Storms Drop In Late Tonight

GENERAL OVERVIEW: AN ACTIVE WEATHER PATTERN WILL AFFECT MUCH OF THE CENTRAL AND EASTERN UNITED STATES THROUGH THE EARLY PART OF THE FORECAST PERIOD, WITH A SIGNIFICANT SEVERE THUNDERSTORM AND HEAVY RAIN THREAT FOCUSED ACROSS THE CENTRAL MISSISSIPPI AND OHIO VALLEYS ON SATURDAY, SHIFTING TOWARD THE GULF COAST STATES AND MID-ATLANTIC ON SUNDAY. A COLD FRONT SWEEPING ACROSS THE CENTRAL AND EASTERN U.S. WILL DRIVE WIDESPREAD RAIN AND THUNDERSTORM ACTIVITY THROUGH EARLY NEXT WEEK. THE WEST WILL REMAIN LARGELY DRY UNDER HIGH PRESSURE, THOUGH A LOW PRESSURE SYSTEM NEAR SOUTHERN CALIFORNIA WILL BRING SOME PRECIPITATION TO PORTIONS OF THE SOUTHWEST AND INTERMOUNTAIN WEST. ABOVE-NORMAL TEMPERATURES WILL DOMINATE THE WEST THROUGH MUCH OF THE PERIOD, WHILE BELOW-NORMAL TEMPERATURES SPREAD ACROSS THE CENTRAL U.S. BEHIND THE FRONTAL PASSAGE.

EAST:

Today, a broad area of rain and thunderstorms is ongoing across the Northeast, Great Lakes, Ohio Valley, and into the Southeast, associated with a low pressure system and trailing cold front. The most significant threat is focused across the central Mississippi Valley into the Ohio Valley, where heavy rain and flash flooding are possible, and severe thunderstorms are also a threat across portions of Missouri, Illinois, Indiana, Arkansas, and into Tennessee and Kentucky. Rain and thunderstorms extend broadly from the Great Lakes southward through the Tennessee Valley and into the Southeast and along the Gulf Coast.

By Sunday, the heavy rain and flash flooding threat shifts southward and eastward, with heavy rain and flash flooding possible across portions of eastern Texas, Louisiana, Mississippi, and Arkansas. A separate area of severe thunderstorm potential develops across the Mid-Atlantic, including portions of New Jersey, Delaware, Maryland, Pennsylvania, and into New York. Rain and thunderstorms continue across much of the Southeast, Gulf Coast, and into the Northeast as the frontal system progresses eastward.

By Monday and Tuesday, a low pressure system tracks northeastward, with rain and thunderstorms continuing across portions of the Ohio Valley, Tennessee Valley, and into the Mid-Atlantic and Northeast. Rain coverage gradually diminishes across the Southeast as the frontal boundary pushes offshore. By Wednesday, a new low pressure system develops across the central Plains, with a warm front extending eastward and a cold front dropping southward, bringing rain and thunderstorms back into portions of the Midwest and Ohio Valley, with rain continuing across the Northeast and Mid-Atlantic.

Temperature Anomalies:
-Days 1-3: Temperatures will be above normal across the Northeast and Mid-Atlantic, running roughly 6 to 12 degrees above average in some areas. The Southeast and Ohio Valley will be near to slightly above normal.
-Days 4-6: Above-normal temperatures persist across portions of the Northeast and Mid-Atlantic, while much of the Ohio Valley and Great Lakes region trends below normal, with anomalies of 6 degrees or more below average in some areas by Day 4 and 5. The Southeast trends toward near normal.
-Days 7-10: Temperatures across the East will be near to slightly above normal across the Mid-Atlantic and Southeast, while the Great Lakes region may see some slight below-normal readings. Conditions trend closer to normal for most of the East by the end of the period.

CENTRAL:

Today, rain and thunderstorms are widespread across the central and southern Plains, the Midwest, and into the western Gulf Coast region, associated with the broad low pressure and frontal system. The severe thunderstorm threat is particularly notable across portions of Kansas, Missouri, Oklahoma, and Arkansas, with heavy rain and flash flooding also possible across this same corridor. Thunderstorms extend southward into Texas and along the Gulf Coast.

By Sunday, the main precipitation focus shifts toward the Gulf Coast states, with heavy rain and flash flooding possible across eastern Texas, Louisiana, and Mississippi. Rain and thunderstorm activity continues across portions of the southern Plains and into the lower Mississippi Valley. The central and northern Plains begin to dry out behind the frontal passage.

By Monday and Tuesday, precipitation activity diminishes across much of the central Plains and Midwest as high pressure builds in behind the departing frontal system. Some rain and thunderstorm activity lingers across the southern Plains and Gulf Coast. By Wednesday, a new low pressure system develops across the central Plains, with a cold front extending southwestward and a warm front pushing eastward, bringing renewed rain and thunderstorm chances to portions of the central Plains and Midwest.

Temperature Anomalies:
-Days 1-3: Temperatures across the central Plains and Midwest will trend from near to slightly above normal on Day 1 to significantly below normal by Day 3, with anomalies of 6 to more than 12 degrees below average developing across the central and northern Plains, Kansas, Nebraska, Iowa, and into Missouri behind the frontal passage.
-Days 4-6: Below-normal temperatures persist and expand across the central Plains, with anomalies of 6 to more than 12 degrees below average across portions of Kansas, Oklahoma, Nebraska, and into the Missouri Valley. The southern Plains near Texas trend toward near normal by Day 5 and 6.
-Days 7-10: Below-normal temperatures continue to be indicated across portions of the northern and central Plains, particularly across Montana, Wyoming, and the Dakotas, though anomalies moderate somewhat. Much of the southern Plains trends toward near normal conditions.

WEST:

A low pressure system is located near southern California through the early part of the forecast period, bringing some rain and thunderstorm activity to portions of the Desert Southwest, the southern Rockies, and the Intermountain West. Scattered rain and thunderstorms are also noted across portions of the Pacific Northwest and northern Rockies. The remainder of the West, including the Great Basin and much of the Pacific Coast, remains largely dry under the influence of high pressure.

By Monday and Tuesday, the low pressure system near southern California persists, continuing to bring some precipitation chances to the Southwest and Intermountain West. The Pacific Northwest sees some lingering rain activity. By Wednesday, precipitation activity across the West diminishes further, with the region trending drier overall.

Temperature Anomalies:
-Days 1-3: Above-normal temperatures are well established across California, Nevada, Arizona, and into the Desert Southwest, with anomalies of 6 to more than 12 degrees above average in some areas. The Pacific Northwest also sees above-normal readings. In contrast, portions of Montana and the northern Rockies are running below normal on Day 1, with that below-normal signal expanding across the northern and central Rockies by Days 2 and 3.
-Days 4-6: Above-normal temperatures continue and expand across the West, particularly across California, Nevada, Utah, and into the Desert Southwest, with anomalies of 6 to more than 12 degrees above average. The Pacific Northwest remains above normal as well. The Intermountain West and portions of the central Rockies trend toward near normal by Day 5 and 6.
-Days 7-10: Above-normal temperatures persist across portions of the Intermountain West, Great Basin, and Desert Southwest, though the signal weakens somewhat. The Pacific Northwest trends toward near normal. Much of the West is near to slightly above normal by the end of the period.

TROPICAL:

A disturbance is being monitored in the northwestern Gulf of Mexico, near the coast of Mexico. The development potential for this system over the next seven days is assessed at less than 40 percent. No other tropical cyclone activity is expected across the Atlantic or Gulf of Mexico during the next seven days. No tropical cyclone activity is expected across the eastern Pacific during the next seven days.