Area Forecast Discussion
Issued by NWS Topeka, KS
Issued by NWS Topeka, KS
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137 FXUS63 KTOP 150809 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 309 AM CDT Sun Sep 15 2024 .KEY MESSAGES... - Temperatures 5 to 10 degrees above normal are forecast to continue through much of next week. - Limited forcing may spark some hit or miss showers and storms across north central KS each of the next couple mornings. - A more organized chance for rain is forecast for Friday and Saturday with chances for measurable precip around 55%. && .DISCUSSION... Issued at 309 AM CDT Sun Sep 15 2024 07Z water vapor imagery showed an upper ridge over the eastern Great Lakes with an upper trough over the Pacific Northwest. The remnants of last week`s tropical system remained over the south placing the forecast area in a col or saddle point within the synoptic pattern. Surface obs showed ridging over the Upper Midwest nosing into northeast KS with troughing along the lee of the southern Rockies. Through Tuesday forcing for precip is progged to remain rather subtle. The main driver of POPs in this period is some isentropic upglide within an area of weak mid level warm air advection. We can see this by the development of some altocumulus over the last couple hours. The RAP/NAM show the better lift and saturation remaining over central KS with forecast soundings suggesting only a few hundred J/kg of CAPE. The HRRR is not developing a lot of convection with the lift, but other CAMs do show a storm or two developing. So there could be a couple isolated updrafts develop through the mid- morning hours and have continued with some slight chance POPs for areas along and west of Abilene to Concordia. A similar setup is forecast for the overnight hours Sunday and into Monday morning. There is a little more consistent signal from the CAMs for elevated showers and storms developing across north central KS, and have some chance POPs as a result. Instability and shear are progged to remain limited so potential for severe storms looks to be close to zero. Warm weather is forecast to persist through the first part of the work week as southerly low level winds become more predominate and allow warm air to persist over the central plains. The forecast has lows and highs generally 5 to 10 degrees above normal for the middle of September. There looks to be two opportunities for more organized precipitation through the end the week. The first looks to be Tuesday night and into Wednesday morning as a shortwave lifts from eastern CO into the northern plains. This wave looks to pass mainly northwest of the forecast area, but models are showing a similar idea for a line of showers and storms forming to the west and moving into parts of north central KS. Confidence is only so-so since the better dynamics pass to the northwest of the area. But GFS and ECMWF ensembles show a better than 50% chance for at least a hundredth of an inch. The second opportunity looks to be late Friday and Saturday as models show a deeper upper trough moving through the central Rockies. Here the GFS and ECMWF ensembles have probabilities of measurable precip between 70% and 90%. The chances for precipitation of at least a half inch are around 40%. Have kept the initial grids from the NBM which gives Likely POPs for Friday night. Well see if trends from the blend follow what the ensemble data suggests. Temps look to remain above normal through Thursday. Increase in clouds and rain chances are expected to keep temperatures closer to normal for Friday and Saturday. && .AVIATION /06Z TAFS THROUGH 06Z MONDAY/... Issued at 1210 AM CDT Sun Sep 15 2024 Weak isentropic lift is progged to remain west of MHK and forecast soundings keep some mixing in the top of the boundary layer to entrain some dry air this morning. So think VFR conditions will prevail. Winds could become light enough in the river valley for some shallow ground fog around sunrise but confidence is to marginal to include in the forecast. A reasonable pressure gradient through Sunday should allow south and southeasterly winds to freshen with some marginal gusts through mid-day. && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Wolters AVIATION...Wolters