


Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
962 ACUS02 KWNS 080558 SWODY2 SPC AC 080556 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Tue Jul 08 2025 Valid 091200Z - 101200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHERN PLAINS AS WELL AS PORTIONS OF THE SOUTHEAST INTO SOUTHERN NEW ENGLAND... ...SUMMARY... At least isolated severe storms are possible in the northern Plains on Wednesday, with locally large hail and areas of severe gusts. Isolated damaging gusts are also possible across parts of the eastern U.S. ... Synopsis ... A midlevel ridge centered over the four corners will begin to break down on Wednesday as a low-amplitude shortwave trough quickly moves from off the northern California coast into the Great Basin. Additionally, a larger amplitude trough will move across southern Canada. Elsewhere, broad mid-level troughing will persist across the eastern US. Surface lee toughing will exist across the northern Plains in response to westerly downslope flow. This westerly flow will help maintain steep mid-level lapse rates into the northern Plains atop a moist boundary layer supported by southerly surface winds on the east side of the northern Plains lee trough. ... Northern Plains ... Strong diurnal heating should allow temperatures to warm into the mid-to-perhaps-upper 90Fs across much of the Dakotas by mid afternoon. This heating, coupled with surface dewpoint temperatures in the 60Fs, will support surface-based CAPE in excess of 2500-3000 J/kg with little to no convective inhibition. Additionally, modest northwest mid-to-upper-level flow on the northeast periphery of the four corners ridge will support somewhat elongated hodographs and effective-layer shear around 30 knots. Despite the region being displaced from the stronger large-scale ascent associated with the aforementioned shortwave troughs, isolated thunderstorms are still expected to develop by late afternoon. The overall thermodynamic and kinematic environment should support multicell clusters to transient supercell structures capable of producing large hail -- perhaps in excess of 2 inches in diameter. By early evening any thunderstorm clusters persisting will pose an increasing damaging wind threat. A categorical upgrade to Level 2/Slight Risk was considered with this forecast. However, given the nebulous forcing mechanisms for initiating thunderstorms, uncertainty remains as to the coverage of severe thunderstorms. As such a Level 1/Marginal Risk was maintained, even though a potential for significant hail exists. ... Southeast US to Southern New England ... Scattered to widespread thunderstorms will develop during the late morning into the afternoon within a moist, unstable, and weakly capped airmass. Precipitable water values around 2" will support water loading of updrafts and a resulting potential for strong thunderstorm winds capable of scattered wind damage. ..Marsh.. 07/08/2025 $$