Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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367 FXUS64 KHUN 061336 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 836 AM CDT Mon May 6 2024 ...New NEAR TERM... .NEAR TERM... (Rest of Today) Issued at 836 AM CDT Mon May 6 2024 Small MCS cluster has shifted into the Chattanooga area, with lingering light rain dissipating rapidly in southern middle TN and northeast AL. Cluster of TSRA in north MS and southwest TN continues to develop, but propagation eastward has been thwarted by subsidence behind the departing shortwave and stability in the wake of previous convection. Thus, confidence in redevelopment for our area today is lowering with time. CAMS guidance suggests this as well. However, will maintain a low PoP just in case for now as we further assess the environment that develops with daytime heating. && .SHORT TERM... (Tonight through Wednesday night) Issued at 443 AM CDT Mon May 6 2024 The remnants of afternoon showers and thunderstorms today should spread east-northeastward and out of the local area shortly after sunset this evening, and although there is a low probability for redevelopment of a few showers after Midnight as low-level SSW flow strengthens ahead of a dryline and broken QLCS surging eastward into the Mid/Upper-MS Valley, we will leave the forecast dry at this time. Otherwise, it will be a very warm night, with lows in the upper 60s for much of the region due to elevated SSW winds and development of low stratus clouds prior to sunrise. Latest solutions from the 00Z CAMs suggest that a subtle surface trough ahead of the Pacific cold front/dryline to our north may initiate the development of thunderstorms to our southwest (across the Arklamiss region) late Tuesday morning that would spread northeastward into our forecast area during the afternoon, with additional storms likely to develop along the same trough across our region as morning low clouds disperse allowing for rapid destabilization early Tuesday afternoon. With mid-level flow predicted to back to W or WSW and increase to 35-45 knots in the wake of a departing shortwave ridge, resultant deep-layer shear will support multicell clusters and perhaps a few supercells that could produce large hail/damaging winds (especially as steepening lapse rates aloft and surface temps in the mid 80s will generate moderate-strong instability highlighted by CAPE in the 2000-3000 J/kg range). This regime may persist into Tuesday evening, with separate clusters of storms (originating along a frontal confluence axis across the OH Valley) perhaps propagating southeastward into our region after Midnight in the presence of a WSW low-level jet of 25-35 knots. With shear and instability remaining favorable for strong-severe storms throughout the overnight hours, a Marginal (Level 2/5) Risk is warranted. During the day on Wednesday, it still appears as if a frontal wave (originating across the southern High Plains Tuesday) will shift northeastward from the OK-KS border into the Mid-MS Valley. Rapid development of intense convection is expected to occur Wednesday afternoon within a very unstable and strongly sheared environment to our northwest (in the vicinity of the cyclone`s trailing cold front from southern MO into northeastern TX). Although there are still some minor differences in timing, this activity should evolve into a potent MCS Wednesday evening as it spreads southeastward, reaching the local CWFA in the 6-12Z timeframe Thursday. Environmental parameters appear quite favorable for a high impact severe thunderstorm event for our region during this timeframe, primarily from the standpoint of large hail and damaging wind. However, if the low-level jet strengthens to 30-40 knots (as indicated by some guidance), then the risk for a few tornadoes will increase as well. && .LONG TERM... (Thursday through Sunday) Issued at 443 AM CDT Mon May 6 2024 Trailing stratiform precipitation in the wake of a rather broad MCS early Thursday morning will likely be in progress across much of the region at 12Z Thursday, but should slowly spread southeastward over the course of the morning. Additional showers and perhaps a few storms may also redevelop during the afternoon as a cold front shifts southeastward through the TN Valley, but airmass recovery in the wake of widespread early morning precip should not be sufficient to raise concern for strong-severe convection. A final round of postfrontal showers may occur late Thursday night, along the northern fringe of another well organized convective complex traveling eastward along the central Gulf Coast. Beyond this point, a cooler/drier airmass in the wake of the cold front will reduce POPs to around 10% on Friday and Saturday. However, there are indications that another Gulf low may develop late in the weekend, with a slight chance POP for showers introduced on Sunday. Highs this weekend will be in the lower 70s, with lows in the l-m 50s. && .AVIATION... (12Z TAFS) Issued at 648 AM CDT Mon May 6 2024 Showers and thunderstorms associated with a northward-moving warm front will continue to impact the HSV/MSL terminals thru late this morning, with TEMPO groups for MVFR conds included btwn 12-16Z (which is also the timeframe when additional AWWs for lightning appear most likely). Beyond this point, the coverage of convection should diminish this aftn and become focused north of the TN River, so we will not mention additional SHRA/TSRA in the forecast at this point. Forecast soundings indicate that skies will begin to clear around sunset, but potential development of BR/FG will be hindered by a persistent SSW wind of 5-10 kts. Low stratus clouds may develop across the region btwn 10-12Z Tuesday, providing MVFR cigs once again. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...17 SHORT TERM....70 LONG TERM....70 AVIATION...70