Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 423 AM EDT Tue Aug 06 2024 Valid 12Z Tue Aug 06 2024 - 12Z Thu Aug 08 2024 ...Tropical Storm Debby is expected to cause potentially catastrophic Flash and Urban Flooding, life-threatening storm surge, and strong winds across portions of north Florida and the Southeast... ...There's potential for Excessive Rainfall and Severe Thunderstorms across portions of the Northern High Plains, Midwest, Lower Great Lakes, Northeast and Mid-Atlantic today... ...There are Excessive Heat Warnings over parts of Central/Southeastern California and the Southwest; Heat Advisories over parts of the Lower Mississippi Valley... Tropical Storm Debby is expected to track up along the Southeast Coast over the next couple of days. Potentially historic heavy rainfall across southeast Georgia and eastern South Carolina through Friday will likely result in areas of catastrophic flooding. Heavy rainfall will likely result in considerable flooding impacts from northern North Carolina through portions of the Mid-Atlantic and southern New England through Sunday morning. Debby is expected to produce potentially historic rainfall totals of 10-20 inches, with maximum amounts of 25 inches. A High Risk (at least 70%) of Excessive Rainfall leading to Flash Flooding is in effect for parts of southeastern Georgia through eastern South Carolina and into far southeastern North Carolina today. On Wednesday, another High Risk will encircle portions of South Carolinas central coast up into southeastern North Carolina. For more information go to hurricanes.gov. A cold front will stall out over the Northeast and act as a focus for thunderstorm activity from the Ohio Valley through the northern Mid-Atlantic and into parts of the Tri-State area today. Tropical moisture from Debby will interact with the stationary front in the Northeast and likely generate heavy rainfall over parts of eastern Pennsylvania, northern Maryland, New Jersey, and the NYC metro area. A Moderate Risk (at least 40%) of Excessive Rainfall leading to Flash Flooding is in effect for the aforementioned areas. The Storm Prediction Center issued a Slight Risk (level 2/5) of Severe Thunderstorms for portions of northern Ohio, Pennsylvania and western/northern New Jersey, where damaging wind gusts and hail are possible. A Slight Risk (at least 15%) of Excessive Rainfall is also in effect for parts of southern New Jersey, northeastern Maryland and northern Delaware, where lingering showers may produce isolated flash flooding Wednesday morning before the stationary front turns cold and moves offshore. Elsewhere, mid-level energy propagating over the Northern High Plains will support thunderstorm activity today. The Storm Prediction Center issued a Slight Risk of Severe Thunderstorms capable of producing large hail and strong to severe wind outflow gusts with this activity. Isolated instances of Flash Flooding are also possible from these storms. Surface high pressure will penetrate the Northern/Central Plains over the coming days, and usher in a cooler airmass with high temperatures in the 60s and 70s, representing a 15-25 degree departure from normal. Warm air will remain locked in over much of the southern tier states with a heat wave developing over the Lower Mississippi Valley through the end of the week. Monsoonal storms are forecast to continue across parts of the Southwest and Four Corners this week. Shortwave energy will promote excessive rainfall across southern Arizona today. A Slight Risk of Flash Flooding is in effect for far southern Arizona as a result. Upper-level ridging across much of the Southwestern United States will continue to generate Excessive Heat, particularly across portions of central and southern California, into the Desert Southwest and the Intermountain West where Excessive Heat Warnings and Heat Advisories are in effect. Kebede Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php