####018005678#### FXUS64 KTSA 162355 AFDTSA Area Forecast Discussion National Weather Service Tulsa OK 655 PM CDT Fri May 16 2025 ...New AVIATION... .KEY MESSAGES... Issued at 255 AM CDT Thu May 15 2025 - Shower and thunderstorm chances for northwest AR through mid afternoon today, then, a slight chance for storms for far southeast OK during the late afternoon. Some storms could be severe, with large hail the primary threat. - An unsettled weather pattern continues through the weekend and into early next week. Severe thunderstorms are expected at times. - Cooler and drier weather for the middle of next week. && .SHORT TERM... (The rest of this afternoon ) Issued at 106 PM CDT Fri May 16 2025 A surface boundary is advancing east through the area, currently it stretches from northwest AR back into south-central OK. Earlier, showers and storms had formed in the unstable air ahead of this boundary but have since moved east. CAMs are in good agreement that the next round of storms will form right as they are exiting southeast OK this afternoon. This may occur if sufficient surface heating breaks the capping inversion. Forecast profiles support all severe hazards, but large hail in particular. With that said, all areas east of the boundary should remain alert for potential severe weather. By early evening, any storms should be south or east of the area. Due to the cooler and drier air behind the boundary, temperatures will drop into the 50s north of I-40 tonight. It will be a bit warmer south of I-40 where some moisture return will begin, with lows generally in the low to mid 60s. && .LONG TERM... (Tonight through Friday) Issued at 106 PM CDT Fri May 16 2025 During the day Saturday the boundary will drift back to the north, with deep moisture filling in near and south of I-40. Meanwhile, another weak cold front will sag south out of the north, combining with the existing boundary near I-40 for the middle part of the day. This merged boundary will then gradually lift back north and wash out, with deep moisture filling the forecast area by late afternoon or evening. With plenty of moisture, deep instability, and good wind shear, thunderstorms (some of which could be severe) are expected. Lift will increase later in the day as an approaching upper level wave passes through. Storms will focus south of I-40 through mid afternoon before spreading north and east into the late afternoon and evening. The threat of storms will continue overnight, especially north of I-40 and towards northwest AR. Temperatures will be warm Saturday, with highs in the 80s and lows in the 60s. Model guidance is in pretty good agreement that storm activity will light up along the remnant 850 hPa frontal boundary Sunday afternoon into the overnight hours, which should be oriented NW- SE, roughly in the vicinity of northeast OK into west-central AR. With very high PWAT near 1.5" (dewpoints into the low 70s) and strong warm advection, areas of heavy rainfall and isolated severe storms are likely. We will remain within the warm sector Monday, with dew points again surging into the 70s. Additionally, stronger lift and shear will spread into the area as the upper level trough approaches. Forecast soundings are concerning, with most forecast metrics looking conducive for higher end severe weather potential. The expectation is that during the afternoon storms will develop along the dry line before moving east across the area. All severe hazards would be possible with any discrete storms, perhaps transitioning to more of a QLCS system with time. The SPC has already increased severe weather probabilities to slight to enhanced (15-30%) for this period, which seems well warranted given the parameter space. A cold front will push through later Monday, bringing much drier and cooler air. This should set is up for a quieter period mid week. Better moisture and storm chances return by late week. && .AVIATION... (00Z TAFS) Issued at 655 PM CDT Fri May 16 2025 VFR is expected to prevail at all TAF sites through the period. Storms that form this evening/tonight should stay well east of the forecast area. Skies should clear overnight, with mid/high level clouds increasing through the day Saturday. Storm chances will increase across south/southeast OK by mid-afternoon and spread northeastward with time through the late afternoon hours. Included PROB30 groups at MLC, TUL, RVS, and FSM for thunderstorms, generally between 20z-00z/3pm-7pm. Confidence of timing for storms is low at this time. Winds stay light and will veer from the east/northeast to the south/southeast in the afternoon. However, winds may become strong and erratic underneath thunderstorms that occur. Additionally, ceilings may briefly lower to MVFR in thunderstorms. Mejia && .PRELIMINARY POINT TEMPS/POPS... TUL 57 83 64 82 / 0 20 50 50 FSM 62 89 68 87 / 0 30 50 40 MLC 61 86 68 85 / 0 40 30 30 BVO 51 80 60 81 / 0 10 60 60 FYV 55 85 63 82 / 0 20 60 60 BYV 56 84 61 82 / 0 10 60 60 MKO 58 85 64 82 / 0 30 50 50 MIO 53 80 61 81 / 0 10 70 70 F10 59 85 66 82 / 0 30 40 40 HHW 65 86 68 83 / 10 50 30 30 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...06 LONG TERM....06 AVIATION...67 ####018007374#### FXUS65 KTFX 162355 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 555 PM MDT Fri May 16 2025 Aviation Section Updated. .KEY MESSAGES... - Daily rounds of scattered showers and thunderstorms are expected through Saturday. - Widespread rain and mountain snow returns Saturday night through Monday morning, with winter impacts mostly over and above pass level late Sunday through Monday morning. - The unsettled spring weather pattern continues for much of next week, with daily rounds of scattered showers and thunderstorms. - Near to slightly below average temperatures are generally expected for the next seven to ten days. && .DISCUSSION... /Issued 259 PM MDT Fri May 16 2025/ - Meteorological Overview: A moist and modestly unstable westerly flow aloft becomes more southerly on Saturday in advance of an approaching Pacific trough. Scattered, mostly afternoon, showers and thunderstorms are expected today and Saturday, with a few stronger storms over the southwest Saturday afternoon/evening before the activity gradually transitions to stratiform rain while moving northward into North- central MT Saturday night. Periods of rain and mountain snow will then continue through Monday morning. Ensembles are in agreement with the primary mid- level low moving southeastward from the Pacific NW through ID and eventually into the Great Basin. Much of the precipitation will be associated with a developing H700 that will move through the southern half of the state. This set up will encourage widespread rainfall with totals generally ranging between a third to one inch of moisture for most locations Saturday night through Monday afternoon. Of course there are some variations among deterministic models highlighting different localized areas with rainfall amounts in excess of one inch. Snow levels will begin to fall from 8,000 feet Sunday morning to as low as 5,000 feet Sunday night into Monday morning. Most of the winter impacts will be observed during this time, especially where the areas of heaviest precipitation temporarily drops snow levels even further. Most of the precipitation ends in a east to west fashion on Monday, but the overall unsettled weather pattern will continue for the remainder of the week. A progressive westerly flow will send shortwaves through the Northern Rockies for periods of scattered showers and thunderstorms and breezy conditions, though there are uncertainties with the timing and positioning of each system. Temperatures will continue to roughly remain near seasonal averages. - RCG - Forecast Confidence & Scenarios: Widespread rain and snow Saturday night through Monday morning... Confidence continues to increase in regards to widespread rain and mountain snow during this period. Although ensembles are largely in agreement with the positioning of the trough, there are differences among their members with the precise locations of heavier rainfall. Overall, probabilistic guidance supports widespread liquid equivalent precipitation amounts between a half and one inch Saturday night through Monday afternoon. Nearly the entire forecast area has a 60% + of seeing a half inch or more of moisture, but only areas over and near the Southern Rocky Mountain Front and the Central MT island ranges have a greater than 40% chance for an inch or more. Impacts are expected to be limited, but the situation will be monitored for potential hydrologic impacts, including unexpected water rises. Please see the hydrology section for more information. Colder air on the backside of the low pressure system will begin to lower snow levels Sunday morning, falling to around 5,000 feet by Monday morning. Areas receiving heavier precipitation may see their snow levels briefly drop an additional 500 to 1,000 feet. Current probabilistic guidance keeps the greatest chances (70% +) for 2 inches of snow or more above 7,000 feet. While this will hold true for much of the event, it does not reflect the lowering snow levels form heavier/convective precipitation or H700 temperatures bottoming out as low as -8C over the southwest Sunday night and Monday morning. Yes, the most impactful snows will be above pass level, but brief winter road impacts down to the valley floors over Central and Southwest Montana are certainly not out of the question. - RCG && .AVIATION... 17/00Z TAF Period Predominately low-VFR/VFR conditions are expected throughout the 1700/1800 TAF period across the North Central and Central Montana terminals (i.e. KCTB, KHVR, KGTF, KLWT, and KHLN), with scattered rain showers moving across/near the KLWT, KHVR, and KCTB through 03-07z Saturday. Further south across the terminals of Southwest Montana (i.e. KBZN, KEKS, and KWYS) rain showers and/or low CIGS will bring MVFR/low-VFR conditons through generally 07-13z Saturday, with most shower activity ending prior to 09z Saturday. Clearing skies through sunrise on Saturday will then aide in patchy fog developing across Southwest through North Central Montana; however, confidence in fog reducing VIS/CIGS at any given terminal remains too low for mentioning in this TAF issuance. Mountain obscuration will gradually decrease through Saturday morning, especially over Central and North Central Montana. - Moldan Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .HYDROLOGY... A Pacific weather system will bring periods of widespread rain and mountain snow Saturday through Monday morning. The precipitation will begin in the form of scattered showers and thunderstorms over Southwest Montana Saturday afternoon before gradually transitioning to areas light to moderate rainfall as it expands northward into the plains Saturday evening and night. Periods of rain and mountain snow will then continue for all areas through Monday morning. Total liquid precipitation amounts will generally fall between a half and one inch with localized higher amounts. Snow levels will gradually lower beginning on Sunday, falling to as low as 5,000 feet by Monday morning. A few rivers are forecast crest near bankfull towards the end of the event. This includes the Gallatin River at Logan and the Jefferson River near Three Forks. With lowering snow levels and generally slow rain rates, flooding is generally not expected; however, those near waterways or areas normally susceptible to flooding should remain situationally aware of their surroundings in case localized heavier rainfall brings unexpected water rises. - RCG && .PRELIMINARY POINT TEMPS/POPS... GTF 37 66 47 54 / 20 20 60 100 CTB 36 64 42 50 / 30 10 50 90 HLN 38 66 46 54 / 20 30 80 100 BZN 39 65 42 53 / 60 30 70 100 WYS 32 59 35 46 / 80 30 90 100 DLN 36 61 40 49 / 50 30 90 90 HVR 41 68 43 54 / 50 50 40 80 LWT 37 62 42 54 / 50 40 60 90 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls ####018003826#### FXUS63 KDLH 162356 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 656 PM CDT Fri May 16 2025 .KEY MESSAGES... - Rain showers continue tonight and Saturday with minimal accumulations. - Turning much cooler this weekend with highs in the 40s and 50s. - Frost and a potential freeze possible Sunday night into Monday. && .DISCUSSION... Issued at 335 PM CDT Fri May 16 2025 Vertically stacked low pressure was located over western Minnesota this afternoon. Areas of light showers were rotating around the low across the Northland. The low will slowly meander across eastern Minnesota and northern Wisconsin overnight, ending up across Upper Michigan by Saturday morning. With a northwest flow regime on the backside of the low, light showers will persist Saturday into Saturday night as the low continues to move further east. Cooler air will also arrive with the northwest flow bringing highs in the 40s and 50s for Saturday and Sunday. This will be around 10 to 20 degrees below normal for mid-May. High pressure builds in on Sunday with east to northeasterly winds across the region. The coolest highs Sunday will be near Lake Superior as a result. Global models keep some shower activity over the region Sunday, but this is hard to believe given the building high and drier air pushing in. Overnight lows Saturday night and Sunday night will fall into the 30s with some upper 20s possible Sunday night as well. This will lead to widespread areas of frost across the Northland each night with a freeze possible Sunday night across parts of northeastern Minnesota. Much of next week looks dry with upper ridging in place. A system will move across the Central Plains into Mid-Mississippi Valley Monday into Tuesday, but the high pressure in place overhead looks to keep the effects of this system to our south. There may be some shower activity late week into the weekend in spots, but global models are telling different stories keeping overall confidence low. Temperatures will slowly warm back into the 60s over the course of the week, but persistent easterly flow off the lake will keep temperatures cooler near the lake. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 656 PM CDT Fri May 16 2025 A mix of VFR to MVFR ceilings currently occurring across the area will deteriorate to MVFR to IFR ceilings with VFR to MVFR visibilities in scattered light rain this evening into Saturday morning before conditions improve back to MVFR late in the TAF period Saturday afternoon as the low pressure system shifts east. Can't rule out some LIFR conditions tonight, but probabilities of this occurring are 10-20%. Winds should ease and become variable this evening into early tonight before turning northwesterly into Saturday with gusts picking up to 20-25 knots. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 335 PM CDT Fri May 16 2025 No marine concerns are expected over the next 48 hours. Light showers will persist for tonight into Saturday night. Winds tonight into tomorrow will be northwesterly at 5 to 15 knots before becoming easterly Saturday night and Sunday. Winds of 5 to 15 knots will be seen on Sunday with gusts to 20 knots at the head of the lake. A period of stronger easterly winds is expected for next week starting on Monday which may lead to conditions hazardous to small craft. For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt. && .DLH WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. MARINE...None. && $$ DISCUSSION...BJH AVIATION...Rothstein MARINE...BJH ####018004028#### FXUS63 KGRR 162357 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 757 PM EDT Fri May 16 2025 .KEY MESSAGES... - Scattered Showers and Storms Tonight - Gusty Winds and Lingering Rain Showers Saturday - Cooler Temperatures into Next Week && .DISCUSSION... Issued at 300 PM EDT Fri May 16 2025 - Scattered Showers and Storms Tonight Another round of showers and storms is expected to move through after 8pm tonight. Storms could be strong to severe with damaging winds being the primary hazard, but can't rule out hail or a tornado with this evenings storms. We'll need to monitor convection currently in Missouri as it tracks northeast into southern Michigan and the showers and storms that develop in Wisconsin as they move across the lake. There is some uncertainty with the exact variables in play this evening. Model solutions vary with the amount of instability available along with the LCL values as storms approach. Hence why we can't completely rule out any one hazard. There is higher confidence in the source of lift with the 500 mb positive vorticity advection with the upper level low currently over Minnesota and with the 850mb 40 to 45 knot jet also bringing with in some moisture. Showers and storms will also be moving into a more mixed out environment, meaning there is an ample amount of dry air toward the surface. Downdraft CAPE values will be in the 800 to 1000 J/kg range as storms approach leading to the higher confidence in the damaging wind potential. - Gusty Winds and Lingering Rain Showers Saturday As the previously mentioned upper level low tracks through the northern Great Lakes, low level moisture and lift will bring some lingering showers to the area Saturday. It will also bring gusty westerly winds with gusts in the 30 to 40 mph range. As the low departs Saturday night winds subside and dry conditions return. Highs Saturday are only expected to be in the 50s to low 60s. - Cooler Temperatures into Next Week Pressure heights increase Sunday into Monday with dry conditions expected. Thereafter the pattern becomes a little less certain looking at the ensemble clusters and the 500mb flow. An upper level low will be in the vicinity but the timing and placement vary based on each cluster which impacts our rain chances through the remainder of the week. It does look like most of the rain will be to our south, but the placement of the low will determine how far north rain will spread. Either way it doesn't look like a total washout, but temperatures will remain on the cooler side with highs in the 50s and 60s and lows mainly in the 40s. Sunday night and Monday night there is a chance for temperatures to drop into the mid to low 30s for areas north of I-96. These temperatures could result in frost damaging susceptible vegetation. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 755 PM EDT Fri May 16 2025 Radar has become more active over western Lower during the past hour or so. Latest models indicate that we'll see a broken line of convection move across the terminals this evening with showers possible overnight. Cigs will fall to MVFR by sunrise and remain there the rest of the period. && .MARINE... Issued at 300 PM EDT Fri May 16 2025 Thunderstorms will be possible again tonight and may produce strong winds. Gusty southerly winds continue and become more westerly into Saturday as low pressure moves across the northern Great Lakes. Waves build into Saturday with heights of 4 to 7 feet. Winds and waves gradually subside Saturday night. Northwest winds may pick back up to Small Craft Advisory levels Sunday afternoon. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...Small Craft Advisory until 2 AM EDT Sunday for LMZ844>849. && $$ DISCUSSION...RAH AVIATION...04 MARINE...04 ####018004665#### FXUS63 KIWX 162358 AFDIWX Area Forecast Discussion National Weather Service Northern Indiana 758 PM EDT Fri May 16 2025 .KEY MESSAGES... - There is a chance for storms this evening, mainly between 7pm and 10pm EDT. A few thunderstorms could become severe with damaging winds the primary threat, mainly south of US 24. - Cooler and breezy on Saturday. - Periodic rain chances return next week, mainly Tuesday through Thursday. && .UPDATE... Issued at 745 PM EDT Fri May 16 2025 Fairly complicated set up here in the short term for here in northern Indiana. Which is probably not so much for forecasters for locations across the High Plains in which these very dry low level convective events are more commonplace. We have the synoptic winds from the southwest being amplified by convective outflows. These winds have then been kicking up dust/dirt back over central IL and has pushed this dust into northern IN with even some additional dust being added locally. Did address the wind/dust potential initially with an SPS but with the increase in wind speeds/dust decided to go with a combination of Severe Thunderstorm warnings for the winds and a blowing dust advisory for of course the dust. This is one event that will stand out in the future for sure. && .DISCUSSION... Issued at 215 PM EDT Fri May 16 2025 A shortwave, 70-80 kt 500 mb jet, and an attendant cold front track through this evening into the early overnight through the base of an Upper Midwest upper low. The associated shot of deeper ascent and some low level moisture return with a developing low level jet should bring a period of scattered showers/storms to most of the area this evening. Still cannot rule out a few strong to severe storms, mainly south of US 24, as shear profiles are favorable for organized convection. Instability is the limiting factor however with MLCIN and dry air to overcome, though incoming height falls/cooling aloft, and some last minute low level theta-e advection, should eventually allow updrafts to break the cap with MLCAPE potentially surging into the 1000-1500 j/kg range (highest southeast of US 24). High DCAPE with steep 0-3km lapse rates favor a downburst wind threat if any multicell clusters/lines emerge. Overall confidence in anything more than isolated strong to severe cells is low, with greater probs for severe storms off to the south near the primary moisture/instability axis. Cold advection on the southern fringes of a stacked low moving east through the Great Lakes region will provide significantly cooler and breezy conditions post-frontal later tonight into Saturday. Cyclonic flow around the low will also allow stratocu to build in for a time, especially north of US 30 where non zero chances for a rogue sprinkle/shower will exist. Sunday is definitely the preferred weekend day weather-wise as high pressure nudges in from the north with sunshine, lighter winds and slightly warmer temps. Next week continues to look wet at times as an upper low cuts off and slowly tracks east through the Central US and Great Lakes. The greatest chances for rain are the Tuesday through Thursday periods, with temperatures generally below average for mid-late May. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 757 PM EDT Fri May 16 2025 Complicated TAF period at least in the short term with southerly gusty winds being amplified by thunderstorm outflows and also kicking up dust and locally dropping vsbys due to the blowing dust. This will be expected through 03z Sat for KSBN and 04z KFWA. Will continue to monitor as this may take a bit longer to push through. Wind gusts up to 35 kts expected with slightly higher gusts possible at times through 04z Sat. South to southwesterly Winds back to more westerly late in the period and slightly decrease through the remainder of the TAF period. Gusts still expected around 25 kts. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Blowing Dust Advisory until 11 PM EDT /10 PM CDT/ this evening for INZ005>009-012>015-017-018-020-022>027-032>034-103- 104-116-203-204-216. OH...Blowing Dust Advisory until 11 PM EDT this evening for OHZ001- 002-004-005-015-016-024-025. MI...Blowing Dust Advisory until 11 PM EDT this evening for MIZ078>081-177-277. MARINE...Small Craft Advisory until 5 PM EDT Saturday for LMZ043-046. && $$ DISCUSSION...Steinwedel AVIATION...Andersen UPDATE...Andersen ####018004700#### FXUS64 KSJT 162359 AAA AFDSJT Area Forecast Discussion...UPDATED National Weather Service San Angelo TX 659 PM CDT Fri May 16 2025 ...New AVIATION... .KEY MESSAGES... - Isolated potential for a severe thunderstorm this afternoon and early evening from Brownwood to Brady to Mason and east. - Increasing chances for showers and thunderstorms Saturday through early next week. Strong to severe storms will be possible in the afternoons/evenings. && .SHORT TERM... (This evening through Saturday) Issued at 132 PM CDT Fri May 16 2025 SPC has added a slight risk of severe thunderstorms from Brownwood to Brady to Mason today. While storms are conditional, the slight risk looks good, as the instabilities in that area have increased with MUCAPES in the 4000 J/KG range. A cumulus field was also developing from Junction to Mason. If storms develop, very large hail of 3 inches+ are possible. Most of this activity should ending by 7 PM CDT, but carried it over for a few hours past 7 PM. A similar situation will exist for Saturday afternoon as a dryline forms along a Sonora to San Angelo to Abilene to Throckmorton line, with very unstable air with dew points in the lower 70s to the east. SPC again has a slight risk/along and east of the dryline, Storm activity may be conditional, depending on breaking the cap, but it develops, very large hail and damaging winds will be possible. Mild temperatures in mid 60s to lower 70s are expected tonight, with highs in the mid and upper 90s Saturday. && .LONG TERM... (Saturday night through next Friday) Issued at 215 PM CDT Fri May 16 2025 By Saturday night, the dryline and associated thunderstorm activity should mix back westward, with the potential for thunderstorms developing along the retreating dryline across parts of West Central Texas Saturday night into early Sunday morning. A similar setup will be in place for Sunday afternoon and evening, with much of the area under a Marginal Risk for Severe Weather and the northern portions of the Big Country under a Slight Risk. We would not be surprised to see the area of Slight Risk across the Big Country on Sunday extend further south and eastward once the high-resolution models can extend out that far and confirm the low level moisture and dryline position. For the beginning of the work week, there remains some chances for another round of showers and thunderstorms mainly over our eastern-most counties during the day, then spreading west into the evening and overnight hours before dissipating early Tuesday morning. Drier conditions will likely return for Tuesday and persist through the end of next week, with afternoon high temperatures in the low 80s to low 90s for the first half of next week increasing into the low to mid 90s by next Friday. && .AVIATION... (00Z TAFS) Issued at 657 PM CDT Fri May 16 2025 Expect VFR conditions to prevail overall through the next 24 hours. A few thunderstorms this evening were over far southeastern parts of west-central Texas, and will not affect any of our TAF sites. Considerable high cloud coverage will continue over the area tonight into the day Saturday. May have some patchy low cloud development between 11Z and 15Z Saturday over our southeastern counties, and this may potentially affect KJCT and KBBD briefly. Any lower ceilings would be MVFR. Scattered thunderstorm development is expected Saturday afternoon and evening (20-24Z) mainly east of a Sonora to San Angelo to Coleman line. Uncertain with coverage and placement at this time, but have seen enough indications to include Prob30 groups at KBBD, KJCT and KSOA. If a thunderstorm directly affects a TAF site, reductions in ceilings and visibilities could occur, along with a possibility of gusty winds and hail. Variable winds this evening will become southeast overnight. On Saturday, winds will be generally from the south at KBBD and KJCT. For our other TAF sites, expect south to southwest winds during much of the day. && .PRELIMINARY POINT TEMPS/POPS... Abilene 91 68 96 69 / 0 0 20 20 San Angelo 94 67 98 69 / 0 0 20 10 Junction 98 70 99 68 / 20 20 30 10 Brownwood 90 68 96 68 / 20 20 40 20 Sweetwater 93 67 95 69 / 0 0 10 10 Ozona 94 70 96 71 / 0 0 20 10 Brady 94 71 97 70 / 20 20 40 20 && .SJT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...04 LONG TERM....TP AVIATION...19 ####018005510#### FXUS63 KFSD 162359 AFDFSD Area Forecast Discussion National Weather Service Sioux Falls SD 659 PM CDT Fri May 16 2025 .KEY MESSAGES... - Strong winds and patchy rain showers diminish this evening. - Patchy frost possible on Sunday morning. - Elevated instability Sunday night into Monday morning could lead to isolated severe storms, with hail the main threat. - Widespread rain and isolated thunderstorms are expected Monday into Tuesday. EC ensemble and GEFS still pretty bullish for 1" or more rainfall amounts (40-70% chance). && .DISCUSSION... Issued at 155 PM CDT Fri May 16 2025 Low pressure will shift east of the area tonight into Saturday, slackening the pressure gradient and taking the lift with it. So winds will diminish tonight, although they remain breezy into Saturday, and showers should mainly be out of the area by mid evening. Saturday night into Sunday morning a surface ridge of high pressure noses into the area which will allow winds to drop further, likely less than 5 mph in many locations. This will then allow temperatures to drop with lows likely sneaking into the mid 30s in some locations. This may lead to some frost across the area and will need to be watched as the chance for lows below 35 are running about 30- 50% north of I-90. Sunday will see increasing easterly flow and increasing cloud cover as low pressure deepens over the Northern and Central Rockies. A fairly weak mid level wave will swing north into central SD with some moisture return in the mid levels as well. This should result in some spotty showers during the day, mainly west of I-29. Otherwise highs will likely top out in the 60s. Sunday night will see a much better surge of elevated warm and moist advection. Models are indicating about 500-1500 J/kg CAPE with 20-30 knots of elevated speed shear which could result in some isolated, elevated hailers. Currently timing for this would be in the evening to overnight hours. Fairly deep easterly flow in the lower levels should help preclude any wind threat. As this wave of lift moves through Sunday night into Monday morning some question marks arise for Monday and just how much and how widespread rain and thunderstorm chances will be. If enough warm air aloft moves in, the dendritic layer is well elevated and fairly dry, so instability will be needed to get showers and thunderstorms going. Most models do indicate decent instability (1000 J/kg CAPE) through the day, but are less agreeable on this warm layer aloft potentially cutting off development. On thing that continues to work in favor of additional development is a persistent inflow from the southeast of moisture and a bit more unstable air which should help produce enough lift for further development. One big thing to watch will be the upper level low and how this wobbles eastward with the potential for another low to develop in roughly IA Monday evening as a jet races into the Central Plains. This could bring a more distinct northern edge to the heavier rain and thunderstorms Monday afternoon into Tuesday morning and keep the bulk of this activity across NE and IA. Tuesday will likely see rain diminish from northwest to southeast as the low pressure wraps up and moves southeast. Still a lot of question marks regarding just where and when this low will end up, but for the most part unless some major changes occur, rainfall will be much diminished by Tuesday night. Flow becomes more westerly aloft Wednesday into Friday which should allow for milder temperatures and more sporadic chances for showers and thunderstorms. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 655 PM CDT Fri May 16 2025 Scattered showers will continue to fade through the evening as its parent low pressure system slides east of the area. MVFR clouds will linger; however, through the rest of the night and into Saturday morning. Biggest forecast challenge of the period was ceiling heights from KHON to KFSD in regards to the 2 kft level. Guidance indicates constant fluctuation on either side of 2 kft through much of the night into tomorrow morning in those locations. Based on downstream observations and which guidance has the best handle on the situation, opted to stay at 2 kft for KHON and mostly just below 2 kft for KFSD. All the clouds associated with this low pressure system will move away from southwest to northeast through the day Saturday, starting along the Missouri River Valley by mid-morning Saturday. These clouds will clear the entire area by Saturday afternoon, leaving mainly clear skies in place to end the period. Gusty 30-35 kt northwest winds will continue through this evening. Winds will gradually diminish through tonight and into Saturday morning. Gusts will be in the 15-20 kt range to end the period. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...Wind Advisory until 7 PM CDT this evening for SDZ038>040-050- 052>071. MN...Wind Advisory until 7 PM CDT this evening for MNZ071-072-080- 081-089-090-097-098. IA...Wind Advisory until 7 PM CDT this evening for IAZ001>003- 012>014-020>022-031-032. NE...Wind Advisory until 7 PM CDT this evening for NEZ013-014. && $$ DISCUSSION...08 AVIATION...Samet ####018006190#### FXUS64 KMEG 162359 AAA AFDMEG Area Forecast Discussion...UPDATED National Weather Service Memphis TN 659 PM CDT Fri May 16 2025 ...New AVIATION... .KEY MESSAGES... Updated at 633 PM CDT Fri May 16 2025 - A regional outbreak of severe thunderstorms is likely this afternoon into tonight with strong tornadoes, perhaps long tracked, damaging winds and very large hail. - An Enhanced (3 out of 5) to Moderate (4 out of 5) Risk for severe weather is in effect across the northern half of the Mid- South this afternoon into tonight. - Saturday will be mostly dry and warm. - Scattered showers and thunderstorms will persist from Saturday night through the middle of next week with chances for severe storms each day, especially Tuesday. && .DISCUSSION... (This evening through next Thursday) Issued at 214 PM CDT Fri May 16 2025 A significant severe weather outbreak is expected today. Storms have already produced significant hail and damaging winds this morning and minimal airmass modification in their wake. Tropical humidity remains across the entire region with 70+ F dewpoints within an increasingly warm boundary layer. Storms are expected to fire later this evening both along and ahead of a cold front positioned over OK/KS. These storms will head east, likely congealing into a line with the potential for scattered development out ahead. Today's environment is climatologically rare for the Midsouth in late spring. A stout EML has been positioned over the region for the past few days, containing 700-500 mb lapse rates into the 8 C/km range and continues to persist today. Surface insolation, albeit muted under a thick cirrus shield, in conjunction with these lapse rates will allow for MLCAPE of 3500+ J/kg this evening. Upper wind fields are expected to contain a strengthening mid- level jet streak during this time frame as well with the Midsouth optimally positioned under the right entrance region. Lift from this feature is expected to collate with peak heating, significantly reducing capping. Surface convergence will be somewhat nebulous this afternoon where a few renegade cells are possible, but the highest confidence for storms is still with the cold front as it passes through. Once storms are able to form, they will find themselves within a well-sheared environment with bulk shear in excess of 50 knots. Low- level hodograph curvature will be lacking early on which suggests a large (2"+) hail threat during the early evening. Very cold 850-700 mb wet bulb temperatures could create strong cold pools and a strong (75+ mph) damaging wind threat. As the evening progresses, low-level hodographs are anticipated to enlarge with both 0-1km and 0-3km SRH approaching the 200-300 m2/s2 range along and north of I-40 suggesting a higher tornado threat. Storm mode is still the largest question regarding the potential for significant tornadoes this evening. If prefrontal supercells are able to form, significant tornadoes are possible. Along the front, initially discrete storms are expected to congeal into a line with time. Tornadoes within this regime will be most likely while storms are discrete before being undercut by strengthening cold pools. Regardless, today has the potential to be a dangerous day with an Enhanced (3 out of 5) Risk to a Moderate (4 out of 5) risk for severe weather in effect across much of the region. Large (2+ inch) hail, swaths of strong (75+ mph) straight line winds, and the potential for strong tornadoes exists. The cold front will continue south through the night, eventually stalling somewhere over N MS. Temperatures should cool a bit tomorrow with a few diurnally driven showers across N MS. A threat for a few stronger cells containing marginally severe hail and damaging wind is possible. This threat also exists Sunday as the stalled boundary begins to lift north as a warm front in response to a new trough moving east through the Western CONUS. The western trough is expected to traverse the Central CONUS Monday, reaching the Midsouth Tuesday. Another warm, tropical airmass will be in place as this system approaches. Model guidance continues to place a surface low over the Midwest with a cold front moving through the region during the evening. Strong upper flow will overspread a destabilizing airmass, resulting in another chance for severe weather as outlined by the SPC. Specific details on hazards and the magnitude of any severe threat are hard to pin down at this time. However, at least a damaging wind and hail threat are possible. Models currently struggle to produce the low level SRH necessary for a widespread tornado threat, but some spin ups could be possible within an organized line of convection. This forecast is still several days out and will likely change through the weekend. So, stay tuned for updates. Ensembles are in good agreement with the upper flow taking a northwesterly orientation through the end of the week after the frontal passage Tuesday. Strong surface high pressure in combination with this upper pattern will lock in colder air through the end of the week. Highs are currently expected to remain in the 70s and low 80s to end the period with mostly dry weather. && .AVIATION... (00Z TAFS) Issued at 658 PM CDT Fri May 16 2025 Though delayed, TSRA development is underway along a cold front extending from west central to northeast AR. Additional isolated TSRA development further south, will likely merge with the frontal convection as we move through the evening. The net effect is a slower arrival time of TSRA at MEM, and a more linear convective mode, i.e., a broken line. The northern portion of the line will be more progressive, and the orientation of the line should extend from MEM to MKL around 05Z. PWB && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$ PUBLIC FORECAST...JAB AVIATION...PWB