UPDATE ON SEVERE WEAHTER THREATS FOR SATURDAY AND SUNDAY

The above image is the SPC severe weather outlook for Saturday. They continue to highlight north central and western Maryland in a level 2/5 slight risk of severe weather, with a level 1/5 marginal risk for the rest of our viewing area.

Most of Saturday will be dry and we expect very little if any storms during the daylight hours. This is due to the lack of a triggering mechanism to get storms to develop. That said, if by chance a storm were to form, it would likely be severe and capable of producing damaging winds or a tornado.

The models have come into agreement that a line of showers and thunderstorms will move into southern PA and far northern MD between 8pm and midnight Saturday night. Its going to be a very humid night, so there will be at least some instability to work with, along with plenty of wind shear. Assuming that the line of storms maintains its intensity, there could be a risk of isolated wind damage and isolated tornadoes across southern PA and northern MD. Overall, the risk is fairly low but its not 0. 

In the image below, I've outlined the areas at highest risk for isolated tornadoes using the RRFS model from WeatherBell Maps:

As far as hazards go, the ingredients favor primarily a risk of isolated damaging winds (gusts 50-60mph) as well as the chance for a few isolated tornadoes. Any thunderstorm will also produce dangerous lightning and very heavy rainfall rates as well. Hail is not really a concern in this situation. Again these will be isolated and not everyone will see the listed hazards.

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On Sunday, the threat shifts east. The image above is the SPC severe weather outlook for Sunday. A slight risk (level 2/5) for severe weather has been issued for areas east of Frederick, and a marginal risk (level 1/5) has been issued for areas west of there.

A cold front will be sliding through during the afternoon. The atmosphere will be very unstable with 2000-3000 j/kg of cape and 30-40kts of wind shear. This will create an environment very favorable for severe thunderstorms. The question we have is the timing of the cold front. If it speeds up, the the threat of thunderstorms will be confined to areas east of I-95 and especially the eastern shore. If it slows down a bit, then the risk would extend further west and include much of our area. Right now, the highest confidence for severe weather is along and east of I-95.

The main hazards on Sunday will be from damaging winds (gusts of 60-70mph possible) and large hail possibly the size of half dollars. There will also be a low end tornado threat in any supercell that can become established. And of course heavy rain and lighting will also occur in any storm. Storms should be more numerous on Sunday, but still not everyone will see these above hazards.