Area Forecast Discussion
Issued by NWS Huntsville, AL
Issued by NWS Huntsville, AL
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150 FXUS64 KHUN 081728 AFDHUN Area Forecast Discussion National Weather Service Huntsville AL 1228 PM CDT Wed May 8 2024 ...New AVIATION... .NEAR TERM... (Rest of Today) Issued at 950 AM CDT Wed May 8 2024 Some light rain showers have been observed over the local area this morning, as strong WAA continues over the region south of a warm front. A cluster of strong thunderstorms can be seen moving east through the I-40 corridor east of Nashville. This will be important to watch throughout the day as we will remain in a warm and moderately unstable environment. Though the better synoptic forcing and main round of strong/severe thunderstorms is not expected until late this evening/overnight, will keep a close eye our for mesoscale boundaries that could provide enough lift to generate storms this afternoon. Given a look at model soundings, any storms that are able to form this afternoon will be in an environment conducive for all forms of severe weather given a likely supercell storm mode. Expect cloud cover to thin late this morning, as already seen over NW AL, and will allow sfc temps to rise into the mid to upper 80s. Given recent satellite trends, did raise highs slightly during the morning update as well as tweaked sky cover and PoPs to better match current trends. Be sure to keep checking in for updates today as the afternoon round of storms remains highly conditional but likely impactful if storms are able to form. && .SHORT TERM... (Tonight through Friday night) Issued at 437 AM CDT Wed May 8 2024 The forecast for tonight remains rather complicated, largely due to the weak nature of deep-layer forcing for ascent across our region and fact that thunderstorms will be tied to processes occurring well to our northwest. However, at this point, the most likely scenario seems to be that the risk for severe thunderstorms across our CWFA may increase as early as the 0-3Z timeframe, either from isolated cells that develop to our southwest late this afternoon and spread northeastward, or with development of new storms along outflow from widespread convection to our north that may drift southwestward into southern TN/northeast AL. A separate MCS may also evolve this evening out of convection that develops late this afternoon along the cyclones cold front (extending from the low southwestward into north central TX). Precisely where this system will develop and track is still uncertain, but present indications are that it would not arrive in our forecast area until the 6-9Z timeframe at the earliest (and perhaps as much as 3-6 hours later than this). The combination of 40-50 knot WSW flow aloft and steep mid-level lapse rates atop a moist boundary layer (featuring dewpoints in the u60s-l70s) will support a risk for large hail and damaging winds, with a modest SW low-level jet of 25-35 knots providing sufficient shear in the 0-1km layer for a lower-end risk for tornadoes. Several CAMs suggest that convective outflow will eventually outrun the MCS as we move forward in time, with extensive trailing stratiform rain and embedded thunderstorms expected to gradually spread southeastward and out of the region by 18Z Thursday. The actual cold front should shift southeastward late Thursday afternoon and exit the forecast area during the evening hours, as another broad complex of thunderstorms tracks eastward along the central Gulf Coast. Although redevelopment of showers and storms along the cold front appears unlikely in our region, we have indicated a low-medium chance POP on Thursday night to account for some uncertainty regarding the path of the MCS to our south and potential for the northern edge of the stratiform rain shield to graze our region. In the wake of any lingering morning precipitation on Friday, dry conditions are currently predicted on Friday and Friday night. However, with a longwave trough expected to cross the region on Friday and a trailing vort max digging southeastward into the region Friday night, a fair amount of mid-level cloud cover is anticipated (and perhaps even a few very light showers). These two periods will mark the coolest of the forecast, with highs in the u60s-m70s Friday and lows in the u40s-l50s Friday night. && .LONG TERM... (Saturday through Tuesday) Issued at 437 AM CDT Wed May 8 2024 A generally dry weather pattern will continue across the region this weekend. However, a clipper system diving southeastward into the western Great Lakes will send a reinforcing cold front through the region on Saturday, perhaps bringing a few light showers to locations north of the TN River. Chances for rain will begin to slowly return to the region as early as Monday, which is when a series of lower-latitude troughs may initiate the development of one or more areas of low pressure across the western Gulf of Mexico that would shift northeastward early next week. Due to indications of a modifying low-level airmass across the TN Valley, instability will gradually increase as we move forward to Tuesday, with a low chance for thunderstorms apparent as well. && .AVIATION... (18Z TAFS) Issued at 1228 PM CDT Wed May 8 2024 VFR to MVFR cigs have prevailed across the region this morning and are forecast to persist through the majority of the TAF period. Chances for showers and thunderstorms will increase later this evening in the 00-01z timeframe, some of which could be severe. The risk for storms will persist through the morning hours, and reductions to IFR/LIFR conditions will be possible within heavier storms. Frequent lightning, wind gusts up to 50-60kts, and large hail will be the main concerns overnight. Gradient winds sustained at 12-15kts with gusts up to 25kts will also be possible outside of any thunderstorm activity. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...25 SHORT TERM....70 LONG TERM....70 AVIATION...25