MD 1852 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR SOUTHEASTERN PENNSYLVANIA...NEW JERSEY...DELAWARE...CENTRAL MARYLAND...AND ADJACENT PORTIONS OF NORTHERN VIRGINIA...INCLUDING DC
Mesoscale Discussion 1852 NWS Storm Prediction Center Norman OK 1029 AM CDT Thu Jul 31 2025 Areas affected...southeastern Pennsylvania...New Jersey...Delaware...central Maryland...and adjacent portions of northern Virginia...including DC Concerning...Severe potential...Watch possible Valid 311529Z - 311800Z Probability of Watch Issuance...60 percent SUMMARY...Thunderstorms are in the process of developing, and likely to gradually intensify through 1-4 PM EDT, accompanied by increasing risk for potentially damaging wind gusts. A brief tornado might also be possible, particularly across parts of east central and southeastern Pennsylvania into central New Jersey. DISCUSSION...Perhaps aided by forcing for ascent downstream of a short wave perturbation progressing through the southern periphery of larger-scale positively tilted mid-level troughing overspreading the northern Atlantic Seaboard, thunderstorms appear to be initiating along a stalled to slow moving frontal zone, and east of a weak surface low, across the northern Mid Atlantic. This is occurring as insolation within a boundary-layer characterized by seasonably high moisture content (including mid 70s F surface dew points) erodes inhibition. Lapse rates are generally modest to weak, and the boundary layer is not forecast to become deeply mixed, due to the moisture, but profiles still appear supportive of CAPE on the order of 1000-2000 J/kg. Beneath the southern fringe of the stronger westerlies, where flow at altitudes as low as 500 mb is around 30-40 kt, deep-layer shear is strong and supportive of supercell structures, and perhaps an organizing cluster, with potential to produce strong surface gusts aided by heavy precipitation loading and evaporative cooling in downdrafts. Thermodynamic profiles appear generally warm with limited potential for severe hail. A brief tornado might not be out of the question, but low-level hodographs, particularly south of the surface front, are likely to remain generally weak. ..Kerr/Smith.. 07/31/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OKX...PHI...CTP...LWX... LAT...LON 39747713 40357698 40687612 40957453 40617390 39087505 38667600 38597718 39107734 39747713 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 INRead more