Mostly Quiet and Dry End to Month

General Overview: AN ACTIVE WEATHER PATTERN WILL CONTINUE ACROSS THE PACIFIC NORTHWEST, NORTHERN ROCKIES, AND SOUTHEAST COAST WITH RAIN AND THUNDERSTORMS FORECAST. SIGNIFICANT ABOVE-NORMAL TEMPERATURES WILL DOMINATE THE NORTHERN PLAINS AND UPPER MIDWEST THROUGH THE FORECAST PERIOD. TWO HURRICANES, HUMBERTO AND IMELDA, ARE TRACKING OFFSHORE ALONG THE ATLANTIC COAST.

EAST:  A high pressure system will bring generally dry conditions to much of the Northeast and Mid-Atlantic states through this week. Along the Southeast coast, rain and thunderstorm activity will develop, particularly across Florida, Georgia, and the Carolinas. These storms are associated with moisture from Hurricane Humberto, which is tracking offshore in the western Atlantic. By late week, high pressure will remain in place over the Northeast, helping to push the coastal precipitation southward. The Gulf Coast will see scattered showers and thunderstorms, particularly in Florida where tropical moisture remains in place.

Temperature Anomalies:

-Days 1-3: Near normal temperatures across most of the Northeast and Mid-Atlantic, with slightly above normal temperatures (2-4°F) in parts of the Ohio Valley and Great Lakes region.

-Days 4-6: Warming trend begins with temperatures climbing to 3-6°F above normal across much of the Northeast and expanding into the Mid-Atlantic states.

-Days 7-10: Continued above normal temperatures (4-8°F) across the Northeast and northern portions of the Mid-Atlantic, gradually moderating toward the end of the period.

CENTRAL:  Generally dry conditions will persist over much of the Plains early this week, with shower and thunderstorm chances persisting along the Lower Mississippi Valley. A low pressure system moving through the Central Plains mid this week will bring scattered precipitation to portions of Missouri and surrounding states. As the week progresses, a cold front will push through the Northern Plains, bringing a chance of rain and thunderstorms. By the weekend, a developing low pressure system in the Northern Plains will bring more organized precipitation to the region, with a warm front/cold front combination affecting the Upper Midwest and Great Lakes.

Temperature Anomalies:

-Days 1-3: Significantly above normal temperatures (8-12°F) across the Northern Plains and Upper Midwest, with the warmest anomalies centered over North Dakota, South Dakota, and Minnesota.

-Days 4-6: Continued well above normal temperatures (8-12°F) across the Northern Plains and Upper Midwest, gradually expanding eastward into the Great Lakes region.

-Days 7-10: Above normal temperatures (4-8°F) persisting across the Northern Plains and Upper Midwest, though gradually moderating by days 9-10 as the pattern begins to change.

WEST:  An active weather pattern will affect the Pacific Northwest and Northern Rockies with multiple systems bringing rain and mountain mixed precipitation. Low pressure systems along the West Coast will drive periods of rain and thunderstorms across Washington, Oregon, Idaho, and western Montana. The Southwest will experience generally dry conditions with areas of low pressure over Nevada and Utah bringing scattered precipitation to the Great Basin. By late week, a more organized system will bring increased precipitation chances to the Pacific Northwest and Northern Rockies, with some rain and thunderstorm activity developing in parts of California.

Temperature Anomalies:

-Days 1-3: Near to slightly below normal temperatures along the immediate Pacific Coast, with above normal temperatures (4-8°F) across the interior Northwest and Northern Rockies.

-Days 4-6: Continued near to slightly below normal temperatures in parts of California and the Pacific Northwest, with above normal temperatures persisting across the interior Northwest.

-Days 7-10: Cooling trend with below normal temperatures (2-6°F) developing across portions of the interior West, particularly in Nevada, Utah, and Idaho, while the rest of the region trends toward near normal.

TROPICAL:
ATLANTIC BASIN:
1. Central Tropical Atlantic: Hurricane Humberto is currently located approximately 265 miles SW of Bermuda, moving north-northwest at 14 mph. Humberto is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale and has maximum sustained winds of 115 mph. Humberto will continue to move north over the 12-24 hours before turning northeast by late Tuesday. Humberto will then rapidly accelerate off to the northeast and further out into the open Atlantic into the late week. No impacts to the U.S. are expected with this storm system.

2. Southwestern Atlantic: Tropical Storm Imelda currently resides approximately 145 miles N of Great Abaco Island, and is moving north at 7 mph. Imelda has sustained winds of 65 mph. Imelda will continue to organize and strengthen today as it takes a  northeast turn over the next 12 hours. Imelda will bring periods of rain, breezy winds, and rough seas to areas along the Florida coastline as Imelda passes nearby. Imelda is expected to become a hurricane within the next 12 hours. Fortunately, steering flow and its interaction with nearby Hurricane Humberto will keep Imelda offshore and will even push Imelda farther out to sea 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 through Tuesday due to its proximity to the coast. Any impacts from Imelda will dissipate by late Wednesday.

EAST PACIFIC BASIN: 

1. An area of disorganized convection is noted well off the southwest coast of Mexico. A slow organization will likely occur through the next several days due to a conducive environment, and a tropical cyclone is likely to form around the middle of the week. Tropical formation chance through 48 hours is high at 90%, and tropical formation chance through 7 days is high at 90%. No immediate concerns to land are anticipated, although DTN will monitor the latest forecast for any changes.