Cooler Temps Linger In West

General Overview: AN ACTIVE WEATHER PATTERN WILL UNFOLD ACROSS MUCH OF THE CONTIGUOUS UNITED STATES OVER THE NEXT SEVERAL DAYS, WITH THE MOST SIGNIFICANT HAZARDS CENTERED ON THE SOUTH CENTRAL REGION AND GULF COAST. A LOW PRESSURE SYSTEM TRACKING ACROSS THE SOUTH-CENTRAL STATES WILL BRING A THREAT OF THUNDERSTORMS, WITH HEAVY RAIN PARTICULARLY THREATENING PORTIONS OF THE LOWER MISSISSIPPI VALLEY AND GULF COAST THROUGH THE WEEKEND. MEANWHILE, A BROAD AREA OF THUNDERSTORM ACTIVITY WILL SPAN FROM THE CENTRAL PLAINS INTO THE OHIO AND TENNESSEE VALLEYS ON FRIDAY, BEFORE THE FOCUS OF HEAVY RAIN AND FLASH FLOODING SHIFTS SOUTHWARD INTO THE LOWER MISSISSIPPI VALLEY AND ADJACENT GULF COAST AREAS THROUGH SATURDAY. A COLD FRONT PUSHING INTO THE PACIFIC NORTHWEST WILL BRING PRECIPITATION CONCERNS TO THAT REGION BY MONDAY AND TUESDAY. TEMPERATURES WILL TREND PROGRESSIVELY WARMER ACROSS THE NORTH CENTRAL PLAINS AND GREAT LAKES THROUGH THE EXTENDED PERIOD.

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EAST: The eastern United States will be influenced by an active frontal pattern to open the period. On Friday, a low pressure system positioned near the Tennessee Valley will have a warm front extending northeastward toward the Mid-Atlantic coast and a cold front pushing southward through the Southeast. Rain and thunderstorms will be widespread across the Ohio Valley, Tennessee Valley, and into the Mid-Atlantic and portions of the Northeast, with the potential for heavy rain and flash flooding across parts of the Ohio Valley and central Appalachians. A broad area of rain extends well into the Great Lakes and portions of the Northeast as well. 

By Saturday evening, a low pressure center has shifted eastward into the Mid-Atlantic region, with a warm front extending offshore and a cold front draped southward through the Southeast. Rain and thunderstorm coverage will continue across much of the East, from the Southeast northward through the Mid-Atlantic and into southern New England. Heavy rain and flash flooding remain a concern across portions of the Southeast and Mid-Atlantic corridor. The Great Lakes region will continue to see rain. As the low tracks offshore by Sunday and Monday, high pressure builds in behind it, gradually drying out conditions across the Northeast and Mid-Atlantic. By Monday and Tuesday, a high pressure center settles over the Mid-Atlantic, bringing a period of quieter weather to much of the eastern seaboard, though some lingering rain and thunderstorm activity will persist across the Southeast and Gulf Coast states. A cold front sweeping through the Northeast by Tuesday will push any remaining shower activity offshore.

Temperature Anomalies:

– Days 1-3: Temperatures will run below normal across much of the Northeast and Great Lakes region, with anomalies of 3 to 6 degrees below average in some areas. Slight above-normal readings are noted along portions of the Southeast coastal plain.

– Days 4-6: A notable warming trend develops, with temperatures climbing to 3 to 6 degrees above normal across the Great Lakes and Ohio Valley. The Northeast transitions from near-normal to slightly above normal by Day 6, with locally stronger positive anomalies developing across the Upper Great Lakes.

– Days 7-10: Above-normal temperatures become well established and widespread across the Great Lakes, Ohio Valley, and Northeast, with anomalies of 6 to 12 degrees above average in some areas, particularly across the Great Lakes region. This warm pattern appears persistent through the end of the period.

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CENTRAL: The central United States will be the focal point for the most significant weather hazards during the early part of the forecast period. On Friday, a low pressure system over the Southern Plains will be the primary driver of active weather, with severe thunderstorms possible across portions of the South Central region, particularly over western Texas, Oklahoma, and surrounding areas. The threat of large hail, damaging winds, and tornadoes cannot be ruled out in this zone. Simultaneously, a broad swath of rain and thunderstorms extends from the Central Plains northward through the Upper Midwest and into the Northern Plains, with rain and thunderstorm activity widespread from Kansas and Missouri northward through Iowa and into the Dakotas. Heavy rain and flash flooding are a significant concern across portions of the Lower Mississippi Valley and adjacent areas, including Louisiana, Arkansas, and Mississippi.

By Saturday, the severe weather threat shifts, and the heavy rain and flash flooding hazard becomes the dominant concern, with a particularly dangerous flooding situation possible across portions of the Lower Mississippi Valley, including Louisiana and adjacent areas. Thunderstorm activity remains widespread from the Central Plains through the Midwest. As the weekend progresses into early next week, the low pressure system tracks eastward and the central region gradually dries out from west to east. By Monday and Tuesday, precipitation activity across the Central Plains diminishes considerably, though some lingering thunderstorm activity may persist across the South Central states and Gulf Coast. A new frontal system will begin to approach the Northern Plains from the northwest by Tuesday.

Temperature Anomalies:

– Days 1-3: A pronounced cold anomaly is evident across the Central and Northern Plains and into the Rockies, with temperatures running 6 to more than 12 degrees below normal in some areas, particularly over the central Rockies and High Plains. The South Central region sees near-normal to slightly below-normal readings.

– Days 4-6: A dramatic pattern change unfolds, with temperatures surging well above normal across the North Central Plains and Northern Rockies. Anomalies of 6 to 12 degrees above normal develop across the Northern Plains and spread southward and eastward through the Midwest by Day 6. The South Central region remains near to slightly below normal.

– Days 7-10: The above-normal temperature regime becomes entrenched across the North Central Plains, Upper Midwest, and Great Lakes, with anomalies of 6 to 12 degrees above average persisting. The South Central region gradually moderates toward near-normal readings by the end of the period.

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WEST: The western United States will be relatively quiet to start the period, though a series of low pressure systems will bring increasing precipitation chances to the Pacific Northwest and Intermountain West as the week progresses. On Friday, a low pressure system off the Pacific Northwest coast will bring some rain and mountain snow to the coastal ranges and Cascades, with light precipitation also noted across portions of the northern Rockies and Intermountain region. The Desert Southwest and California will see largely dry conditions to start, though isolated shower activity is possible across the higher terrain.

By Monday, a more organized low pressure system moves onshore into the Pacific Northwest, bringing a cold front, an occluded front, and a warm front into the region. This system will produce rain along the coast and lower elevations, with snow possible at higher elevations in the Cascades and northern Rockies. Rain and mixed precipitation will spread inland across the Intermountain West. By Tuesday, the cold front associated with this system pushes southward through the Great Basin, bringing precipitation chances to a broader area of the West, including portions of Nevada and the interior Southwest. Snow and mixed precipitation will be possible across the higher terrain of the Rockies and Cascades during this timeframe.

Temperature Anomalies:

– Days 1-3: Temperatures will be running below normal across portions of the Pacific Northwest and northern Rockies, with anomalies of 3 to 6 degrees below average. California and the Desert Southwest will see temperatures slightly above normal, particularly along the California coast and Central Valley.

– Days 4-6: A warming trend takes hold across much of the West, with above-normal temperatures developing broadly from the Pacific Northwest through the Intermountain West and into the Rockies. Anomalies of 3 to 6 degrees above normal are widespread, with locally stronger positive anomalies across the northern Rockies and Pacific Northwest interior.

– Days 7-10: The warming trend across the West becomes more mixed. A notable cold anomaly develops across the Great Basin, California, and portions of the Southwest, with temperatures running 6 to more than 12 degrees below normal in some areas, particularly across Nevada and the central Rockies. The Pacific Northwest interior and northern Rockies retain some above-normal readings early in this period before the cold anomaly expands westward.

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TROPICAL: The Atlantic basin and the Eastern Pacific basin are both quiet at this time, with no activity anticipated over the next 7 days.