####018002542#### FXUS61 KILN 171933 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 333 PM EDT Sat May 17 2025 .SYNOPSIS... High pressure will build across the area for the beginning of the week. A large upper level low pressure system will move in towards the middle of the week bringing cool, unsettled conditions. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... With the loss of diurnal heating, wind gusts and clouds will diminish. Pressure gradient will only slowly relax and so some winds should persist through the night. Some clouds may linger through the night as well although most area will become mainly clear. Temperatures will drop into the lower to mid 50s. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Surface high pressure will build in and heights aloft will slowly build as well. Diurnal cumulus will still occur, especially from west central into central Ohio, but will not be as extensive as today. Then some cirrus will start to spill into the area on Sunday night. Temperatures will be near normal. && .LONG TERM /MONDAY THROUGH SATURDAY/... Showers will move across southeast Indiana, northern Kentucky, and southwest Ohio on Monday. There will be a lull in the precipitation activity Monday evening before a low pressure system brings showers and thunderstorms to the region late Monday night through Tuesday night. There is the potential that some of the storms across southwestern portions of the region could reach strong to severe levels on Tuesday, however confidence was not high enough to include in the HWO at this time. Several additional disturbances work through the region Wednesday through Saturday keeping precipitation chances in the forecast during this time. After thunder chances during the day on Wednesday, not expecting a lot in terms of thunder for the remainder of the long term with a cooler temperature pattern. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... VFR will prevail. Broken to scattered cumulus will diminish towards 00Z although it may not completely dissipate. Gusts up to 30 kt in west winds will continue early but end towards 00Z. West winds 5 to 10 kt will persist. OUTLOOK...MVFR ceilings and visibilities are possible on Wednesday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM... AVIATION... ####018008541#### FXUS63 KILX 171933 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 233 PM CDT Sat May 17 2025 .KEY MESSAGES... - Localized blowing dust could result in pockets of visibility down to one mile at times through 8 PM this evening. - Unsettled weather returns late Sunday night through Wednesday, with several rounds of showers and storms expected during that period. Some of the storms could be severe on Monday and Tuesday, and locally heavy rainfall in excess of 2" is also possible (30-50% chance). && .DISCUSSION... Issued at 231 PM CDT Sat May 17 2025 An upper low was evident in satellite imagery northeast of the Great Lakes. Central IL remains in the cyclonic flow regime associated with this low pressure system, with breezy westerly winds gusting up to 35 mph. These gusts are right around the threshold at which we see blowing dust develop, and we received reports of localized blowing dust reducing vis along I-74 between Bloomington and Champaign between noon and 130pm. No other reports have been received as of this writing. A blowing dust advisory was issued for most areas east of the IL River and north of I-70. The counties included in the advisory were based on the counties where tile drainage is most prevalent, which our local research has identified as being a factor that can increase the blowing dust potential. Wind gusts should diminish into this evening (and thus the threat of blowing dust will as well). The remainder of the weekend should be pleasant across the region as a weak sfc high pressure shifts through, resulting in light winds and mostly clear skies on Sun. Temps tonight will be on the cool side, with lows ranging from the mid 40s in the north to mid 50s in the south. Typical lows for this time of year are in the low/mid 50s. Highs should be seasonable on Sunday, in the mid 70s. Late Sun eve, CAMs suggest a back door cold front emanating from NE IL pushing southwest across the ILX CWA. Current timing suggests this occurs between 9pm Sun and 1am Mon, but that could be adjusted slightly in subsequent forecasts. The main impact with this front would be a shift from light winds to northeasterly winds that could gust 20-25 mph. *** MONDAY - TUESDAY SEVERE STORM POTENTIAL *** Attention then turns to a slow-moving, long wave trough that is set to emerge onto the central Plains Sun-Mon. This system will result in an unsettled pattern locally, with multiple rounds of storms possible Mon-Tues including a chance for both severe storms and locally heavy rainfall. The severe storm hazards will be modulated in large part by the position of a warm front. The first chance for precip is during the pre-dawn hours of Mon AM. At this time, the warm front is likely to be positioned south of the ILX CWA. Between upscale growth of convection across the Plains as well as LLJ forcing into the warm front, most models bring precip into the ILX CWA by 2-3 AM Mon. There is a broad spread in the models in terms of how much elevated instability is present at that time, ranging from less than 1000 J/kg to upwards of 2000 J/kg depending on the guidance source, but given the synoptic placement of this precip the thinking is if a severe threat exists it would primarily be for hail. There may also be a marginal threat for strong wind gusts depending on how organized the incoming convection is. Eff inflow layer shear of 50+ knots could be sufficient for these storms to maintain an organized structure capable of those stronger wind gusts. The main takeaway is to expect scattered showers and storms very early Monday morning, with the highest chances across the southern half of the ILX CWA. As we progress through this event, the repeated rounds of convection leave uncertainty as to where the warm front will be positioned. There is good consistency in the storm evolution early Mon AM, and I suspect those storms could reinforce the warm front further to the south. Thus I lean more towards the 17.12z deterministic NAM solution which has the warm front further south (south of the ILX CWA during the day Mon) compared to the GFS solution. Guidance has a relative lull in precip activity during the day Mon, before becoming more widespread into the evening as the LLJ forcing returns. While precip coverage is less certain during the day Mon, guidance shows a plume of steep mid-level lapse rates advecting into the area, increasing the potential for large hail with any storms that do form. If we are correct in favoring the southern solution for the warm front placement, hail would continue to be the primary hazard into Mon night. Will note that the frontal placement will still need to be monitored closely as the environment appears quite favorable for tornadoes across the warm sector Mon night. The precip timing trends outlined above seem to be well reflected in the latest NBM PoPs: 60-80% chance Mon AM, 20-50% chance Mon afternoon, then a greater than 90% chance into Mon night. On Tues, the sfc low is expected to track across the ILX CWA. This would bring the warm front further north, and provide a window where portions of the ILX CWA are in the warm sector (best chance being east of I-55/south of I-74). Within this area, a volatile environment with strong instability (potentially over 3000 J/kg of MUCAPE), strong deep layer shear over 50 knots, two fronts (warm front and cold front) and a triple point could support severe storms capable of all hazards across east-central IL Tues afternoon, assuming sufficient atmospheric recovery occurs after any earlier storms. The placement of the SPC Day 4 severe thunderstorm outlook still looks well aligned with today's 12z model guidance, but probabilities may increase in later outlooks if current guidance holds. *** MONDAY - TUESDAY HEAVY RAIN POTENTIAL *** The other concern with this system is the potential for locally heavy rainfall. Guidance depicts PWAT values between 1.25-1.75", which is around the 95th percentile of climatology. Forecast soundings from the NAM suggest a warm cloud layer depth (cloud base to freezing level) of 10-12 kft for much of the period from early Mon AM through Tues AM. Warm cloud layer values above 10kft suggest efficient rainfall rates. The one limiting factor could be the kinematics (see the high deep layer shear values referenced above). The residence time of any individual cell will not be too long at any one location, so it would take multiple rounds of storms over the same area, or perhaps training storms, to drive higher rainfall totals. Currently, the NBM has a 70-90% chance of total rainfall exceeding 1" across most of the ILX CWA, and a 30-50% chance of 2" of rain. As CAMs start to encompass the full event, we'll get a better idea of what kind of localized, higher end rainfall amounts could occur. WPC has issued a slight risk of excessive rainfall for the southwest CWA on Monday, while the entire area is encompassed in a slight risk for Day 4. *** REST OF THE WEEK *** As the sfc low slides east by Wed, breezy northerly flow will persist across IL through the day, with forecast soundings suggesting mostly cloudy skies and perhaps some light showers. Temps will be seasonably cool, with highs barely climbing into the low 60s. The rest of the week features a weak, broad sfc high nudging into the region, which should result in gradually weakening wind speeds and mostly dry conditions during the day Thursday-Friday (less than 20% chance precip). Erwin && .AVIATION... (For the 18z TAFs through 18z Sunday Afternoon) Issued at 1214 PM CDT Sat May 17 2025 Gusty west winds will remain in place this afternoon, with 20-30 kt gusts common. Brief visibility reduction in blowing dust is possible but this should be localized so will leave out of TAFs. Winds to subside by early evening and remain 10 kt or less through Sunday morning. Scattered cu this afternoon will diminish by early evening then just cirrus for the remainder of the forecast. 25 && .ILX WATCHES/WARNINGS/ADVISORIES... Blowing Dust Advisory until 8 PM CDT this evening for ILZ030-031- 037-038-041>057. && $$ ####018007681#### FXUS63 KGLD 171934 AFDGLD Area Forecast Discussion National Weather Service Goodland KS 134 PM MDT Sat May 17 2025 .KEY MESSAGES... - Very low chance for an isolated thunderstorm in northeast Colorado late this aft-eve (~5-10 pm MDT). Severe weather is not anticipated. Otherwise, thunderstorm development (if any) this aft/eve will be confined well south of the NWS Goodland CWA. - Strong southwest winds will develop behind a northward advancing dryline Sunday afternoon, mainly along and south of I-70 where sustained winds at 30-40 mph and gusts up to 55 mph are possible. - Severe storms capable of producing very large hail, damaging winds and an isolated tornado are possible over northern portions of the area Sunday afternoon, mainly along/north of Highway 36 between 4-8 pm MDT / 5-9 pm CDT. && .SHORT TERM /THROUGH MONDAY NIGHT/... Issued at 1235 AM MDT Sat May 17 2025 For the remainder of tonight, a few clouds are forecast to move over the area as mid to upper level moisture streams over the Front Range. At the surface, temperatures are forecast to lower into the upper 30s and 40s with calm winds across much of the area. For Saturday, relatively mild conditions are forecast for the area as the area is forecast to be under ridging aloft. With it, mostly sunny skies, highs in the 70s, and initially light winds around 10- 15 mph are forecast. As the day goes on, the next upper trough is forecast to move more east into the Mountain West and help develop surface low pressure along the Front Range. As the low pressure develops, the pressure gradient is forecast to increase through the day and strengthen winds in Eastern Colorado and neighboring counties. Speeds could reach 25 mph with gusts to 35 mph later in the afternoon. Late Saturday afternoon and through the night, the forecast still calls for some showers and storms to try and make their way into parts of the area. A potential batch is forecast to develop along the higher terrain in Eastern Colorado, along the eastern edge of the low. Severe storms look to be unlikely with this batch given forecast soundings suggesting low instability (CAPE < 1000J/KG and mid-level lapse rates around 8.0 C/KM) and relatively weak winds through the cloud layer (mid level winds and corfidi downshear vectors around 30-40 kts). This batch of storms is forecast to struggle to reach the area as the air is forecast to be a bit drier in the low to mid-levels in Eastern Colorado. The second potential batch favors southern and eastern portions of the area, closer to Central Kansas. This batch has the better chance to be severe, if it can form. Guidance continues to suggest that a capping inversion will be over most of this area and limit thunderstorm potential. If storms do form, some guidance suggests that elevated instability may be able to move in as moisture streams into the area in the low levels. With this, there could be enough instability for some quick storms to fire and produce hail up to half dollar in size (MUCAPE around 1500-2000 J/KG, mid-level lapse rates around 8-9 C/KM). The best chance looks to be late in the afternoon and during the early evening hours. As the evening continues, more low level moisture is forecast to stream into the area from the southeast. With this, there is the possibility that fog and even some dense fog could develop. There are still some questions about where the saturated air will develop along with if the winds will be too strong and mix out the lower level saturation, but most of Northwest Kansas could see fog late in the night Saturday and into early Sunday. If the fog and/or low level clouds develop, locales underneath would likely stay in the upper 40s and 50s for lows. The rest of the area is forecast to cool into the low to mid 40s. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Issued at 133 PM MDT Sat May 17 2025 For the extended period starting Tuesday a surface low remains in place around the South Dakota/Minnesota/Nebraska/Iowa state lines as breezy to gusty NW winds are forecast to continue across the area in response to this low. Wind gusts of 45-55 mph are currently forecast with sustained winds around 25-35 mph as 30 knot 850mb jet remain in place during the afternoon and a 45-50 knot 700mb jet remains in place, assuming if some mixing can occur then would not be surprised if a rogue 60 mph gust occurs if these trends hold. At this time Tuesday is forecast to remain dry but if the low sets up a little further west then some vorticity maxima may lead to some spotty showers through the afternoon as well. Wednesday morning as this low moves it a cold front and associated surface high is forecast to move into the area which is forecast to drop Wednesday morning lows into the 30s. An associated surface high also moves into the area with the front which is forecast to bring a period of lighter winds before they shift to the west. If this shift to the west is slower to occur then temperatures may drop even further which may bring some frost or maybe freeze concerns to portions of the area which would be impactful given we are well past our climatological last freeze date. Luckily this surface high is forecast to be short lived as a lee trough ahead of western CONUS ridging develops and pushes this out of the area. Some guidance does indicate a weak wave moving through with this activity which may try to spark some storms during the evening hours so will need to keep an eye on this. Thursday and through the remainder of the extended period weak mid level ridging is forecast to take place across the Inter Mountain west which if current placement holds puts the region on the eastern periphery of this feature. Typically in these patterns weak waves that are not handled well by long range deterministic guidance moves through the area; what makes this interesting is that there are already some signals are some embedded waves which makes me think that another active pattern may emerge late week and next weekend. With this still being 5-7 days out a lot can and will change but it does appear that additional potential for severe weather may return again for portions of the area. As for temperatures for the extended period. Tuesday is forecast to start out fairly cool with high sin the mid 60s to low 70s across the area before warming back into the upper 70s my Wednesday and into the mid 80s again Friday especially as that ridge begins to make itself known. For low temperatures as mentioned above, some concern for frost and maybe freeze to start the period before a recover to more seasonable lows in the upper 50s and mid 50s by the latter portion of the week. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1200 PM MDT Sat May 17 2025 VFR conditions will prevail this afternoon into tonight. MVFR- IFR ceilings will rapidly develop around, or shortly before, sunrise Sunday morning at both terminals. Ceilings will lift to VFR during the late morning and early afternoon (~17-19Z Sun). ESE to SE winds at 10-17 knots will prevail this afternoon and overnight.. increasing to 15-25 knots late Sunday morning. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...None. CO...None. NE...None. && $$ SHORT TERM...KAK LONG TERM...Trigg AVIATION...Vincent ####018006146#### FXUS63 KDDC 171934 AFDDDC Area Forecast Discussion National Weather Service Dodge City KS 234 PM CDT Sat May 17 2025 .KEY MESSAGES... - Severe thunderstorms are decreasing in potential for later today with only the Comanche/Barber county area still holding a notable (>20%) chance - Strong severe storms capable of all hazards are expected in the far eastern counties on Sunday, with a notable amount of uncertainty still lingering - A line of storms is forecast to sweep across SW Kansas Monday that may strengthen to severe thresholds upon reaching the eastern portion of the CWA && .DISCUSSION... Issued at 233 PM CDT Sat May 17 2025 The cold front associated with the deep low pressure system that have moved over the Great Lakes has moved across the forecast area. This will help keep highs lower today with the coolest highs that SW Kansas has seen this week. Elsewhere, RAP mesoanalysis portrays a deepening trough over the Pacific Northwest. Modest winds are expected to continue today out of the east/southeast at around 15-20 mph. Current surface analysis depicts a surface low along the NM/TX border with a dryline draped across western Texas. Thunderstorm chances continue to be contingent on the amount of moisture that can flow this far north before the late afternoon. CAMs simulate convection where the individual CAMs have the moisture reaching, with a general consensus that any convection that does occur will be limited spatially in the southeastern counties in the CWA. Most CAMs had 60F dewpoints just barely creeping into the CWA, but the moisture has not advected like expected and continues to limit storm chances as the final outcome appears drier and drier. If these trends continue, SW Kansas may miss out of thunderstorms entirely. Despite this pessimism, ensembles still have a 35-40% chance for thunderstorm development across Comanche and Barber counties. The uncertainty remains in the moisture and the northward extent of the convection. If development is slightly southward than currently expected or does not propagate as far north as forecast, the amount of convection the CWA will experience will be limited if any at all. Supercell development will be favored with large (two inch) hail being the primary threat. Other limiters in a top-end severe threat is the upper-dynamical support and cap development. Convection is expected to breach the cap, but may not continue northward enough into Kansas. With all the caveats aside, strong thermodynamic ingredients exist with NAMNST forecast soundings having >2000 J/kg CAPE, >300 m2/s2 0-3km SRH, and >40 KTs effective shear. Low stratus and patchy fog are forecasted across the center of the CWA with lowered visibilities from around 6 AM until around 9 AM. The previously mentioned lack of moisture may reduce the impact any fog/stratus may have. Ensembles have highs in the upper 80s and into the 90s for most of the CWA except for the northeast portion. Later into the late afternoon, severe thunderstorms possibilities return. Uncertainty still remains with Sunday especially as initiation is heavily reliant on Saturday's thunderstorm activity. The deep trough is expected to move over Colorado by tomorrow, attempting to build off of the moisture transport on Saturday to provide ample moisture for thunderstorm development. Ensembles and models have a substantive dryline deepening and moving around the highway 283 corridor. CAMS have initiation starting along the eastern column of counties and moving northeastward. If this trend holds, the overall impact on the CWA as a whole will be minimal. However, if supercells are able to quickly form and strengthen, all severe threats are possible including giant large (4 inch hail). Unlike storms on Saturday, the upper-level dynamical support is notable with subtle CVA and decent correlation with the upper-level jet streak. CIN from NAMNST forecast soundings are exceeding 200 J/kg, and is the greatest limiter regarding severe storm development other than the moisture supply. Assuming this can be overcome, CAPE values over 3000 J/kg and SRH values around 250 at SFC-1km/SFC-3km will be plenty for supercell development and maintenance. The threat for tornadoes maximizes as the low-level jet strengthens around 0z, but it is expected that most if not all storms will have exited the forecast area by then. Monday has another round of thunderstorm possibilities as the trough and deep low moves over the forecast area. Longer-ranged CAMs have a line of storms developing across the forecast area in the evening. As these storms move eastward, the storms will enter a more favorable environment for severe weather along the eastern counties yet again with very high CAPE and shear values along with the better areas with moisture. Beyond Monday, ensembles have a dry, warming trend for SW Kansas. Highs on Tuesday starting in the 60/70s and ending in the 80/90s by the end of the week. Long-ranged ensembles hint at chances (15-20%) for precipitation to return on Friday, but with the multiple rounds of storms in the way and temporal uncertainty future forecasts will provide more clarity on the potential. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1145 AM CDT Sat May 17 2025 VFR conditions are expected at the start of the TAF period with east/southeast winds at 15-20 KTs and gusts up to 25 KTs. Around 10z, enough moisture is expected to reach SW Kansas for low stratus and potentially fog to develop. The lower cloud cover is expected to impact all TAF sites with MVFR flight conditions forecast and as low as IFR with the fog most likely for GCK and DDC. LBL may remain at VFR through the period with ceilings close to MVFR thresholds. && .DDC WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...KBJ AVIATION...KBJ