Showers and Thunderstorms
Showers and thunderstorms are expected across mainly eastern areas today. A few stronger storms are possible.
GENERAL OVERVIEW: AN ACTIVE WEATHER PATTERN IS UNDERWAY ACROSS MUCH OF THE CONTIGUOUS UNITED STATES. A COMPLEX LOW PRESSURE SYSTEM AND ASSOCIATED FRONTAL BOUNDARIES ARE DRIVING WIDESPREAD RAIN, THUNDERSTORMS, AND HEAVY RAIN THREATS ACROSS THE CENTRAL AND EASTERN PORTIONS OF THE COUNTRY THROUGH THE EARLY PART OF THE FORECAST PERIOD. THUNDERSTORM ACTIVITY WILL REMAIN WIDESPREAD FROM THE PLAINS THROUGH THE GULF COAST AND INTO THE SOUTHEAST AND MID-ATLANTIC OVER THE NEXT SEVERAL DAYS. HEAVY RAIN AND FLASH FLOODING CONCERNS ARE NOTABLE ACROSS PORTIONS OF THE UPPER MIDWEST AND CENTRAL PLAINS EARLY IN THE PERIOD, SHIFTING EASTWARD AS THE WEEK PROGRESSES. THE WEST WILL SEE ACTIVE CONDITIONS AS WELL, WITH MULTIPLE LOW PRESSURE SYSTEMS AND FRONTAL PASSAGES BRINGING RAIN AND MIXED PRECIPITATION TO THE PACIFIC NORTHWEST AND INTERMOUNTAIN WEST. ABOVE-NORMAL TEMPERATURES WILL BE WIDESPREAD ACROSS THE CENTRAL AND SOUTHERN PORTIONS OF THE COUNTRY THROUGH MUCH OF THE PERIOD, WHILE BELOW-NORMAL TEMPERATURES LINGER ACROSS PARTS OF THE NORTHERN ROCKIES AND PACIFIC NORTHWEST EARLY ON.
EAST:
The eastern United States will be influenced by a broad area of rain and thunderstorms during the first day of the forecast, with precipitation extending from the Great Lakes region southward through the Ohio Valley and into the Mid-Atlantic and Southeast. A cold front pushing through the region will help organize shower and thunderstorm activity. A low pressure center near the New England coast will contribute to rain along the Northeast coastline as well. Heavy rain and flash flooding are possible across portions of the upper Midwest and into the Great Lakes region on Sunday into Monday, with that heavy rain threat highlighted across Iowa, Missouri, and into Wisconsin and Michigan. Severe thunderstorms will also be possible across portions of the upper Midwest, including Wisconsin and Michigan, on Monday.
As the week progresses into Tuesday and Wednesday, the frontal system will continue to push eastward, with rain and thunderstorms shifting into the Ohio Valley, Tennessee Valley, and Mid-Atlantic. By Wednesday evening, rain coverage extends from the Great Lakes southward through the Ohio Valley and into the Southeast and Gulf Coast. A low pressure system developing off the Southeast coast by Wednesday will help sustain rain and thunderstorm activity along the Atlantic Seaboard. By Thursday, rain and thunderstorm activity continues across the Northeast, Great Lakes, and Ohio Valley, with a high pressure system building in from the north helping to push the precipitation shield eastward. Thunderstorm activity persists along and south of a slow-moving frontal boundary across the Tennessee Valley and Southeast through the latter part of the week.
Temperature Anomalies:
-Days 1-3: Temperatures will be near to slightly above normal across much of the East. The Great Lakes region and portions of the Ohio Valley will see temperatures running a few degrees above normal on Day 1, with above-normal readings also noted across portions of the Mid-Atlantic and Southeast. Conditions trend warmer across the Tennessee Valley and Southeast by Day 3, with anomalies of 6 to locally over 12 degrees above normal across portions of the central and southern Appalachians and Tennessee Valley.
-Days 4-6: A pronounced warm anomaly develops and expands across the Ohio Valley, Tennessee Valley, and into the Mid-Atlantic and Southeast, with temperatures running 6 to over 12 degrees above normal across portions of Kentucky, Tennessee, Indiana, and Ohio. This warmth persists and broadens through Day 6, encompassing much of the eastern Great Lakes, Ohio Valley, and Mid-Atlantic.
-Days 7-10: Above-normal temperatures gradually moderate across the East, though readings remain slightly above normal across portions of the Southeast and Mid-Atlantic through Day 8. Conditions trend closer to normal across most of the East by Days 9 and 10.
CENTRAL:
The central United States will be very active during the early part of the forecast period. On Sunday, widespread rain and thunderstorms are ongoing across a large area stretching from the central and southern Plains northward through the Midwest and into the upper Great Plains. A complex low pressure system with multiple centers and associated warm and cold fronts is driving this activity. Heavy rain and flash flooding are possible across portions of Iowa, Nebraska, and Missouri on Sunday, with that threat highlighted across those areas. The threat for heavy rain and flash flooding shifts northward and eastward into Wisconsin and the upper Midwest on Monday, with severe thunderstorms also possible across portions of Nebraska and into the upper Midwest.
By Tuesday evening, a low pressure system tracking across the central Plains will continue to organize rain and thunderstorm activity from the southern Plains northward through the Midwest. Rain and thunderstorm coverage remains extensive across the central and southern Plains, the western Gulf Coast, and into the Midwest. A cold front pushing southward will help delineate the precipitation shield. By Wednesday, the low pressure system shifts eastward, with rain and thunderstorm activity focusing more across the central Plains and into the Midwest, while a new low pressure system develops along the Pacific Coast and begins to push a cold front into the Intermountain West. By Thursday, a low pressure system over the central Plains with an attendant cold front will continue to support rain and thunderstorm activity across the central Plains and into the Midwest, with coverage extending from the northern Plains southward through Kansas and into Oklahoma.
Temperature Anomalies:
-Days 1-3: Temperatures across the central United States will be notably above normal, particularly across the southern Plains. Oklahoma, Kansas, and portions of Texas will see temperatures running 6 to over 12 degrees above normal on Days 1 through 3. Portions of the central Plains and Midwest will also be above normal, though by lesser amounts. The northern Plains will be near normal to slightly below normal early in the period.
-Days 4-6: Above-normal temperatures persist and expand across the central United States, with the greatest anomalies centered over Oklahoma, Kansas, and Missouri, where readings may run 6 to over 12 degrees above normal. The warmth extends northward into the Midwest and eastward into the Ohio Valley through Day 6. The northern Plains will see a gradual return toward near-normal conditions.
-Days 7-10: The warm anomaly across the central United States gradually diminishes, with temperatures trending closer to normal across the northern and central Plains by Days 9 and 10. Some above-normal readings may linger across the southern Plains and lower Mississippi Valley through Day 8.
WEST:
The western United States will see an active pattern driven by multiple low pressure systems and frontal boundaries. On Sunday, rain and mixed precipitation are ongoing across portions of the Pacific Northwest, with low pressure systems affecting Washington, Oregon, and Idaho. Rain and thunderstorm activity is also present across portions of the Great Basin, the Desert Southwest, and into the southern Rockies. Multiple low pressure centers are scattered across the Intermountain West, contributing to unsettled conditions. By Monday evening, rain continues across portions of the Pacific Northwest and into the northern Rockies, with mixed precipitation possible across portions of Idaho and Montana. The low pressure activity across the Desert Southwest and southern Rockies also continues to support scattered rain and thunderstorms across those areas.
By Tuesday evening, a low pressure system along the California coast will push a cold front into the region, bringing rain and thunderstorm activity to portions of the Desert Southwest and southern Rockies. Rain continues across portions of the Pacific Northwest and northern Rockies as well. By Wednesday, the cold front pushes further inland, with rain and thunderstorm activity spreading across the central and southern Rockies and into the Desert Southwest. A high pressure system over the central Rockies will help to limit precipitation across portions of the Great Basin. By Thursday, rain and thunderstorm activity continues across portions of the central and southern Rockies and into the Desert Southwest, with a high pressure system over the central Rockies keeping conditions drier across the Great Basin and northern Rockies.
Temperature Anomalies:
-Days 1-3: Temperatures across the West will be below normal across portions of Montana, northern Idaho, and into the northern Rockies, with anomalies of 6 to over 12 degrees below normal across parts of Montana on Day 1. The Pacific Northwest and northern Rockies will also see below-normal readings on Days 2 and 3, with anomalies of 6 to locally 12 degrees below normal across Oregon, Washington, and Idaho. The Desert Southwest and southern portions of the West will be above normal, with anomalies of a few degrees above normal across Arizona, New Mexico, and southern California.
-Days 4-6: Below-normal temperatures across the northern Rockies and Pacific Northwest gradually moderate, though some areas of Montana and the northern Rockies remain slightly below normal on Day 4. The Desert Southwest and southern California continue to see above-normal temperatures through Day 6. Much of the Great Basin and central Rockies will be near normal through this period.
-Days 7-10: Temperatures across the West trend closer to near normal across most areas by Days 7 through 10, with only modest above-normal anomalies lingering across portions of the Pacific Northwest, the Great Basin, and the Desert Southwest.
TROPICAL:
In the Atlantic basin, a tropical disturbance is being monitored in the central Atlantic Ocean, located roughly midway between the U.S. East Coast and the Lesser Antilles. This system has a less than 40 percent chance of development over the next seven days and is forecast to drift generally westward. No immediate threat to land areas is anticipated at this time.
In the eastern Pacific, Tropical Storm Norbert is currently located in the central eastern Pacific Ocean, well southwest of the Mexican coast. The storm is forecast to track generally westward, and a nearby disturbance to the east of Norbert’s current position carries a greater than 60 percent chance of development over the next seven days. Additionally, a separate disturbance is being monitored well to the west of Hawaii in the central Pacific, though development is not expected from that system. Neither Norbert nor the associated eastern Pacific disturbances pose an immediate threat to the continental United States.