More Rain Monday

Saturday 2/16/08:

1. Chilly today and tonight: A cold front cut through the region Friday evening and allowed a bubble of modified arctic air to move into New England. While the brunt of the cold is to our north, we are still feeling the effects of the chilly air mass. The morning sounding from Chatham showed 925 mb temperatures of -11C, with 850 mb readings about a degree colder than that. With a north-to-northwest wind aiding in the delivery of the cold air, readings of this nature should cap highs in the upper 20s today. Winds will die down tonight and skies will remain clear, which will allow for some good radiational cooling. Lows should easily drop into the 10s in most spots. The exception may be out near Provincetown where the wind may have a tougher time quitting, which could keep readings in the low 20s.

2. After the quick hitting surge of cold of Saturday, southerly winds will take over on Sunday and allow milder air to build back into the Northeast. So despite a very cold start, highs will end up near 40°F during the afternoon. In fact, computer guidance wants to push readings into the low to mid 40s across parts of the Cape, but given the very chilly start and some advancing clouds, I'm not quite sold we can get that high - perhaps by evening readings will rise into the lower 40s, but for a daytime temperature, I suspect we're closer to 40°F. Either way, this will ensure that the next weather system approaching late in the weekend is a rain-maker here on the Cape.

3. Another rain event Monday. A strong low pressure area will track from the Southern Plains to the Great Lakes during the second half of the weekend, dragging a potent cold front across the eastern part of the country. Very mild air will surge northward ahead of the storm, producing a widespread rain storm for much of the east. In fact, even ski country is likely to see a good deal of rain from this storm system as the cold air is quickly scoured out. Rainfall totals should not be as impressive as last weeks storm, but a .5 to 1 inch rainfall is expected and certainly some brief downpours are possible Monday morning as the heaviest action slides through. With such a mild air mass being transported northward in advance of a fairly strong cold front, conditions will be marginally favorable for a rumble of thunder. We will have to watch the wind once again. A powerful low level southerly jet on the order of 70 knots will be cranking in advance of the storm. While conditions won't be favorable for dragging too much of this wind to the surface, we could see 40 to 50 mph wind gusts and I wouldn't be surprised to see some of wind alert from the National Weather Service.

4. Turning colder next week. A deep upper level trough will set over the eastern half of the country behind the storm system, allowing for colder air to move back in for the rest of the week. By the middle of the week, we may stuck in the 20s once again.