Currently after a somewhat prolonged heat wave, a much cooler weather pattern is taking hold and for now with Canadian high pressure in place, much drier conditions, with temperatures today through Thursday near to below average , however looking at the satellite , tropical trouble is already brewing for the eastern seaboard , for our forecast area it comes Friday into Saturday of this week
The next 48 -60 hours will be dry, tranquil and comfortable, warm days and chilly nights , but we see a pretty impressive trough for this time of year coming in from the west , and at the same time an area of low pressure starting to get its act together over the southern Gulf of Mexico
This low could develop into a tropical storm over the next 48 hours, and it is expected to be absorbed into the coming trough, and be bought up the east coast , with it being absorbed into the trough and the system coming up the coast hitting chilly waters the system will not be fully tropical , but it will still have all its tropical moisture, the trough coming in from the west will also have its own low pressure that will track west of the area, and this will make for very wet times for the east coast Thursday night through Saturday
This tropical system will not get very strong as conditions will not be favorable for anything more than a minimal tropical storm, the main issue with this will be the abundant tropical moisture and thus the threat for very heavy rain and flooding.
Now there will likely be 2 distinct rounds here, the first one will come late Thursday night and especially Friday, associated with the low pressure expected to develop along the trough and track to our NW , we will see some of the tropical moisture begin to get entrenched into this system , and this will bring a round of steady and heavy rain to a lot of the area , the north and west sections especially , there could be thunderstorms associated with this as well but nothing severe is expected , areas like southern NJ, Maryland Delaware etc will see the least amount from this round while areas like NW NJ, NE PA points northwest will likely see heavy rain and thunderstorms with potentially a couple to several inches of rain
We see the rain will first low will swing through mainly northern portions of the area, with southern areas just seeing showers and maybe an isolated storm , and round 2 is associated with the tropical low that will develop over the northeast Gulf
After potentially a brief break , the tropical or at this point in time likely either extra tropical or sub tropical depending , the low is expected to ride up the coast, this round of rain will be the most intense and likely focused more towards the coast, this will feature periods of very heavy rain, tropical downpours, gusty winds and potential flooding issues, I do want to stress that this looks like a relatively weak low so wind wont be much of an issue here most likely, breezy yes but damaging is not expected by a long shot , a steady raw southeasterly wind at 15-25 with gusts up to 30 are expected with some higher gusts possible along the coast unless the track of this low shifts west and we end up on the east side which is not expected at this time , flooding rains may be a different story
The low will continue its ride NE up the east coast, the bulk will be Friday night and early Saturday before it exits north and east, the good news with this is that it looks like a pretty quick hitter so the rain will begin to clear out by Saturday afternoon, but with a frontal boundary hanging along the coast some showers will be possible through Saturday night before totally clearing out
The rainfall forecast from the HPC/WPC shows us a widespread 3-5 inches of rain , I overall agree although I am thinking this may be just a tad to aggressive right now as there is uncertainty on whether the heaviest rains with round 2 will be along the coast or just offshore , some areas could see locally higher amounts than shown above if the heaviest rains with round 2 do occur inland and not offshore , so we still have some uncertainty here so I will continue to update through the week, just be prepared for very heavy rainfall from Friday morning through Saturday morning which could lead to widespread flooding.