Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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140 FXUS64 KHUN 211113 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 613 AM CDT Tue May 21 2024 ...New AVIATION... .NEAR TERM... (Today) Issued at 320 AM CDT Tue May 21 2024 A large area of high pressure continues to be in place over much of the southeastern CONUS. A frontal boundary is draped northwest of this feature through the northern Great Lakes region southwest into Iowa and extreme southeastern New Mexico. Much of the weather across the country is focused along this front with several impulses or areas of low pressure moving along it to the northeast. One of these pieces of energy is centered over central Michigan. Most of the energy associated with it remains over the Great Lakes region, but a weak trough axis extends SSW from it into central Ohio and SE Kentucky. This feature is helping to produce just enough weak convergence for an area of cloud cover that has developed over eastern TN and northern GA. Most of the area in northern Alabama and southern middle Tennessee is still experiencing clear skies though. Winds are still light and variable (3 mph or less) across most areas near and east of the I-65 corridor. Expect this to continue at least through 4 AM or so in those areas. Given the current dewpoint depressions in our typical fog prone areas near and east of the I-65 corridor (0 to 4 degrees), patchy fog was added near Lewis Smith Lake, the DeKalb Valley areas, and the Paint Rock River Valley. Not sure if it will become dense or very widespread since models do start to pick up winds to around 5 mph between 5 AM and 7 AM. The exception to this might be far eastern Alabama in the valley areas, but confidence is too low to include that in the forecast right now. With winds picking up first west of the I-65 corridor already, think that a pretty good gradient of temperatures will be experienced when you wake up this morning. Lows west of the I-65 corridor will likely only drop to the mid to upper 60s. Further east, lows will likely drop to between 60 and 65 degrees. During the day today, the upper level ridging south of this front remains fairly stout or strengthens a bit. This should continue to keep showers and thunderstorms well north of the area. Another disturbance along the front moves northeast into the western Great Lakes area, bringing them more showers and thunderstorms. There may be some isolated to scattered showers or storms develop to our east in northern GA or eastern Kentucky, as the weak trough axis producing cloud cover there now shifts a bit further east. This cold produce enough cloud cover over portions of NE AL and Franklin county (TN) to keep temperatures a tad cooler in the afternoon than further east. Despite that it will be a very warm day with highs in the mid to upper 80s there. Further west, expect highs to reach the 85 to 90 degree range. && .SHORT TERM... (Tonight through Friday) Issued at 320 AM CDT Tue May 21 2024 The axis of the upper level ridge (though still strong) weakens and a weak pre-frontal axis extending SSW of the impulse moving into the western Great Lakes region along the front makes some headway east towards the area. This will likely be able to produce some strong to severe storms near the axis of this pre-frontal trough axis. However, this will still be centered to our west and affect mainly the Mississippi Valley region. Further southeast, the eastern edge of this activity could approach north central MS and the Nashville area towards daybreak on Wednesday. Expect mainly mostly clear to partly cloudy conditions tonight, but some mostly cloudy conditions may start pushing into the area around daybreak. Southerly winds will likely remain between 5 and 10 knots through much of the evening. The exception to this might be in far eastern Alabama. There, some patchy fog may be possible. With increasing moisture advection over the area and higher winds, expect temperatures to only drop into the 65 to 70 degree range in most areas. The exception might be again far eastern Alabama, where some lows could drop into the 60 to 65 degree due to the lighter winds in that area. During the day on Wednesday, most guidance continues to flatten out the ridge aloft a bit more over the southeast. However, it still appears that the ridge is strong enough to stall the front just northwest of the area during the day across eastern Oklahoma NE into Kentucky. This will likely keep convection to our northeast still. However, on and off mostly cloudy conditions will likely occur. This should keep high temperatures a bit cooler than the previous day, only climbing into the mid to upper 80s across the area. Winds could become lighter again Wednesday night. This could set the stage for some more widespread fog development if thicker and more persistent cloud cover wasn`t expected. Not much changes Wednesday night, but models do slightly weaken the upper ridge southeast of the front just a bit more. This could allow maybe for a 20 to 40 percent coverage of showers or storms to make it into areas mainly north of the Tennessee River. At this time, do not think these would be severe. On Thursday into Friday, things don`t change much as another stronger impulse of energy forms along the stalled front over eastern Texas. We will likely be on the very edge with similar shower or thunderstorm chances. Again, more persistent cloud cover will likely keep highs in the lower to mid 80s both days. Lows will be very sultry only dropping into the 66 to 71 degree range. && .LONG TERM... (Friday night through Monday) Issued at 320 AM CDT Tue May 21 2024 This impulse along the front swings east Friday night and south of the area Saturday night. This subsequently bring medium to high (40-70%) chance for showers and storms to the area. General view of the storm environment would favor plenty of CAPE with sufficient shear to support at least a few organized strong storms, with gusty winds and hail (along with locally heavy downpours) being the main threats on Friday night into Saturday night. We`ll remain in a fairly active pattern through the the upcoming Memorial Day holiday weekend, with zonal low aloft allowing for additional shortwaves to traverse the region. Subsequently, medium chances (40-60%)for showers/storms will be present in the forecast both Sunday and Monday. && .AVIATION... (12Z TAFS) Issued at 613 AM CDT Tue May 21 2024 Light or calm winds will likely continue after 12Z. However, southerly winds are expected to become more established during the day today between 5 and 10 knots gusting to between 10 and 15 knots after 15Z. We should lose the wind gusts tonight, as winds remain between 5 and 10 knots. VFR conditions are expected throughout the TAF period. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...KTW SHORT TERM....KTW LONG TERM....KTW AVIATION...KTW