Today will feature more of the heat and humidity we saw yesterday as a cold front approaches then crosses the region.
Satellite imagery this morning shows a mix of sun and clouds across the region with the sunniest spots currently being along the coast and the cloudiest spots currently being found in the north/mountains.
As the morning goes on, I’d expect some of this cloud cover to burn off and by noon, we should be enjoying partly to mostly sunny skies across the region. The coastal plain will, as per usual, be sunniest. This sunshine will help push temps into the low-mid 90s for southern NH and much of the coastal plain of ME. As the front crosses the region this afternoon, winds will shift towards the west which means that the coast will no longer have access to the cooling influence of the Gulf of Maine. As a result, expect temps to spike into the upper 80s/low 90s all the way to the beaches. The exception, of course, will be far southern parts of the Midcoast peninsulas where winds coming from the west will still have access to some water.
During all this heat, unfortunately the humidity will remain high. Dew points will be stuck at or above 70 for most of the region today despite the drying influences of downsloping. As a result, heat index values will push towards 100 across southern NH and SW ME. The rest of the ME foothills/coastline will see heat index values in the mid/upper 90s. As a result, heat advisories have been issued for our entire area outside the mountains for this afternoon. This heat will be dangerous if proper precautions aren’t taken. Basically, try to limit strenuous activity during the heat of the day and be sure to stay hydrated.
With all this heat and humidity and a cold front in the vicinity, we would be making a big mistake to neglect talk of thunderstorms this afternoon. The biggest limiting factor in this afternoon’s severe weather will be that it’s too hot aloft to support thunderstorms without a strong initial upward push (this is known as a capping inversion). So we won’t see very many storms. That said, for the one or two that might pop up along the coastal plain this afternoon, the environment will be very favorable for damaging winds in addition to heavy rain and frequent lightning. So you probably won’t see a thunderstorm this afternoon, but if you do, it could be a fairly strong one. The best chance for storms will be closer to the coast during the early/mid afternoon hours.