A strong southerly flow of pure tropical air will bring showers to Maine today and some of them could contain some pretty heavy rain. There’s a lot of transition about to take place in the atmosphere and as I look into next week I see another chance of a cold rain, perhaps even the first flakes of snow in the higher elevations of the mountains. This will be followed by another warm-up for the final week of the month.

The simple explanation for the rain today is colder drier air to the west of New England lifting the warm and humid air over us now and bringing showers, possible thunder and copious amounts of rain. The piece of the atmospheric puzzle that is a bit unknown is how much; if any of the moisture from hurricane Gonzalo will be pulled into our weather system to enhance the rain. The picture below is from the water vapor channel of the GOES satellite. The white shading represents high levels of moisture while darker colors are dry. Note the dark eye (drier) in the center of hurricane Gonzalo.

The map below is from the GFS model. I put a circle around Gonzalo and a rectangle around the tropical moisture plume ahead of the cold front affecting our region. There appears to be some interaction between the two which will likely enhance the rainfall late today and overnight. This would mean that some areas could see over 2 inches of rain. Even without the connection to Gonzalo’s moisture this is a very juicy weather system and will bring plenty of rain to the area.

Humidity levels will run high into the evening and temperatures mild. The home-bound commute will be a wet one with some areas seeing big puddles. We haven’t had a lot of rain this fall, so the upside of this precipitation is that we do need rain as we head into winter.

After the system passes a return to sunshine happens Friday. It’s still going to be quite mild with highs 65-70. It won’t be as humid. Friday night is also a mild night with low temperatures remaining in the lower 50s for much of the night.

A cold front crosses the area late Saturday and ushers in the coldest air of the season so far. This change will be dramatic and noticeable. Highs on Sunday, in spite of abundant sunshine will struggle to reach 40F in the mountains and only in the lower 50s along the coast. It’s really going to feel like late fall come Monday morning with a hard freeze over the far interior and perhaps a frost along the coast. Monday through Wednesday mornings could see frost anywhere so use the weekend to move plants inside or at least be prepared to cover them up next week.

Another weather system may bring a period of cold and damp weather at the tail end of next week prior to another warm-up next weekend. Of course this is getting to the edge of the reliability of a forecast so expect some changes to this part of the prediction in the coming days.

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