Area Forecast Discussion
Issued by NWS Twin Cities, MN
Issued by NWS Twin Cities, MN
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780 FXUS63 KMPX 020346 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 1046 PM CDT Mon Jul 1 2024 .KEY MESSAGES... - Widespread showers and thunderstorms this evening through Tuesday. Locally heavy rainfall possible, primarily across southern Minnesota & western Wisconsin. - Thunderstorms and locally heavy rainfall likely for the 4th of July && .DISCUSSION... Issued at 355 PM CDT Mon Jul 1 2024 Current observations across much of our sites reporting breezy conditions out of the south-southeast ranging between 25-35 mph. Upper-level cirrus continues to spread in overhead out ahead of our next system that is approaching from the west. As mentioned in the previous discussion, a strengthening low level jet is a likely culprit to the showery activity beginning to show up on reflectivity early this afternoon across eastern SD and western MN. So far though, most rainfall does not appear to be reaching the ground likely due to dry air within the boundary layer. Temperatures this afternoon will reach the low to mid 70s. Tonight, upper-level troughing as well as a strengthening jet streak will reach the northern plains where WAA is strongest. Hi-Res forecast soundings showing PWATs of rich Gulf moisture exceeding 1.8" well into MN and WI. The convergence of these elements will create an environment able to provide widespread showers and a few thunderstorms with locally heavy rainfall possible. Current timing window for development occurs this evening from west to east between 7-10 PM tonight. Although storms are possible, the past few model runs bring the greatest severe threat mainly across the Dakotas. However, a few storms in western MN could produce isolated large hail and damaging wind gusts. Latest forecasted QPF amounts through Tuesday morning show southeastern MN and WI counties along and south of the I-94 corridor having the greatest potential for observing between 1 to 1.25 inches of rain. Farther north and west across eastern MN and counties north of I-94 in WI could range between 0.75 inches to an 1 inch. Areas farther west can expect a half an inch or less. The system will be slow to exit Tuesday morning to our west as a cold front becomes occluded over northwestern MN. Therefore kept chance PoPs for much of Tuesday especially for both east and southern MN and western WI. Skies will gradually clear to where some sunshine peaks through for parts of western MN tomorrow afternoon. Tuesday`s highs temperatures will reach the lower 80s and then upper 70s across western WI where cloud cover will be more prevalent. Another shortwave associated with the larger troughing pattern ejects late Tuesday afternoon and could provide enough support for more showers/storm across southeastern MN and western WI. Wednesday will be warmer and potentially the nicest day of the entire week. Flow will become zonal above surface high pressure. Skies are forecast to be mostly clear with highs reaching the low to mid 80s. Thursday, a developing wave over the PacNorthwest is progged to strengthen over the upper midwest Thursday afternoon. We dont want to put any rain on the firework fuses but ensemble guidance isn`t giving us many "oohs or ahs" to marvel over in terms of dry conditions. NBM guidance continuing to show likely PoPs across much of upper midwest through the afternoon/evening hours. Ensemble guidance continues to hint at heavy rain potential with QPF amounts nearing an inch. Rain chances continue into the weekend however coverage will not be as widespread and heavy rain threats look to decrease. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1041 PM CDT Mon Jul 1 2024 Rain shield continues to blossom this evening across MN/WI such that all sites are not only reporting precip but also seeing most already down to MVFR range for ceilings. Confidence high enough to maintain prevailing -SHRA/-RA at all terminals, not so much for TSRA so have maintained CB/TS generally in TEMPO groups. Precip will move out of the area prior to daybreak for the MN sites, lasting a little longer for the WI sites, but ceilings will gradually drop through the duration of the rainfall. MVFR ceilings will likely drop to IFR levels closer to the end of the rainfall. Conditions will gradually improve during the day Tuesday with VFR conditions being realized mid- to- late day. That said, there is a mentionable chance for late afternoon SHRA/TSRA over southern-eastern MN into western WI so it warrants keeping that PROB30 going late tomorrow afternoon. Winds will remain breezy from the SE through the overnight hours, then diminish and veer to SW behind the swath of rainfall. KMSP...Best timing for any TS into MSP still looks to be through 08z, with the timing for rainfall ending altogether around 11z-12z. Will still expect ceilings under 2 kft for the Tuesday morning push, potentially into IFR range after sunrise and through at least midday. Ceilings may return to MVFR range for the afternoon push but still likely below 2 kft. There is still a mentionable chance for late Tuesday afternoon SHRA/TSRA reaching MSP so it warrants keeping that PROB30 going late tomorrow afternoon. Winds will still be breezy throughout the overnight hours and beyond sunrise, generally in the 150-170 direction. Stronger winds may be found at the 1-2 kft levels into the early morning hours, not quite meeting the LLWS definition but with a vector difference as those winds will be more S to SW, there is a bit of low level turbulence that may be experienced overnight through the pre-dawn hours. /OUTLOOK FOR KMSP/ WED...VFR.Wind WSW M10-15G20 kts. THU...VFR. PM MVFR SHRA/TSRA.Wind SE 5-10 kts FRI...MVFR SHRA/TSRA likely. Wind NE 5-10 G15-20 && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ DISCUSSION...Dunleavy AVIATION...JPC