####018007950#### FXUS63 KMQT 031710 AFDMQT Area Forecast Discussion National Weather Service Marquette MI 110 PM EDT Fri May 3 2024 .KEY MESSAGES... - Active pattern continues through next week as a series of low pressure systems track across the U.S. and affect Upper MI. Above normal precipitation expected, including chance of thunderstorms at times. - Mostly above normal temperatures expected, generally 5 to 10 degrees above normal on the majority of days thru the middle of next week. && .SHORT TERM /TODAY/... Issued at 504 AM EDT Fri May 3 2024 Current water vapory imagery/RAP analysis highlight a well-defined shortwave rotating over the MN/Canada border with its associated occluded front already well into Upper Michigan. As expected, showers have quickly tapered off with frontal passage with the only activity on latest radar mosaic concentrated over the easternmost portions of the UP. And, even these should taper off by mid- morning. So far, convective activity has been non-existent, but still cannot rule out a few rumbles of thunder over the far eastern counties after sunrise. Most of the forecast area will be sunny this morning as forecast soundings trend toward a dry column. The exception will be the eastern third of the UP where it will take a bit longer for the moisture/cloud cover to clear out. Gusty southwest winds in the 20 to 30 mph range, especially across the western UP will contribute to rapidly falling dew points and temperatures climbing into the upper 60s/low 70s (inland). Recent rainfall will, however, mitigate today's fire weather threat. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Issued at 542 AM EDT Fri May 3 2024 Overall, the first half of the extended period (tonight through Monday night) is mostly dry and sunny as high pressure tracks across the area with just a brief chance for rain showers on Saturday. Elevated fire wx conditions may occur each day Sat - Mon, but are more likely on Sunday and Monday when sunny skies help us dry out. On the other hand, we return to a pattern with frequent rain chances for the Tuesday thru Friday time frame as a broad area of low pressure spins across the region. There are early signals for a prolonged stretch of drier weather starting the weekend of May 11/12, but temperatures appear to average near normal at this time. Starting with tonight, weak surface ridging to our east results in light southerly flow with upper level cloudiness spreading across the western UP overnight. Mostly clear skies across the east should allow for good radiational cooling into the upper 30s away from downsloping along the Lake Superior shoreline. The next weather maker approaches Saturday morning and most guidance suggests a weak but deepening surface low. Rain chances spread across the western UP during the morning which keeps high temps cooler (around 60F) compared to the central and especially the east where highs approaching 70F are forecast. Warmer temps/deeper mixing across the east within the dry pre-frontal air mass suggests potential for locally elevated fire wx conditions. It's worth noting that both NAM and GFS soundings show single digit RH values in the mid-level dry layer that we'll be mixing into. Increasing cloud cover should limit mixing potential, but conditions appear to be trending more volatile across the east ahead of Saturday's rain chances. The cool front and associated rain chances spread across the central and eastern UP during the afternoon and evening, respectively. The NAM-3km even delays precip at Newberry until around midnight or 3-5 hours later than the GFS. HREF ensemble mean MUCAPE remains less than 100 J/kg, but HRRR simulated radar indicates an increasingly convective pattern as showers track east across the area. Overall, the forecast may still exaggerate the rain potential with this system since model soundings only show a 3-6 hour window of rain chances at any one location. Limited instability and duration indicate light amounts are most likely. Dry high pressure settles across the area on Sunday allowing sunny skies to spread across the area during the morning hours. In fact, CAMs suggest potential for fog resulting from moisture lingering in a boundary layer inversion beneath clearing mid/upper level clouds. A more straight-forward radiation fog setup could materialize Sunday night under high pressure, clear skies and light winds. Otherwise, fire weather is the primary concern for the Sunday-Tuesday period. Sunday and Monday are both likely to see min RH dipping below 30% across the interior, but light winds temper the fire wx threat. Stronger winds are expected on Tuesday and if the dry air mass lingers a bit longer then Tuesday likely represents a more volatile combination of low RH and winds. However, that possibility depends on rain chances being delayed until late in the day which current model blends do not indicate. Late week rain chances are associated with a deep closed low developing across the Northern Plains late on Monday that slowly spins eastward over the subsequent week. Moderate rainfall and embedded thunderstorms are again possible with the warm front passage Tuesday/Wednesday followed by spottier showers Thursday/Friday. A cold core upper low suggests a large diurnal component to the late week shower activity. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 109 PM EDT Fri May 3 2024 VFR conditions continue through most, if not the rest of the TAF period as weak ridging moves over us the rest of this afternoon. Starting late tonight, another low pressure currently over the Central Plains lifts northeastward towards the Upper Midwest and brings more rainfall to the west as soon as Saturday morning (although some sprinkles could be seen here and there tonight). This incoming rainfall could bring MVFR and possibly lower conditions back across KIWD by the end of the TAF period. Meanwhile, expect the gusty WSW'rly winds to die down later today as the sun sets. While we could see some marginal LLWS over the TAF sites (namely KCMX), the chance is only around 20 to 30%. Therefore, LLWS was not put into the KCMX TAF at this time. && .MARINE... Issued at 542 AM EDT Fri May 3 2024 Light winds, mainly out of the south-southeast are currently being observed across Lake Superior and winds are expected increase while veering southwesterly today. While gusts up to 25kt are expected over western Lake Superior this afternoon, winds diminish to less than 20kt tonight. Expect winds mostly below 20kts across Lake Superior this weekend, but northwesterly winds increase to around 20 knots Saturday night behind a cold front before becoming light again on Sunday. High pressure that arrives over the Upper Great Lakes late this weekend shifts eastward on Mon while a deep low pressure emerges over the western Dakotas. This will result in increasing easterly winds late on Mon into Tue when gusts up to 30kts are expected. Patches of locally dense fog are occuring over western Lake Superior this morning, which is expected to push mainly into Canadian waters as south/southwesterly winds increase today. If fog does not clear off of the lake today then additional rain chances on Saturday may result in increasing fog coverage. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Small Craft Advisory until 5 PM EDT this afternoon for LSZ242>244-247. Lake Michigan... None. && $$ SHORT TERM...TDUD LONG TERM...EK AVIATION...TAP MARINE...EK ####018004979#### FXUS63 KOAX 031711 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 1211 PM CDT Fri May 3 2024 .KEY MESSAGES... - Dense fog this morning for much of southwest Iowa and parts of southeast Nebraska is expected to clear around or shortly after 8 AM. - Thunderstorms are expected this evening into the overnight hours south of a line from Columbus to Shelby with a 5 to 10% chance of damaging hail and wind. - There is another chance of severe thunderstorms (15 to 30 percent chance) Monday afternoon and evening. && .DISCUSSION... Issued at 416 AM CDT Fri May 3 2024 Today into Tonight: Water vapor imagery this morning shows a broad trough over the northwest quadrant of the CONUS while a handful of storm clusters travel eastward underneath the southwesterly flow from Texas to the northeastern US. A recent surface map shows the main surface low of the mature cyclone centered over far northwestern Minnesota with its main influence on the local area being a weak ridge of high pressure allowing surface temperatures to cool efficiently and for calm winds, resulting in areas of fog in southwest Iowa and southeast Nebraska. Shortly after sunrise, expect fog to dissipate and for winds to reestablish out of the southeast and increase in speed, with gusts of 20 to 25 mph during the afternoon hours. Highs are expected to climb into the low-to-mid 70s, with an approaching cold front expected to bring our next chance of storms late this evening. By the early evening hours, short-term models are in good agreement that convection will organize along a cold front extending from just southeast of the Nebraska Panhandle northeastward into north-central Nebraska. These storms along the cold front are expected to continue eastward in a QLCS form, passing through the forecast area from 9 PM to 6 AM. With 30 to 40 kt wind shear values expected alongside sufficient ML and MUCAPE around 1500-2000 J/kg in the pre-frontal region, portions of these storm will have the potential to be strong to severe. The timing of storm arrival will oppose storm potential, with nocturnal stability seeming to limit CAM-forecasted wind gust. Nonetheless, steeper lapse rates near the KS/NE border and enhanced surface moisture will give southeast Nebraska the best shot at seeing damaging hail and winds. A lower-end chance of seeing strong to severe storms does extend northward to a line from Columbus to Shelby, but potential will be limited by worse surface moisture and as a result lower instability. Saturday and Beyond: By Saturday morning, we'll be left with northwesterly winds and a break in the action as a weak ridge builds ahead of the next deep system. Highs take a hit both days into the 60s, but they should be an overall nice couple of days. The next focus of the forecast period comes Monday, when a high-amplitude and negatively-tilting trough pivots eastward from the Rockies, shooting a cutoff low northeastward just to the north of the forecast area. With it strong frontal passage will be dragged eastward with steep lapse rates, strong moisture transport, and strong deep-layer shear that will result in another round of strong to severe storms. Long- range model hodographs certainly have enough low-level curvature to entertain a tornado risk, but the orientation of the front and how negatively tilted it will become will have a great deal to say regarding storms' ability to stay discrete or not. Fortunately this round of storms will mark the last for what looks to be the remainder of the work week with increasing chances for moisture returning next weekend and highs in the upper 60s. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1207 PM CDT Fri May 3 2024 VFR conditions this afternoon with some high clouds over northeastern Nebraska and winds out of the southeast. We'll see a line of thunderstorms move across eastern Nebraska overnight tonight along a cold front with winds shifting to northwesterly behind the line of storms. I have given a good estimate of timing for storm arrivals at each of the terminals but this timing may need to be adjusted as we see the complex develop this evening and we get a better idea of timing. Models are fairly confident in MVFR cigs developing behind the line of storms with a shield of light rain. Cigs could lower as low as 700 feet, but more confident in MVFR cigs at this time. Will see how models trend ahead of the next TAF package to see if we need to change post-frontal cigs to IFR (20 percent chance at this time). Expect low cigs to break out by Saturday afternoon. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Petersen AVIATION...McCoy ####018005317#### FXUS65 KTFX 031711 AFDTFX Area Forecast Discussion National Weather Service Great Falls MT 1111 AM MDT Fri May 3 2024 ...Aviation Section Updated... .SYNOPSIS... One more cool and showery day is expected today before milder temperatures move in for the weekend. Another cool and wet Pacific weather system impacts North-central and Southwest Montana Sunday through at least mid next week, with the most significant precipitation and coolest temperatures expected Monday through Wednesday. && .UPDATE... A cool northwesterly flow aloft will continue to support scattered rain and snow showers through the day today, primarily across Central and North-central Montana. No significant changes were needed with the update this morning. -AM && .AVIATION... 1111 AM MDT Fri May 3 2024 (03/18Z TAF Period) Primary concerns through this TAF period will be for lingering low clouds and rain/snow showers, primarily across the plains this afternoon and early evening. Looking ahead toward Saturday, VFR conditions prevail, with a breezy easterly to southeasterly wind developing across the plains by late morning. Mountains will be obscured through the afternoon today across Central and North- central Montana. -AM Refer to weather.gov/zlc for more detailed regional aviation weather and hazard information. && .PREV DISCUSSION... /ISSUED 520 AM MDT Fri May 3 2024/ The latest satellite and meso-analysis shows abundant cloud cover within a northwesterly flow aloft. Light snow showers have been ongoing all night, mostly over the northerly upslope areas adjacent to the Little Belt, Highwood, and Snowy Mountains. This shower activity will more or less persist through this afternoon with the continued northwesterly flow, though accumulation amounts will generally be negligible. Transient ridging builds in tonight for clearing skies with temperatures bottoming out in the 20s for most locations. Patchy fog development can be expected in spots, but shouldn't be a widespread problem. With one more day of ridging aloft, Saturday should be the driest day over next week while temperatures climb to near of slightly above average. Deep southerly flow aloft develops over Southwest MT Saturday night ahead of a closed low moving onto the Pacific NW coast. This system will trek eastward into S ID on Sunday, placing the Northern Rockies on the ascent side of the system for northward expansion of shower and isolated thunderstorm activity, though temperatures will remain near average for one more day. H700 flow slows down by Sunday afternoon and MU CAPE looks to be around 100 to 300 J/kg (highest southwest MT), so not expecting anything beyond general thunderstorm risks at this time. Ensembles remain in decent agreement with the aforementioned closed low swinging NE into E MT and slowing down some Monday through early Thursday. Although, there are differences on the precise path of the low, most favor cool, wet, and windy periods during this timeframe. According to the NAEFS Standardized Anomaly, H700 temperatures are forecast to be around -8C for much of this event, which would support mountain accumulating snow, but mostly rain at lower elevations. Current probabilistic forecasts for rainfall highlight the eastern portions of North-central MT with the highest chances (50 to 70%) for 1 inch of rainfall during the 72 hr period ending next Thursday at 6 am, with nearly all locations in the CWA standing at least a 50% for a quarter inch of rainfall for the same time period. The one drier exception looks to be southwestern valleys from Dillon to the Three Forks area. As mentioned earlier, thermodynamic profiles should confine accumulating snow to mountain areas, with the Little Belts and the Madison/Gallatin ranges seeing 60% + chances for 8 inches of snow or more Monday through Thursday, with most of it falling Tuesday night into Wednesday. H700 flow on the backside of this low will be at or above the 30 to 40 kt range for an extended period, resulting in gusty to at times strong northwesterly surface winds. While all days Monday through Wednesday look to be on the windier side, Tuesday is being singled out by the EC Extreme Forecast Index and NBM probabilistic forecasts as the windiest day overall, with many locations seeing 70% + chances for wind gusts above 40 mph. Drier and milder conditions move in for Thursday and Friday of next week, though around 50% of the ensembles support weaker troughing remaining in place for non-zero chances for precipitation and near average temperatures heading into next weekend. - RCG && .PRELIMINARY POINT TEMPS/POPS... GTF 50 26 63 42 / 30 0 0 10 CTB 49 26 59 37 / 20 0 0 10 HLN 54 31 68 44 / 10 0 0 10 BZN 51 28 66 41 / 10 0 0 10 WYS 46 20 60 36 / 0 0 0 30 DLN 52 30 65 44 / 10 0 0 40 HVR 50 27 63 39 / 40 0 0 0 LWT 42 23 59 37 / 40 0 0 10 && .TFX WATCHES/WARNINGS/ADVISORIES... None. && $$ http://www.weather.gov/greatfalls ####018007594#### FXUS63 KLSX 031711 AFDLSX Area Forecast Discussion...Updated Aviation National Weather Service Saint Louis MO 1211 PM CDT Fri May 3 2024 .KEY MESSAGES... - An active weather pattern will continue this weekend and through much of next week, bringing multiple chances of showers and thunderstorms to portions of the area. - This pattern will lead to a chance of isolated strong to severe thunderstorms on Saturday, with additional strong to severe thunderstorm chances next week. However, details pertaining to any severe thunderstorm threat next week are unclear at this time. && .SHORT TERM... (Through Saturday Night) Issued at 313 AM CDT Fri May 3 2024 Current water vapor imagery shows a trough over the western CONUS with a shortwave moving through the Upper-Midwest and Northern Plains. At the surface, a low is in a similar location, with its cold front seen in surface observations moving into northeastern and central Missouri. Forcing from the front and a weak shortwave aloft continue to drive scattered showers across the area. As the shortwave progresses eastward and the front exits the area later this morning, rain chances will wind down and end west to east. Despite easterly-northeasterly winds behind the front today as high pressure settles into the Midwest, mid- to upper-level flow from the south-southwest will reduce the potency of this post-frontal airmass and keep temperatures at to just above climatological normals. Despite the front clearing the CWA, it will not have scrubbed southern portions the area of boundary layer moisture completely. As a weak shortwave moves through the Mid-South during peak heating this afternoon, this low-level moisture will yield upwards of around 1,000 J/kg of SBCAPE that will lead to isolated thunderstorm development mainly over far southeastern Missouri. Thunderstorms are not expected to be strong, as weak 0-6km bulk shear of roughly 15-20 kts will produce updrafts that are weaker and short-lived. Convection will dissipate during the early evening as the sun begins to set and instability wanes. Tonight, the aforementioned surface high will move eastward and return southerly low-level flow to the area. In turn, low-level moisture will begin advecting into the CWA ahead of a cold front moving across the Great Plains toward the Middle Mississippi Valley. Convection associated with the front will approach the CWA early tomorrow morning, but will be in the process of decaying. So, while I can't rule out very isolated damaging wind gusts across northeastern Missouri, strong to severe thunderstorms Saturday morning are unlikely. The better chance for severe weather comes Saturday afternoon as the cold front moves into the area and a subtle shortwave travels overhead. Then, guidance consensus is that roughly 1,500 J/kg of SBCAPE will be present among 25-30 kts of 0-6 km bulk shear. Another round of showers and thunderstorms is expected along and ahead of the front in this environment, leading to an chance for isolated strong to severe thunderstorms capable of large hail and damaging wind gusts during the afternoon and evening. The amount of instability is conditional on how much clearing of convective debris from the early morning storms can occur prior to peak heating. If clouds stay thicker and more widespread, we could see less instability and weaker storms. Elmore && .LONG TERM... (Sunday through Thursday) Issued at 313 AM CDT Fri May 3 2024 At the start of the extended period, guidance consensus is that southwesterly flow aloft will still be in place over the Middle Mississippi Valley. Both deterministic guidance and ensemble clusters show a shortwave within this flow moving out of the Southern Plains and into the Middle Mississippi Valley through the day on Sunday and into Monday, though, there remain differences in the phasing of this feature. A quicker solution would lead to a faster surface low and rain chances during Sunday afternoon mainly along and south of I-70, while a slower solution would lead to much of Sunday being dry across the area with rain moving in during the overnight hours. Regardless, guidance consensus is that the surface low will weaken as a warm front stalls somewhere across the Midwest. As we get into early next week, confidence in the evolution of the upper-level pattern and thusly local surface conditions decreases. In general, a trough will deepen over the western CONUS as a shortwave swings through the Great Plains and into the Upper Midwest. In turn, a surface low will follow a similar trajectory and occlude as it swings a cold front through the Great Plains and toward the Middle Mississippi Valley Monday into Tuesday. Guidance differs on the progression of this front through the region, with some stalling it west of the CWA while others have it clearing the CWA. However, if the latter solution materializes, the front will quickly lift northward as a warm front for Wednesday. Narrow temperature spread among ensemble guidance for Wednesday showing temperatures rising compared to Tuesday provides high confidence that in some way, the CWA will be in the warm sector on Wednesday as the western trough reloads. Additional shortwaves will round the trough as it begins to edge eastward, sending another surface low through the Midwest Wednesday into Thursday. This low will swing a cold front through the CWA, with a majority of guidance having it clear the CWA. Through this stretch (Monday-Wednesday), the CWA at times will be in the warm sector multiple times beneath southwesterly flow and in proximity to a warm and/or cold front. This does set the stage for the potential for strong to severe thunderstorms, and severe probability guidance from Colorado State University shows portions of the area with heightened probability through these days. However, severe thunderstorm potential will hinge on the location and timing of the fronts - something that is uncertain at this lead time. As a result of the cold front passing through the area sometime Wednesday into Thursday, ensemble consensus is that temperatures will cool by the end of the week into next weekend as the trough continues eastward and northwesterly flow aloft sets up over the Midwest. By how much temperatures will cool is uncertain, however, as temperatures range by about 10 degrees between the 25th and 75th percentile. Confidence is high in temperatures being at or below climatology given the 75th percentile hovering around seasonal normals. Elmore && .AVIATION... (For the 18z TAFs through 18z Saturday Afternoon) Issued at 1204 PM CDT Fri May 3 2024 IFR/MVFR ceilings have been slow to scatter this morning. Observations have shown very gradual improvement, but restricted flight conditions will likely last into early afternoon. Otherwise, winds will veer to southeasterly overnight and to southwesterly by 18z Saturday. By this time, a cold front will be approaching the forecast area, introducing the chance of showers and thunderstorms and a wind shift to northwesterly to all terminals Saturday afternoon into evening. Jaja && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX ####018003311#### FXUS64 KOHX 031712 CCA AFDOHX Area Forecast Discussion...Corrected for Wording National Weather Service Nashville TN 1202 PM CDT Fri May 3 2024 ...New SHORT TERM, LONG TERM... .SHORT TERM... (Rest of today through Saturday) Issued at 1200 PM CDT Fri May 3 2024 There are just so many ways one can state that an unsettled weather pattern will persist through this entire forecast period. Looking at the short term part, maybe some breaks in potential rounds of showers and storms, earlier this afternoon and across locations around and west of I-65 corridor on Saturday afternoon. Yes, a few strong storms may be possible at times, but really not expecting any organized severe storm potential. Lows tonight will be seasonably mild in low to mid 60s. Highs on Saturday will also be above seasonal normal values ranging upper 70s to lower 80s, mid 70s higher elevations of Cumberland Plateau Region. && .LONG TERM... (Saturday Night through next Friday) Issued at 1200 PM CDT Fri May 3 2024 Looking into a little bit more detail here, mid state will remain in the warm sector of synoptic surface frontal systems to our west and north with prevalence of southwesterly flow aloft and potentially more upper level disturbance passages than one can count embedded within this flow aiding in these rounds of convective developments. Just like in the short term, some strong storms may be possible at times, but all in all, really not expecting any organized severe storm potential at this time. The only exception to this is the hinting by SPC in its latest Day Five Outlook of strong convection being possible near Land of the Lakes Region on Tuesday. Temperatures will continue to be seasonably warm. As for all these rounds of showers and storms expected, total rainfall amounts this afternoon through Friday afternoon are expected to generally range 2.5" to 3.5." && .AVIATION... (12Z TAFS) Issued at 615 AM CDT Fri May 3 2024 Showers have spread across Middle Tennessee this morning, and it appears that low ceilings are soon to move in as the boundary layer becomes more saturated. Rain chances stay with us for the foreseeable future, so get used to these kinds of TAFs. There is some instability in the atmosphere, especially during the afternoon, so we've included a few hours of VCTS after 18Z. However, we don't expect any sort of organized convection, so it is difficult to pinpoint any exact timing of thunderstorm activity due to their scattered nature. Rain chances will taper off (temporarily) by this evening. && .PRELIMINARY POINT TEMPS/POPS... Nashville 80 66 82 65 / 90 50 70 50 Clarksville 78 63 80 64 / 90 50 50 40 Crossville 74 61 74 60 / 100 50 80 50 Columbia 80 63 80 64 / 90 60 70 50 Cookeville 76 63 76 62 / 90 50 80 50 Jamestown 75 61 76 60 / 100 50 80 50 Lawrenceburg 80 64 79 64 / 90 60 70 50 Murfreesboro 80 64 79 63 / 100 40 70 50 Waverly 79 63 80 64 / 80 50 50 50 && .OHX WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...JB Wright LONG TERM....JB Wright AVIATION.....Rose ####018006285#### FXUS64 KMRX 031713 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 113 PM EDT Fri May 3 2024 ...New AVIATION... .UPDATE... Issued at 947 AM EDT Fri May 3 2024 Showers continue to move through the southern Appalachians this morning. Very little if any lightning is occurring at this time with the showers, but expect as the day goes on we should see a bit more electrical activity going on. No major changes were made to the forecast outside of hourly PoP values to line up with radar trends this morning. && .SHORT TERM... (Today and tonight) Issued at 330 AM EDT Fri May 3 2024 Key Messages: 1. Increasing chances of showers and storms this morning through the evening, with a potential lull in activity overnight. 2. While severe weather is not expected, a few instances of small hail, wind gusts up to 40 mph, and locally heavy downpours are possible this afternoon. Discussion: Upper level disturbances will bring increasing chances of showers and storms to the forecast area today. Regional mosaic radar already depicts a rain shield moving into western Kentucky, central Tennessee, and eastern Mississippi this morning. Precipitation chances will gradually increase across our forecast area through the morning hours, with just general rain showers as the predominant weather type. As we transition into the afternoon hours, hi-resolution models suggest development of MLCAPE in the 300-800 J/kg range, which will lead to increasing chances of thunder. A weak shear profile and mid level lapse rates struggling to reach 6C/km should keep any storms from reaching severe levels, although, any stronger storm could lead to locally gusty winds up to 40mph and pea-size hail. PWAT values will generally approach near 1.4 inches. This is around the 90th percentile based on sounding climatology out of BNA. As such, we cannot totally rule out some isolated flooding concerns with any slow moving or training convection this afternoon. Thankfully, below normal rainfall over the last month has allowed for 1 hr FFGs of 1.8-2.3" across the forecast area, really minimizing this threat. A marginal risk for excessive rainfall covers areas generally along and west of I-75 - where the better chance for relatively more effective convection exists. Temperatures will typically be near normal. Ensemble guidance suggest we may see a window of little to no activity during the late evening/overnight hours. && .LONG TERM... (Saturday through Thursday) Issued at 330 AM EDT Fri May 3 2024 Key Messages: 1. An unsettled pattern is expected through the extended period with daily scattered to numerous showers and storms. More organized convection is possible by Wednesday/Thursday of next week. 2. Temperatures will be generally above normal, especially next week. Saturday through Monday At the start of the period, a fairly weak upper-level flow pattern will be in place with a shortwave moving in from the west. With broad moisture and surface heating, Saturday will consist of scattered to numerous convection throughout the day. Based on the weak flow, the convection will be thermodynamically-driven as very minimal shear will be present. Overall, instability will be fairly typical of the summer, i.e. near 1,000 J/kg of MLCAPE. PWATs will also be 1.4 inches or higher, which is around the 90th percentile for this time of year. With these conditions, some stronger storms with gusty downburst winds are possible, in addition to locally heavy rainfall rates. Thankfully, fairly dry conditions, including low-end drought, will keep any flooding concerns very localized. Heading towards Sunday, gradual height rises are expected with embedded shortwave energy and similar thermodynamic conditions. This will lead to slightly warmer temperatures than on Saturday with additional showers and storms expected. A closed upper low will also be noted to our west and will approach towards Monday. This may lead to slightly better coverage than on Sunday, but the overall impact will be the same. Tuesday through Thursday The unsettled pattern will continue into the middle of the week with continued embedded shortwave, broad moisture, and surface heating on Tuesday. By Wednesday to Thursday, however, a more dynamic pattern is anticipated with the upper jet (in excess of 100 kts) dipping further south. Upper-level divergence will help to strengthen the 850mb, possibly to in excess of 40 kts. A surface front will also slowly drift southward. While discrepancies still exist, these indications suggest an environment with potentially better thermodynamics and deep-layer shear sufficient for more organized convection than in the earlier part of the extended period. At this time, low probability HWO wording will be kept to encompass the multiple rounds of convection and potential locally heavy rainfall. However, the Wednesday to Thursday timeframe will be something to watch for more organized and/or robust convection. && .AVIATION... (18Z TAFS) Issued at 111 PM EDT Fri May 3 2024 Showers and thunderstorms can be expected in the southern Appalachian region through the rest of the daytime hours today. Difficult to say exactly when a storm may impact a terminal and there could be several rounds of storms through the evening hours. Expect mostly showers, but cannot completely rule out lightning in the vicinity of the airports. We should see a lull in activity overnight, with more widespread storms and lightning expected tomorrow. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 66 81 64 84 / 70 80 40 70 Knoxville McGhee Tyson Airport, TN 63 78 63 82 / 70 90 50 70 Oak Ridge, TN 63 78 62 82 / 60 90 50 70 Tri Cities Airport, TN 61 76 60 80 / 50 90 60 80 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ SHORT TERM... LONG TERM....BW AVIATION...