIDGE BUILDING OVER THE GULF THURSDAY WITH  
REDUCED CHANCE OF PRECIP. THE OFFICIAL FORECAST ALSO SHOWS THAT  
IDEA, BUT OTHER MODELS BRING A NEW LOW OVER THE SOUTHERN HALF OF  
THE AREA, SO THINGS COULD CHANGE. AS OF NOW, THERE IS AGREEMENT ON  
A LARGER SYSTEM APPROACHING FROM THE SW NEXT SATURDAY.  
 
THE GFS CONTINUES TO BE THE OUTLIER WITH PLACEMENT OF THE TUESDAY  
LOW AND HAS A MUCH MORE ACTIVE PATTERN THAN OTHER MODELS BEYOND  
THAT TIMEFRAME. WPC NOTED THIS AS WELL AND USED MORE OF THE 12Z  
ECMWF AND I FOLLOWED SUIT. FORECAST CONFIDENCE DECREASES FOR THE  
SECOND HALF OF THE WEEK DUE TO MODEL SPREAD.  
 

 
   
AJK WATCHES/WARNINGS/ADVISORIES
 
 
PUBLIC...NONE.  
MARINE...GALE WARNING FOR PKZ052.  
SMALL CRAFT ADVISORY FOR PKZ012-042-043-051.  
 

 
 

 
 
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