1/24 – Brittany’s “Incoming Rain” Tuesday Evening Forecast

This is the time frame that will be looked at the most. A warm front will lift out of the gulf and move over the area around noon today. This front will allow some sh/ts to develop by the afternoon hours. The environment will be continually changing with respect to dynamics and kenematics. Values starting out this morning around 6am will be on the low end as far as shear and lift values. But this will change to some very robust numbers 12hr later. Any value one looks at will be through the ceiling. This scenario would normally be a home run hit out of the ball park for severe wx. But the window will be tight to get this sfc based. The warm sector with CAPE values at their highest will be in and around 600J over areas of the north shore while these values could reach up to 1kJ for some south shore areas, so we would have a high shear low CAPE event. The next thing that is glaringly obvious is the almost 1c inversion and almost isothermal layer between 925 and 850mb. It is possible that this layer can cool as it is lifted and the sfc warms just a bit causing the line to become sfc based shortly after 00z this evening. This would cause anything that is found rotating whether minor or strong to not reach the sfc until after 00z. Then it depends on exactly where the line of storms is when it does. Dry air peaks at 700mb and is found ahead of and moving in rapidly behind this line as well. This would cause very strong downdrafts to occur along the entire line. Most of this wind would not reach the sfc until after 00z but gradient winds will already be quite high so it wouldn`t take much to reach the sfc to cause a problem. This changes once the line can be sfc based around or after 00z today. When most of this wind can reach the sfc, the line should easily produce winds in excess of 50mph. Momentum transfer could even be calculated to bring these numbers northward. Again, this will be mainly where this isothermal layer can be eroded. Very high rain rates of 3 to 4 inches per hour over about an hour could cause some flooding issues for a few locations, but the pace of this line will be quite fast so widespread flooding does not look to be the biggest issue with this line. We will hold off on a flash flood watch for now as the main issue is already being highlighted. Once the front clears the area it will flush dew pts and temps rapidly. Winds become northwest and will remain moderate to strong for some areas before easing Thursday.

Cool dry air mass will remain over the area through much of the week and the next best rain chances come in for the weekend with a new cold front moving through by the start of next week.

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