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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.


Sunday, July 16, 2023

SPC Jul 16, 2023 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1257 AM CDT Sun Jul 16 2023 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL PLAINS AND NEW ENGLAND... ...SUMMARY... Scattered large hail (some very large) and severe wind is possible across the Central Plains. A few tornadoes will be possible across portions of the Northeast. Isolated damaging wind gusts will be possible from the Red River to the Gulf Coast. ...Synopsis... A large upper-level trough, centered over the western Great Lakes early this morning, will continue to amplify through the day. A weak surface low is expected to develop across western/central New York this morning. Farther west, a cold front extends from Upper Michigan, across central Wisconsin, into northern Iowa and northern Nebraska. The front will continue south/east across the Great Lakes but is expected to stall across the Plains/Corn Belt by mid-day. ...Mid Atlantic to New England... A very moist airmass is in place across the East Coast with 1.9 to 2.2 inch PWAT values on most 00Z RAOBs and mid 70s dewpoints from the Carolinas to New England. Within this moist environment, SPC mesoanalysis suggests an uncapped ML parcel across much of New England early this morning which should remain through mid-day. Therefore, despite expansive cloud-cover and minimal surface heating, expect 1000-1500 J/kg MLCAPE across New England this morning. Across the same region, surface flow will strengthen somewhat in response to the developing surface cyclone. A 40 knot low-level jet will develop and overspread New England between 12Z and 18Z. This will yield 0-500m SRH around 100 to 150 m2/s2 with clockwise curvature in the lowest 1km. Given the moist profile, lapse rates will be very poor which may result in relatively weak updrafts. However, if stronger, sustained updrafts can develop, a couple of tornadoes are possible across portions of New England, primarily before 17Z. ...Central Plains into the Midwest... A cluster of elevated thunderstorms, visible on composite radar across northeast Wyoming/southwest South Dakota will likely be ongoing at the beginning of the period across south-central Nebraska. Evolution of this activity remains unclear as some 00Z CAM guidance shows it persisting through the morning and intensifying by early afternoon as the boundary layer destabilizes while other guidance has morning activity decaying and new afternoon convection developing along the remnant outflow boundary. Regardless of the exact solution, there will be some threat for severe wind gusts and large hail across northeast Kansas and vicinity. Across central Kansas, confidence is higher for a very unstable airmass to develop with the outflow boundary from morning convection, potentially acting as a focus for thunderstorm development during the afternoon. Strong instability and 45-50 knots of effective shear will support supercell storm mode with the potential for some very large (2+ inch) hail. Storms may eventually congeal into a cluster across central Kansas with an increasing damaging wind threat into the evening. ...TX/OK Red River to the Central Gulf Coast... Thunderstorms will likely be ongoing at the beginning of the period near the Red River. A cold pool is expected to emanate eastward from this cluster across north Texas during the morning. A very unstable airmass is expected by mid day with temperatures in the 90s and dewpoints in the upper 70s yielding 3000 to 4000 J/kg MLCAPE. Thunderstorms are expected to reintensify/develop downstream by midday/early afternoon. Despite mostly weak shear (15 to 20 knots), some damaging wind gusts will be possible given the extreme instability present in the region. ..Bentley/Wendt.. 07/16/2023 Read more CHECK UPDATE ZOOM GRAPHIC
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