Area Forecast Discussion
Issued by NWS Twin Cities, MN
Issued by NWS Twin Cities, MN
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149 FXUS63 KMPX 021415 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 915 AM CDT Sun Jun 2 2024 .KEY MESSAGES... - Severe thunderstorms & localized heavy rain possible this evening, especially across western and central Minnesota. - Another chance for widespread rain and potentially severe thunderstorms is likely Tuesday. - Pleasant and mainly dry weather expected Wednesday into next weekend. && .UPDATE... Issued at 847 AM CDT Sun Jun 2 2024 Usually at this point in the morning we like to see models coming into agreement, with confidence increasing on what the strong/severe potential later in the day will look like, but today is not that day! The biggest change we`ve seen comes from the HopWRFs and the HRRR, both of which show the showers over eastern SoDak in the zone of enhanced h85 southerly flow plodding east through the morning across MN, reaching the Twin Cities around 20z or 21z, though it looks like activity should be on the downward trend by the time they get as far east as the metro as they will be running away from the instability. It looks like we`ll see quite a bit of disorganized activity within the zone of enhanced southerly h85 winds and moisture transport before any sort of more organized line arrives this evening. We still expected a more organized line of storms to move through tonight as the west edge of the LLJ works across the area, but how much of a severe threat we`ll have is looking a bit more uncertain given all of the pre-line activity expected. To this point, the biggest change we`ve made to the going forecast is to increase PoPs quite a bit (up to the 50% range for now) for this afternoon into eastern MN. For those hoping for another nice early summer afternoon to enjoy some outdoor activities may be a little disappointed to need an umbrella... && .DISCUSSION... Issued at 405 AM CDT Sun Jun 2 2024 High clouds associated with a line of thunderstorms that have developed ahead a weak boundary moving across Nebraska and Kansas are making their way northward early this morning. The 06z WPC surface analysis depicts a warm front across central Minnesota, where some ACCAS have developed over the last few hours. Further west back into North Dakota, a few isolated thunderstorms have developed. Southerly flow will continue to bring warm, moist air northward through this morning and into the early afternoon while the parent surface low lifts into the western Dakotas. Aloft, a subtle shortwave will push through this afternoon with an increasing LLJ nosing into southwestern Minnesota. This could be enough to spark some storms across southern Minnesota and northern Iowa during the afternoon. This would be well ahead of the convection that will be forming over the Dakotas and moving into Minnesota during the evening along the cold front that hi-res models have been advertising over the past couple of days. The main question with this earlier chance of storms will be how it will impact the later, main line of storms coming out of North Dakota. As these North Dakota storms develop and progress eastward this afternoon, they are expected to grow upscale into a QLCS during the early evening hours. CAMs show this line diving south across central Minnesota and eventually weakening. Wind will be the main threat, but a few spin ups along the line in western Minnesota aren`t out of the question along with some hail. Even being only 12-18 hours out from the event, there are still some questions and discrepancies in timing and the southern extent of this line. As previously mentioned, there`s the question of storms firing across southern Minnesota during the afternoon. There`s also the model differences in the timing of the eventual QLCS from the Dakotas. The ARW is by far the fastest, with the QLCS moving through the Twin Cities around sunset while the majority of other CAMs hold off until around or after 06z. There are also differences in strength/coverage of the line as it moves into a more stable environment to the east, but current thinking is that it will be tough for western Wisconsin to see much in the way of severe storms by early Monday morning. Showers will linger across eastern portions of the forecast area during the first half of the day before clouds clear from west to east with mostly sunny skies expected area wide by Monday evening. The clear skies will be short lived as cloud cover quickly returns overnight into Tuesday as yet another warm front lifts northward. Tuesday looks like it has the potential to be another active weather day with the threat of heavy rainfall and a few severe thunderstorms. With the return of strong southerly flow, dew points look to climb into the mid to upper 60s with temperatures in the low 80s, despite ample cloud cover. Forecast soundings have PW values of nearly 2", which is impressive considering the 90th percentile for June 4 is not even 1.5". Aloft, a 500mb trough will take on a negative tilt as it progresses across southern Canada and the western Dakotas. A surface cold front is forecast to quickly move through the area during the afternoon, which would be favorable timing for thunderstorm development. Heavy rainfall in addition to a few strong to severe storms look increasingly likely for Tuesday afternoon and evening. Both of these threats are covered by an ERO Slight Risk and a SWODY3 Marginal Risk respectively. The middle of the week through the remainder of the period looks to be much cooler and quieter as we see northwest flow return. A cutoff low looks to stall over the northern Great Lakes through Friday. At the surface, breezy west to northwesterly winds are expected with gusts of 30-35 MPH possible on Thursday. Highs in the low to mid 70s with minimal chances for afternoon showers are expected through the end of the period. && .AVIATION /12Z TAFS THROUGH 12Z MONDAY/... Issued at 622 AM CDT Sun Jun 2 2024 VFR conditions this morning but chances for showers and thunderstorms increase this afternoon into the evening and overnights hours. A few storms could produce severe weather at KAXN and KRWF, with decreasing chances to the east at the remainder TAF sites. Fog and stratus may develop late tonight after the storms move through. KMSP...This morning should be dry, but the thunderstorms in the Dakotas will be moving eastward this morning. They are expected to weaken, but if they maintain themselves then MSP could see thunder chances this afternoon, as opposed to later this evening and overnight. Fog and stratus may develop late tonight after the storms move through. /OUTLOOK FOR KMSP/ MON...MVFR/-RA early chc TS, then VFR. Wind W 5-10 kts. TUE...VFR early, then MVFR/SHRA with -TSRA/IFR possible. Wind S bcmg W 10-20 kts. WED...VFR. Wind W 20G35 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ UPDATE...MPG DISCUSSION...Dye AVIATION...JRB