Scattered Showers and Thunderstorms Possible Across the Southwest

General Overview: ACTIVE WEATHER PATTERN ACROSS THE NATION WITH HEAVY RAIN AND POTENTIAL FLOODING IN THE OHIO VALLEY AND TENNESSEE VALLEY THROUGH MIDWEEK. THUNDERSTORMS WILL DEVELOP ACROSS THE SOUTHEAST AND GULF COAST STATES WHILE THE SOUTHWEST SEES HEAVY RAIN POTENTIAL IN NEW MEXICO. TEMPERATURES WILL TREND ABOVE NORMAL FOR MOST OF THE COUNTRY, PARTICULARLY ACROSS THE NORTHERN PLAINS AND ROCKIES.

EAST:  
A significant weather system will impact the eastern United States through midweek, with a low pressure system moving through the Ohio Valley and Tennessee Valley regions. Heavy rain and potential flash flooding will be the primary concern across these areas on Wednesday into Thursday, with rainfall amounts potentially reaching flood stage in some locations. The Northeast will experience widespread rain and thunderstorm activity as moisture spreads northeastward. 

By Thursday, the system will begin to push offshore, but rain and thunderstorm activity will continue across much of the Eastern Seaboard. A cold front will sweep through the region by Friday, helping to clear conditions but maintaining some shower activity along coastal areas. The Southeast and Gulf Coast will experience persistent thunderstorm activity through the weekend as the frontal boundary stalls.

Temperature Anomalies:

-Days 1-3: Generally above normal temperatures across most of the East, with anomalies of 3-6°F above normal. The Northeast will see the warmest conditions relative to normal.

-Days 4-6: Temperatures moderating but remaining slightly above normal for most areas, with the warmest anomalies shifting toward the coastal Southeast.

-Days 7-10: Near normal temperatures returning to much of the region, with only slight positive anomalies remaining along the Atlantic coast.

CENTRAL:  
The Central United States will experience an active weather pattern as a low pressure system moves through the Ohio Valley and Tennessee Valley. Heavy rain and thunderstorms will affect areas from the Tennessee Valley northward through the Ohio Valley on Wednesday, with potential flash flooding concerns. The system will gradually shift eastward by Thursday, with high pressure building in behind it.

The Central Plains will see generally drier conditions under the influence of high pressure, though some thunderstorm activity may develop along frontal boundaries. By the weekend, a new frontal system will begin to approach from the northwest, bringing increased chances for precipitation to the Northern Plains and Upper Midwest.

Temperature Anomalies:

-Days 1-3: Above normal temperatures across most of the region, particularly in the Northern Plains where anomalies will reach 6-8°F above normal. The Central Plains and Midwest will see more moderate warming of 3-5°F above normal.

-Days 4-6: Continued above normal temperatures, especially across the Northern Plains and Upper Midwest where anomalies remain 6-8°F above normal.

-Days 7-10: Persistent above normal temperatures across the Northern Plains and Upper Midwest, with the warmest anomalies (6-10°F above normal) concentrated in the Dakotas and Minnesota.

WEST:  
The Western United States will see a mix of weather conditions. The Southwest, particularly New Mexico and Arizona, will experience heavy rain and potential flash flooding through Thursday. Low pressure systems along the Pacific Northwest coast will bring periods of rain to coastal areas and higher elevation snow to the northern Rockies.

By late week, high pressure will build across the Great Basin and Rockies, leading to drier conditions for much of the region. The Pacific Northwest will continue to see occasional precipitation as systems move onshore. The Southwest will gradually dry out, though thunderstorm activity may persist in parts of Arizona and New Mexico through the weekend.

Temperature Anomalies:

-Days 1-3: Above normal temperatures across most of the West, with the exception of slightly below normal temperatures in parts of Colorado. The Pacific Northwest and Northern Rockies will see temperatures 3-6°F above normal.

-Days 4-6: Continued above normal temperatures, particularly in the Northern Rockies and Pacific Northwest where anomalies will reach 6-8°F above normal. Some cooling to near normal in the Southwest.

-Days 7-10: Persistent above normal temperatures across the Northern Rockies and Northern Plains, with anomalies of 6-10°F above normal. The Southwest returns to near normal temperatures.

TROPICAL:
ATLANTIC BASIN: 
1. Central Tropical Atlantic: Shower and thunderstorm activity associated with a tropical wave located about midway between the Lesser Antilles and the Cabo Verde Islands continues to increase. Environmental conditions remain favorable for tropical development, with a tropical depression expected to form within the next 48 hours or so. Tropical formation chance through 48 hours is high at 70 percent.

2. Extreme northeastern Caribbean Sea: A tropical wave located over the Windward and Leeward Islands continues to produce disorganized showers and thunderstorms. Environmental conditions appear favorable for slow development over the next few days as the wave moves westward to west-northwestward. By late week, the system is expected to slow down and turn more northwestward, and a tropical depression could form late this week when the system is over the southwestern Atlantic Ocean or near the Bahamas. Tropical formation chance through 48 hours is low at 30 percent and formation chance through 7 days is high at 70 percent.

EAST PACIFIC BASIN: Hurricane Narda remains off the coast of southern Mexico, or about 450 nautical miles south of Cabo San Lucas, and is moving west at 13 mph. Narda is expected to continue on a westerly path and farther out to open sea through the mid-week period before taking a slight northwesterly turn late week into the coming weekend. Steady strengthening is forecast over the next few days, and Narda is expected to become a major hurricane by Friday evening. No impacts to the U.S. are expected with Narda.