####018006593#### FXUS63 KDTX 162305 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 705 PM EDT Fri May 16 2025 .KEY MESSAGES... - Showers and thunderstorms are likely again early tonight. The potential exists for storms to become strong to severe between 9 pm and 1 am, capable of producing damaging winds and large hail. - Cooler conditions this weekend, with westerly wind gusts 30 to 40 mph on Saturday. && .AVIATION... Early evening VFR and lake breeze enhanced SE wind leads to another round of thunderstorms with scattered to numerous coverage that is on schedule to move across Lower Mi from mid evening until exiting into Ontario around 2 AM. The activity is associated with strong Midwest low pressure drawing moisture and instability back northward into Lower Mi ahead of the trailing cold front. Storms are expected to affect all SE Mi terminals with a few reaching strong to severe intensity with strong wind gusts and brief MVFR/IFR restriction. A few hours of VFR occur in the system dry slot after the storms/cold front move east later tonight. This precedes MVFR ceiling as it expands eastward from the Midwest where coverage is widespread within the low pressure pattern. Gusty wind also becomes a weather highlight late tonight and especially in the morning through Saturday afternoon. West gusts well in into the 30 knot range are expected as the boundary layer builds which also helps ceiling break into low end VFR in the afternoon into Saturday evening. For DTW/D21 Convection... A few showers percolate nearby to the south and east of the terminal early this evening. Otherwise, clusters of storms ongoing from Upper Mi, WI, and IL/IN are on schedule to reach the DTW area after 02Z. A few could be strong to severe with strong wind and hail possible. THRESHOLD PROBABILITIES... * Medium for ceiling at or below 5000 feet with storms tonight, then high Saturday morning and midday. * Moderate for thunderstorms after 02Z tonight. && .PREV DISCUSSION... Issued at 344 PM EDT Fri May 16 2025 DISCUSSION... Southeast Michigan holding position late this afternoon immediately downstream of a closed mid level pivoting across Wisconsin. A warm but drier profile now entrenched, with a brief window of deeper stability in residence now evident by a simply a limited coverage of diurnal cu. Dry and stable conditions to hold through at least 00z, with attention tonight shifting to a mid level perturbation shearing out ahead of the main height fall center. Noted increase in forced ascent attendant to this feature set to sweep across the local area 01z-07z. Renewed boundary layer moistening will commence at the same time, offering at least a weakly unstable low level environment. Mixed signal yet across the model solution space on possible degree of destabilization, with variability noted in dewpoint recovery by as much as 8-10 degrees. This will impact both prospective coverage and vigor of any convective development within this window. Assuming the upward vertical motion field can overcome residual capping issues, then potential exists for cells to attain greater updraft depth given very steep mid level lapse rates. Background wind field more than sufficient to offer organization to any vigorous updrafts. This conditional setup carries enough potential should greater instability materialize to warrant an upgrade in the Day 1 SPC outlook to a slight risk for southern portions of the area, highlighting a damaging wind gust and hail threat. A secondary window exists for sub-severe convective development with the actual cold frontal passage late tonight. Mid level low offers greater influence on conditions to start the weekend, with the circulation center passing thru northern lower MI during the daylight hours Saturday. Cold front exits to the east Saturday morning, with ensuing cold air advection battling daytime heating throughout the day. Minimal thermal recovery expected off morning lows. Temperatures parked in the upper 50s to lower 60s. Notably breezy conditions as mixing capitalizes on a firm west- southwest gradient. Gusts in excess of 30 mph Saturday afternoon. Moist cyclonic flow engaging daytime heating will maintain a chance of showers. Seasonably cool conditions persist Sunday under deeper layer northwest flow. Aside from a broad, thicker diurnal stratocu field, generally benign weather conditions to finish the weekend as general subsidence takes control. Cooler and drier profile maintains residence Monday as low level northeast flow governs conditions under building high pressure from the north. A high amplitude, slowly evolving large scale pattern emerges for the midweek period. Southeast Michigan likely holds position between the high to the north and organizing low pressure to the west. Potentially unsettled conditions at times this period, depending the pace and trajectory of the closed low. Maintenance of east flow with prospective cloud/shower potential on the rise will keep temperatures on the cooler side of average through the rest of the week. MARINE... Low pressure tracks over Lake Superior this evening sweeping a respectable cold front late this evening. A broken line of showers and storms likely develops in advance with isolated embedded strong to severe thunderstorms possible. Moderate west-southwest winds follow Saturday with the strongest winds (20-30kts) expected over the southern half of the region where the gradient is strongest. Small craft advisories have been issued for all nearshore waters daytime Saturday as a result. Low fully departs Sunday shifting winds to the northwest. Gusts peak near 20kts during the day before weakening overnight as weak high pressure slides overhead. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...Small Craft Advisory from 8 AM to 10 PM EDT Saturday for LHZ421-422- 441>443. Lake St Clair...Small Craft Advisory from 8 AM to 10 PM EDT Saturday for LCZ460. Michigan waters of Lake Erie...Small Craft Advisory from 8 AM to 10 PM EDT Saturday for LEZ444. && $$ AVIATION.....BT DISCUSSION...MR MARINE.......KDK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit. ####018007464#### FXUS63 KLMK 162307 AFDLMK Area Forecast Discussion National Weather Service Louisville KY Issued by National Weather Service Kansas City/Pleasant Hill MO 707 PM EDT Fri May 16 2025 .KEY MESSAGES... * SIGNIFICANT SEVERE WEATHER OUTBREAK POSSIBLE LATE THIS AFTERNOON INTO THIS EVENING. * All severe weather hazards are on the table, including damaging winds, large hail, tornadoes, and torrential rainfall. A few strong tornadoes and instances of very large hail are possible. && .SHORT TERM /THROUGH SATURDAY NIGHT/... Issued at 443 PM EDT Fri May 16 2025 A significant severe weather outbreak is forecast across the western Ohio Valley this afternoon and tonight. Currently across our region, earlier clouds and rain have moved out and we've begun to heat up. Temperatures were generally in the upper 70s to the lower 80s across the region with the urban heat island in the lower 80s. Satellite imagery shows where buoyancy is located, which is just south of the I-64 corridor where the cloud field clearly shows horizontal convective rolls indicative of strong deep layer shear. ACARS soundings out of SDF show that CINH is just about eliminated while BNA is free and clear of any capping. We've seen some convection try to fire down in the Lake Cumberland area. This is in area of localized surface mass convergence. An outflow boundary from previous convection extending east into JKL's area will likely continue to wash out with time. Convection down there has continued to struggle. There appears to be a boundary extending from roughly Somerset northwestward to about Owensboro. Latest WoFS runs along with the operational HRRR suggest that some isolated-scattered convection may try and get going along that boundary. If so, model proximity soundings would suggest supercellular development posing an all hazard risk. The main severe weather risk will come later this evening as an impressive band of supercells across western IL and eastern MO works eastward into southern IN and western KY. We're still seeing a bit of variance in trying to time this stuff through the region. So for this update, it appears that this activity would move into our western area by early evening and then into the I-65 corridor by mid- evening. This activity could surge a bit more as the cold pool gets more established and it can get into the Bluegrass/Lexington area by mid-late evening. This line will be capable of producing damaging swaths of wind. Wind gusts of 65-75 mph will be possible with this line, especially in the apex of the surges. QLCS tornadoes are likely as well as the low-level jet axis will increase across the region this evening resulting in very favorable hodographs. Large hail will be possible within the squall line as well. However, the larger hail will be more confined to any discrete supercell. Plentiful CAPE in the 0-15C layer and steep low-mid level lapse rates suggests that 1-2.5 inch hail could occur. Later tonight, there is a possibility that the squall line could become more east-west oriented down across southern KY. If this were to occur, training of heavy convection would occur resulting in an increased flood risk. Given the rainfall this morning and the possibility of this scenario playing out, a Flash Flood Watch was issued earlier today to cover this threat. Most of the convective activity with the line should exit our area in the 1-2 AM EDT time frame. Bottom line, significant severe weather is possible late this afternoon and this evening. Make sure you have multiple ways to receive warnings and a plan in place should a warning be issued! Drier, cooler and less humid weather is expected for Saturday with highs in the lower-mid 70s over southern IN and upper 70s to lower 80s down across southern KY. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 443 PM EDT Fri May 16 2025 Saturday Night through Monday Night... Dry conditions are expected Saturday night with lows in the upper 50s to around 60. For Sunday, we'll see some weak ridging build in from the west. A low-level flow will allow for some moisture return across western and southern KY could result in some scattered showers. Highs on Sunday will be in the upper 70s with a few 80s down across southern KY. By Sunday night, upper level ridging will build slightly more northward into the region. A warm frontal boundary is expected to lift northward through the region bringing additional showers and storms to the region. Lows Sunday night will be in the upper 50s north of the front, but south of the front overnight lows will be in the low-mid 60s. By Monday and into Monday night, the warm front is likely to stall out across the region with areas of showers and storms. Model soundings do show some instability and adequate shear for organized storms. Though, the best shear/instability remains well west of our region. ML guidance agrees with this, but does have some low probabilities out in our western area. Highs will range from the mid-upper 70s over the Bluegrass to the lower 80s over the southwest area. Lows Monday night will be in the 60s. Tuesday through Friday... Upper level low over the northern Plains will get into a Rex block type pattern by late Tuesday and into Wednesday. Aforementioned warm front will remain in our region and will serve as a focus for additional shower and thunderstorm development. Some strong/severe storms are possible as the low and frontal boundary pass through the region. Highs Tuesday will be in the upper 70s to the lower 80s with overnight lows in the upper 50s/lower 60s. Highs Wednesday look to be cooler with readings in the upper 60s to lower 70s. Upper low looks to move from the Midwest into the Great Lakes region by Thursday with the Ohio Valley remaining in a cool cyclonic flow. We'll likely need to keep some scattered showers in at least for Thursday with drier weather for Friday. Highs both days will be in the upper 60s to the lower 70s with overnight lows in the upper 40s to the lower 50s. && .AVIATION /00Z TAFS THROUGH 06Z SUNDAY/ ... Issued at 707 PM EDT Fri May 16 2025 The primary concern for this issuance is the timing into each terminal of convection and the then the timing of the exiting in the southeast portion of the area tonight. A couple areas of concern initially. 1) The supercell in southern KY is tracking east, right toward KBWG. Timing the leading edge of this cell into that terminal gives an arrival time of 00Z. Going forecast had this depicted but have refined the timing of this cell to move east of KBWG by 02Z. It looks like there could be a lull in activity at this site the 2) the main line moves through the area overnight. It looks like the scattered supercells developing along the front will merge/ develop into a line of storms that tracks through the entire area. So have tried to time the front through which ends convection from 03Z to 06-07Z. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ SHORT TERM...MJ LONG TERM...MJ AVIATION...CDB ####018006755#### FXUS62 KCAE 162308 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 708 PM EDT Fri May 16 2025 .SYNOPSIS... The weekend looks warm and humid with a few afternoon and evening showers and thunderstorms possible. The next significant chance of rain comes during the middle of next week with warm temperatures persisting. && .NEAR TERM /UNTIL 7 AM SATURDAY MORNING/... Key Message(s): - A few showers or thunderstorms are possible towards daybreak across our northern and western counties. Temperatures have slowly begun to fall as the sun lowers to near the horizon. The fall should accelerate for a couple of hours immediately after sunset with the loss of daytime heating. We then turn our attention toward the severe convection over the lower Ohio Valley. The thunderstorms should make steady progress toward the southeast late tonight and start to approach the upstate during the early morning hours. However, mid level support for thunderstorms is much lower in our area by sunrise, so expect just remnants to approach the northwestern CWA with possibly a few showers and an isolated thunderstorm by daybreak. && .SHORT TERM /7 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... Key Message(s): - An approaching cold front could spark a few showers or thunderstorms Saturday morning and again Sunday afternoon. - Winds may be breezy at times on Saturday, especially over area lakes. - Continued warm and humid through the weekend. Guidance continues to show a weak cold front passing through the region on Saturday. Rain chances continue to decrease and will be highest in the morning across our northwestern counties and the CSRA associated with the aforementioned decaying convection. The 12Z HRRR in particular shows a complex of thunderstorms moving into the CSRA from the west so maintained Slight Chance PoPs there while decreasing them below 15 percent elsewhere. SPC maintains a Marginal (1/5) risk for severe weather in their latest Day 2 SWO so will continue to monitor new guidance and update the forecast as needed. However, at the moment any severe threat should be isolated. It will be breezy at times across the forecast area on Saturday, especially on area lakes. Latest guidance shows some lakes, especially Lake Murray, near Lake Wind Advisory criteria. Since its is only marginal at this time, will hold off on issuing a LWA with this forecast package. With more clouds around, temperatures should be slightly cooler than today albeit still above seasonal values. The front may stall near the region on Sunday keeping clouds in place. In addition, our Georgia counties are in a Marginal (1/5) risk for severe weather in the SPC Day 3 SWO. This is where Slight Chance PoPs are maintained for Sunday afternoon. Many locations could remain rain free through the weekend but everyone should stay weather aware in case an isolated thunderstorm approaches your area. Temperatures Sunday should be a degree or two lower than on Saturday but once again above average. && .LONG TERM /MONDAY THROUGH FRIDAY/... Key Message(s): - Warm and humid conditions continue, with showers and thunderstorms possible each afternoon through mid-week. Upper ridge axis will shift across the CWA on Monday. Low pressure in the central Plains and Mississippi Valley will reactivate the stalled front over GA/SC that day; it will advect NE'ward from then through Wednesday. There remains some disagreement among models how quickly this occurs. A gradient of instability from SW to NE across the CWA is likely Monday, but the strength of any cap appears uncertain at this time, and other than the general weak forcing associated with the front, we may be for want of a triggering mechanism. There remains some indication from the global models that a convectively generated shortwave will round the ridge Monday which could promote initiation. For now a mostly slight-chance to chance PoP appears appropriate. By Tuesday chances shift mainly from Columbia northeast nearer the front, with profiles drying aloft from the southwest making convection less likely. Temperatures will trend warmer over these two days, with much of the area within a couple degrees either side of 90. Enough 0-6km shear will be present those days that if any convection does fire some damaging wind or large hail are not out of the question; confidence remains low partly due to the spread in depicted CAPE. Pattern change will begin by Wednesday as central CONUS trough pushes into the East. Guidance has come into better agreement in how this pans out, notably the Canadian GDPS/GEPS having trended faster and less supportive of an upper low cutting off. PoPs rise to likely Wed as the shortwave and sfc reflection pass by to our north. Severe threat likely will be greatest that day as cold front moves in and 0-6km shear peaks at 50-60 kt. Temps will fall back into the mid 80s Wed under cloud cover, and then at or below normal Thursday with less humidity. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... Mainly VFR Conditions Expected through the TAF Period. Plenty of high level cloudiness will be streaming across the region overnight and through much of the day on Saturday. This should be the primary cloud group for much of the period at all taf locations. Exception may be at ags/dnl sites Saturday morning shortly after sunrise, where a brief ceiling around 5kft may be found as diminishing area of showers moves in from the northwest ahead of an approaching cold front. Most guidance is indicating that showers will be all but gone as these clouds push through the CSRA, and will no longer include any vcsh at those locations due to low confidence. Otherwise, southwesterly winds should be stronger at the TAF sites on Saturday as the front passes through the region, with some wind gusts around 25 knots at all taf locations during the afternoon hours. EXTENDED AVIATION OUTLOOK... Mainly VFR conditions expected through the period barring low end chances for showers and thunderstorm each afternoon which could cause brief restrictions. && .HYDROLOGY... Most rivers are either near crest, or have already crested and are falling. River flooding remains along the the Congaree River, and long both the North and South forks of the Edisto River. River levels will continue to fall through the weekend. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$