Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 256 PM EST Tue Dec 12 2023 Valid 00Z Wed Dec 13 2023 - 00Z Fri Dec 15 2023 ...Heavy Snow potential across parts of the Central/Southern Rockies/High Plains... ...Lake effect snow downwind of the Great Lakes beginning today... ...Heavy downpours and scattered flash flooding forecast for South Florida Thursday... ...Above average temperatures for the Midwest/Great Lakes as the East Coast remains a bit chilly... A developing upper-level low over the Southwest and associated surface frontal system will bring a period of heavy snow to portions of the Central/Southern Rockies, and spread into the adjacent High Plains Wednesday into Thursday. The heaviest snow in the mountains should be confined to the San Juans and Sangre de Cristos of south-central Colorado/north-central New Mexico where over a foot of snow is possible. There is more uncertainty in the precipitation forecast for the Plains which will be dependent on the surface low track and temperatures, likely hovering near freezing, and will dictate how much precipitation falls as rain or snow. Currently, the expectation is that areas of northeastern New Mexico and southeastern Colorado have the highest chance for heavy snowfall of 4-10". Surrounding areas including into southwestern Kansas and the Oklahoma and Texas Panhandles will also have the chance to see some wintry precipitation, including snow and freezing rain. Some locally heavy rainfall will also be possible where temperatures remain warmer over West Texas, particularly on Thursday. To the east, mean northwesterly flow setting in over the Great Lakes following a cold front passage will lead to some lake-effect snow for favorable downwind locations through Wednesday. Some more moderate totals of 3-6" are most likely downwind of Lakes Superior and Ontario. Winds will be rather gusty across the region. Meanwhile, a stalled frontal boundary meandering near South Florida as well as very moist, easterly flow into the area will lead to shower and thunderstorm chances through at least Thursday. Some locally very heavy downpours are looking more likely for Thursday, where a Slight Risk of Excessive Rainfall (level 2/4) has been introduced for the threat of several inches of rain and some scattered instances of flash flooding. Elsewhere, a system approaching the Pacific Northwest will bring some light to moderate lower elevation/coastal showers and snow for the higher mountain peaks. Areas of the northern tier of the country from the Northern Plains into the Midwest and Great Lakes will see a warming trend to end the work week. Highs for much of the Upper Midwest/Great Lakes will be well into the 40s Thursday, upwards of 15 degrees above average. Temperatures will be a bit cooler Wednesday and Thursday for the East Coast following a frontal passage, with 20s and 30s for New England and 40s for the Mid-Atlantic into portions of the Carolinas. Conditions will be running at or above average from the eastern Southern Plains to the Lower Mississippi and Tennessee Valleys, as well as across much of the West. Temperatures will be chilly for portions of the Central/Southern Plains where wintry precipitation is expected, with highs in the 30s and 40s. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php