646 FXUS63 KABR 240526 AAC AFDABR Area Forecast Discussion...UPDATED National Weather Service Aberdeen SD 1126 PM CST Tue Jan 23 2024 .KEY MESSAGES... - Cloudy conditions are expected through the week. Expect periods of dense fog and/or drizzle. With nighttime temperatures below freezing, any fog or drizzle that occurs will produce slick spots on untreated roadways. - High temperatures trending into the 30s and 40s for the end of the week into the weekend. (10-20 degrees above normal) - Very low probabilities for precipitation (less than 10%) && .UPDATE... Issued at 1123 PM CST Tue Jan 23 2024 See updated aviation discussion below. UPDATE Issued at 905 PM CST Tue Jan 23 2024 Seeing some areas of reduced visibilities in fog across parts of the CWA, but not any real widespread areas of dense fog. Expect this will change as we get into the overnight hours, so will leave the current Dense Fog Advisory in place and monitor for possibly having to extend it eastward later tonight. No changes made to winds or temperatures at this time. && .SHORT TERM /THIS EVENING THROUGH WEDNESDAY NIGHT/... Issued at 147 PM CST Tue Jan 23 2024 High pressure at the sfc and very weak flow aloft will keep the status quo going forecast-wise through Wednesday night. Persistent low cloud cover, dense fog redevelopment overnight and the possibility of very light freezing drizzle will remain across the region in the short term. Temperatures are a bit of a question mark. Was surprised to see a 10 degree diurnal difference today from the James Valley east given the low cloud cover. This was likely due to the breezy (10 to 15kt) southerly sfc flow. Not as sold on this happening Wednesday anywhere except west river where they may see some sunshine briefly during the afternoon. Blended in some NAMNest (which has a good handle on the cloud cover) to try to capture this thinking in the grids. Looks like everywhere in the cwa will be above normal, though, with lows in the 20s and highs creeping into the 30s. Kept the dense fog advisory in place west of the James into Wednesday morning with the expectation that vsby will tank again this evening. Will likely need to add an advisory from the James Valley to the Coteau tonight, but according to guidance, the quarter mile or less vsby may not happen until after midnight. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Issued at 147 PM CST Tue Jan 23 2024 The long term consists of persistent clouds along with fog as low level moisture hangs around through the end of the week. The main challenge with this will be the temperatures and how high and low our temps get. Ensembles agree on a trough continuing to push east Thursday morning with winds going from zonal to northwest flow on the backside of it. At the surface a back door cold front will push through. UL ridge moves in behind this through Friday morning, along with a surface high. Another trough/sfc trough moves west to east late Friday into early Saturday and surface high shifting east. Looking well into the extended, a large ridge sets up over the western CONUS this weekend as clusters have a good handle on it. Next week, models are still in agreement with this large ridge over much of the central CONUS by the middle of next week with minor differences in amplitude and timing, with UL winds out of the southwest. With this setup, overall dry weather expected through the weekend into the middle of next week. 850mb temps will warm to +1 to +3C for the end of the week with northwest winds and up to +4 to +7 Sunday into Monday. By the middle of next week these temps range from 10 to 12C per ensemble mean! Looking at bufkit, we probably will not mix that high as several GFS bufkit soundings across our CWA really only mix to 900 or slightly above into next week. However, this is just GFS. If we lose some of this snow pack for next week, mixing levels will be higher, so that will be a factor on how warm we get (and we have more sun Saturday and onward). 925mb temps are a little different between EC and GFS as GFS keeps temps cooler than EC. For example, 925mb temps for 00Z Friday are showing -1C to -4C and EC is -2 to +2C across the CWA. By Saturday, we really see 925mb temps warming over the central and western CWA, ranging from +3 to +5 (model depending). Monday GFS is showing +1 to +10 where EC is +1 to +12, so some discrepancies continue. 2m temps per mean ensemble (ENS/GEPS/GEFS) for KABR is only a few degrees spread in the lower to mid 30s Thursday/Friday. The spread increases to over 10 degrees for next week with the 95th percentile in the upper 40s Monday-Wednesday. If we can melt most of this snow, highs could get into the 50s! It is struggling with lows as there is more than a 5 degree spread. NBM is pretty similar (little cooler bias) with less of a spread for the end of the week (in the 30s) with quite the spread next week (at least 10+ degrees spread). For ex, Wednesday could be in the lower 40s to the the lower 50s and dewpoints into the 30s. So even with this spread, confidence is high on warming temperatures as temps will range 10 to 20 degrees above normal! The warmest temperatures will lie west of the MIssouri River with the mean NBM temps in the 30s/40s end of the week and well into the 40s/50s by next week. So with the warmer air over the colder surfaces and still dealing with snow depth. GFS 925mb RH remains in the 90 percentile over the CWA through Friday (drier air at 850) before drier air moves in west to east on Saturday. NBM cloud cover backs this up as we start to see clearing west to east Friday night into early Saturday. With the ridge moving in next week, skies look to remain a blend of clouds and sun. So for Thursday into Friday, with LL moisture, expect fog chances to continue (maybe some drizzle) as wind remain light before increasing a bit Friday afternoon. Roads could be slick during the overnight hours as temps dip below freezing with any freezing fog that occurs. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1123 PM CST Tue Jan 23 2024 Terminals KABR,KATY,KPIR,KMBG IFR cigs will remain over the majority of the area overnight through the day Wednesday. Fog will be a concern again tonight as well, with periods of MVFR vsbys falling to IFR levels overnight into Wednesday morning. By midday or so, vsbys in fog will rise to MVFR levels. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...Dense Fog Advisory until 9 AM CST /8 AM MST/ Wednesday for SDZ003>005-009-010-015>017-033>037-045-048-051. MN...None. && $$ UPDATE...Parkin SHORT TERM...Wise LONG TERM...MMM AVIATION...Parkin