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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