For the weather this work week to be fairly quiet, we sure do have a lot of weather that we need to talk about!
We will start with a look at the regional satellite and radar composite across the Southeast early this Tuesday morning. We've had a weak disturbance skirting areas of eastern Tennessee overnight, with a slight enhancement in cloud cover. Some forecast models had shown a few showers over there for early this morning, but it's mainly been dry. Locally, we are mostly clear across southern middle Tennessee and northwest Alabama early this morning. High pressure is centered over the region, and that is keeping us mostly clear and quiet here.
Today and be another mostly sunny day, and temperatures get disrespectfully hot by mid/late September standards as we head into the afternoon. We start the day in the upper 60s around daybreak, and then we warm through the 70s and 80s through the morning and midday until most of us top out in the mid to upper 90s by afternoon! No, we are no stranger to occasional hot weather this time of year. We have had triple digits in September, and occasionally even October, but our average daytime high for the final 10 days of the month usually runs below 85 degrees, and gets to 79 by the end of the month!
We expect more of the same for Wednesday with mostly sunny skies and highs again in the mid to upper 90s. Heat index values both this afternoon and on Wednesday are likely to be near or just over 100 degrees. We look to stay dry through Wednesday, but a frontal boundary moves through on Thursday, and that might bring a stray shower or two to the area. Most of us, though, should stay dry. The big change it will bring is a significant drop in temperatures! We go from highs in the low to mid 90s on Thursday (the first official day of fall) to highs in the upper 70s to lower 80s by Friday! Temperatures moderate back into the mid to upper 80s over the weekend as the next disturbance in the northwest flow approaches.
A few stray showers can't be ruled out Saturday evening and overnight into early Sunday morning as deeper moisture moves back northward into the area, but better rain chances arrive Sunday into Sunday evening as another cold front approaches. We are holding rain chances at 40% for now, but we may be bumping those up, as it looks like we have a decent shot at scattered to possibly somewhat numerous showers and thunderstorms across the area. A few storms may have gusty winds or heavy rainfall.
Showers look to come to an end as we head into Monday morning, and then we're back to gradually clearing skies by the afternoon and cooler and drier weather for a time behind the front for the first part of next week.
We continue to monitor tropical activity in the Atlantic basin, and first up is Hurricane Fiona. as of the overnight advisory, Fiona has now become a major Category 3 hurricane with maximum sustained winds of 115 mph. Fiona is expected to reach Category 4 status as it heads northward over the next few days. Fiona will not be a direct impact to the mainland United States, but it may have significant impacts on Bermuda and Newfoundland through the end of the week and into the weekend, from south to north along its path.
Off to the east and northeast of Fiona's track, out in the open Atlantic, there is a disturbance that has a decent shot at becoming a short-lived tropical depression over the next few days as it moves northward, before conditions become more hostile for development. Of more interest is a tropical wave east of the Windward Islands that will be moving into the Caribbean later this week. The National Hurricane Center now gives it a 40% chance of becoming a tropical depression or stronger over the next five days, and models/ensembles are showing increasing agreement that a system to watch could indeed develop over the Caribbean late this week or this weekend. High pressure ridging will be building back across the western Atlantic after Fiona lifts out in a few days, and this will take the Caribbean system on a more west or west-northwest track. While it is way too far out to try to guess intensity or the ultimate destination, there is an increasing potential for a tropical system moving from the northwest Caribbean into the Gulf of Mexico as we go into next week. We will be watching this carefully in the coming days and will be providing updates as things become more clear.