Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
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362 ACUS01 KWNS 221955 SWODY1 SPC AC 221953 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0253 PM CDT Sat Jun 22 2024 Valid 222000Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN PARTS OF THE MIDWEST AND SOUTHERN NEW ENGLAND... ...SUMMARY... Scattered severe thunderstorms are possible through this evening across parts of the Midwest, mainly posing a risk of damaging winds and a few tornadoes. Scattered damaging winds are possible over southern New England through early evening. ...20Z Update... The severe weather forecast largely appears on-track with only a couple of adjustments based on latest observational/guidance trends. Isolated, high-based thunderstorms should develop farther southwest in southeast MT and northwest SD within a similar moderate westerly mid-level flow regime to ND. Across east-central Lower MI, a confined corridor of enhanced low-level SRH persists ahead of a low-topped convective rain cluster. There is still potential for this activity to deepen into thunderstorms amid MLCAPE near 500 J/kg with a low-probability tornado/wind threat, before spreading into Saginaw Bay. To its south, warm mid-level temperatures/weak lapse rates yielding meager buoyancy suggest that upstream thunderstorms across the Upper MS Valley should weaken as they cross southern LK MI this evening. Please see MCD 1373 for short-term discussion on the southern New England severe threat. ..Grams.. 06/22/2024 .PREV DISCUSSION... /ISSUED 1129 AM CDT Sat Jun 22 2024/ ...Midwest into Lower MI... A moderately strong mid-level shortwave trough over the eastern Dakotas will track into the upper MS valley this afternoon. The main synoptic surface boundary extends from northern IA into southern WI, with strong heating and ample low-level moisture present to the south. Present indications are that scattered thunderstorms will develop along the boundary by mid-afternoon and sag southward across eastern IA and northern MO/IL through the evening. Forecast soundings show moderate CAPE values and favorable deep-layer shear for convective organization and a few supercells, capable of damaging winds, hail, and a few tornadoes. The main limiting factors for a more significant severe weather event appear to be the warm temperatures aloft and resulting weak lapse rates, and CAM solutions indicating a rather quick evolution into more linear storm-modes. ...Southern New England... A cluster of thunderstorms currently over eastern NY is expected to intensify and track southeastward along a surface boundary into southern New England this afternoon. This may result in a corridor of locally damaging wind gusts. Have therefore added a small SLGT risk area. Please refer to MCD #1371 for further details. ...Western FL Peninsula... Strong heating is resulting in a hot/humid airmass over the western FL peninsula today, with temperatures in the mid 90s. Combined with dewpoints in the mid-upper 70s, steep low-level lapse rates, and high PWAT values, the environment appears favorable for a few wet microbursts later today. Several morning CAM solutions suggest organized outflow from early storms over eastern FL may further increase the risk of strong wind gusts. $$