Hazardous air quality and widespread smoky conditions will persist through Wednesday afternoon and evening throughout the Northeast and Mid-Atlantic as smoke associated with wildfires in Canada continues to push southward into the lower 48.
Article continues below
As a nearly stationary upper-low churns off the New England coastline, sustained northerly winds will allow the smoke to spread southward, with major metro areas such as Boston, New York City, Philadelphia, and Washington D.C.
expected to experience unhealthy air quality levels for all age groups through Thursday, before winds shift more easterly, pushing smoke further west into the interior Northeast and Ohio Valley on Friday.
It is important to limit time outdoors, as exposure to air pollutants can aggravate health problems such as asthma, heart disease, and lung disease.
To ensure proper safety, take breaks when possible or wear a mask that will help protect you from the smoke.
In addition to the smoke, breezy winds and low humidity over portions of the Lower Great Lakes and Mid-Atlantic, where conditions remain very dry due to a recent lack of rainfall, have prompted an Elevated Risk of Fire Weather from the Storm Prediction Center through Wednesday afternoon.
Elsewhere, there will be numerous chances for heavy rainfall across the interior Pacific Northwest and Intermountain West through Friday as anomalous moisture from the Gulf of Mexico continues to stream northwestward into the region between a closed low across the Great Basin and an upper-level ridge in the Plains.
Wet antecedent soil conditions in conjunction with isolated heavy rainfall rates approaching 1"/hr in developing thunderstorms could lead to flash flooding concerns through Wednesday afternoon across the central and northern Rockies, resulting in an expansive Slight Risk of Excessive Rainfall for the region.
The threat of heavy rainfall will continue into Thursday and Friday, with the primary risk area shifting into Montana and Idaho as the upper low pushes northward.
48-hour rainfall totals across western Montana may approach 1-2", with locally heavier amounts possible as developing thunderstorms produce rainfall rates of up to 1"/hr, resulting in the issuance of a Slight Risk of Excessive Rainfall for the region through Friday.
Temperature-wise, with the aforementioned persistent upper-low across the Northeast, conditions will remain cool through the end of the week with temperature anomalies of 10-20 degrees below average, as daytime highs remain in the upper 60s to low 70s.
Similarly, most of coastal California will remain in the 60s while highs will be warmer, but still below average, in the interior valleys and Desert Southwest, with 80s to low 90s expected.
In contrast, under the ridging across the Plains and Northwest, temperatures will be as much as 10-20 degrees above average.
High temperatures on Wednesday and Thursday in the Northern Plains and interior Pacific Northwest will be in the upper 80s to low 90s. ■