Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 249 PM EST Tue Feb 11 2020 Valid 00Z Wed Feb 12 2020 - 00Z Fri Feb 14 2020 ...An upgrade to Moderate Risk of excessive rainfall has been issued for the Upper Tennessee Valley and Cumberland Plateau for Wednesday. A Slight Risk remains today (Tuesday) from eastern Texas, northern Louisiana, southern Arkansas expanding into the Upper Ohio Valley... ...A Slight Risk of Severe Weather has been issued by the Storm Prediction Center (SPC) across the Lower Mississippi Valley... ...Heavy snow is possible over parts of the Southern Rockies today into early Wed morning... ...Light-to-moderate snow is possible with some mixed freezing rain will be possible across central IND-OH, northern PA into NY and West-Central New England though Wednesday night... A frontal zone from the Mid-Atlantic back to deep south Texas will be the focus for the development of a strong surface cyclone overnight Tuesday into Wed. A mid to upper level cyclone currently over northern Old Mexico is already supporting heavy snow generation across the Southern Rockies of New Mexico with 6 to 12 inches of snow forecast with localized higher amounts in the highest peaks. Warm, moist air over the Western Gulf, supported by the upper-level cyclone will lift north with the potential for scattered to widespread moderate and sometimes heavy rainfall across Eastern TX to the Lower Mississippi Valley tonight, with possible wintry mix conditions along the north and western fringes in Western Oklahoma to Missouri. Overnight into Wednesday morning, rainy conditions across Eastern Texas into southern Arkansas will provide the potential for 2 to 3 inches of rainfall and the potential for flooding/flash flooding conditions to arise. As such, the Weather Prediction Center has issued a Slight Risk of excessive rainfall for this area. By tomorrow (Wed) morning, a surface low pressure will develop and deepen across the eastern coast of Texas into western Tennessee. This will bring very moist/unstable air across the Lower Mississippi Valley capable of producing thunderstorms capable of severe weather, and so a Slight Risk was issued by the Storm Prediction Center. These thunderstorms will have ample moisture and capability of continuing very heavy rainfall and flooding conditions across the Lower Mississippi Valley into the Tennessee Valley. With the potential of 2 to 3 inches of rain over highly saturated areas; the Weather Prediction Center has upgraded to a Moderate Risk of excessive rainfall from Central Tennessee into south-central Kentucky with a Slight Risk extending into the Upper Ohio Valley and Cumberland Plateau. Extensive Flash Flood Watches have been issued by the majority of the forecast areas described above from eastern TX to southern Ohio/West Virginia. By Thursday morning, the surface low will have quickly progressed into the Upper Ohio Valley/Allegheny Plateau with the cold front pressing through the Appalachian mountains. Further north, an Arctic air mass will have dropped south across the Northern Plains with temperatures about 10-20 degrees below average behind the front reaching into the Upper Midwest by Thursday morning. The combination of the moisture drawn out of the Gulf ahead of the front and approaching colder air from the north will support the threat for light to occasionally moderate snows north of the front in IND, OH, PA and New York, with some mixing and potential for freezing rain conditions. Temperatures behind the Arctic cold front will expand across the Upper Midwest and into the Western Great Lakes by the end of the forecast period (Thursday night) with similar 10-20 degree below average values expected. Gallina Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php