A stagnant upper-level pattern with a trough near the West Coast and a ridge/high in the south-central U.S. will continue to support ample monsoonal moisture from the eastern Pacific coming into the Southwest.
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This entrenched pattern will lead to additional showers and storms across the Four Corners states through the next couple of days and beyond.
A Slight Risk (level 2/4) of excessive rainfall remains in place through tonight across southwestern parts of Colorado and northwestern New Mexico with a broader Marginal Risk for surrounding areas, and Marginal Risks are outlined for the Four Corners region through the latter part of the workweek.
There is enhanced potential for flash flooding since antecedent conditions are wet due to previous rounds of rain, including increasingly moist soil conditions and increasing streamflows, especially for areas with burn scars that see heavy rainfall.
Additionally, Marginal Risks of severe weather and flash flooding are in place for parts of California through tonight as high winds and rain rates may be possible with repeating storms.
But there is also a possibility of dry thunderstorms over parts of California, Nevada, Utah, and northern Arizona over the next couple of days, which could lead to wildfires.
Meanwhile, scattered thunderstorms are now ongoing as of Wednesday afternoon across parts of the Mid-Atlantic and interior Northeast back into the Ohio Valley near a frontal system.
Slight Risks of both severe weather (particularly for high winds) and excessive rainfall with scattered heavy rain rates are in place for parts of these regions through tonight.
A stationary front is lingering on the back end of the frontal system in the central/southern Plains, which may lift a bit northward tomorrow.
This boundary should provide a focus for moisture and spark storms over the next few days there.
Marginal Risks of excessive rainfall are in place for storms that may train, but severe weather is also possible, especially tomorrow when there is a Slight Risk for severe thunderstorms, particularly for hail and wind but with a few tornadoes possible.
Additionally, rain and thunderstorm chances are forecast to increase tomorrow into Friday in the north-central U.S. ahead of a stronger cold front.
By Friday a Slight Risk of excessive rainfall is outlooked for parts of North Dakota and Minnesota.
The central Great Basin into parts of the Four Corners states should remain on the cool side with below normal temperatures due to the cloud cover and storm chances.
The Northeast/Mid-Atlantic will also see cooler than normal temperatures Thursday behind a backdoor cold front.
Then a cold front is expected to spread below normal temperatures across the Northwest Thursday into Friday.
However, elsewhere, sweltering heat is forecast to continue and build, with much of the South and the Plains particularly hot over the next few days.
Expect additional record highs (for both maxes and mins) Thursday and Friday across the Gulf Coast states, with highs in the 100s and lows in the mid-upper 70s.
Temperatures also heat up well into the 90s Thursday in the northern Plains to Upper Midwest, and into the 100s into the central Plains Friday. ■
A clipper system will move quickly across the northern Plains into the Midwest Friday and the Northeast by Saturday, bringing a wintry mix of rain and snow showers ahead of a sweeping cold front.