National Weather Summary for Thursday, September 20, 2018
by David Moran, on Sep 20, 2018 10:58:12 AM
Thunderstorms are expected to develop from the Central Plains into the Great Lakes on Thursday ahead of a cold front. In addition to this thunderstorm activity, there will be a risk for excessive rainfall from the Southern High Plains into the Upper Great Lakes.
- Thunderstorms from the Central Plains into the Great Lakes on Thursday
- Excessive Rainfall Thursday from the Southern High Plains into the Upper Great Lakes
- Potential for Thunderstorms Friday from the Ohio Valley into the Northeast
- Risk for Excessive Rainfall from the Southern Plains into the Mid Mississippi Valley Friday and Saturday
- Tropical Update
Thunderstorms from the Central Plains into the Great Lakes on Thursday
An intensifying area of low pressure is forecast to lift northeastward from the Central Plains, across the Upper Midwest, and into the Great Lakes today. The trailing cold front will move eastward across the area providing a focus for thunderstorm development. Instability will build during the afternoon and evening; with support from a strong upper level disturbance, thunderstorms are expected to develop. Damaging winds, large hail, and tornadoes will be potential hazards with these storms. The highest risk will be over northern Iowa, southeast Minnesota, and western Wisconsin.
Major Cities in Region: Mason City, IA, Rochester, MN, Wausau, WI, Marquette, MI
Thunderstorm Risk for Thursday
Excessive Rainfall Thursday from the Southern High Plains into the Upper Great Lakes
A cold front advancing eastward through the central US will likely produce scattered to widespread showers and thunderstorms across the region today. With deep moisture spreading northward from both the Gulf of Mexico and the tropical East Pacific Ocean, there will be a risk for excessive rainfall. Widespread amounts of 1-2 inches with locally higher amounts in excess of 3 inches are expected. Given recent heavy rains over the Upper Midwest, there will be an increased risk for flooding.
Major Cities in Region: Amarillo, TX, Sioux Falls, SD, Omaha, NE, Duluth, MN, Wausau, WI
Rainfall Accumulation for Thursday
Potential for Thunderstorms Friday from the Ohio Valley into the Northeast
A cold front associated with the area of low pressure described above is forecast to track eastward across the Great Lakes and into the Northeast on Friday. Scattered thunderstorms are forecast to develop along and ahead of the front by the afternoon and evening as instability builds due to daytime heating. Thunderstorms will be strong to severe with damaging winds and hail the primary hazards, but a few isolated tornadoes cannot be ruled out.
Major Cities in Region: Evansville, IN, Indianapolis, IN, Louisville, KY, Cincinnati, OH, Columbus, OH, Cleveland, OH, Pittsburgh, PA, Buffalo, NY, Albany, NY, Portland, ME, Augusta, ME
SPC Convective Outlook for Friday
Risk for Excessive Rainfall from the Southern Plains into the Mid Mississippi Valley Friday and Saturday
Widespread showers and thunderstorms associated with a slow moving cold front will spread from west to east across the Southern Plains into the mid-Mississippi Valley on Friday and Saturday. Model guidance is indicating the potential for a significant rainfall event over this region, especially over central Oklahoma, as the front interacts with deep low level moisture spreading northward. Rainfall amounts of 2-4 inches with locally higher amounts in excess of 6 inches are forecast. This will lead to an increased risk of flooding and perhaps some travel issues for the end of the week.
Major Cities in Region: Wichita Falls, TX, Oklahoma City, OK, Tulsa, OK, McAlester, OK. Fayetteville, AR
Rainfall Accumulation for Friday and Saturday
An area of thunderstorms associated with a westward-moving tropical wave is located about 850 miles east of the Windward Islands. Although this disturbance shows signs of organization, there is no evidence of a surface circulation at this time. Some additional development may occur today before conditions become unfavorable for development tonight.
Enhanced Infrared Satellite
A Look Ahead
Heavy rain will continue across portions of the Southern Plains into the Mid Mississippi Valley on Sunday. By Monday, this activity will move into the Ohio Valley. A few thunderstorms may develop across the Northern Plains and Upper Midwest on Monday ahead of a cold front. Thunderstorm activity will extend from the Great Lakes into the Plains Tuesday. On Wednesday, showers and thunderstorms will span from the Northeast to the Lower Mississippi Valley.