Strong to severe storms are impacting the region currently, as forecast. The strongest storms are across SW areas which is as forecast as well. Storms will continue across the region through this evening before dying out with the loss of heating from the sun. Tomorrow will be warm and dry as high pressure builds in but the quiet weather only lasts a day and by Monday, another cold front will be at our doorstep with the chance for showers and storms, some of which could be severe.
Another shortwave will be digging south across Eastern Canada Monday and out ahead of it, divergence aloft and convergence at the surface thanks to an approaching cold front will provide the large scale rising motion necessary for strong storms. As of now, model guidance is in agreement we will have a trigger for storms Monday. Also of note is that the large scale pattern of NW flow around the NE side of the Central US heat dome supports this shortwave crossing the area Monday. We have our trigger. Now will there be enough fuel for strong storms? Instability is the biggest question at the moment.
Most model guidance suggests that winds will be out of the SE for most of the day Monday. A SE wind is one off the cold Gulf of Maine which would keep temps in the 70’s for most. That SE wind and those low temps would sufficiently stabilize the atmosphere so that we would stay more or less storm free. This could change, however. A peek at the Euro ensemble guidance suggests that timing remains uncertain and the potential exists for winds more out of the S or SW following the passage of a warm front. Euro ensemble mean CAPE shows this potential with values between 1,000 and 1,500 j/kg Monday afternoon. The timing of both the warm and cold fronts will be watched closely in the coming days to determine if strong storms indeed can form.
One thing to keep in mind is that even without typical severe storm impacts (hail, wind, etc.), there could very well be heavy rain on Monday. Guidance is pointing to Precipitable Water values (PWATs) of near 2″ which is tropical. Be aware that even without a severe thunderstorm threat, there very well may be a heavy rain threat. We do need the rain, however as southern areas are in moderate to severe drought.
Warm and dry conditions return for the middle of next week and a more substantial rain event hopefully will arrive by the end of next week into next weekend. More on that as we get closer.
I’ll have more updates on this event on Twitter tonight and tomorrow.