Scattered Showers and Storms

General Overview: ACTIVE WEATHER PATTERN ACROSS THE WEST WITH SIGNIFICANT PRECIPITATION EXPECTED IN THE PACIFIC NORTHWEST AND NORTHERN ROCKIES. MIXED PRECIPITATION INCLUDING RAIN AND SNOW WILL IMPACT THE NORTHERN TIER WHILE THUNDERSTORMS DEVELOP ALONG THE GULF COAST AND FLORIDA. WELL ABOVE NORMAL TEMPERATURES WILL DOMINATE THE NORTHERN PLAINS AND UPPER MIDWEST THROUGH THE PERIOD.

EAST:  A high pressure system will bring generally dry conditions to much of the Northeast and Mid-Atlantic states for the first part of the forecast period. By Thursday, a low pressure system develops off the East Coast, bringing rain and thunderstorm activity to coastal areas of the Carolinas. Unsettled conditions will persist across the southeast late this week and this weekend with daily chances for showers and thunderstorms expected. Strong high-pressure across the northeast will generally prolong dry weather across the region. 

Temperature Anomalies:

-Days 1-3: Near normal to slightly above normal temperatures across most of the East, with the warmest anomalies (2-4°F above normal) in the interior Northeast.

-Days 4-6: Warming trend continues with temperatures 3-6°F above normal spreading across much of the Northeast and Mid-Atlantic, while the Southeast remains closer to seasonal averages.

-Days 7-10: Temperatures moderate to near normal or slightly above normal (1-3°F) across most of the region, with the warmest anomalies remaining in the Northeast.

CENTRAL:  The Central Plains and Midwest will experience relatively quiet weather initially, but changes arrive as the week progresses. A low pressure system developing in the Northern Plains will bring rain to parts of the Dakotas and Minnesota by midweek. As this system moves eastward, precipitation will spread into the Upper Midwest. The Southern Plains will remain mostly dry through the period. By the weekend, a new frontal boundary pushes through the region, bringing a chance of showers and thunderstorms to portions of the Central Plains and Midwest. Arkansas and eastern portions of Oklahoma may see some thunderstorm activity associated with moisture from the Gulf.

Temperature Anomalies:

-Days 1-3: Significantly above normal temperatures across the Northern Plains and Upper Midwest, with anomalies of 8-12°F above normal in the Dakotas, Minnesota, and parts of Iowa. The Southern Plains will be 2-5°F above normal.

-Days 4-6: Continued very warm conditions across the Northern Plains and Upper Midwest with peak anomalies of 10-14°F above normal in parts of South Dakota and Nebraska. The warmth expands eastward into the Great Lakes region.

-Days 7-10: Gradual moderation of temperatures with anomalies decreasing to 2-6°F above normal across most of the region by the end of the period.

WEST:  An active weather pattern will dominate the Western states, with multiple systems bringing precipitation to the Pacific Northwest and Northern Rockies. Rain and mountain snow will be widespread across Washington, Oregon, Idaho, and western Montana. Mixed precipitation is expected in the higher elevations of the Northern Rockies, with accumulating snow possible for elevated areas. The Southwest will remain mostly dry, with high pressure centered over Colorado and Utah bringing stable conditions. By the weekend, a new frontal system pushes inland, bringing another round of precipitation to the Pacific Northwest and Northern Rockies. California will see varying conditions, with some coastal rain possible in the northern portions of the state while southern areas remain dry.

Temperature Anomalies:

-Days 1-3: Near to slightly below normal temperatures along the immediate Pacific Coast and in areas receiving precipitation. Interior portions of the Southwest will be near to slightly above normal.

-Days 4-6: Cooling trend in the Northwest with areas of below normal temperatures (-3 to -6°F) developing in parts of Idaho, Wyoming, and Montana. The Southwest remains near normal.

-Days 7-10: Temperatures moderate to near normal across most of the West by the end of the period, with only isolated areas of slight anomalies.

TROPICAL:
ATLANTIC BASIN:
1. Central Tropical Atlantic: Hurricane Humberto is currently located approximately 275 miles NW of Bermuda, moving east-northeast at 10 mph. Humberto is a category 1 hurricane on the Saffir-Simpson Hurricane Wind Scale and has maximum sustained winds of 80 mph. Humberto will continue its rapid acceleration off to the northeast and further out into the open Atlantic as the week progresses. No impacts to the U.S. are expected with this storm system.

2. Southwestern Atlantic: Hurricane Imelda currently resides approximately 520 miles west-southwest of Bermuda, and is moving east-northeast at 17 mph. Imelda has sustained winds of 85 mph and is considered a category 1 hurricane. Fortunately, steering flow and its interaction with nearby Hurricane Humberto will keep Imelda offshore and will push Imelda farther out to sea, with acceleration to the northeast expected over the next several days by late Tuesday and early Wednesday. Still, its proximity periods of rain, rough seas, and the risk of rip currents will be possible from northern Florida into the Carolinas today due to its proximity to the coast. Any impacts from Imelda will dissipate by tonight.

EAST PACIFIC BASIN: 

1. Offshore Southwest Mexico: Tropical Storm Octave is currently located approximately 885 miles south-southwest of the Southern tip of Baja California, moving north-northwest at 7 mph. TS Octave currently has sustained winds reaching 45 mph. Octave will slowly travel north over the next 12 hours, with a northwest turn expected late today and into this weekend. No impacts to the U.S. are currently expected with this storm system.

2. Offshore Southwest Mexico: An area of low pressure is expected to form off the coast of southwestern Mexico in a couple of days. Thereafter, environmental conditions are expected to be conducive for additional development, and a tropical depression will likely form late this week or this weekend while the system moves generally west-northwestward, parallel to but offshore of the southwestern coast of Mexico. Tropical formation chance through 48 hours is low at 20%, and tropical formation chance through 7 days is high at 80%. No immediate concerns to land are anticipated, although DTN will monitor the latest forecast for any changes.