Warm Temperatures Persist

General Overview: WIDESPREAD RAIN AND THUNDERSTORMS WILL IMPACT THE EASTERN THIRD OF THE COUNTRY THROUGH FRIDAY, WITH HEAVY RAIN POTENTIAL ALONG THE ATLANTIC COAST. MEANWHILE, THE SOUTHWEST FACES CRITICAL FIRE WEATHER CONDITIONS AND POTENTIAL FLASH FLOODING IN ARIZONA THROUGH THE WEEKEND. HURRICANE NARDA IS NOTED NEAR THE BAJA PENINSULA. TEMPERATURES WILL TREND ABOVE NORMAL FOR MUCH OF THE NORTHERN TIER, PARTICULARLY IN THE NORTHERN PLAINS WHERE SIGNIFICANT WARMTH BUILDS BY EARLY NEXT WEEK.

EAST:  A progressing low-pressure system will bring widespread rain and thunderstorms to the Northeast and Mid-Atlantic regions today. Low pressure systems tracking along the coast will produce areas of heavy rainfall, particularly from the Carolinas northward through New England. The heaviest precipitation is expected today, with rain gradually diminishing by Saturday as the system moves offshore. A cold front will push through the region by Friday evening, helping to clear conditions for the weekend. By Sunday and Monday, high pressure builds in from the north, bringing drier conditions to most of the region. Some lingering showers may affect coastal areas of the Southeast through the weekend.

Temperature Anomalies:

-Days 1-3: Generally slightly above normal temperatures (+3 to +6°F) across much of the region, particularly in the Northeast and Mid-Atlantic states.

-Days 4-6: Near normal to slightly above normal temperatures (+1 to +3°F) for most areas, with cooler conditions returning to parts of the Northeast by day 6.

-Days 7-10: Temperatures trending near normal for most of the region, with some slightly above normal readings (+2 to +4°F) in parts of the Mid-Atlantic.

CENTRAL:  High pressure will dominate the Central Plains late this week and into this weekend, providing generally dry conditions. A cold front will push through the northern portions today, bringing cooler air to the Upper Midwest. Low pressure developing in the southern Plains by Friday will bring increasing chances for thunderstorms across portions of Missouri and Kansas. The weekend looks to remain mostly dry across the Central Plains and Midwest, with high pressure rebuilding. By early next week, a warming trend will develop across the northern Plains and Upper Midwest as ridging builds.

Temperature Anomalies:

-Days 1-3: Near normal temperatures for most areas, with slightly above normal readings (+3 to +5°F) in the northern Plains.

-Days 4-6: Warming trend developing with above normal temperatures (+6 to +10°F) across the northern Plains and Upper Midwest, particularly in the Dakotas.

-Days 7-10: Significant above normal temperatures (+8 to +12°F) across the northern Plains and Upper Midwest, with warmest anomalies in North Dakota and northern Minnesota. Near normal temperatures for the southern Plains.

WEST:  Critical fire weather conditions will affect portions of the Southwest, particularly Arizona, where high pressure combines with dry conditions. Areas of low pressure along the West Coast will bring periods of rain to the Pacific Northwest and northern California late this week. The Southwest will see a threat of heavy rain and potential flash flooding in Arizona, with a high pressure system over Colorado helping to direct moisture into the region. By the weekend, drier conditions will prevail across much of the West, though thunderstorm activity may continue in parts of the Southwest. Low pressure systems will affect the Pacific Northwest periodically through the period.

Temperature Anomalies:

-Days 1-3: Above normal temperatures (+3 to +6°F) across much of the Northwest and northern Rockies, with some cooler than normal spots (-3 to -6°F) in parts of southern Arizona and New Mexico.

-Days 4-6: Continued above normal temperatures (+4 to +8°F) for the northern Rockies and northern Plains, with near normal temperatures elsewhere.

-Days 7-10: Above normal temperatures (+3 to +6°F) persisting across the northern Rockies and northern Plains, with near normal conditions for the Southwest and California.

TROPICAL:
ATLANTIC BASIN: 
1. Central Tropical Atlantic: Tropical Storm Humberto currently exists approximately 505 miles ENE of the Northern Leeward Islands and is moving west-northwest at 12 mph. Humberto is expected to continue northwestward over the next several days, with a northward turn expected sometime early next week. No impacts to the U.S. are currently expected with Humberto.

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 medium at 50 percent and formation chance through 7 days is high at 80 percent.

EAST PACIFIC BASIN: Hurricane Narda remains off the coast of southern Mexico, or about 580 miles south-southwest of Cabo San Lucas, and is moving west at 10 mph. Narda is expected to take a slight northwesterly turn late this 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.