Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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585 FXUS64 KHUN 220246 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 946 PM CDT Tue May 21 2024 ...New NEAR TERM... .NEAR TERM... (Rest of tonight) Issued at 946 PM CDT Tue May 21 2024 A 500-mb ridge (which was aligned across the TN Valley earlier this evening) will progress southeastward overnight, with WSW flow aloft predicted to increase into the 30-40 knot range by sunrise. A gradual increase in the coverage/density of convective debris clouds (originating from thunderstorms to our west) is expected in this regime, and this coupled with light southerly winds at the surface should result in a rather warm night featuring lows ranging from the m60s (NE) to u60s (NW). Current thinking is that the cold front (responsible for convection to our west) will decelerate as it shifts southeastward through the Mid-MS Valley during the early morning hours, likely in response to the eastward motion of a trailing shortwave trough across the central Rockies/High Plains and subsequent development of a secondary frontal wave across northwest TX. However, due to the increase in deep-layer steering flow, it would certainly be possible for weakening clusters of thunderstorms to move off the front, perhaps grazing the northwestern portion of our CWFA around or shortly before 12Z Wednesday. Thus, we have maintained a low (20-30%) POP for portions of northwest AL/southern TN during this timeframe. In spite of strengthening flow aloft, weak instability will limit storm intensity should any convection survive as far east as our region, with occasional lightning the primary concern. && .SHORT TERM... (Wednesday through Friday) Issued at 228 PM CDT Tue May 21 2024 Moisture will continue to increase across the region as an upper trough axis shifts east across the Great Lakes, pushing the ridge axis farther east. Wednesday will be another dry day with afternoon temperatures nearing 90 degrees despite the increasing cloud cover. As broad upper troughing becomes more dominant, this will result in increasing chances (20-50%) for showers and thunderstorms by Thursday. These storms will be primarily diurnally driven as a sfc cold front is held up to our north and west. By Friday, a shortwave trough axis will swing across the area, and combined with rich moisture will result in medium (40-60%) chances of showers and thunderstorms. Given that this is more typical of a summer-time pattern, some of these storms could be on the strong side and could produce gusty winds and small hail, but the chance for widespread severe storms looks very low and confined to areas farther west. Daily highs will remain in the mid to upper 80s with lows near 70 degrees. && .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... (00Z TAFS) Issued at 702 PM CDT Tue May 21 2024 Conditions will remain VFR at the HSV/MSL terminals throughout the valid TAF period, with few high-based Cu expected to dissipate over the course of the evening as bkn-ovc layers of convective debris clouds begin to spread eastward into the region. Although the cold front responsible for thunderstorm activity to our west will decelerate as it tracks southeastward through the Mid-MS Valley overnight and should stall before reaching our area tomorrow morning, the close proximity of the boundary may result in a few showers and storms across NW AL/southern TN throughout the day. However, anticipated storm coverage does not warrant inclusion of VCTS or PROB30 groups for KMSL at the current time. Sfc winds will remain from SSE overnight and SSW during the day tomorrow, with sustained speeds of 5-10 kts. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...70/DD SHORT TERM...25 LONG TERM...KTW AVIATION...70/DD