SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1129 PM CST Thu Dec 18 2025 Valid 191200Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MID ATLANTIC... ...SUMMARY... Isolated damaging winds may accompany convection over the Mid Atlantic today. ...Mid Atlantic... Late-evening water-vapor imagery depicts a notable midlevel trough over the MS Valley, shifting east in line with latest model guidance. This feature is forecast to take a more negative-tilt orientation by late morning as 100+kt 500mb speed max develops/translates across the Mid Atlantic by 18z. Impressive 12hr height falls at 500mb will overspread the OH Valley into New England where values will range from 240-300m in response to this strong feature. Needless to say, very strong wind fields will provide background support for organized frontal convection. HREF guidance is in general agreement that a narrow strongly forced line of convection will develop along the surging cold front early in the period. Forecast soundings do not exhibit more than weak SBCAPE with this frontal convection, but some mixing is expected given that 0-3km lapse rates should be on the order of 7 C/km. 40kt mean wind within this layer is expected to contribute to gusty winds with this activity. Have introduced MRGL Risk of damaging winds to account for strong gusts with a narrow line of convection that will surge east along the front. Given the limited buoyancy across southern New England will not introduce wind probabilities at this time. ..Darrow/Squitieri.. 12/19/2025
