U.S.: Southern storms, upper midwest wintry travel hazards, another western atmospheric river event
KEY POINTS
- Travel conditions could be treacherous at times
- Freezing rain amounts up to at least a quarter of an inch are probable
- The greatest threat for heavy rain to produce flash flooding is forecast over parts of Mississippi
Two major storm systems are anticipated to impact the Nation over the next few days, with one currently situated over the central and eastern U.S., while another enters the West Coast by Wednesday.
Article continues below
Several inches of rain falling in a short amount of time could lead to several flash floods, with some potentially becoming significant.
Heavy snow is likely to the northwest of this low throughout central/southern Minnesota and into northern Wisconsin/U.P. of Michigan, with light freezing rain amounts extending just to the south of the better snow chances.
Residents are urged to plan ahead before traveling and make a plan if located in a flood-prone region.
Snow should decrease in intensity throughout this region by Wednesday night as the robust influx of moisture shifts to the East Coast.
An anomalous and record-breakingly warm airmass surging up the eastern U.S. will allow for precipitation to fall as rain outside of northern New England.
Damaging wind gusts, large hail, and tornadoes are possible.
Freezing rain amounts up to at least a quarter of an inch are probable and could lead to scattered tree damage and power outages.
With the extremely warm and moist airmass in place across the East Coast and Southeast, heavy rain and severe thunderstorms are likely ahead of an approaching cold front as it swings eastward tonight.
The greatest threat for heavy rain to produce flash flooding is forecast over parts of central/southern Mississippi, where a Moderate Risk (level 3/4) of Excessive Rainfall has been issued.
Several inches of rain falling in a short amount of time could lead to several flash floods, with some potentially becoming significant.
Residents are urged to plan ahead before traveling and make a plan if located in a flood-prone region.
Never drive through flood waters! Additionally, severe thunderstorms are possible from the central Gulf Coast to the southern Appalachians and Southeast through early Wednesday.
Damaging wind gusts, large hail, and tornadoes are possible, with the threat gradually weakening as the showers and storms push into Georgia and northern Florida.
The other major weather story is about to enter the picture as an intense storm system over the eastern Pacific sends a strong atmospheric river into California on Wednesday and Thursday.
A plethora of hazards are forecast, with heavy rain and strong winds expected to be the most widespread impact.
Widespread rainfall amounts of 3 to 6 inches are anticipated, with locally higher amounts throughout the coastal ranges and over northern California.
These rainfall amounts would normally not lead to widespread or significant impacts, but recent rainfall has left soils saturated and susceptible to flooding and rapid runoff concerns.
Sensitive terrain will also have the potential for landslides.
A Moderate Risk of Excessive Rainfall has been issued for the northern and central California coast, where flooding impacts are most likely.
The heavy rain threat will shift southward along a cold front by late Wednesday into early Thursday into parts of southern California.
However, by this point the area of heavy rain should be rather progressive and limit major impacts, with more scattered flooding concerns possible.
Another aspect of this storm system will be the widespread hazardous winds to move onshore.
Wind gusts up to 70 mph are possible across coastal ranges, while valley locations see gusts up to 50 mph.
Power outages could become a more widespread issue where heavy rain and saturated soils lead to more downed trees.
Rough surf is inherently likely along coastal regions as the high winds lead to hazardous seas.
Lastly, the high terrain of the Sierra Nevada is forecast to experience extremely heavy snow rates above 3 inches per hour.
These rates are probable for areas residing above 5000 feet and will make travel very dangerous to impossible at times.
White out conditions will also be a concern when combined with gusty winds.
Residents and visitors located in California over the next few days are advised to check their local forecast and plan ahead for potentially hazardous weather conditions. ■