The upper level ridge of high pressure responsible for the heat wave in the West will expand across the Southwest and Gulf Coast states.
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Record breaking heat is expected in the Four Corners states, Texas to the Lower Mississippi Valley, and South Florida each day.
Daytime highs will routinely reside in the triple digits in the Desert Southwest and Texas.
The Gulf Coast and Mid-South can expect daytime highs in the mid-upper 90s that coincide with oppressively high dew points, resulting in sweltering heat indices between 105-115F.
Daily low temperatures will remain quite warm, breaking record warm daily minimums in some areas, allowing for minimal relief from the heat overnight.
An expansive area of Excessive Heat Warnings and Heat Advisories remains in the Southwest, Southern Plains, western Gulf Coast, and even parts of South Florida where the air-sea interaction is leading to a feedback loop between the air and water temperatures due to the lighter than average wind flow.
Please visit heat.gov for more information on impacts from the heat wave.
The Northeast and Mid-Atlantic will continue to see hot and humid conditions through Tuesday, despite the recent passage of a weak cold front.
To the west, a stronger cold front will provide the Midwest and Great Lakes with cooler than normal temperatures.
Some locations in the Upper Midwest will struggle to get out of the 70s for highs on Tuesday.
In the north-central Pacific ocean, Tropical Storm Calvin will continue to weaken as it approaches the island of Hawai'i, where tropical storm watches are in effect -- late Tuesday into Wednesday, with the system becoming a tropical depression later on Wednesday.
The system should lead to locally heavy rainfall, as much as 4-7 inches on windward slopes, as it passes by the 50th state.
Rough seas are also possible.
See Central Pacific Hurricane Center advisories on Calvin for more information on the storm.
Back in the Lower 48, numerous showers and thunderstorms will engulf portions of the Midwest and much of the East on Tuesday and Wednesday.
On Tuesday, the threat for heavy and excessive rainfall become heightened over the Northeast as a cold front approaches from the west.
On Tuesday and Wednesday, portions of the Ohio Valley have heightened risks of excessive rainfall, with the best chance of severe weather near the Illinois/Missouri border on Tuesday per Storm Prediction Center outlooks, with lower chances in the Plains and Ohio Valley on Wednesday.
For exact threat levels and related discussions, see WPC excessive rainfall outlooks and SPC Convective Outlooks.
Canada's has witnessed their most extensive wildfires on record in 2023 based on area burned; an area approaching the size of Kentucky.
Smoke from the Canadian wildfires will remain in the picture through Tuesday as northwesterly winds aloft that originate from Canada continue to direct smoke into the Lower 48.
There are Air Quality alerts issued for areas the include the northern High Plains, the Midwest, Great Lakes, central Tennessee and North Carolina, and into the Northeast where higher concentrations of smoke will result in unhealthy air quality for sensitive groups.
Smoke concentrations should diminish over parts of the Heartland on Tuesday, but may still cause poor air quality along the East Coast. ■