Area Forecast Discussion
Issued by NWS Topeka, KS
Issued by NWS Topeka, KS
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247 FXUS63 KTOP 180813 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 313 AM CDT Wed Sep 18 2024 .KEY MESSAGES... - A few isolated thunderstorms will be possible across the area today and tomorrow with hail and wind associated with the most intense storms. - Above normal temperatures through Friday with Thursday likely the warmest day with heat indices around 100 degrees over northeastern into east central areas. - Welcome and more widespread rain chances come into Saturday and Sunday periods. Could see up to 2-3 inches in some areas with best chances north I-70. && .DISCUSSION... Issued at 311 AM CDT Wed Sep 18 2024 Currently, at the 07Z hour, the upper air pattern across the CONUS shows an area of upper low pressure over the southeastern states working into the Carolinas. A broad trough with a pair of upper lows is situated over the western CONUS with the eastern flank upper low over the northern Rockies and associated negatively tilted trough working over the High Plains region. The local forecast area will remain just to the southeast of the best forcing for ascent with this feature which has implications for the isolated to scattered nature of any storms today and Thursday. Low level moisture is still of good quality from south to north with dewpoints well into the 60s from northern Texas into the Dakotas. For today, a gradual eastward progression of overnight convection will work into north central Kansas areas with weak isentropic ascent along the 310K surface through this morning before weakening into midday. Expectation is for non-severe showers and storms to work into north-central KS areas with only light rainfall amounts expected for this round. Could see a few isolated showers and storms form again over western areas into this evening but not expecting widespread coverage due to weaker instability over the region due to lapse rates generally not as steep into the area as the upper low over and associated trough lift north of the region along with best shear and mid-level speed max. By late this afternoon the EML in place may weaken in some areas with updrafts allowed to grow into storms. Could still see the risk of hail and strong downdraft winds over north central areas mostly. On Thursday, the instability axis is allowed to advance east with better quality theta-e advection due to the overnight LLJ set up across the area. Deeper mixing into the day allows for high temperatures to reach the middle 90s with increasing dewpoints working into the region with persistent southerly flow before veering into the evening. This setup looks to increase the overall instability across the forecast area. Still not seeing much in the way of forcing for ascent or strong low level convergence. Expecting isolated to scattered storms - if they form - once again. The environmental setup would favor more potential for downburst type storms into Thursday evening if they do end up forming. Could also see some hail potential if a given storm can remain persistently strong with a generally tall updraft. Overall, shear profiles suggest storms may not be highly organized again once they are allowed to form with sufficient weakening of the EML. Perhaps the most anticipated part of the forecast may come into the late Saturday and Sunday periods when the second upper level low and trough finally emerges from the central Rockies. Persistent forcing along with moist theta-e advection into the area along with low to mid level convergence could allow for some heavy rainfall totals over a 24 to 48 hour period. Forecast anomalies suggest PWAT amounts to exceed the 90th percentile. Could see some areas record 2-3 inches or possibly more generally north of I-70. Considering the area is currently in abnormally dry to moderate drought conditions, this looks to be welcome news. Temperatures fall back to around normal after this second trough and upper low work through the area. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 1223 AM CDT Wed Sep 18 2024 Have maintained a VFR forecast for the period. Uncertainty remains with any showers or storms that make a run at the KMHK terminal early this morning into midday time frame. Generally, expect storms to continue to weaken and break apart with eastward advancement. Thus, chances remain too low to include mention in the forecast at this time. Will monitor for amendments or update in the next forecast cycle. No significant wind shifts anticipated this period and gusty winds can be expected into the morning and afternoon with mixing effects. && .CLIMATE... Issued at 632 PM CDT Tue Sep 17 2024 Record high temperature data for September 19: Record maximum temperature Forecast maximum temperature Topeka 99, set in 2022 96 Concordia 101, set in 2022 92 && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Drake AVIATION...Drake CLIMATE...Poage