Conditions are expected to improve by Thursday.
Wednesday May 25 will be a Code Orange Air Quality Action Day for the state of Delaware.
A strong area of high pressure will build over the mid-Atlantic region beginning Wednesday. Temperatures will jump up to summer-like values, reaching the upper 80s. Upwind ozone to the west is well into the unsafe range on Tuesday, and this air will move into the forecast area Wednesday.
This transport pattern, plus full strong late May sun and light surface winds, will allow ozone to quickly climb up into the unsafe range, mainly at locations in northern Delaware. Particles are on the rise upwind as well, which will promote threshold moderate conditions across the state on Wednesday.
The chance for Code Orange ozone will drop slightly Thursday. Although it will be another day of sunny skies, light winds, and very warm conditions, surface winds will shift southerly, which may be enough to limit ozone to the upper moderate range.
On Friday, it will still be warm, but winds aloft will also shift southerly, which will bring even cleaner air into the forecast area, allowing ozone to drop lower into the moderate range.
Particles will rise slightly higher into the moderate range on Thursday, in response to increasing humidity, before dropping back down into the good range on Friday.
For more information, contact the state of Delaware Department of Natural Resources and Environmental Control at 302-739-9402.