Although an area of persistent troughing which has kept the area chilly this spring has remained in place, a high pressure system to our north led to downsloping westerly and northwesterly winds this afternoon. This warmed temperatures up to around 70 in most of the area, while keeping the atmosphere very dry, with dewpoints in the low 30s. The dry conditions in combination with the trough that is still in-place will allow temperatures to drop pretty quickly tonight, as areas in the interior could have temperatures falling into the upper 30s, and frost is possible. Elsewhere, low temperatures will probably fall in the 40s — still definitely chilly enough for the light jacket tonight.
Starting tomorrow, the weather pattern will begin to change. Warmth and moisture from the south and west will try to push towards our area, while the troughing will remain to our north and east. This will create a battleground, and a resulting warm front.
The above image shows the frontal boundary pretty clearly — the front is shown more clearly at the 850mb level, since surface temperatures are a bit more uniform due to continued downsloping flow. This will once again make surface temperatures a bit warmer for tomorrow than what they normally would be in our otherwise cooler airmass. This will allow high temperatures to approach 70 degrees again. Warm 850mb temperatures result in the potential for greater warmth given sunshine, but that potential is not always realized — and this is where the forecast becomes a bit more tricky for later in the week, which will be illustrated shortly.
Where the strong southwesterly flow at 850mb meets with the much lighter winds, is the general location of the frontal boundary, further illustrated by the strong temperature gradient. The continued northwest flow on the cold side of the boundary at 850mb will help keep things dry tomorrow, but once those southwest winds from 850mb approach in association with the front, our 850mb temperatures will rise, and the moisture in the atmosphere will increase significantly. This allows for the chance of showers and potentially even a thunderstorm on Wednesday night into Thursday morning. The warmer airmass will not allow temperatures to fall as much, as they will remain around 50.
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