SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1117 AM CDT Sat May 17 2025 Valid 171630Z - 181200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING OVER NORTHEAST TEXAS...SOUTHEAST OKLAHOMA...SOUTHWEST ARKANSAS...AND NORTHWEST LOUISIANA.... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF UPSTATE NEW YORK AND WESTERN NEW ENGLAND... ...SUMMARY... Severe thunderstorms producing large to very large hail, damaging gusts and a couple of tornadoes are expected across the southern Plains. Additional severe storms are possible across the Northeast. ...Central TX/Southern OK into the ArkLaTex Region... Morning water vapor loop shows a well-defined shortwave trough over southern AZ tracking northeastward. Ahead of this system, southerly low-level winds and steep lapse rates aloft have established a very moist and extremely unstable air mass from southern OK into central TX. Dewpoints in the low/mid 70s and ample daytime heating will yield afternoon MLCAPE values over 4000 J/kg. As the upper system and associated mid-level jet max approach the dryline, thunderstorms are expected to rapidly develop by mid-afternoon. Splitting supercells capable of very large hail will be the main initial concern, along with damaging winds and a tornado or two. Most model solutions suggest upscale growth of these storms into a bowing MCS by evening, tracking eastward across the ArklaTex region. Have extended the ENH a little farther east to accommodate this scenario, with damaging winds and large hail being the main concerns. This cluster of storms may persist overnight, tracking into central/northern MS. ...Northwest OK... The plume of dense cirrus ahead of the AZ shortwave trough will move east of northwest OK by late afternoon, allowing strong heating and destabilization. This combined with southeasterly low level winds near a retreating warm front will provide a corridor of strong instability and favorable low-level shear for supercell development. The coverage of storms in this area is uncertain and varied between the morning CAM solutions. However, the storms that form will pose a risk of very large hail, damaging winds, and a tornado or two. It is also unclear how far east this threat may persist, with some concern for an MCS tracking into northeast OK overnight. ...NY/New England... A progressive shortwave trough and associated mid-level jet is tracking eastward across the Great Lakes region today. Cooling temperatures aloft and strong daytime heating will lead to pockets of moderate CAPE and steep low/mid level lapse rates. Storms are beginning to form across NY and will move into a progressively more favorable air mass for strong/severe convection (including a few supercells) by mid-afternoon. Locally damaging winds are the main concern, but the strongest cells could also produce hail and perhaps a tornado or two. Refer to MCD #837 for further details. ..Hart/Moore.. 05/17/2025