Weather Alerts For Johnstown, PA

There is a Slight Severe Storm Risk for your location. Continue reading for today's outlook from the National Weather Service's Storm Prediction Center. -------------------- National Severe Storm Outlook THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN IOWA AND NORTHERN ILLINOIS THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHEAST/MID-ATLANTIC STATES SUMMARY Widespread severe thunderstorms are expected across parts of the Midwest and Great Lakes region, including Iowa, northern Missouri, northern Illinois and southern Wisconsin to Lower Michigan and northern Indiana. This includes the potential for widespread/intense damaging winds, large hail, and tornadoes, some of which may be strong. Midwest/Great Lakes Portions of the region have been upgraded to a Moderate Risk. Another very active day with widespread/intense severe storms is expected regionally. A consequential severe risk is already ongoing this morning across Iowa/far northern Missouri, and will continue east-northeastward and become more prominent regionally during the day. A well-organized/eastward-accelerating bowing cluster of storms, now supported by an apparent MCV, has had a history of measured severe-caliber wind gusts overnight and in the predawn hours from southeast Nebraska into southern Iowa. A similar severe risk should continue east-northeastward through midday across eastern Iowa/far northeast Missouri toward northern Illinois, with more of a surface-based/tornado risk potentially unfolding relatively early today aside from a continued prominent damaging wind threat. Scenario is supported by a robust southwesterly low-level jet/moisture transport, even with some diurnal weakening of the low-level jet possible. Also influential is a prominent/increasingly neutral-tilt-shortwave trough and jet streak crossing the Corn Belt, notably strong features by mid-June standards. Convective overturning/outflow from last evening's MCS are still residual factors evident this morning in observational data/supplemental 3D mesoanalysis across far eastern Iowa, far northeast Missouri into central Illinois. This is sampled by the 12z observed sounding from KILX/Lincoln, IL. These residual factors may somewhat southward-focus the peak/most-intense severe weather later today, with more uncertainty progressively northward in general proximity to Lake Michigan latitudinally, including parts of Wisconsin/Michigan. The timing/residual impacts of this morning's MCS across Iowa/northern Missouri into northern Illinois and severe potential in its wake near the surface low and front, and/or to its (MCS) north-northeast are a bit less uncertain. That said, mass response/fluxes related to the dynamic shortwave trough/speed max will be notable and consistent with heightened severe-potential even if outflow/cloud debris exists and sub-regional areas of destabilization are sub-optimal. Details of later-afternoon severe potential is somewhat contingent on how the morning MCS further evolves, but a window for redevelopment in its immediate wake will probably exist. This will lead to a renewed round of severe storms as development occurs near the cold front, and perhaps preferentially favors prior outflow, with a damaging wind and tornado risk continuing eastward this evening as the low-level jet re=intensifies and as storms gradually grow upscale toward Lake Michigan and across Illinois/Indiana/Lower Michigan. Eastern Kansas and Southern Plains Additional thunderstorm development is expected along the trailing cold front into portions of the central/southern Plains. Deep layer shear will be maximized in the post-frontal environment; however, around 20-30 kt of effective bulk shear and moderate to strong instability will support some supercell structures capable of large hail and damaging winds. Storm motions and boundary parallel shear will likely lead to clustering and messy modes over time. Mid-Atlantic ad central Appalachians Forcing for ascent from multiple shortwave disturbances across the northeast and dewpoints in the 60s to 70s F will support development of widely scattered thunderstorms by afternoon across the Mid-Atlantic into the central Appalachians. Though vertical shear will be generally weak, moderate to strong instability will be in place will support stronger updrafts capable of damaging winds. It is likely that several clusters will emerge with potential for organizing along cold pools and more focused corridors of damaging wind potential.