Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 340 PM EDT Fri May 11 2018 Valid 00Z Sat May 12 2018 - 00Z Mon May 14 2018 ...Severe thunderstorms will be possible on Saturday across portions of the upper Midwest, upper Ohio Valley and northern Mid-Atlantic states... ...Critical fire danger exists across the Southwest and southern Rockies... ...Rain and late season mountain snow expected across the Intermountain West and northern to central Rockies... Over the next few days, a wavy and quasi-stationary front will remain in place stretching from the central High Plains east all the way to the Mid-Atlantic states. Meanwhile, along this front there will be multiple waves of low pressure tending to advance east along it. These waves of low pressure coupled with warm, moist air lifting north from the Gulf of Mexico and overrunning the front will foster an expansive area of showers and thunderstorms. The activity will cover a large area including much the central Plains, Midwest and areas east across the lower Great Lakes, Mid-Atlantic and southern New England. In fact, there will be a concern on Saturday for severe thunderstorms from the upper Midwest east across the upper Ohio Valley and through the northern Mid-Atlantic region. The greatest risk at this time appears to be focused on eastern Ohio and northern West Virginia east across Pennsylvania, northern Maryland and New Jersey which is where the Storm Prediction Center has highlighted an enhanced risk of severe weather. In addition to the severe weather threat, heavy rainfall will also be a concern going through the weekend along and generally north of this frontal zone. Some of the heaviest totals this weekend are expected to be over the lower Great Lakes, upper Ohio Valley and the northern Mid-Atlantic region where as much as 1 to 2 inches of rain possible. Some localized flooding concerns will be possible as a result. Much of the northern tier states will be cooler through the weekend, as high pressure will straddle this region from west to east. Meanwhile, across the South, the temperatures will be near or above normal. An exception will be over Florida where an area of disturbed weather associated with an upper low should bring plenty of clouds and a threat of locally heavy rainfall. The heaviest rains should be along the east coast of Florida where locally 2 to 3 inches of rain can be expected from late Saturday through Sunday. This will certainly keep temperatures relatively cooler as well. Locally hot, dry and windy conditions will prevail across much of the Southwest U.S. and toward the southern Rockies which will maintain a critical fire weather threat. Many of these areas are in an extreme to exceptional drought, and unfortunately most of this region is not expected to see any rain through the weekend. Rain and late season mountain snow though is expected farther north across the West with a large scale upper trough amplifying and closing off over the Intermountain West. The heaviest rain and snowfall totals should be over the northern and central Rockies, where moist easterly flow into the terrain will enhance precipitation for the favored upslope regions. Orrison Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php