Warm Temps Continue

**GENERAL OVERVIEW:**

An active weather pattern is unfolding across much of the United States as we move through the coming days. The dominant story early in the period is a significant heavy rain and flash flooding threat across the Ohio Valley and portions of the mid-South, driven by a slow-moving low pressure system and associated frontal boundaries. Simultaneously, a severe thunderstorm threat is developing across the Northern Plains. Widespread thunderstorm activity will persist across a broad swath of the country from the Central Plains eastward through the Southeast and into the Northeast. The Pacific Northwest and portions of the Mountain West will see ongoing precipitation, including mixed precipitation at higher elevations. As the period progresses, a series of frontal systems will continue to push precipitation eastward, with the overall pattern remaining unsettled through the end of the forecast window. Above-normal temperatures will be a recurring theme across much of the central and eastern United States throughout the period, while portions of the northern Rockies and eventually the Central Plains will experience below-normal temperatures as the pattern evolves.

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**EAST:**

The most significant weather threat across the East during the opening days of the forecast period is a **heavy rain and flash flooding** concern centered over the Ohio Valley, extending into portions of the mid-South and Tennessee Valley. This threat is explicitly highlighted and should be considered the primary hazard for the region. A slow-moving low pressure system and associated frontal boundaries are focusing heavy rainfall across Illinois, Indiana, Kentucky, Tennessee, and surrounding areas through Tuesday. Residents in these areas should be prepared for the potential for dangerous flash flooding.

Thunderstorm activity is widespread across the broader East, encompassing the Southeast, Gulf Coast, Mid-Atlantic, and portions of New England through Tuesday evening. A high pressure system positioned offshore the Mid-Atlantic coast is helping to funnel moisture into the region, supporting continued convective activity.

By Wednesday evening, the low pressure system has shifted eastward, with a new low developing near the Great Lakes region. A warm front extends southeastward from this system, and rain and thunderstorm coverage remains extensive across the Great Lakes, Ohio Valley, Mid-Atlantic, and into New England. The Southeast continues to see thunderstorm activity as well, with a separate high pressure center anchored over the South Central states helping to maintain a moist, unstable airmass across the region.

Into Thursday evening, the low pressure center has consolidated over the upper Midwest near the Great Lakes, with a cold front sweeping southward and eastward. Rain and thunderstorm coverage remains broad across the Great Lakes, Ohio Valley, and into the Southeast and Mid-Atlantic. The cold front’s passage will eventually bring a drier, cooler airmass into the region from the north and west.

By Friday evening, the cold front has pushed well to the east and southeast, now extending from the Northeast southward through the Mid-Atlantic and into the Southeast. Rain and thunderstorm activity continues ahead of this boundary across the Mid-Atlantic, Southeast, and Gulf Coast. Behind the front, conditions begin to dry out across the Great Lakes and Ohio Valley, though scattered rain lingers across portions of the Northeast as the system exits to the east.

**Temperature Anomalies:**
– **Days 1–3:** Temperatures across the Great Lakes, Ohio Valley, and Northeast are running notably above normal, with anomalies of 6°F or more above average across much of the Great Lakes and into New England by Day 2 and Day 3. The Mid-Atlantic also features above-normal readings, generally in the 3–6°F range. The Southeast and Gulf Coast are near to slightly above normal.
– **Days 4–6:** Above-normal temperatures persist and intensify across the Great Lakes and Northeast, with anomalies exceeding 12°F above normal in portions of the upper Great Lakes by Day 4. The Mid-Atlantic and portions of the Ohio Valley remain above normal in the 3–9°F range. By Day 5 and Day 6, the above-normal signal remains strong across the Great Lakes and Northeast, with the Mid-Atlantic and portions of the Southeast also running above average.
– **Days 7–10:** The above-normal temperature signal gradually moderates across the East. By Days 7–8, above-normal readings persist primarily across the Northeast and Mid-Atlantic, with anomalies of 3–6°F. By Days 9–10, the anomaly signal weakens considerably across most of the East, with conditions trending closer to normal across the Ohio Valley and Southeast, while the Northeast retains a modest above-normal signal.

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**CENTRAL:**

The Central region is home to two notable hazards during the opening days of the forecast period. First, a **severe thunderstorm threat** is explicitly highlighted across portions of the Northern Plains, specifically over the Dakotas and into southern Minnesota, valid through Tuesday into Wednesday. This threat warrants close attention as strong to severe convection is possible in this area. Second, a broad area of thunderstorm and rain activity extends across the Central Plains and South Central states, with activity stretching from the Midwest southward through the Mississippi Valley and into the Gulf Coast region.

On Tuesday evening, a low pressure system is positioned over the Northern Plains with a cold front extending southward into the Central Plains and a warm front arcing eastward. Thunderstorm activity is widespread from the Central Plains through the South Central states and into the Gulf Coast. The Northern Plains and upper Midwest are also seeing rain and thunderstorm activity.

By Wednesday evening, the synoptic pattern evolves with the primary low shifting toward the Central Plains and a cold front pushing southward. An occluded front extends northward into the Northern Plains. Thunderstorm activity remains widespread across the Central Plains, South Central states, and into the Gulf Coast. The Northern Plains and upper Midwest continue to see precipitation, with rain coverage extending broadly across the region.

Into Thursday evening, a low pressure center is positioned over the Central Plains with a cold front extending southward and eastward. Thunderstorm and rain coverage remains extensive across the South Central states, with activity also present across portions of the Central Plains and into the Gulf Coast. The cold front’s progression will gradually push the precipitation shield eastward.

By Friday evening, the Central region sees a general decrease in precipitation coverage as the frontal system exits to the east. A low pressure system remains over the Central Plains, but the most active weather has shifted eastward. Scattered rain and thunderstorm activity persists across portions of the South Central states and into the Gulf Coast, while the Northern and Central Plains begin to dry out behind the departing frontal boundary.

**Temperature Anomalies:**
– **Days 1–3:** The Central region features a pronounced above-normal temperature signal across the Northern Plains and upper Midwest, with anomalies of 9–12°F or more above average in portions of the Dakotas and Nebraska on Day 1. The Central Plains and South Central states are also above normal, generally in the 3–6°F range. By Days 2 and 3, the above-normal signal expands and intensifies across the upper Midwest and Central Plains, with anomalies of 6–12°F widespread.
– **Days 4–6:** Above-normal temperatures persist across the upper Midwest and portions of the Central Plains through Day 4, with anomalies of 6–9°F. By Days 5 and 6, the above-normal signal begins to erode across the Northern Plains and Central Plains, with conditions trending closer to normal or near normal across much of the Central region. The South Central states remain near to slightly above normal.
– **Days 7–10:** A significant pattern change is evident by Days 7–10, with below-normal temperatures developing across the Central Plains and spreading into the upper Midwest. By Day 8, anomalies of 6–9°F below normal are depicted across portions of the Central Plains and into the Midwest, with the core of the cold anomaly intensifying through Days 9 and 10. By Day 10, below-normal temperatures of 6–9°F extend from the Northern Plains southward through the Central Plains and into portions of the South Central states, representing a notable cooldown for the region.

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**WEST:**

The West features an active precipitation pattern across the Pacific Northwest and portions of the northern Rockies throughout much of the forecast period. On Tuesday evening, rain and thunderstorm activity is widespread across the Pacific Northwest, with snow noted at higher elevations in the northern Rockies and Cascades. A cold front extends southwestward from a low pressure system off the Pacific Coast, with mixed precipitation present at higher terrain elevations in the Northwest.

By Wednesday evening, multiple low pressure systems are positioned along the Pacific Coast and across the Great Basin, maintaining an unsettled pattern across the Pacific Northwest and northern Rockies. Rain coverage remains extensive across the Northwest, with mixed precipitation continuing at higher elevations. The Great Basin and Southwest are generally dry.

Into Thursday evening, a low pressure system is positioned over the Southwest, and rain and thunderstorm activity is present across portions of the Pacific Northwest and northern Rockies. The Southwest and Great Basin remain largely dry, though isolated convection is possible near the Southwest low.

By Friday evening, the Pacific Northwest continues to see rain and shower activity, while the remainder of the West is predominantly dry. The Southwest low has weakened, and the overall precipitation threat across the West diminishes somewhat heading into the weekend.

**Temperature Anomalies:**
– **Days 1–3:** The northern Rockies, including portions of Montana and Idaho, are running below normal on Day 1, with anomalies of 3–6°F below average. The remainder of the West is generally near normal to slightly above normal, with modest above-normal readings across portions of the Desert Southwest and southern Rockies. By Days 2 and 3, the below-normal signal in the northern Rockies persists, while the Southwest and southern Rockies maintain a slight above-normal temperature signal.
– **Days 4–6:** Below-normal temperatures expand across the northern Rockies and into portions of the Mountain West by Day 4, with anomalies of 6–9°F below normal in the northern Rockies. By Days 5 and 6, the below-normal signal shifts and focuses over the central Rockies and portions of the Mountain West, while the Pacific Coast states begin to trend above normal. California and the Southwest see above-normal readings of 3–6°F by Day 6.
– **Days 7–10:** The Pacific Coast states, particularly the Pacific Northwest and California, feature above-normal temperatures of 6–9°F or more by Days 7–9, with the warmth most pronounced along the coast. Meanwhile, the interior Mountain West and portions of the northern Rockies remain below normal, with anomalies of 3–6°F below average. By Day 10, the above-normal signal along the Pacific Coast remains robust, while the interior West trends closer to normal.

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**TROPICAL:**

Tropical cyclone activity is not anticipated across the Atlantic basin or Gulf of Mexico during the next seven days. In the Eastern Pacific, a tropical disturbance designated as Tropical Depression Two-E is currently located off the Pacific Coast of Central America and southern Mexico. This system is being monitored for potential development. Additionally, the remnants of a previously named system, Amanda, are located in the central Eastern Pacific well southwest of the Mexican coastline; further development of this system is not expected. Neither of these Eastern Pacific systems poses a direct threat to the continental United States at this time.