The period will open with an active weather pattern. A cold front will slowly press south through early week. At the same time, Hurricane Ida is forecast to make landfall along the north-central Gulf Coast (likely along the LA coastline) Sunday afternoon, and as a major hurricane at that. The remnant moisture of Ida will lift north before curling east. Eventually, we believe the remnant moisture of Ida will get tangled up with the aforementioned cold front. While we’ll need to keep a close eye on data to see if any adjustments are needed early week, as of now, we believe the heavy rain threat will lie just south of our immediate area (more so along and south of the OH River). We’ll keep a close eye on things. Regardless, scattered to numerous showers and thunderstorms are expected as the cold front sinks south. By midweek, the region will be in a much drier (and somewhat cooler) northeasterly airflow. Dry conditions are expected to continue into the holiday weekend ahead with slowly moderating temperatures.
The overall weather pattern in the week ahead will feature an expanding ridge of high pressure into the Ohio Valley and lower Great Lakes. This will lead to oppressive heat and humidity expanding northeast (multiple days of highs into the lower 90s with high humidity values will make it feel closer to 100° through early and middle parts of the work week). Meanwhile, a persistent trough will continue to take up residence through the early part of the forecast period across the northern Rockies (additional early season snow will fly for the high peaks above 12k feet). The other big story during this forecast period? Henri, of course. Henri will deliver quite a blow to our friends in New England beginning later today, continuing a heavy interior rainfall threat through the early and middle part of the work week.
Back here on the home front, each and every day will feature isolated storm coverage. While “isolated” is the key word, if you find yourself under one of these storms, a quick 1″+ of rain is a good bet with the moisture content we’ll be dealing with. Somewhat better storm coverage is anticipated during the 2nd half of the work week (we’ll label it “widely scattered to scattered.” ;-)).
The past 36 hours has provided a nice change of pace as of late with lower humidity and cooler temperatures. (Several reporting sites across northern Indiana are in the lower 50s this morning with middle 50s as far south as the Indianapolis suburbs). As we look to start the new week, humidity will be on the increase along with a daily chance of scattered thunderstorms beginning as early as Monday, continuing Tuesday. We will try and inject briefly drier air in here Wednesday which should reduce coverage of “splash and dash” storms before scattered storms return to close the week. As we look ahead to Saturday, better storm coverage is expected as a cold front moves through the region.
A couple of other items of interest on a broader scale include the first snow of the young season falling across the northern Rockies this week, as an early shot of winter-like air descends south from Canada. Also, from a tropical perspective, we’ll keep close eyes on what comes of Fred and Grace. As it sits today, we still don’t anticipate impacts here in central Indiana from either systems.
A secondary cold front will slip through the state this afternoon and may spark an isolated shower or thunderstorm, but “isolated” is the key word. Most will stay rain free in the upcoming week as high pressure dominates. This will be a quieter start to August than is typical, and also much cooler and less humid than we’d expect. In fact, multiple nights this week will feature low temperatures falling into the mid and upper 50s, especially outside of the city, itself. Out next best chance of organized showers and thunderstorms can be expected next Sunday. Enjoy the unusually quiet, cool, and dry weather. We’ll moderate (and turn more active) as we head into Week 2…
The upcoming 7-day period will place the Great Lakes and Ohio Valley in a northwest flow aloft. This is a notorious pattern for “ridge riding” thunderstorms to roll right into the general region (and sometimes during the hours not typical for storms this time of year – overnight and early morning). While it’s impossible to say exactly when and where these potential storm clusters may track, we’ll keep a watchful eye on the short term period through midweek across our general area. Sometimes these storm clusters are capable of more widespread damaging wind. While the most persistent, serious heat will be well off to our northwest, we can expect a few hot days to open the forecast period (low 90s) before we cool significantly late next week and into next weekend.