Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 452 PM EDT Tue Sep 10 2013 Valid 00Z Wed Sep 11 2013 - 00Z Fri Sep 13 2013 ...Relief from the recent heat and humidity is in the forecast for the Midwest and Ohio Valley... ...Strong to severe thunderstorms will be possible from the Great Lakes into northern New England... ...Heavy showers and thunderstorms will persist over the Southwest...promoting additional concerns for flash flooding... Much of the Midwest...Ohio Valley...and Mid-Atlantic states will start to see some relief from the recent heat and humidity as a large scale upper trough begins to amplify over the Eastern U.S.. The associated surface boundary will serve as a focal point for scattered convection as it presses southeastward through the Great Lakes and Middle Mississippi Valley on Wednesday and crosses the Appalachians on Thursday. The greatest chance for any heavy rains and severe weather with this feature will be from the Lower Great Lakes into New England...where SPC is highlighting a slight risk area. Temperatures and dewpoints behind the main boundary will certainly be lower...but the real cool down will be with a reinforcing secondary front dropping out of Canada early in the forecast period. Widespread showers and thunderstorms will continue across much of the Southwest...Southern to Central Rockies...and adjacent High Plains the next few days. Energy within an a weak upper low aloft...combined with anomalous moisture getting funneled into the region...should help ignite and fuel moderate to locally heavy rains...promoting additional concerns for flash flooding. Elsewhere across the southern tier...moist easterly flow will support continued showers and thunderstorms across South Texas. Also...a weak upper low meandering over Florida should help spark convection across the sunshine state Wednesday and Thursday. Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php