Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 410 AM EDT Thu Jul 06 2017 Valid 12Z Thu Jul 06 2017 - 12Z Sat Jul 08 2017 ...Areas of heavy rain possible from the Ohio Valley into the central Appalachians through tonight... ...Severe thunderstorms possible over the upper Midwest today... ...Temperatures are expected to approach daily records across much of the interior western U.S. for the next few days... A subtle area of low pressure over the central Mississippi Valley is beginning to accelerate toward the east-northeast along a weak frontal boundary. This weak low, a likely consequence of antecedent thunderstorm clusters interacting with the weak front, is expected to help focus and enhance precipitation ahead of and along its track. Although the system is not expected to produce widespread heavy rain, heavy downpours could be triggered at any time given the presence of tropical moisture already in place. The heaviest rains are likely to occur near and along the stationary front from the Ohio Valley across the central Appalachians where the low center is expected to track through tonight. By Friday morning, computer models suggest the low will begin to intensify as it moves along the southern New England coast. It appears that a period of enhanced rainfall with gusty winds can be expected across southern New England before the low moves rapidly into the Canadian Maritimes on Saturday. Slightly drier air will move into the East Coast behind a weak cold front on Friday before the next cold front reaches the Appalachians by early on Saturday. This front is expected to trigger strong to severe thunderstorms from across the northern Plains and upper Midwest today before moving rapidly into the Great Lakes on Friday. Please refer to products issued by the Storm Prediction Center for further details on the severe weather threat. Over the western U.S., a large upper-level ridge of high pressure will dominate the weather pattern through the end of the work week. Sufficient moisture and instability will be in place beneath the ridge for isolated to scattered thunderstorms across much of the interior terrain, particularly during the afternoon and evening hours. The ridge will support well above average temperatures, particularly from the Northwest to the northern Rockies, where afternoon highs are forecast to be 10 to 20 degrees above average into Saturday. Many locations will see temperatures approaching daily record highs through Saturday. Under the excessive heat along with areas of thunderstorms, fire danger will remain very high across the interior mountains. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php