Area Forecast Discussion
Issued by NWS Topeka, KS
Issued by NWS Topeka, KS
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905 FXUS63 KTOP 041951 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 251 PM CDT Thu Jul 4 2024 .KEY MESSAGES... - Low chance (20% or less) for storms this afternoon or early evening, mainly in Anderson County. - Dry weather Friday and most of Saturday gives us a short break from the wet pattern. - Another chance for storms Saturday night into Sunday, otherwise slightly below normal temperatures continue into next week. && .DISCUSSION... Issued at 251 PM CDT Thu Jul 4 2024 Surface cold front has continued to trend faster this morning, and is through most of the forecast area as of 19Z. It has also become more diffuse, but looks to be located near the I-35 corridor. As clouds have cleared, this should allow for enough destabilization for 1000-2000 J/kg of MUCAPE, but convergence still looks weak along the boundary. Lapse rates also don`t look overly impressive (7 deg C/km at best) and the best upper support remains well north of the area with the trough axis over the northern Plains. All this points to low confidence in storm development along the front before it exits the area completely. Previous runs of CAMs were hinting at post-frontal storms rooted somewhere in the 850-700mb layer along the boundary at that level, but more recent HRRR and RAP runs have backed off on this, so confidence is low on that possibility as well. Have maintained PoPs around 20-25% to account for it, but even that may be overdone at this point. If any storm were to develop, Anderson County stands the best chance of seeing strong winds with it, but once again even that is low. All storm chances should come to an end by 8pm. Sfc high pressure pushes into the area tonight into Friday while the upper trough passes well northeast. Even with clearing skies and light winds, current thinking is that the drier air behind the front should preclude the development of fog but still something to monitor for the overnight hours. A quiet Friday is forecast with lows around 60 and highs in the 80s. Northwest upper flow sets up Saturday with return flow developing in the lower levels. This looks to bring some warmth and moisture back into the region, though perhaps not quite to the extent that we`ve had recently. Still, a shortwave passing through the flow aloft brings our next best chance for showers and thunderstorms late Saturday through Sunday. If north central KS sees these early enough Saturday, the environment could be supportive of damaging wind gusts as forecast soundings show an inverted-V type of profile. The main time period for storms, however, looks to be Sunday afternoon and evening for the entire area when PoPs increase to 60-70%. Although Pwat forecasts around 1.5" are not nearly as high as the moisture has been recently, there is still plenty of time for this to change and places that have seen repeated rounds of heavy rain could still have issues with this. Mid-range guidance indicates rain amounts up to 1" or even 1.5" on the higher end may be possible. The main troughing pattern looks to set up east of the region to bring more subdued weather for the early part of the next work week. Temperatures remain slightly below average for early July with highs mostly in the 80s and lows in the 60s. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1232 PM CDT Thu Jul 4 2024 Seeing the clouds breaking up in eastern KS via satellite, so expecting VFR conditions to return to TOP/FOE in the first hour or so of the period. Frontal boundary has passed all terminals, so the chance for any isolated showers or rumbles of thunder to impact terminals is very low the rest of today. Hi-res guidance has been backing off on any post-frontal activity as well. With clearing skies and light winds overnight, will monitor potential for patchy fog especially in the river valley, but there may be enough dry air advecting into the area to preclude this, so confidence in that is low at this time. Otherwise, expect NW winds under 10 kt through the period. && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Picha AVIATION...Picha