030 FXUS63 KMPX 140833 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 333 AM CDT Sun Aug 14 2022 .DISCUSSION...(Today through Saturday) Issued at 325 AM CDT Sun Aug 14 2022 KEY MESSAGES: - A Dense Fog Advisory has been issued for central MN through 10am this morning. Visibilities a 1/4 mile or below are expected. Reduced visibilities from fog are also possible elsewhere. - Fog likely again Sunday night into early Monday morning, mainly across eastern MN and west-central WI. - Near or slightly below normal temperatures for this week with chances for several small rounds of precipitation. Over the past few hours, fog that started in north central MN has steadily built south into our CWA as clear skies and calm winds in central and western MN allow for maximum radiational cooling of the near surface layer. With hi-res forecast soundings across central MN showing a saturated boundary layer just before sunrise, this fog is expected to be very thick. Multiple sites across central MN have already reported visibilities at a 1/4 mile. As such, a Dense Fog Advisory has been issued for central MN through 10am this morning where visibilities a 1/4 mile or below are expected. Areas of fog are also likely in western and south-central MN, though visibilities should not be as low. Still, traveling could be dangerous where fog is thicker. Across southeastern MN and western WI, fog is possible, though the stratus deck that has persisted overnight has kept temperatures from cooling to or near the dewpoint so far. After the fog burns off, Sunday will be dry but how much sun we see uncertain. The airmass remains relatively unchanged from yesterday. Thus while the aforementioned stratus deck has been slowly decreasing coverage overnight, would not be surprised to see at least partly cloudy skies for a good portion of the forecast area into this afternoon. Have decreased high temperatures by a few degrees so values range from the mid to upper 70s. Sunday night should be very similar to the previous night, perhaps a couple degrees warmer, with fog again possible in eastern MN and western WI. For the rest of the week, we will start with the easy part of the forecast. Temperatures are forecast to remain stagnant with highs in the mid 70s to lower 80s while lows range in the mid 50s to lower 60s. Precipitation chances throughout the week are more difficult to pin down. Southwestern MN could see some rain Monday as a mid-level vorticity max passes from SD into IA. Meanwhile, guidance also suggests showers and thunderstorms are possible across the northern half of MN Monday into Monday night from a separate vorticity max. Heading thru the week, forecast models show the flow becoming weak and disorganized allowing these mid-level impulses to "hang around" the Northern Plains and kick off more diurnally driven showers and thunderstorms. PoPs range from 20-40% through Thursday as rather still large spread exists between models' precip location and timing. More certain PoPs may occur late in the week as long-range guidance shows an upper-level trough diving south through the Northern Plains from central Canada. As usual, differences in trough placement and strength do exist between the model suites. But, this potential feature is more synoptic in nature so it reasons to be more predictable than what we will be dealing with earlier in the week. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1059 PM CDT Sat Aug 13 2022 Low stratus is lingering across much of the region tonight, and the question remains whether or not this will transition to fog later tonight and Sunday morning, or if it will remain as MVFR to possibly IFR stratus. Forecast soundings off the RAP show that low stratus is more likely to the east at KMSP/KMKT/KEAU/KRNH, with fog likely to the west, so tried to transition this way in the TAFS. VFR conditions should return for Sunday. KMSP... Continues with the trend of more low stratus than fog overnight in the TAFs, but could see some fog develop at KMSP if clearing happens before sunrise. Winds will be light, and become more easterly for Sunday. /OUTLOOK FOR KMSP/ Mon...VFR. Wind SE 5-10 kts. Tue...VFR. Wind SE 5-10 kts. Wed...VFR. Wind S 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ DISCUSSION...CTG AVIATION...JRB