593 FXUS63 KARX 181746 AFDARX Area Forecast Discussion National Weather Service La Crosse WI 1146 AM CST Mon Dec 18 2023 .KEY MESSAGES... - Briefly colder temperatures today with gusty (30-45 mph) winds slowly diminishing. - There is high confidence for another extended period of above average temps through Christmas with little rain potential until at least late this week. && .DISCUSSION... Issued at 316 AM CST Mon Dec 18 2023 Today-Tonight: Colder and Windy A blustery, colder day is on tap for today with low-level cold advection persisting in the wake of the departing shortwave trough. Despite strong subsidence behind the wave and clearing skies in the wake of early morning post-frontal flurries/stratus, highs likely will only reach the 20s. Wind chills may fall towards zero for a time this morning in spots. Wind fields and mixing will be strongest through the early morning hours with gusts of 30 to 45 mph likely. The winds will slowly diminish through the day as high pressure approaches from the plains. Tonight will be the coldest of the next week with winds becoming light as the surface ridge axis passes across the Upper MS Valley. Tuesday-Sunday: Trending Warmer There is little change in forecast expectations for the remainder of the week as a more zonal, split flow pattern emerges and anomalous northern stream ridging develops across the Midwest/Great Lakes through the week. This will result in an extended period of above to well above average temps right through the Christmas holiday. Some increase in clouds is expected on Tuesday as warm advection develops and south winds become breezy, but dry conditions are expected through mid to late week. There is some spread in the degree of warming, but the middle of the NBM temperature distribution (25th- 75th percentile) supports highs ranging from the upper 30s to lower 50s later in the week with a smaller (10-15%) subset of the distribution indicating highs farther into the 50s by next weekend. Lows by late week once again likely will be near or above average daytime highs for late December. Along with the warmer air, increasing moisture will advect northward through the week with precipitable water values rising above the 90th percentile in the NAEFS for the end of the week into the weekend. However, confidence is still relatively low on the evolution of individual waves in the flow later in the week into the weekend, so chances for rain towards late Thursday into Friday remain modest for now (up to 30-40%). There is a somewhat stronger signal for a system to impact the region around Christmas, but spread in potential outcomes is quite large right now. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... Issued at 1145 AM CST Mon Dec 18 2023 Northwest winds gradually subside this afternoon and fall under 5-10 kts by sunset. These winds switch to the S/SSW overnight and quickly increase during the morning hours with gusts of 20-30 kts by midday Tuesday. There may be a 1-3 hour period of LLWS along and west of a CCY to RST line before winds pick up in the morning hours on Tuesday, but given its lower probability, have not included in the RST TAF at this time. Aside from some high MVFR to low VFR ceilings east of a EAU to PVB line this afternoon, VFR conditions are forecast for the TAF period. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...JM AVIATION...Skow