317  
FXUS63 KDLH 270552  
AFDDLH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DULUTH MN  
1252 AM CDT FRI APR 27 2018  
   
SHORT TERM
 
(THIS EVENING THROUGH FRIDAY)  
ISSUED AT 229 PM CDT THU APR 26 2018  
 
WITH THE ONGOING EVENT IN SUPERIOR, WISCONSIN, MAIN CONCERN FOR  
TONIGHT WILL BE THE WINDS FOR THE DISPERSION OF SMOKE. NORTHEAST  
WINDS 10 TO 15 MPH BECOMING LIGHT AND VARIABLE AFTER SUNSET. WINDS BECOMING  
SOUTHWEST AROUND 5 MPH AFTER MIDNIGHT. WINDS WILL SHIFT TO THE  
WEST AROUND 8 AM, THEN NORTH BY LATE MORNING, WINDS 10 MPH GUSTING  
TO 17 MPH. WINDS IN THE AFTERNOON WILL SWITCH OUT OF THE  
NORTHEAST AT 10 MPH, GUSTING TO 15 MPH.  
 
A VERY SHORT BREAK FROM THE CLOUDS AND PRECIPITATION WILL OCCUR  
THIS EVENING BEFORE A MORE POTENT SHORTWAVE TROUGH WILL QUICKLY  
DIVE SOUTHWARD FROM MANITOBA CANADA OVERNIGHT. THIS SHORTWAVE  
LOOKS TO HAVE BETTER LIFT ASSOCIATED WITH IT, PER THE THALER QG  
OMEGA PROGS. DEEPER MOISTURE WILL PERSIST FOR LONGER WITH THIS  
SHORTWAVE COMPARED TO THE ONE FOR THIS MORNING, SO PRECIPITATION  
EFFICIENCY WILL BE MORE ROBUST WITH THIS SECOND WAVE. THE THERMAL  
PROFILES INDICATE A MIX OF PRECIP TYPES, PRIMARILY A MIX OF RAIN  
AND SNOW DUE TO 925 MB LOW-LEVEL TEMPERATURES DIPPING TO NEAR ZERO  
DEGREES. THE BEST CHANCES OF SNOW ACCUMULATION WILL BE OVER THE  
MINNESOTA ARROWHEAD AND POINTS SOUTHEAST INTO NORTHWEST WISCONSIN.  
FORECAST SNOW ACCUMULATION THROUGH FRIDAY MORNING WILL BE LIGHT,  
WITH ONLY UP TO ONE INCH POSSIBLE, WHICH IS CONSISTENT WITH THE  
SREF ENSEMBLE MEAN VALUES IN THESE AREAS, ALTHOUGH THESE VALUES  
MAY EVEN BE TOO HIGH STILL DUE TO ABOVE FREEZING SURFACE  
TEMPERATURES PER MNDOT RWIS STATIONS. SOME LINGERING PVA AND LOW-  
LEVEL SATURATION WILL LINGER SOME CHANCES OF PRECIPITATION INTO  
FRIDAY AFTERNOON, WHEN PRECIPITATION TYPES WILL BE IN THE FORM OF  
RAIN. THERE MAY EVEN BE A RUMBLE OF THUNDER IN NORTHWEST WISCONSIN  
DUE TO INCREASED INSTABILITY DUE TO STEEPENING LOW-LEVEL LAPSE  
RATES. MUCAPE VALUES ARE GENERALLY AROUND 50 J/KG, SO ONLY PUT IN  
A SLIGHT CHANCE OF THUNDER IN THE FORECAST.  
   
LONG TERM
 
(FRIDAY NIGHT THROUGH THURSDAY)  
ISSUED AT 229 PM CDT THU APR 26 2018  
 
A MILD AND DRY WEEKEND FOLLOWED BY NUMEROUS CHANCES FOR RAINFALL AND  
EVEN A FEW THUNDERSTORMS NEXT WEEK. SUNNY WITH HIGHS IN THE 50S TO  
NEAR 60 ON SATURDAY, 60S TO NEAR 70 SUNDAY. IT WILL ALSO BE VERY DRY  
THROUGH THE WEEKEND WITH RELATIVE HUMIDITY VALUES FALLING TO 20 TO  
30 PERCENT ON SATURDAY, THOUGH LACK OF MUCH WIND WITH THE HIGH  
PRESSURE NEARLY CENTERED OVER THE REGION WILL MITIGATE A FIRE  
WEATHER RISK, BUT ON SUNDAY STRONGER SOUTHERLY WINDS COMBINED WITH  
AGAIN LOW RELATIVE HUMIDITY VALUES COULD LEAD TO A HIGHER RISK FOR  
FIRES TO SPREAD EASILY. THESE DRIER CONDITIONS ALSO MEAN THAT WHILE  
THE DAYS WILL BE WARM, LOWS ON FRIDAY NIGHT AND SATURDAY NIGHT WILL  
BE ON THE CHILLY SIDE IN THE 20S TO NEAR 30 FRIDAY NIGHT, MID 20S TO  
MID 30S ON SATURDAY NIGHT. INCREASING CLOUDS SUNDAY NIGHT INTO  
MONDAY WITH AN INCREASING CHANCE FOR PRECIPITATION (ALL RAIN)  
THROUGH MONDAY AND TUESDAY, WITH A CHANCE FOR A FEW STORMS MONDAY  
EVENING INTO TUESDAY.  
 
ON THE SYNOPTIC SCALE A BROAD MID/UPPER LEVEL LONGWAVE RIDGE WILL  
BUILD FROM THE ROCKIES INTO THE MIDWEST THROUGH THE WEEKEND, WITH AN  
UPPER LOW/MID-LEVEL LONGWAVE TROUGH THEN DEEPENING ACROSS THE  
WESTERN STATES LATE IN THE WEEKEND. AT LOW LEVELS A BROAD AREA OF  
HIGH PRESSURE WILL BUILD ACROSS THE UPPER GREAT LAKES/UPPER MIDWEST  
ON SATURDAY, GRADUALLY BUILDING TO THE SOUTHEAST TOWARDS THE WORK  
WEEK. AS THE SURFACE HIGH BUILDS EAST OF THE NORTHLAND,  
SOUTH/SOUTHWESTERLY FLOW AT LOW LEVELS WILL RESULT IN WARM AND MOIST  
AIR ADVECTING INTO THE REGION AT LOW LEVELS. AN BROAD WARM FRONTAL  
ZONE TRACKS ACROSS THE UPPER MIDWEST MONDAY INTO MONDAY NIGHT WHICH  
COULD RESULT IN SHOWERS AND EVEN A FEW THUNDERSTORMS. THE BEST  
CHANCE FOR WIDESPREAD PRECIPITATION AND THUNDERSTORMS WILL BE ON  
TUESDAY WHEN THE NORTHLAND WILL BE WITHIN THE WARM SECTOR AHEAD OF A  
COLD FRONT AND THERE WILL BE DECENT ELEVATED INSTABILITY IN PLACE.  
THE COLD FRONT WILL TRACK FROM NORTH TO SOUTH OF OUT CANADA INTO THE  
UPPER GREAT LAKES ON TUESDAY INTO TUESDAY EVENING WHICH COULD RESULT  
IN SHOWERS AND STORMS, WITH GUIDANCE CURRENTLY DEPICTING THE BEST  
CONDITIONS FOR PRECIP NORTH AND WEST OF THE IRON RANGE. IN ADDITION  
TO THE PRECIP, CONFIDENCE IS HIGH IN VERY STRONG SOUTH-SOUTHWEST  
WINDS AHEAD OF THE COLD FRONT ON TUESDAY WITH GUSTS PERHAPS  
APPROACHING 45 MPH FOR AREAS SOUTH OF HIGHWAY 2 IN EAST-CENTRAL MN.  
BEYOND THE COLD FRONT TEMPERATURES A COOLER NORTHWEST FLOW PATTERN  
SETTLES IN FOR THE REST OF THE WORK WEEK, RESULTING IN TEMPS FALLING  
BACK TO NEAR-NORMAL VALUES.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)  
ISSUED AT 1239 AM CDT FRI APR 27 2018  
 
A VIGOROUS UPPER LEVEL SHORTWAVE AND SURFACE LOW WILL SLIDE  
SOUTHEAST ACROSS THE REGION OVERNIGHT AND INTO THE DAY FRIDAY.  
HIGH RESOLUTION MODELS GENERALLY KEEP THE PRECIPITATION TO THE  
NORTH AND EAST OF KBRD, WITH THE LOWEST CIG'S/VSBY'S ACROSS THE  
EASTERN AREAS AS WELL. SOME MVFR CONDITIONS ARE EXPECTED TO  
DEVELOP THROUGHOUT THE NIGHT AND INTO FRIDAY, WITH A WIDE VARIETY  
OF WIND DIRECTIONS AND SPEEDS AS WELL.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
DLH 34 51 28 51 / 40 40 20 0  
INL 33 46 25 57 / 40 20 10 0  
BRD 38 53 30 58 / 10 10 0 0  
HYR 31 53 24 52 / 30 30 10 0  
ASX 30 51 26 48 / 50 40 10 0  
 

 
   
DLH WATCHES/WARNINGS/ADVISORIES
 
 
WI...NONE.  
MN...NONE.  
LS...NONE.  

 
 

 
 
SHORT TERM...LE/WM  
LONG TERM...JJM/STEWART  
AVIATION...DAP  
 
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