606 FXUS63 KTOP 131154 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 654 AM CDT Sat Oct 13 2018 ...Update to aviation forecast discussion... .SHORT TERM...(Today and tonight) Issued at 353 AM CDT Sat Oct 13 2018 Early this morning surface high pressure was centered east of the CWA with water vapor imagery showing the remnants of Sergio tracking across Texas. An expansive area of low stratus was noted across Missouri and extending westward into far eastern Kansas. With yesterday's rainfall and light winds present, areas of dense fog were developing along the edge of the status and in nearby river valleys. With model guidance suggesting areas of 1/4 mile or less visibilities persisting through sunrise, have issued a Dense Fog Advisory for portions of far northeast/east central KS through 14z today. While the nearby stratus was keeping temperatures in far eastern KS a few degrees warmer in the low 40s, mostly clear skies elsewhere kept temperatures a bit cooler in the mid/upper 30s as the light southerly winds were not providing much advection of 'warmer' air into the region. The combination of these cooler temperatures, light winds, and surface moisture should result in some patchy frost development this morning. For today, models are in decent agreement in keeping moisture associated with the remnants of Sergio south of the CWA, with focus instead shifting to another mid-level trough starting to dive southward from Canada into Montana and the Dakotas this morning and deepen across the High Plains through tonight. This deepening trough will push a surface cold front southward into northwest/north central KS this afternoon and progress southeastward across the CWA tonight. With model soundings showing ample low-level dry air in place through the day, expect much of northeast and east central KS to remain dry with some scattered light rain showers starting to develop across north central KS during the afternoon. With essentially no instability present, expect just rain showers as the front moves into the area. As model soundings show the low-levels gradually saturating during the evening and overnight hours, have increasing PoPs from west to east across the CWA. As for temperatures, the combination of southerly winds and partly to mostly sunny skies across much of the CWA should allow temperatures to quickly rise this morning into early afternoon before cloud cover increases across north central KS with the approaching front. As a result, expect highs to range from the upper 50s to low 60s from east to west. As winds shift to the northwest tonight with the frontal passage, expect decent CAA to cause temperatures to quickly drop (especially across north central KS), with lows ranging from the mid 30s to mid 40s from northwest to southeast across the CWA. .LONG TERM...(Sunday through Friday) Issued at 353 AM CDT Sat Oct 13 2018 Focus for these periods remains in first few periods with a strong cold front surging south through Kansas under persistent strong southwest flow aloft. Mid-level saturation should be easy to come by though still have questions on ice crystals in the cloud in central and southern areas and this coinciding with winter precip-supporting temps in the lower levels. Also, the dominating source for lift appears to be the frontogenesis alone, and there are some indications of a slower frontal progression, so getting the best forcing aligned with the cold temps in northwest locations is again not certain. Model consensus still suggests portions of north- central Kansas will receive enough precip in the deep cold air for accumulating snow amounts. Lapse rates aloft still suggest some CSI to near CI in place for periodic stronger precip rates and this could be enough for accumulations on all surfaces. Will go ahead with an Advisory where confidence in the above is the highest. Frontogenesis weakens with mid-level drying for decreasing precip trends Sunday night for less impactful precip in the southeast. Temperatures Sunday night will likely bring a hard freeze to a least northwestern locations so those with interests susceptible to temps in the mid to upper 20s may want to take action today. Surface ridge settles into the central Plains Monday for a little recovery in temps and another cold night Monday night with another potential hard freeze. Conditions improve into the mid week with moderating temperatures and modest winds. There remains some potential for some showers around Thursday night as southwest flow taps into some increasing moisture as an upper trough lifts northeast out of the desert Southwest. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) Issued at 646 AM CDT Sat Oct 13 2018 For the 12z TAFs, LIFR conditions are expected this morning as areas of dense fog were present near KTOP/KFOE with 1/4 mile or less visibilities at times. These conditions should improve by mid to late morning with VFR conditions likely through the remainder of the day. Overnight, a cold front will track southeastward across the TAF sites, causing winds to shift to the north- northeast and cloud ceilings to drop back to MVFR. However, there is still some model uncertainty with when overnight to expect these MVFR cigs to develop over the TAF sites. Scattered rain showers may begin to develop near KMHK late overnight, with better chances for rain showers near KTOP/KFOE beyond the end of the TAF period. && .TOP WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory until 9 AM CDT this morning for KSZ011-012- 024-026-039-040-055-056. Winter Weather Advisory from 7 AM to 10 PM CDT Sunday for KSZ008- 009-020. && $$ SHORT TERM...Hennecke LONG TERM...65 AVIATION...Hennecke