Scientific Forecaster Discussion
000 FXUS63 KMKX 240818 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 318 AM CDT Tue Oct 24 2017 .DISCUSSION... Today and tonight...Forecast confidence is high: Rain on the back side of strong low pressure will continue into this morning. The rain will wind down northwest to southeast mid- morning into the afternoon as drier and colder air advects into the area. Clouds will hang on through the day today, but are then expected to clear out quickly west to east during the evening hours. Highest wind gust potential today is a bit tricky given limited mixing early due to clouds and precip, but increased mixing later as colder air advects in. Gusts look borderline for a Wind Advisory, but close enough to leave the advisory as is. Clouds will move back in from the northwest later tonight as a quick moving shortwave approaches. Models show a little precip with this waves as well. It will take a little while for the low levels to saturate before any precip has a chance to make it to the ground. Soundings do look saturated enough by the early morning hours for some low precip chances. Left rain/snow mention going, with temps in the lowest 1-2 kft right on the border of rain or snow. Wednesday - Confidence...Medium Potent 200-300 millibar jet streak will put southern WI right in the vicinity of the left front quad. Impressive 500 millibar wave rides through as well during the morning hours. Bufkit soundings are showing the GFS drier within the column with window of low level saturation brief if at all. Meanwhile the NAM saturates the column for a longer period in the morning though still a close call on precip type with wet bulb considerations. Will have both rain and snow in the grids. QPF amounts are on the low side. Not expecting any snow accumulation with ground still warm. This should all exit for the afternoon hours with low level RH lingering longer than the 700 RH so clouds may be stubborn for a time in the afternoon. Thursday - Confidence...Medium Surface ridge shifts to the east and sets up a milder return flow with precip associated with next low remaining to our north or northwest. Some disagreement amongst the models on how warm 925 temps will rebound to. The GFS is the warmest with readings pushing 11c while the NAM and ECMWF keep readings more in the middle single digit range celsius. Will lean towards the GFS MOS/Superblend guidance at this time. Thursday night through Sunday - Confidence...Low to Medium Another mid level trough will carve out across the Upper Midwest and linger this period. The GFS is actually the slowest suggesting the influence of the circulation could linger into Sunday while the ECMWF is a bit more progressive. Initial precip on Thursday night shows a max across northern or central WI from the GFS/GEM and ECMWF while the NAM shows more across southern WI. This initial batch looks warm enough to remain all liquid. Colder air is proggd to wrap in for the weekend as the low heads to the northeast so potential of a mix returns. QPF amounts not all that impressive. Monday - Confidence...Medium Mid level ridging finally works in and there is consensus between the GFS and ECMWF to go with the dry look of the Superblend pops. && .AVIATION(09Z TAFS)...Rain will persist into this morning across the area, winding down northwest to southeast mid-morning into the afternoon. Most places will have MVFR ceilings today, though some IFR spots possible this morning. Also, seeing a location or two that are slow for ceilings to lower at the moment, but expecting these holdouts to drop to MVFR in the next couple hours. Northwest winds are still expected to be quite gusty today. Clouds will clear out west to east this evening. More clouds are expected to move in from the northwest later tonight into Wednesday morning as a quick moving wave approaches. Some light precip is likely with this wave, with a period of snow or rain/snow mix possible. No accumulations are expected given mild ground temps and borderline air temps for snow. && .MARINE...Gale force northwest winds are likely today on the back side of strong low pressure. The strong winds will slowly wind down during the evening and early nighttime hours. Highest waves will be toward open waters due to the offshore nature of the winds. Left the current marine Small Craft Advisory and Gale Warning timing as is. Winds could hit advisory levels again Thursday night into Friday as low pressure moves through the area. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...Wind Advisory from 7 AM this morning to 7 PM CDT this evening for WIZ046-047-051-052-056>060-062>072. LM...Small Craft Advisory from 6 AM to 9 AM CDT this morning for LMZ643>646. Gale Warning from 9 AM this morning to 4 AM CDT Wednesday for LMZ643>646.