Area Forecast Discussion
Issued by NWS Twin Cities, MN
Issued by NWS Twin Cities, MN
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778 FXUS63 KMPX 261100 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 600 AM CDT Wed Jun 26 2024 .KEY MESSAGES... - Isolated showers possible this morning. Best chance for a few hundredths of rain will be across southwest Minnesota through 7 AM. - Next periods of unsettled weather will be Thursday night into Friday and again Monday into Tuesday.&& .DISCUSSION... Issued at 258 AM CDT Wed Jun 26 2024 Early morning water vapor imagery captures a shortwave sliding to the southeast from North Dakota into Minnesota. Showers have developed ahead of this feature and can be seen moving through west central Minnesota on KMPX imagery at this hour. The shortwave and associated showers are forecast to drift southeast across southern Minnesota and western Wisconsin through daybreak. We do not expect much in the way of QPF from these showers given the sampled dry air across the region, however hi-res guidance has displayed that the best chance for a few hundredths of rain will be across southwestern MN. Dry weather, sunshine, light northwest winds, and more comfortable levels of humidity will win out for the remainder of Wednesday, with highs in the mid 70s...enjoy! The forecast will remain quiet for most of Thursday, with highs once again forecast to climb into the mid 70s. A mid-level shortwave will develop east of the Rockies during the day, in response to an upper- level trough digging into the Pacific Northwest. The eastward advance of the shortwave and associated warm air advection will be a focus point for the return of precipitation chances by Thursday afternoon across western Minnesota. Our latest forecast grids reflect only chance PoPs (~30%) across western Minnesota until after 00z, as the initial wave of warm air advection driven precipitation will likely struggle to hold together due dry air in place (captured on forecast soundings). PoPs will quickly increase to the 60-80% areawide overnight into Friday morning, as more widespread precipitation develops in response to a strengthening low-level jet. An initial glance at the forecast data depicts another airmass capable of producing heavy rain due to PWATs in the 1.75"+ territory, however deeper inspection may help to quell those concerns from a widespread perspective. As mentioned in previous AFDs, there will likely be two focus points for heavy precip (along the surface warm front near the US/Canada border & to the south along the Iowa/Missouri border). The 00z guidance has captured this idea once again, supporting the idea that a 0.25-0.5" can be expected for most locations. The concern for locally heavier rainfall would be tied to any convection that occurs, but that potential appears isolated overnight due to a lack of forecast instability. The morning batch of rainfall will likely be exiting to the east by mid-morning, with a lull in the action expected. With the cold front forecast to still be trailing to the west, we have included chance PoPs (30-40%) for a showers and storms across eastern MN/western WI through Friday afternoon/evening. The setup for severe weather is not overly impressive following the morning rain, but the combination of ~1000 j/kg of MLCAPE, sufficient shear, and ample moisture will support the potential for a few stronger storms capable of producing damaging winds and large hail. SPC has introduced a Day 3 Marginal Risk to support this potential. The latest LREF (Global Ensemble Suite comprised of the GEFS/EPS/CMC) shows a 90% probability of less than 1.0" falling across south central Minnesota and western Wisconsin, which includes any additional rainfall from any storms that fire Friday. Northwest winds on the backside of the departing system will bring cooler and comfortable air for the weekend. Highs will reach the upper 60s to low 70s on Saturday and warm a few degrees into the low to mid 70s on Sunday. The pleasant weather will give way to our next chance for widespread rain for the start of next week, as a deeper trough digs into northern CONUS and spawns another round of rain and thunderstorms. The trough is forecast to become negatively tilted across the Upper Midwest by Monday evening, which may be the upper- level support needed for a more pronounced severe weather threat, though it will take a few days to better define the setup. LREF PWAT`s climb towards to higher end of sounding climatology again, which means that this storm system will reinforce the ongoing hydro concerns regardless of any severe weather threat that develops. The progressive nature of the upper-level pattern should support a quick departure of this system and a drier trend looking towards Independence Day. && .AVIATION /12Z TAFS THROUGH 12Z THURSDAY/... Issued at 600 AM CDT Wed Jun 26 2024 The isolated morning showers have been 10SM -RA and have been on a downward trend. So all remaining SHRA was removed from the TAFs due to limited aviation impact. Mostly clear skies after the isolated showers come through. There could be some diurnal cumulus to form that could be MVFR if a ceiling were to form. Winds will be light and variable this morning and again tonight. Winds this afternoon will be around 10 knots with some gusts up around 15 to 20 knots from the north/northwest. KMSP...All rain was removed with the 09Z AMD and kept out as the isolated showers stayed to the south of MSP. Today could see some gusts up to 20 knots from the north northwest. /OUTLOOK FOR KMSP/ THU PM...MVFR/SHRA. Wind S 5-10 kts. FRI...VFR/MVFR, chc -TSRA. Wind SE 10-15 kts. SAT...VFR. Wind NW 10-15G25 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ DISCUSSION...Strus AVIATION...NDC