Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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702 FXUS63 KDLH 040834 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 334 AM CDT Tue Jun 4 2024 .KEY MESSAGES... - Dense fog expected over much of western Lake Superior into this evening with some inland as well this morning. - A line of showers and thunderstorms develop along a cold front today, mainly this afternoon into the evening. A few storms may become severe and also contain a heavy rain threat which may lead to localized flooding. - There will be more showers Wednesday and periodic chances that continue into early next week. Rainfall amounts mid week into the weekend will be lighter than what is expected today. && .DISCUSSION... Issued at 334 AM CDT Tue Jun 4 2024 Surface low pressure stretched from Alberta southeast through the Plains with a center along the north central South Dakota and North Dakota border. Water vapor imagery depicted the upper low over the Montana/Saskatchewan border. The upper trough will move east today and the surface low will lift northeast and congeal well north of the International Border. A cold front will push into the Northland this afternoon and exit tonight. Areas of fog and stratus, most widespread over northwest Wisconsin into northeast Minnesota will lift through the day but take longest around Lake Superior due to off lake winds that will occur through most of the day. A warm and moist airmass will precede the cold front today with PWAT values rising to 1.6" and surface dewpoints will climb into the mid- sixties with a few spots as high as the upper sixties. Highs will climb well into the seventies to lower eighties, away from Lake Superior. MLCAPE values are expected to climb to 1000-2000j/kg ahead of the front. Deep southerly flow ahead of the front will be in place and was aiding in drawing moisture north. Deep layer shear will be from 25 to 30 knots ahead of the front to 35 knots very close to it. There will be a severe threat, especially for cells close to the front where the shear is greatest. Forecast soundings show decent low level curvature in the hodographs but with a messier appearance above. Given the stronger forcing with the front and upper trough, storm mode should transition to a line or line segments fairly quickly. CAMS do show some individual storms for a time and hail from penny to half dollar still looks reasonable. There will also be a wind threat, especially as storm mode changes to more linear. Given the deep layer winds, 2-7KM, and 0-6KM shear vectors are all parallel or nearly parallel to the front today, heavy rain will be another threat. Storm motions will have a south to north component within the west to east line movement. This will lead to some training and with the higher moisture, flooding may result. The heavy rain that fell 24-36 hours ago over portions of the Northland will have soils primed. The HREF is showing the heavy rain threat with some pockets in the LPMM to 3" and some larger areas of 1-2". We will maintain the Flood Watch. The main window for severe will roughly be from 2 pm to 9 pm, guidance is in fairly good agreement on this. The SPC outlook for severe storms for much of our area is a 2 out of 5. The upper trough will be over the region Wednesday through Thursday and cooler temperatures will move in. The cooler temperatures aloft and upper low will keep chances for showers going through Thursday but they will be most widespread Wednesday. Chances will be greatest during the afternoon and evening hours during and just after peak heating. The rainfall Wednesday/Thursday will be much lighter than what is expected today. A western upper ridge does build late week into the weekend but the Northland remains close to the upper low and we carry chances for showers and a few thunderstorms in spots into early next week. Rainfall amounts will be relatively light. Highs late week into early next week will be near normal. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1238 AM CDT Tue Jun 4 2024 Conditions varied widely across the Northland. Fog was developing and stratus was expanding. IFR conditions will expand over northwest Wisconsin and around Lake Superior with some fog further inland as well. IFR or lower visibility and ceilings will occur at KHYR/KDLH/KHIB and could occur at KBRD but higher clouds moving in there should lower the chances some. The fog and stratus will lift for most through the day but take longest around Lake Superior which will see off lake winds through most of the day which won`t help matters. A cold front will push through the Northland Tuesday afternoon and evening bringing with it showers and thunderstorms. Some of the storms during the afternoon and evening could be severe with large hail and damaging wind both threats. Showers and some isolated thunderstorms will continue after the main line of storms push through but will eventually end from west to east. Gusty southerly winds will occur prior to the front with decent mixing leading to gusts of 20 to 25 knots. Winds will switch to west or southwest behind the front and be quite a bit lighter through Tuesday night. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 334 AM CDT Tue Jun 4 2024 Fog, dense in spots, will occur today into tonight over portions of the area. Easterly winds will continue today and then turn westerly as a cold front moves through this evening/overnight. The wind switch should aid in ending the dense fog threat. Showers and thunderstorms will develop along the front as well and some of the storms could be strong to severe with large hail and winds to 45 knots possible. Westerly winds on Wednesday will be strongest from Silver Bay to the Twin Ports to Port Wing and some gusts of 20 to 25 knots will be possible. Westerly winds will increase further on Thursday with widespread speeds of 15 to 25 knots with gusts around 30 knots. Hazardous conditions will occur, especially for smaller vessels and a Small Craft Advisory will likely be needed. For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt. && .DLH WATCHES/WARNINGS/ADVISORIES... MN...Flood Watch from 1 PM CDT this afternoon through Wednesday afternoon for MNZ034-036-038. WI...Flood Watch from 1 PM CDT this afternoon through Wednesday afternoon for WIZ001>004-006>009. MARINE...Dense Fog Advisory until 10 PM CDT this evening for LSZ140>146. Dense Fog Advisory until 10 AM CDT this morning for LSZ150. && $$ DISCUSSION...Melde AVIATION...Melde MARINE...Melde