Looking Over The New JMA Weeklies…
The JMA Weeklies update every Thursday morning and this gives us another tool to look at when developing the forecast over the upcoming 3-4 weeks. Here are some highlights from the most recent update:
Week 1
The big story in Week 1 is the surge of tropical moisture with the area of disturbed weather in the GOM (Gulf of Mexico). Unfortunately, it’s not until possibly Week 2 that remnant tropical moisture may interact with an approaching cold front to provide better rain chances here. The big story for the balance of the upcoming Week 1 period, locally, will be the heat. An unseasonably warm stretch will continue through the Memorial Day weekend and on into the middle of next week.
Week 2
The model shows a bit of a transition in the pattern with the core of the heat shifting west during the Week 2 period. With this, there are some hints that the pattern will turn increasingly wet and stormy, locally, including a backing off of the extreme 90° heat.
Weeks 3-4
An intriguing “ring of fire” pattern develops in the Weeks 3-4 time frame. If correct, this would result in a more active pattern across the Mid West with a busy northwest flow pattern emerging. Storm complexes are notorious for tracking in a northwest to southeast fashion around the hot dome. Sure enough, the model is going with a wetter than normal pattern here. It’s hard to disagree with that given the look at 500mb.
The other big story, especially for those planning to attend the race, will be increasing humidity over the weekend. Forecast dew points will approach and exceed the 70° mark Sunday afternoon, providing a very tropical feel to the air.
By the time all is said and done late Monday night and early Tuesday, expect widespread rainfall totals between 0.50″ and 1″ with locally heavier amounts where the stronger storms track.
High pressure will build into the region through the midweek stretch and result in increasingly sunny and pleasant conditions. With a drier air mass in place, overnight lows will fall into the 50s through the midweek period.
Our attention will then shift to the potential of strong thunderstorms late Sunday. Higher resolution guidance suggests storms will begin to rumble into western Indiana late Sunday evening (around 9p to 10p) before tracking east into the overnight hours.
With a stalled front nearby, shower and thunderstorm chances will remain in our forecast into the middle of the week. While it won’t rain the entire time, unsettled conditions will remain into Wednesday before high pressure provides drier conditions Thursday and most of Friday.
Otherwise, look for considerable cloudiness and highs topping out in the lower 70s today.
As we look ahead to the end of May, there really aren’t any significant changes to the overall warmer than normal theme we’ve enjoyed so far this month. Longer range guidance off of the European ensemble continues to support broad scale upper ridging across the Mid West and Ohio Valley and a corresponding warmer than average regime. From a precipitation perspective, the next couple of weeks do look more active compared to the dry start to the month. Case in point, the balance of the upcoming week will be dominated by a stalled frontal boundary. While we’ll have to fine tune exactly where the front stalls, daily chances of showers and thunderstorms (scattered fashion) can be expected.
