399  
FXUS63 KDLH 132051  
AFDDLH  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DULUTH MN  
351 PM CDT MON JUL 13 2020  
   
SHORT TERM
 
(THIS EVENING THROUGH TUESDAY NIGHT)  
ISSUED AT 351 PM CDT MON JUL 13 2020  
 
AN APPROACHING COLD FRONT WILL LEAD TO DEVELOPING SHOWERS AND  
THUNDERSTORMS THIS EVENING. AN UPPER LEVEL TROUGH CURRENTLY LOCATED  
OVER EASTERN MONTANA WILL CONTINUE TO WORK ITS WAY EASTWARD, WHICH  
WILL HELP TO PROVIDE ADDITIONAL LIFT. THE COMBINATION OF THE COLD  
FRONT AND UPPER LEVEL TROUGH IS EXPECTED TO LEAD TO THUNDERSTORM  
DEVELOPMENT AFTER 00Z THIS EVENING. THE PRIMARY MODE OF THESE STORMS  
IS EXPECTED TO BE LINEAR, AS CAMS HAVE BEEN IN DECENT AGREEMENT.  
HOWEVER, THERE IS THE POTENTIAL FOR SOME DISCRETE CONVECTION,  
PRIMARILY IN THE SOUTHWESTERN PORTION OF THE CWA. A FEW OF THESE  
STORMS MAY BE SEVERE, PARTICULARLY IN THE BRAINERD LAKES AREA. MAIN  
HAZARDS INCLUDE DAMAGING WINDS, LARGE HAIL, ISOLATED TORNADOES, AND  
VERY HEAVY RAIN.  
 
ASSESSING THE ENVIRONMENT THIS EVENING, THE INGREDIENTS FOR SEVERE  
CONVECTION ARE PRESENT. 0-6 KM BULK SHEAR VALUES ARE FORECASTED TO  
BE BETWEEN 40-50 KNOTS. MLCAPE VALUES ARE EXPECTED TO BE BETWEEN  
1500-2000 J/KG. THIS AMOUNT OF INSTABILITY SHOULD HELP TO MAINTAIN  
THE STORMS, BUT LIMIT THE ABILITY FOR LARGE HAIL DEVELOPMENT.  
MOISTURE ADVECTION IS EXPECTED TO BE PLENTIFUL AS A LOWER LEVEL JET  
FROM THE SOUTH IS EXPECTED TO ADVECT A MOIST AIRMASS NORTHWARD. PWAT  
VALUES AROUND 1.5 INCHES COULD POTENTIALLY LEAD TO VERY HEAVY  
RAINFALL. WHEN ASSESSING THE POTENTIAL FOR TORNADOES, THE BRAINERD  
LAKES HAVE THE MOST FAVORABLE ENVIRONMENT ACCORDING TO SPC. 0-1 KM  
SRH FROM THE HRRR HAS BEEN QUITE IMPRESSIVE, WITH OVER 400 M2/S2  
AROUND THE TIME OF STORM DEVELOPMENT. ONE POTENTIAL LIMITING FACTOR  
TOWARDS TORNADO DEVELOPMENT WOULD BE THE HIGH LCLS, WHICH ARE  
CURRENTLY FORECASTED TO BE ABOVE 2 KM. REGARDLESS, THE RISK FOR  
TORNADOES IS STILL PRESENT AND WILL BE SOMETHING TO WATCH FOR IN THE  
STORMS THIS EVENING.  
 
FOR TUESDAY, SHOWERS AND THUNDERSTORMS ARE POSSIBLE, PARTICULARLY IN  
NORTHWEST WISCONSIN. A FEW OF THESE STORMS MAY BECOME SEVERE IN THE  
AFTERNOON. SPC CURRENTLY HAS MOST OF NW WI UNDER A MARGINAL RISK FOR  
SEVERE STORMS TOMORROW. LOOKING AT THE ENVIRONMENT, SHEAR OF 40-50  
KNOTS IS POSSIBLE, WITH MLCAPE VALUES OF 500-1000 J/KG. POSSIBLE  
THREATS INCLUDE DAMAGING WINDS, LARGE HAIL, AND A FEW ISOLATED  
TORNADOES. BY TUESDAY EVENING, THE SHOWERS AND THUNDERSTORMS WILL  
EXIT THE AREA, LEADING TO DRY CONDITIONS FOR TUESDAY NIGHT.  
TEMPERATURES TOMORROW ARE EXPECTED TO FEEL MUCH MORE COMFORTABLE,  
WITH HIGHS BEING IN THE MID 70S.  
   
LONG TERM
 
(WEDNESDAY THROUGH MONDAY)  
ISSUED AT 351 PM CDT MON JUL 13 2020  
 
A PROGRESSIVE PATTERN WILL BE IN PLACE FOR THE EXTENDED PERIOD WHILE  
STILL MAINTAINING ABOVE NORMAL TEMPERATURES.  
 
OVERALL, BROADSCALE MOISTURE IS LIMITED THROUGH THE WEEK, BUT A  
LARGE PLUME OF RICH PWAT AIR GETS ADVECTED NORTHWARD BY THE WEEKEND.  
THIS WILL SET THE STAGE FOR ANOTHER GOOD OPPORTUNITY FOR STRONGER  
STORMS - ESPECIALLY SINCE SHEAR BECOMES A LOT MORE PREVALENT AS  
FLOW TURNS ZONAL. SO, FRIDAY THROUGH SUNDAY MAY BE AN ACTIVE  
PERIOD FOR STORMS.  
 
AFTERWARDS, A DRIER AIR MASS MOVES IN AND A WEAK UPPER LEVEL RIDGE  
TRIES TO BUILD TO OUR WEST.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)  
ISSUED AT 1247 PM CDT MON JUL 13 2020  
 
VFR CONDITIONS ARE EXPECTED THIS AFTERNOON. CLOUD COVER WILL  
INCREASE THIS AFTERNOON AS A COLD FRONT APPROACHES FROM THE WEST.  
STRONG THUNDERSTORMS ARE EXPECTED THIS EVENING, WITH TIMING BEING  
FROM 01Z TO 05Z LEADING TO POSSIBLE MVFR TO BRIEFLY IFR CONDITIONS.  
A FEW STORMS MAY BE SEVERE, PARTICULARLY IN THE BRD AREA. IMPACTS  
INCLUDE DAMAGING WINDS, LARGE HAIL, ISOLATED TORNADOES, AND VERY  
HEAVY RAIN. FOLLOWING THE STORMS, FOG IS POSSIBLE PRIMARILY FOR HIB.  
SHOWERS RETURN TUESDAY MORNING WITH CEILINGS GENERALLY MVFR TO VFR,  
WITH THE CHANCE FOR A FEW EMBEDDED THUNDERSTORMS. SEVERE WEATHER IS  
NOT EXPECTED TOMORROW. EXPECT A WIND SHIFT TO WESTERLY OVERNIGHT  
INTO TOMORROW MORNING FOLLOWING THE PASSAGE OF THE COLD FRONT.  
 

 
   
MARINE
 
 
ISSUED AT 351 PM CDT MON JUL 13 2020  
 
STRONGER NORTHEAST WINDS THIS EVENING AROUND 10-20 KNOTS WILL  
BECOMING LIGHT AND VARIABLE OVERNIGHT AS A LINE OF SHOWERS AND  
STORMS MOVE THROUGH ASSOCIATED WITH A COLD FRONT. A FEW STRONG  
STORMS ARE POSSIBLE ACROSS WESTERN LAKE SUPERIOR, BUT GENERALLY  
THINKING STORMS WILL WEAKEN BEFORE THEY REACH THE LAKE. CHANCES FOR  
SHOWERS AND A FEW STORMS AGAIN ON TUESDAY ACROSS THE SOUTH SHORE  
WITH WEAK WEST WINDS AROUND 5 TO 10 KNOTS. INCREASING SOUTHWEST  
WINDS WEDNESDAY AND THURSDAY AT 10 TO 15 KNOTS, WITH WAVE HEIGHTS  
BUILDING TO AS HIGH AS 2 TO 3 FEET ACROSS PARTS OF THE NORTH SHORE  
BY THURSDAY.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
DLH 62 73 54 81 / 70 60 0 0  
INL 59 75 55 80 / 70 20 0 0  
BRD 60 73 53 80 / 90 60 0 0  
HYR 65 75 52 81 / 80 90 10 0  
ASX 65 78 55 83 / 70 90 20 0  
 

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

 
 

 
 
SHORT TERM...UNRUH/JJM  
LONG TERM...WOLFE  
AVIATION...UNRUH/JJM  
MARINE...JJM  
 
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