Area Forecast Discussion
Issued by NWS Twin Cities, MN
Issued by NWS Twin Cities, MN
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665 FXUS63 KMPX 211827 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 127 PM CDT Sat Sep 21 2024 .KEY MESSAGES... - Isolated to scattered showers and storms in central Minnesota this morning shifting to southern Minnesota into western Wisconsin later today. - A fall temperature roller coaster with another warm day today before temperatures fall substantially Sunday and warming back up through the rest of the week. && .DISCUSSION... Issued at 240 AM CDT Sat Sep 21 2024 This weekend...Scattered showers with some isolated thunderstorms will continue this morning driven by a LLJ in the warm sector of the advancing system. Another round of showers and thunderstorms is expected today along and ahead of the cold front. With a cap in place there should be a time gap in precipitation later this morning once the LLJ driven convection comes to an end. As the surface heating continues ahead of the front thermal profiles will eventually allow for the cap to break. This will most likely be in the afternoon. By that time the front should get far enough that the most likely areas for rain and thunder will be in the southeastern quarter of Minnesota and into western Wisconsin. The heating under the cap should allow for some instability to form with up to around 1000 J/kg of SBCAPE forecast. Not a great shear setup so the chances for severe storms are low. Any chance for a stronger storm would likely be pulse convection and would not be a long lived strong to severe threat if even occurs. Temperatures will be much cooler behind this front with temperatures across northwestern Minnesota (behind the front) 20 to 25 degrees cooler than southeastern Minnesota (ahead of the front) for today`s forecast high temperatures. Behind this front Sunday will be much cooler with high temperatures in the mid to upper 60s. Also with high pressure moving in, there should be clearing skies during the day. Another system likely staying to our south is unlikely to provide rain chances, but could keep cloud cover longer across southern Minnesota into parts of western Wisconsin. Monday through Friday... The week ahead will be dominated by surface high pressure with little chance for additional rainfall. Also under mostly high pressure expect clear to mostly clear skies. Winds at 850 mb trend back to a southerly or westerly direction with more of a WAA regime in place. This will help provide a warming trend through the week. Bringing Monday`s highs of near 70 up into the upper 70s by the end of the week. Normal high temperatures this time of year are in the upper 60s. So near normal the start of the week warming back above normal for the remainder of the week. Despite annual precipitation numbers still well above normal September has been dry for many, with MSP Airport currently on track for one of the driest Septembers on record. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 111 PM CDT Sat Sep 21 2024 First round of storms is winding down, but a field of accas that extends back into southeast SoDak indicates that the atmosphere isn`t done with thunderstorms yet. There is a cold front from STC down through MKT at 18z, with upwards of 2000 j/kg of muCAPE present out ahead of it, with it certainly possible that as that accas moves over the tongue of instability, it will pop off more storms, hence why we left prob30s in place at MSP/RNH/EAU for later this afternoon. Behind the front, we will see gusty northwest winds deep into the evening, with gusty winds coming back Sunday morning across western WI in particular, where the pressure gradient will be the strongest. KMSP...Given the accas field to the west, left the prob30 going for the potential for on more round of storms to develop before we completely loose the instability. Also, with the front moving through this afternoon. A wind shift requiring a shift over to north flow operations will be needed around 22z. /OUTLOOK FOR KMSP/ MON-WED...VFR. Wind SE 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ DISCUSSION...NDC AVIATION...MPG