A typical summer pattern setting up across the country is expected to largely remain intact as the calendar closes on June and flips over to July.
Article continues below
A broad upper-level ridge and lingering stationary boundary draped across the southern U.S. will continue to trigger additional scattered thunderstorms along the Gulf Coast and into the Southeast.
Rich atmospheric moisture content and light steering winds aloft set the stage for an environment conducive for slow-moving thunderstorms containing torrential downpours and frequent lightning, similar to the last few days.
Storms that remain stationary for a longer duration have a greater chance of causing flash flooding.
Additionally, urbanized locations are more prone to ponding water over mostly impervious surfaces.
In the western Gulf of Mexico, the National Hurricane Center continues to monitor a wave of low pressure that currently has a 40% chance of development over the next 48 hours.
Regardless of whether it becomes a named system or not, tropical downpours associated with this feature are forecast to edge north and west toward the Texas coastal areas beginning this evening.
As the wave moves ashore on Thursday, the coverage of heavy showers and thunderstorms will increase over southeast Texas with an increased threat for Excessive Rainfall rates.
As a result, a Slight Risk has been issued for areas along the southeast Texas coast and in the southwestern suburbs of Houston.
The other regions under the threat of locally heavy rainfall and flash flooding are located across the Southwest and central Rockies.
Monsoonal moisture remaining in place is likely to trigger additional showers and thunderstorms across Arizona today.
By the end of the work-week, an upper level disturbance passing through the central Rockies will help funnel moisture northeastward into Colorado and eventually the central Plains.
Even though much of this region could use the rainfall, downpours in these areas can quickly turn dangerous and lead to flash floods.
For these reasons a pair of Marginal Risks are in place from portions of the Four Corners region on Thursday to the Central Plains on Friday.
Farther north, a cold front swinging across the north-central U.S. will have the potential to spark severe weather through tonight.
The areas most at-risk for severe storms are across the Dakotas and far northwestern Minnesota, where the SPC has issued a Slight Risk (level 2/4) of severe storms.
Damaging wind gusts and large hail are the most likely hazards, with a few tornadoes also possible.
The Marginal severe threat shifts eastward along the cold front on Thursday and into a region stretching from the central Plains to the Upper Great Lakes.
There is no designated Marginal area for Friday as of now, but there is an expansive general thunderstorms area that stretches almost coast-to-coast.
This further highlights the kind of typical summer weather pattern setting in for the first days of July.
Ahead of the aforementioned cold front and associated thunderstorm activity, sizzling heat is forecast across much of the central/northern Plains this afternoon.
Highs are expected to reach into the upper 90s and triple digits from the central High Plains to South Dakota, which equates to around 20 degrees above average.
Critical Fire Weather is also anticipated along with the brief but intense heat.
Red Flag Warnings have been issued for parts of northeast Colorado, northwest Kansas, central/western Nebraska, and south-central South Dakota.
The axis of the hottest conditions versus normal shifts east on Thursday to include a large portion of the country, stretching from the Big Bend of Texas and across Midwest into the Great Lakes and northern Mid-Atlantic.
Highs will be in the 90s for most of these regions with some triple digit heat possible in the central High Plains.
By Friday, stifling heat returns to the Northeast where highs in the 90s will average 10-20 degrees above normal.
Areas that can expect seasonally cooler daytime highs include the Southeast and the Four Corners region where diurnally-driven showers and thunderstorms should produce enough cloud cover to keep daytime highs capped to slightly below normal levels.
Despite the slightly cooler highs in the Southeast, elevated dew points will keep heat indices topping out in the mid 90s through week's end.
Meanwhile, an approaching Pacific trough ushers in cooler conditions to the West Coast starting Friday and temps are forecast to remain on the cooler than normal side through the first weekend of July. ■
Modified arctic air combined with a moisture-laden area of low pressure along the Gulf Coast will continue to allow for a broad area of winter weather impacts from the Lower Mississippi Valley to the Southeast today into early Saturday morning.