853  
FXAK67 PAJK 172250  
AFDAJK  
 
SOUTHEAST ALASKA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE JUNEAU AK  
250 PM AKDT SUN JUN 17 2018  
   
SHORT TERM
 
A PATTERN CHANGE FROM COOL WET AND CLOUDY TO WARM  
DRY AND SUNNY WILL OCCUR IN THE SHORT TERM. SUNDAY NIGHT BEGINS  
WITH A SEASONABLY STRONG WEATHER FRONT PUSHING NORTH OVER THE GULF  
WHICH WILL INTRODUCE GALES OVER THE CENTRAL GULF AND NEAR THE CAPE  
SUCKLING AREA. THE PANHANDLE AS A WHOLE WILL NOT SEE MUCH  
PRECIPITATION ASSOCIATED WITH THIS FRONT WITH THE EXCEPTION OF  
YAKUTAT; WHICH MAY STAY WET INTO TUESDAY. OVER THE NORTHERN  
PANHANDLE THIS EVENING, A CHANCE OF RAIN ASSOCIATED WITH THE  
PREVIOUS FRONT STILL EXISTS.  
 
TOMORROW A DRYING TREND BEGINS WITH SKIES BEGINNING TO CLEAR FROM  
SOUTH TO NORTH AS A SURFACE RIDGE OF HIGH PRESSURE ESTABLISHES  
ITSELF OVER THE EASTERN GULF. THIS WILL ALSO ACT TO BEGIN A  
SIGNIFICANT WARM AIR ADVECTION REGIMEN. THIS NEW PATTERN WILL  
BRING HIGHS IN THE UPPER 60S TO THE OUTER COAST BY TUESDAY.  
HOWEVER, FURTHER INLAND TEMPERATURES WILL LIKELY CLIMB INTO THE  
70S OVER THE NORTHERN PANHANDLE AND APPROACH OR EXCEED 80 OVER  
SOUTHERN PANHANDLE TUESDAY.  
 
ONE LIMIT TO THE CLEARING COULD BE A RELATIVELY ONSHORE FLOW  
PATTERN, WHICH MAY ULTIMATELY CAUSE SOME MARINE STRATUS CLOUDS.  
IF THESE CLOUDS ARE ABLE TO PUSH INLAND, TEMPERATURES MAY NOT  
WARM AS MUCH AS ANTICIPATED.  
 
NOT MANY CHANGES TO THE EXISTING FORECAST WERE MADE. CONTINUED THE  
WARMING TREND OVER THE SOUTHERN PANHANDLE ON TUESDAY.  
ADDITIONALLY WINDS WERE WEAKENED UNDERNEATH THE SURFACE RIDGE;  
HOWEVER, WHERE THERMALLY INDUCED WINDS WILL LIKELY FORM, WINDS  
WERE INCREASED. PRIMARY GUIDANCE WAS A BLEND OF THE GFS AND  
CANADIAN. FORECAST CONFIDENCE IS ABOVE AVERAGE IN THE SHORT TERM.  
   
LONG TERM.../TUESDAY THROUGH SUNDAY/
 
AS OF 9PM SATURDAY. THE  
S-SWLY JET ALOFT WILL BE POINTED AT YAKUTAT AND THE NE GULF COAST  
ON TUESDAY, THEN START TO WEAKEN AND SHIFT BACK WEST FOR  
WEDNESDAY. THIS WILL CAUSE RAIN TO GRADUALLY DECREASE, AND BE  
PREDOMINANTLY ON THE WEST SIDE OF YAKUTAT BY WEDNESDAY AFTERNOON.  
OTHERWISE THE ONSHORE FLOW ALOFT OVER THE REST OF THE PANHANDLE  
WILL KEEP SOME CLOUDS AROUND, BUT LOW LEVEL FLOW WILL BE NWLY WITH  
THE SURFACE RIDGE AXIS OVER THE EASTERN GULF. EXPECT LARGELY  
PARTLY CLOUDY SKIES WITH THE BEST CHANCES FOR LARGER BREAKS ON  
THE LEE SIDE OF THE MOUNTAINS OVER THE INNER CHANNELS, IE. LYNN  
CANAL AND CHATHAM STRAIT, AS WELL AS THE SOUTHERN INNER CHANNELS.  
 
TEMPERATURES WILL BE ONE OF THE BIG STORIES OF THE WEEK. AS OF TODAY  
TEMPERATURES AT 850MB ARE 5-10C FROM NORTH TO SOUTH. BY TUESDAY  
AFTERNOON MODELS HAVE THESE VALUES WARMING TO 16-20C OVER THE  
SOUTHERN PANHANDLE, WITH THE GFS BEING THE COLDEST AND THE ECMWF  
BEING THE WARMEST. THIS WOULD TRANSLATE TO A MAXIMUM POTENTIAL  
TEMPERATURE IN THE HIGH 80S! THEREFORE OUR CURRENT FORECAST IN THE  
MID 70S MAY END UP BEING ON THE CONSERVATIVE SIDE. AREA RIVERS WILL  
LIKELY RESPOND TO THESE HIGH TEMPERATURES WITH SNOW MELTING AT ALL  
LEVELS.  
 
A TROUGH (OR TWO) WILL APPROACH THE REGION FROM THE SW LATE IN  
THE WEEK AND BRING THE NEXT CHANCE OF SHOWERS. MODELS HAVE SHORT  
WAVE TROUGHS PASSING OVER AT DIFFERENT TIMES HOWEVER, SO THERE IS  
SOME UNCERTAINTY. THE GFS SHOWS ONE THURS AFTERNOON (ALTHOUGH WITH  
VERY FEW SHOWERS THANKS TO THE RIDGE) WHILE THE ECMWF AND  
CANADIAN MODELS DON'T BRING IT IN UNTIL FRIDAY MORNING. DUE TO THE  
VARIABILITY WITH LOCATION/TIMING FROM RUN TO RUN HAVE INCLUDED A  
BROADER AREA OF SLIGHT CHANCE SHOWERS FOR BOTH THURSDAY AND  
FRIDAY.  
 
A LOW PRESSURE SYSTEM WITH A BETTER CHANCE OF RAIN MOVES INTO THE  
GULF FROM THE SW SATURDAY NIGHT, THEN LOOKS TO CONTINUE AFFECTING  
THE REGION SUNDAY. THE 3 OPERATIONAL LONG-RANGE MODELS VARY THE  
PLACEMENT OF THE LOW CENTER FROM THE NORTH-CENTRAL GULF TO THE SE  
CORNER NEAR HAIDA GWAII, WITH THE ECMWF IN THE MIDDLE. THE NORTHERN  
POSITION WOULD GIVE RAIN TO MAJORITY OF THE PANHANDLE WHILE THE  
SOUTHERN TRACK WOULD KEEP THE NORTHERN THIRD OF THE PANHANDLE ON THE  
DRY SIDE WITH OFFSHORE FLOW. BOTH SOLUTIONS WOULD BE WET FOR THE  
SOUTHERN PANHANDLE ON SUNDAY.  
 

 
   
AVIATION
 
CONDITIONS CONTINUE TO GRADUALLY IMPROVE OVER THE  
PANHANDLE THIS SUNDAY AFTERNOON. HOWEVER, SOME AREAS HAVE BEEN  
UNDER PERSISTENT IFR CONDITIONS. AS ANOTHER FRONT PUSHES  
NORTHWARD TONIGHT WHICH MAY BRING IN LOWER CONDITIONS NEAR YAKUTAT  
ONCE AGAIN. CONDITIONS ARE EXPECTED TO IMPROVE TOMORROW AS THE  
SURFACE RIDGE BECOMES MORE DOMINANT, BUT THE EARLY HOURS MAY BE  
PLAGUED WITH LOW STRATUS ONCE AGAIN.  
 

 
   
AJK WATCHES/WARNINGS/ADVISORIES
 
 
PUBLIC...NONE.  
MARINE...GALE WARNING FOR PKZ052.  
SMALL CRAFT ADVISORY FOR PKZ036-051.  
SMALL CRAFT ADVISORY DUE TO SEAS FOR PKZ022-041>043-053.  
 

 
 

 
 
JB/FERRIN  
 
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