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After a chilly May featuring all-time record cold to begin the month, the flip to warmer air has been welcome by many over the past 24 hours. This warmer regime will continue into the weekend before getting beaten back next week. This is due to a closed off upper level low that will actually manufacture it’s on chill across the Ohio Valley, Mid-Atlantic, and Southeast during this time frame.
Sometimes it can be like pulling teeth to get these kind of features to leave and models can struggle (case in point, this upper low was originally modeled to be located over Nova Scotia- NOT the Southeast and Mid-Atlantic)!
Nevertheless, we believe the one time expected surge of heat next week will only be a scenario of “delayed, not denied.” By the time we head into Memorial Day weekend, we continue to believe legitimate summer warmth will move in (85°-90° stuff).
The new CFSv2 agrees with the European ensembles above.
Longer range (last few days of May and early June) will depend heavily on what goes on with a combo of the MJO and EPO/ PNA. 2 of 3 of these signals argue for cooler air to return during that time period.
We shall see how it plays out, but our official lean is towards the cooler side of things after the Memorial Day heat. From a precipitation perspective, after the short-term wet period, overall dry conditions are set to return as we wrap up May.
I. After a cold and dry open to May, (Month-to-date, Indianapolis is running 8.4° below avg. and 1.24” below normal in the precipitation department) changes have arrived.
II. A warm front will lift north through the state today and deliver those warmer changes. The transition from cool to more of an early summer feel will be met with a couple rounds of storms today. Some of those storms will be strong to severe (damaging winds being the greatest concern), especially north of the city. Strongest storms should arrive across the northern half of the state during the early to mid afternoon hours.
III. A “half-n-half” weekend is expected. After a wet Friday, drier air is expected to arrive to help us out Saturday. Showers and storms will return Sunday courtesy of a cold front and associated surface low. Locally heavy rainfall will be possible Friday & Sunday and when you add in what falls today, most of the state from the city and points north can expect widespread 2”-2.5” with locally heavier amounts.
IV. An area of low pressure and upper level trough is now shown to “cut off” over the Mid-Atlantic region in the medium range period. This is forecast to dramatically cool the Monday through Thursday time frame (instead of 80s, we’re now talking upper 50s, 60s and low 70s during the period). This is worth keeping an eye on as models can struggle handling these kind of features, but as it stands now, after a brief encounter with warmth this weekend, it doesn’t appear as if we’ll get back to the heat until Memorial Day weekend.
A band of light showers is falling across southern Indiana this morning, but these are expected to diminish before pushing into central Indiana. Most of the remainder of our Wednesday should be rain-free.
The quiet times will give way to a couple of rounds of storms during the overnight and into Friday. Most notably for central Indiana, we think storm chances will increase significantly after midnight and through the predawn hours Thursday. Locally heavy rain and vivid lightning is expected with the stronger storms.
These storms are in association with a warm front lifting north through the state. Speaking of warm, we’ll certainly notice a difference in air masses between today (still relatively cool and dry) and tomorrow (much warmer and more humid). In fact, highs Thursday will flirt with 80° across most of central Indiana.
Once we get rid of the early morning storms, most of the remainder of our Thursday will be dry and feature a return of the sun.
Another round of storms is expected Thursday night into Friday, but most of these will remain well north of our area. A few of these could become severe across northwestern Indiana during this period.
Rain and storm chances will increase once again during the day Friday across central Indiana. A few strong storms will be possible.
As we look ahead to the weekend, it appears we’ll be able to enjoy a mostly dry day Saturday (widely scattered storm possible) before more widespread storms return Sunday. Warm and humid conditions will prevail. A cold front will move through the area early next week which will allow for briefly cooler, drier air to move in during the 1st half of next week. Before that takes place, rainfall amounts between tonight and Sunday are expected to range from 1.5” – 2” with locally heavier totals across central Indiana. Heavier rainfall amounts can be expected across northern Indiana (widespread 3” to 4” amounts during the same period).