Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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344 FXUS63 KDLH 281615 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 1115 AM CDT Tue May 28 2024 .UPDATE... Issued at 1112 AM CDT Tue May 28 2024 Quick update to increase rain shower and thunderstorm probabilities across the Northland for today with cold temperatures aloft with the upper level low. Probabilities were increased the most for the Iron Range and Arrowhead of Minnesota. Given modest instability and weak shear, severe weather is not expected. && .KEY MESSAGES... - Scattered showers and isolated thunderstorms today, with the best coverage in the afternoon. Severe weather is not expected. - Dry weather for Wednesday and Thursday. - Frost Advisory along and north of the Iron Range tonight into early Wednesday morning. Additional frost is possible Wednesday night into early Thursday morning, with the best chances in parts of the Arrowhead and NW WI. - Rain and thunderstorm chances return Thursday night into Friday, with the return of a more active weather pattern continuing into early next week. && .DISCUSSION... Issued at 357 AM CDT Tue May 28 2024 Today: Light to locally moderate rain showers are ongoing in two batches early this morning: one batch in NW WI and a more concentrated band from the Brainerd Lakes up to Hibbing. This activity is associated with forcing from a shortwave trough aloft in cyclonic flow behind yesterday`s departing surface low. Shower activity will shift southeastward into primarily NW WI by mid-morning. Scattered diurnally driven showers develop later this morning and persist through early evening. Modest instability (SBCAPE of 100-300 J/kg in N/NE MN to 300-600 J/kg for locations south and east of a Brainerd Lakes to Twin Ports line) will support isolated airmass thunderstorms developing during this timeframe before diminishing past the early evening. The best thunderstorm potential/coverage will be where instability is highest. 0-6km bulk shear will be 20 knots or less, so thunderstorms are not expected to be strong or severe. Rain accumulations will generally be less than 0.2" through this evening, though a few locally higher amounts up to 0.5" aren`t out of the question for spots that see thunderstorms move overhead. Light northwest winds early this morning gradually shift to northerly today, with gusts up to 15 to 20 mph during the late morning and afternoon. High temperatures will be slightly below normal in the low to mid 60s, albeit slightly cooler near the Lake. Tonight: As ridging begins to approach the Northland from the west tonight, surface high pressure sliding into the region will bring clearing skies and light winds with it. This will result in a favorable radiational cooling setup, with low temperatures tonight into early Wednesday morning dipping into the mid-30s to around 40 degrees in the Northland. The coldest locations are expected to be along and north of the Iron Range where at least patchy frost is looking increasingly likely. Therefore, we have issued a Frost Advisory for those locations. Parts of inland NW WI may also dip into the mid-30s, but expected coverage is too limited with the current forecast to issue a Frost Advisory in NW WI. Wednesday - Thursday: High pressure moves into the Northland under shortwave ridging aloft on Wednesday and gradually slides to our east on Thursday. This will lead to a period of dry weather and mostly clear skies with high temperatures in the mid-60s to low-70s on Wednesday and low- to mid-70s on Thursday. Increasing winds out of the south will begin across north-central MN Wednesday night and then spread across most of the Northland on Thursday with gusts over 20 mph on daytime Thursday. Some patchy frost will be possible again Wednesday night/Thursday morning in the Arrowhead and portions of NW WI where lighter winds could lead to another round of radiational cooling and low temperatures dipping into the mid-30s. Thursday night - Early Next Week: Upper-level troughing cutting eastwards across the Canadian Prairies and Montana/North Dakota on Thursday will push a few embedded pulses of shortwave energy through the Northern Plains and Northland. The first of these shortwaves and attendant surface cold front will slide east across the Northland starting Thursday night and continuing into Friday, with a 60-80% chance of showers and thunderstorms associated with it. The second round of precipitation chances (40-60%) are most likely to arrive on Saturday with the second shortwave with decent ensemble agreement with regards to precipitation timing. There doesn`t look to be any good signal for heavy rain or severe weather for Thursday night into early next weekend. This more active weather pattern persists the remainder of the weekend into early next week as additional shortwaves are forecast to move through a more zonal flow pattern. Ensemble spread increases late weekend into next week, so confidence in timing and amounts of additional precipitation is lower at the moment. && .AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 647 AM CDT Tue May 28 2024 Ongoing light showers from KY49 to KEVM and areas south and east. Conditions have been mainly VFR with these showers, but there have been a few isolated pockets with MVFR visibilities. The morning showers continue to push southeast through NW WI into mid/late morning. Scattered diurnal showers develop again over much of NE MN and NW WI around midday and persist into early evening before diminishing. There is enough atmospheric instability for a few isolated thunderstorms this afternoon. Coverage is too limited to include as a prevailing weather group, but did include VCTS at KDLH and KHYR for this afternoon. May need some updates to the TAF if coverage/confidence trends higher. Some MVFR ceilings are expected for KINL from mid morning into early afternoon. MVFR conditions are also possible if a more moderate shower or any thunderstorms move directly over a terminal today. Light northwest winds turn northerly this afternoon with gusts of 15 to 20 knots, strongest at KBRD and KHIB. Winds turn light to calm this evening and tonight. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 357 AM CDT Tue May 28 2024 Winds will be 15 knots or less through Wednesday night. Northwest winds today veer northerly late this afternoon and evening and northeasterly tonight. There may be some isolated thunderstorms this afternoon into early evening over the far western part of the lake. Northeast to easterly winds persist into Wednesday. While winds are not currently forecast to get above 15 knots for western Lake Superior, one exception on Wednesday could be the Twin Ports due to funneling of winds down the southwest arm of the Lake. Easterly winds will continue into Thursday and be a bit stronger yet as the pressure gradient increases with a departing high pressure to our east. Generally expect 10 to 20 knots with a few higher gusts, with the strongest winds in the Twin Ports. For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt. && .DLH WATCHES/WARNINGS/ADVISORIES... MN...Frost Advisory from 1 AM to 7 AM CDT Wednesday for MNZ010>012- 018-019-021-026. WI...None. MARINE...None. && $$ UPDATE...PA DISCUSSION...Rothstein AVIATION...Rothstein MARINE...Rothstein