Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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282 FXUS63 KDLH 011746 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 1246 PM CDT Mon Jul 1 2024 .KEY MESSAGES... - Isolated to scattered showers and thunderstorms this morning over mainly central to northern Minnesota. - A better chance for showers and thunderstorms late afternoon into tonight with a risk for heavy rain possibly leading to areal/flash flooding. An isolated severe thunderstorm is also possible this evening into the early morning hours. - Another low pressure system will bring more rain, possibly heavy, later Thursday into Friday. && .DISCUSSION... Issued at 350 AM CDT Mon Jul 1 2024 A few showers with an occasional thunderstorm were moving east into our western area early this morning. This is in response to warm air and moisture advection. This activity has been handled poorly by most of the models and even the HRRR has struggled to catch on. We do push POPs further east into northeast Minnesota and far northwest Wisconsin this morning but we think coverage will wane as it pushes further east closer to the high and with time. We have 20-40% POPS through the morning then diminish them for a time. An upper trough will replace the upper ridging that is over the Northland. 500MB height falls of 50-100M are forecast this afternoon into tonight. Increasing southerly flow will draw more moisture north and PWAT values will rise to around 1.75 inches by this evening which is in the 97-99th percentile. A low level jet will also strengthen to 40-50 knots this evening. Marginal instability is forecast today/tonight, partially due to expected cloud cover and some capping. Little MLCAPE is forecast and MUCAPE as high as 500-1000j/kg is forecast by the RAP. Effective shear is marginal. The ECMWF is much lower with forecast MUCAPE. There may be an isolated severe storm this evening into the early morning hours. The main severe threat will be hail to an inch in diameter and perhaps damaging wind to 60 mph. A bigger threat will be heavy rain. Deep layer winds, 2-7km, are south-southwest which will support training showers/storms which could lead to localized heavy rainfall. We`re forecasting a half to 1.5 inches of rain through Tuesday evening, highest over north-central Minnesota and the North Shore and most falling late afternoon/tonight. There is potential for even higher values as seen in the HREF with pockets of 2"+. We will continue the Flood Watch for northern Minnesota but did delay the start by a few hours. Showers and thunderstorms are expected to ramp up in coverage late afternoon into the overnight hours then are expected to diminish from west to east later tonight into Tuesday morning as the low level jet shifts east. More showers and thunderstorms are forecast for Tuesday. A surface front will still be west of the Northland in the morning and will move through Tuesday into Tuesday night. A strong thunderstorm will be possible Tuesday afternoon into the evening with MLCAPE ~500 j/kg and supportive shear. Shower and thunderstorm coverage is expected to be lower than what occurs tonight. Most will be dry on Wednesday but we do carry chances for more showers/storms Wednesday in northern Minnesota which is closer to an upper shortwave. Yet another shortwave and surface low arrive Thursday and departs Friday evening. Another round of showers/storms are expected and there will a risk of heavy rain, especially from central Minnesota into the Twin Ports and over northwest Wisconsin. Northwest flow aloft will send periodic shortwaves southeast through the region with more rain/storm chances this weekend into early next week. These later chances should be more progressive and feature lower PWAT values reducing the heavy rain threat. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1242 PM CDT Mon Jul 1 2024 VFR conditions will prevail into tonight before widespread showers and thunderstorms are expected to move into the region. A few showers and perhaps a thunderstorm will be possible at INL over the next few hours, but any impacts are expected to be brief and minimal. Timing for tonight`s rainfall has been pushed later with activity not expected to start until midnight or later. The threat for any strong storms has diminished and are no longer expected. Ceilings will lower to IFR tonight and remain there through the remainder of the period. Visibilities will drop to MVFR overnight with fog looking to linger through the remainder of the morning hours once rainfall ends. A low level jet will move across part of the region tonight as well. The core of the jet has shifted east with the latest model runs and is only expected to impact HIB, DLH and HYR with low level wind shear during the early morning hours. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 350 AM CDT Mon Jul 1 2024 Most will see winds at or lower than 15 knots today, with the Twin Ports having the best chance at them being a bit higher. Winds will increase a bit tonight, especially along the South Shore. Gusts of 20 to around 25 knots are expected. We issued a Small Craft Advisory late Monday night into Tuesday afternoon from Chequamegon Bay to Saxon Harbor. It`s possible additions to the advisory may be needed as far west as the Twin Ports but confidence is lower there. There will be thunderstorms tonight with the main threat small hail and lightning. The wind will become more southerly for most of the nearshore waters on Tuesday with then from 10 to 20 knots with a few higher gusts. A few more thunderstorms will be possible Tuesday into Tuesday evening. Stronger west or southwest winds will occur Wednesday with them from 15 to 20 knots with higher gusts. Small Craft Advisories may 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 5 PM CDT this afternoon through Tuesday evening for MNZ010>012-018>021. WI...None. MARINE...Small Craft Advisory from 4 AM to 3 PM CDT Tuesday for LSZ121- 148. && $$ DISCUSSION...Melde AVIATION...BJH MARINE...Melde