Ozone Level Particle Pollution Level
Date: Saturday-Monday January 20-22, 2018
Action Day? No

Forecast Discussion:
It will be a delightful weekend across the State of Delaware, with mild and mostly sunny weather, courtesy of a broad area of high pressure. Warm air arriving aloft will promote a very strong surface inversion on Saturday morning and limited vertical mixing during the afternoon. These conditions will favor persistent Code Yellow air quality, mainly in northern Delaware. Sunday’s weather will be similar to Saturday’s with the exception of more clouds in the late afternoon due to a “back door” cold front approaching from the north. Another day of limited vertical mixing will push particles a bit higher in the Moderate range. Monday will also be unseasonably warm, but with mostly cloudy skies ahead of a strong cold front moving in from the west. Sunday’s frontal boundary may stall over the state, which would help to drive particle concentrations even higher. To counter those potential increases, a shift to southerly flow aloft on Monday afternoon will begin to bring clean maritime air into the state. Overall, Moderate air quality is likely to persist.

Extended Forecast:
The strong cold front will move through the state on Tuesday. Periods of heavy rain and gusty winds associated with the frontal passage, along with clean onshore transport aloft, will return particles to the Good range state-wide.