Mesoscale Discussion 2052
Issued: · Valid: –
Summary
Severe thunderstorms are expected across parts of southeastern Pennsylvania, central and southern New Jersey, Delaware, Maryland, and Virginia through early evening. These storms may initially produce tornadoes before bringing an increasing risk of damaging wind gusts toward coastal areas.
Product Text
000 ACUS11 KWNS 201754 SWOMCD SPC MCD 201753 NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-202000- Mesoscale Discussion 2052 NWS Storm Prediction Center Norman OK 1253 PM CDT Thu Aug 20 2026 Areas affected...parts of southeastern Pennsylvania...central and southern New Jersey...north central and eastern Virginia...much of Delaware and Maryland. Concerning...Severe potential...Watch likely Valid 201753Z - 202000Z Probability of Watch Issuance...80 percent SUMMARY...Thunderstorms are likely to develop and intensify through 4-6 PM EDT, accompanied by the risk for a couple of tornadoes initially and increasing potential for strong to severe gusts spreading toward coastal areas into early evening. DISCUSSION...Moderate to strong boundary-layer destabilization is ongoing across much of the northern Mid Atlantic, particularly within seasonably high moisture content air advecting northward through the coastal plain, to the east of deepening (albeit weak) surface troughing to the lee of the Blue Ridge. This is occurring downstream of mid-level troughing, with at least a couple of convectively generated perturbations and belt of augmented westerly flow (30-50 kt in the 700-500 mb layer). It appears that associated forcing for ascent may increasingly begin to impact a corridor from central Maryland through southeastern Pennsylvania by 20-22Z, if not a bit earlier, supporting the initiation of intensifying thunderstorm development. At least initially, this may include a few evolving supercell structures in the presence of strong deep-layer shear. Downstream of a developing wave along a weak low-level baroclinic zone strengthened by differential heating, low-level hodographs are forecast to remain modest to weak. However, they may still be sufficient to contribute to potential for a couple of tornadoes, aided by appreciable near-surface buoyancy developing in associated with insolation, warm advection and dew point increases into the lower 70s F. Otherwise, at least some upscale growth of initial storms will contribute to increasing potential for damaging surface gusts, with additional thunderstorm development southward along and east of the deeper lee surface troughing. ..Kerr/Smith.. 08/20/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PHI...AKQ...CTP...LWX... LAT...LON 39437731 40007709 40347561 40497448 39637445 38797545 38047655 37317704 37667808 38897776 39437731 MOST PROBABLE PEAK TORNADO INTENSITY...100-125 MPH MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN