113 FXUS63 KGRB 111136 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 636 AM CDT Thu Oct 11 2018 Updated aviation portion for 12Z TAF issuance .SHORT TERM...Today...Tonight...and Friday Issued at 332 AM CDT Thu Oct 11 2018 Much quieter conditions through the short-term portion of the forecast. The main concerns will be elevated rivers from recent rainfall along with much colder temperatures and the associated frost/freeze potential. Have issued a freeze warning for southeastern portions of the CWA, where a frost or freeze has not already occurred this season. Today: The strong low pressure system that brought all of the rain over the past couple days will continue lifting to the northeast through the day. On the back side of the low, the pressure gradient will remain fairly tight across the CWA, bringing breezy conditions along with cold air advection. Most locations will see highs today in the low 40s; however, central and north-central WI will likely see highs struggling to climb out of the upper 30s. Otherwise, today will feel very cold compared to the past couple weeks. Wind chill values will likely remain in the low to mid 30s for most locations with maybe even a few upper 20 degree wind chills over north-central WI. Cloud cover will also linger over the north-central locations with continued wrap-around moisture along with delta-T values ranging around 18C on west to northwest flow off Lake Superior. Low level convergence will also be such that at least scattered light rain showers or drizzle may occur over the aforementioned areas. Tonight into Thursday: The pressure gradient will steadily decrease across the area, even though it will not completely relax tonight. This along with some downslope clearing and continued cold air advection will lead to overnight lows dropping to freezing or below for much of the CWA. Opted to issue a Freeze Warning to highlight the freezing potential tonight into early Friday morning for much of the Fox Valley. The Door Peninsula was left out of the warning, due to the still relatively warm waters keeping the temperatures up a bit, likely just above freezing. Issued SPS for the potential for some patch frost over those areas though. Otherwise, mainly dry conditions except over the north-central, where a light rain/snow mixture may occur with the continued wrap-around and favorable delta- T values. Bufkit soundings show that the convective cloud layer may nose just inside the -12C isotherm, introducing some ice into the cloud layer. Again, pointing to the potential for at least some light snow to occur over the north-central overnight into early Friday morning. Quiet weather will be the rule on Friday with generally cloudy skies expected along with continued cooler temperatures. Temperatures will be in the upper 30s north-central and around 40 elsewhere, but the wind will be lighter than today. .LONG TERM...Friday Night Through Wednesday Issued at 332 AM CDT Thu Oct 11 2018 A cool pattern remains expected to be in place across the region over the next week thanks to persistent deep mid-level troughing. Because of the colder pattern, temperatures and precip are both likely to be below normal over the period. Used a blend of the ecmwf and gfs for much of this forecast. Friday night through Saturday night...Surface high pressure will be sliding east from the mid-Mississippi to the Ohio Valley on Friday night. Because of the high passing south of the region, boundary layer winds will likely struggle to decouple, though should be less than on Thursday night. Even so, temperatures remain on track to fall between 30 to 35 degrees over the Fox Valley and Lakeshore, which will likely lead to frost/freeze headlines. Clouds will be on the increase on Saturday as a cold front moves across the northern Mississippi Valley. This front will bring the next chance of precip from late Saturday afternoon into Saturday night. Temps look warm enough that most precip should fall as liquid, though could see a few flakes over the northwoods. No significant changes to temps. Rest of the forecast...Behind the front, another reinforcing shot of cold air will move into the region on Sunday. A shortwave moving across northern WI will bring a chance of light rain and snow showers to the northwoods. High pressure then builds into the area for Sunday night and Monday, which continues to look cool and blustery. Finally, it looks like one more clipper type system will a chance of rain/snow to the area on Tuesday/Tuesday night before the pattern settles down midweek and beyond. && .AVIATION...for 12Z TAF Issuance Issued at 636 AM CDT Thu Oct 11 2018 As a strong low pressure system continues to lift to the northeast of the area, expect gusty winds to linger at each of the TAF sites through late this afternoon. The pressure gradient will relax later tonight into Friday allowing winds to steadily decrease. Otherwise, MVFR conditions will prevail through the first part of this TAF issuance. There will be some improvement at each TAF site later this afternoon through late tonight; however, this will be more notable at GRB/ATW/MTW as winds downslope into those sites. && .GRB WATCHES/WARNINGS/ADVISORIES... Freeze Warning from 1 AM to 9 AM CDT Friday for WIZ038>040-045- 048>050. && $$ SHORT TERM.....Cooley LONG TERM......MPC AVIATION.......Cooley