After several days of warm and moderately muggy conditions over much of the eastern U.S., a cold front moving in from the Great Lakes region will bring a welcomed return of cooler and less humid weather for the end of the week. Meanwhile, scattered rain and thunderstorms are forecast today for parts of the Southeast, central Rockies, and Midwest.

The fire weather threat will reach the critical level in the southwest on Thursday. Elsewhere in the west, the fire weather threat will remain elevated as a system pushes through. Strong winds and thunderstorms capable of producing lightning but little precipitation will move through the region, increasing the chances for a fire to spark and spread quickly.

The NWS Storm Prediction Center is forecasting a Slight Risk for severe thunderstorms for northeastern Pennsylvania central, eastern and upstate New York and western New England. The main threats will be damaging hail and wind. Meanwhile, sea breeze-driven storms will occur this afternoon over the eastern Carolinas. A few strong to severe storms will be capable of damaging winds.

Severe thunderstorm activity will shift to the north on Wednesday, bringing the threat of wind and hail to New England. The Storm Prediction Center is forecasting storms for mid-day ahead of an advancing cold front.

The NWS Storm Prediction Center is forecasting a Slight Risk of severe thunderstorms for parts of the lower Great Lakes region and upper Mississippi Valley, as well as for parts of the Mid-Atlantic, including much of the Carolinas, Virginia and Maryland. The main threats will be large hail and damaging winds, although there is a minimal threat of brief tornadoes.

With daytime temperatures above 100 degrees and dew points in the single digits and teens, the potential for fire weather is increasing in the desert southwest. Wind speeds will increase across this region on Tuesday. Should a fire begin, it will rapidly spread due to the dry and windy conditions.

The NWS Storm Prediction Center is forecasting a Slight Risk of severe thunderstorms through tonight for parts of west/southwest Texas and the Rio Grande Valley. Large hail, damaging winds and isolated tornadoes are possible. Meanwhile, a secondary area of strong to severe storms capable of damaging winds exists from the Mid-Atlantic to the Southeast U.S.

Excessive Heat Watches and Warnings are in effect for portions of southern California and Arizona. Temperatures in excess of 110 degrees are possible over the next few days. This will be the first stretch of excessive heat in this area for 2012.

A slow moving moisture laden storm system will spread an axis of moderate to heavy rain northward from the Piedmont and Mid-Atlantic into Interior New England early this week. Widespread rainfall of one to three inches is expected through early Wednesday with a chance for localized flooding, especially over portions of eastern Pennsylvania.

At the beginning of the year, nearly 55% of Texas was in severe drought or worse. Precipitation over the past four months has alleviated drought conditions across the southern and eastern portions of the state. As of May 8, 2012, only 25% of the state was experiencing severe drought or worse.

Temperatures Saturday morning are cool across the northern tier of the US and into New England, but summer-like heat is returning to the southwestern states today. An Excessive Heat Warning has been issued for the deserts of southeastern California and southwestern Arizona, where temperatures up to 105 degrees are possible Saturday afternoon. Highs in the mid to upper 90s will be common throughout California's Central Valley.

A disturbance moving through the southern Great Plains will continue to provide a threat for severe weather and heavy rainfall across eastern Texas tonight. The threat for heavy rainfall will shift into southeast Louisiana and southern Mississippi for Saturday. Rainfall amounts of 2 to 4 inches, with locally heavier amounts are possible. Repeat areas of very heavy rainfall may result in flash flooding of streets, canals, small stream as well as low-lying and poor drainage areas. Remember: Turn Around Don't Drown

Heavy rainfall and flash floods are possible across southeast Texas and western Louisiana today. Several inches of rainfall are expected, which could lead to flooding of urban areas and small creeks. Meanwhile, isolated severe thunderstorms are possible across the central Gulf Coast, where the main threats will be large hail and damaging winds.

A disturbance moving into the southern Great Plains will continue to provide a threat for heavy rainfall capable of flash flooding across southern Texas tonight. As this system migrates east, expect the flash flood threat to shift into southeast Texas and southern Louisiana for Friday and Saturday. Amounts of 2-4 inches will be common across this region through the period, with locally heavier amounts possible. This system may also lead to river rises across the region for early next week. Remember: Turn Around Don't Drown

Heavy rainfall and flash floods are possible today across central and southern Texas. Several inches of rainfall are expected, which could lead to flooding of urban areas and small creeks. Meanwhile, severe thunderstorms are possible across southern Texas, with large hail, damaging winds and weak tornadoes possible.