FXUS63 KMKX 210609 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 109 AM CDT Tue May 21 2019 .UPDATE... Forecast remains on track through the morning with chances for showers this morning and throughout much of the day, especially further to the west. && .AVIATION(06Z TAFS)... A low pressure system will begin to make its way into the region today with rain showers possible this morning and more likely into the early afternoon. Rain chances will continue through the TAF period primarily in the western half of the state with lesser chances into the evening closer to the shoreline. There will be a brief period in the early evening where areas from Madison and west could see a few hours of MVFR CIGS. By around 00z, low level wind shear at 2 kft will be around 45-50 kts from the east/southeast and will continue through most of the overnight period. Lastly, showers will become likely into the late evening and continue through much of the overnight period with MVFR/IFR CIGS expected to push into the region during this time as well. && .PREV DISCUSSION... (Issued 912 PM CDT Mon May 20 2019) UPDATE... The forecast remains on track for tonight. MARINE... High pressure will move overhead tonight. Light winds are expected into Tuesday morning, but will pick up out of the east to northeast in the afternoon and evening as the high departs ahead of an approaching low. Winds will be gusty out of east to southeast Tuesday night into Wednesday as low pressure lifts through the Northern Plains into western Minnesota. A Small Craft Advisory may be needed for Tue night and Wed. Winds will weaken a little and veer to the southwest Wednesday night as the low departs and high pressure approaches. PREV DISCUSSION... (Issued 651 PM CDT Mon May 20 2019) UPDATE... Cumulus clouds continue to decrease this evening as daytime heating winds down. Mid and high level clouds are moving in from the southwest though, so skies will remain mostly cloudy tonight. Looks dry for most of the night, with a few showers possible southwest of Madison by daybreak Tuesday. AVIATION(00Z TAFS)... VFR conditions are expected tonight into Tuesday morning. Lower clouds are likely to move in from the southwest by the afternoon hours. The MVFR ceilings may be confined to mainly southwest of Madison though, as drier easterly flow will keep bases higher farther to the east. There will be a chance for showers tomorrow, mainly from Madison westward, though a few showers will be possible east as well. Widespread showers and a few storms are then likely Tuesday evening and overnight. Looks like a good chance for low level wind shear Tuesday evening and overnight as well. PREV DISCUSSION... (Issued 238 PM CDT Mon May 20 2019) DISCUSSION... Tonight...Forecast confidence is high. Any clearing of the lower CU/Stratus will be short lived as high clouds will be spreading in quickly from the southwest. Expect dry conditions through the night with another chilly night in the lower to mid 40s. Tuesday...Forecast confidence is medium. The suite of model guidance is quite varied in handling the convection lifting northeast out of Kansas/Missouri and into the western Great Lakes. The convection to the south will weaken, but it will be supported by a decent area of warm air advection and mid level energy. However, it will be swinging well away from the parent low and there will be an increasing dry easterly low level flow that will work to erode the rain is it lifts into Wisconsin. Some of the model guidance keeps southern Wisconsin dry as it wipes this rain out over northern Illinois. Models, like the NAM, are more bullish and bring a decent amount of rain up into the area. The NAM looks way overdone. Something along the lines of the GFS and ECMWF look far more reasonable. Will carry a chance for rain, but no thunder. The west has a better chance for seeing rain vs the southeast. Tuesday night - Confidence...Medium The low level ESE dry feed turns decidedly south in the evening which results in appreciable thermal/moisture advection. This evolves ahead of the low that is proggd to be lifting north through the Plains. Several hundred J/KG of elevated CAPE in place so the thunder mention looks good. there will be a 500 millibar vort max that pivots northeast on the eastern periphery of the main 500 energy well off to our west. Will have definite pops as confidence high that rain will be pretty widespread. Wednesday - Confidence...Medium Thermal ridging builds in briefly with the main advective forcing on the wane. Influence of the plains 500 millibar low lifts to our north bringing a more broad southwest anticyclonic flow for us here. Winds may gust up there pretty good within the windy, warm dry slot portion of the system. Models are showing an 850 wind max anywhere from 30-45 knots during the afternoon/evening. However some disagreement on the pressure pattern and degree of mixing. Should warm nicely with clearing and any mixing with lingering influence of thermal ridge axis. Should see temps warm well into the 70s. Wednesday night and Thursday - Confidence...Medium Models in some disagreement whether showers clip our area along ne-sw oriented frontal boundary. The GFS is a compromise between the more robust ECMWF and benign GEM. So will carry the blended pops for wednesday night. Thursday night through Friday night - Confidence...Medium Things turn unsettled again as the ridge axis shifts east and a return flow sets up. For Thursday night the main forcing will be driven by thermal/moist advection with a hint of a wave trying to move through the mid level ridge axis. Better dynamics and lower level forcing with frontal interactions arriving for Friday into Friday night. Saturday and Sunday - Confidence...Medium The overall model consensus is to send this boundary south of WI with the focus shifting to our south as well. The GEM is an outlier on keeping things unsettled. But for now some suggestion of a surface high working in that would suppress this front to the south. For now will need to at least keep some small pops in the far south due to anticipated frontal proximity and slightly quicker return flow from GFS which brings precip back for Sunday, esp into southwest cwa. Sunday night and Monday - Confidence...Low to Medium The unsettled pattern looks like it will return as yet another system approaches. A frontal boundary to our south will focus activity that could lift up into srn WI. AVIATION(21Z TAFS)...Look for VFR conditions through the TAF period. We should see some clearing of the 4-6kft cloud deck this evening, but more mid and high level clouds will be spreading in from the south through the night. Look for light winds to turn northeast to east on Tuesday and become rather strong and gusty, especially over south central Wisconsin...including KMSN. We could see some light rain spread across southern Wisconsin during the morning and early afternoon. No thunder is expected. MARINE...High pressure will push across the region tonight and Tuesday, slipping east by Tuesday night. Meanwhile, strong low pressure will be lifting north through the Central Plains. Expect light winds tonight. Winds will be northeast to east on Tuesday, becoming more easterly Tuesday night into Wednesday and turning rather strong and gusty. Winds will become southwest by Wednesday night and diminish as high pressure builds back across the area. Winds and waves will likely result in a small craft advisory for the nearshore waters Tuesday night into Wednesday. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...None. && $$ Update...ARK Tonight/Wednesday and Aviation/Marine...DDV Wednesday Night through Tuesday...DDV