Area Forecast Discussion
Issued by NWS Topeka, KS
Issued by NWS Topeka, KS
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054 FXUS63 KTOP 141139 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 639 AM CDT Tue May 14 2024 .KEY MESSAGES... - Mostly dry weather is expected today, aside from a stray shower in far eastern KS this morning. - Shower and storm chances (50-80%) return Wednesday into Thursday. Confidence lowers for rain chances into the weekend. - Temperatures stay near average for the next few days, then warm up for the weekend. && .DISCUSSION... Issued at 402 AM CDT Tue May 14 2024 The 500mb low is situated over western MO early this morning, followed by weak ridging over the central Rockies and the next low- amplitude shortwave over the Intermountain West. Another area of low pressure aloft is noted off the coast of CA. At the surface, we are left in a narrow ridge axis between the low in MO and low pressure in the Dakotas and WY. A few deformation showers remain in far eastern KS on the north and west side of the low to our east, and an isolated shower may still clip our eastern counties this morning. The system should move far enough east after sunrise to bring rain showers to a complete end. Most of today is expected to be dry as we find ourselves between the two systems and the ridge passes through the area. Clouds may be a bit slow to move out in far eastern counties, though highs are still forecast in the 70s area-wide, near average for the middle of May. There are low chances (20-30%) for rain to move into central KS after midnight, but forecast soundings take time to saturate and the better ascent arrives toward Wednesday afternoon and especially evening as the shortwave energy ejects out from the upper trough. For this reason, the highest PoPs (50-80%) continue to be focused in the 00-12Z Thursday time frame. Deep-layer shear is forecast to be in the 30-40 kt range, which could support a few more organized storms if a stronger updraft can get going. "If" is the key word there - the best instability (CAPE of 1000-2000 J/kg) looks to be confined to a narrow corridor along the southwest edge of our forecast area, with instability dropping off as you go north and east. Am not sold on stronger storms developing in areas where only a few hundred J/kg of MUCAPE exists. The amount of instability that storms have to work with may depend on how far north a weak warm front can make it during the day Wednesday, so this will bear watching through the next 36 hours or so. Instability and shear both weaken into Thursday, not enough to eliminate chances for thunderstorms, but enough to lower the likelihood of severe weather. There are still some model differences in how the pattern evolves heading into the end of the week - some suggest the southern stream trough phasing into the northern stream by Friday, while others suggest the southern stream develops into a closed low over the area on Friday. The latter scenario has a greater chance of keeping some showers and thunderstorms around on Friday in eastern areas in particular, so lower-end PoPs remain in the forecast. Ensemble solutions diverge further through the weekend into early next week, so confidence in rain chances continuing through this time period is rather low. Saturday currently looks like the warmest day, as the NBM 25th percentile has forecast highs into the 80s for nearly the entire area with the higher end of the guidance pushing 90 for some locations. So it at least appears likely to see warmer temperatures on the horizon as we head into the weekend. && .AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/... Issued at 639 AM CDT Tue May 14 2024 VFR conditions have mostly returned, though clouds around 10kft may be slow to move east of TOP/FOE. Could periodically see MVFR vis for a few hours this morning as surrounding sites have been reporting BR and TAF sites have seen reduced vis at times as well. Thinking this should mix out later this morning. North winds then pick up, with TOP/FOE getting slightly above 10 kt before decreasing later this afternoon as a ridge axis approaches. Winds overall turn easterly tonight, which could bring MVFR stratus back in from MO late in the period. && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Picha AVIATION...Picha