Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 404 AM EDT Wed Aug 7 2013 Valid 12Z Wed Aug 7 2013 - 12Z Fri Aug 9 2013 ***Warmer and more humid for the Eastern U.S.*** ***Bad weather continues over the Central Plains*** ***Heat wave over the Southern Plains*** After several days of very pleasant weather over the Eastern U.S., the airmass over the region is expected to modify and become increasingly warm and humid through the middle to end of the week as the surface high continues moving offshore. This pattern change will also increase the chances for showers and thunderstorms as moisture arrives from the Midwest states. The presence of a quasi-stationary frontal boundary over the Central Plains and into Missouri, along with an approaching cold front from the Dakotas and shortwave energy aloft, will keep a zone of very stormy weather going through mid-week. Additional thunderstorm complexes will hammer the region with heavy rainfall and intense cloud-to-ground lightning. Another area of organized rainfall and embedded thunderstorms is expected ahead of an advancing cold front over the Great Lakes region and into the Northeast U.S. More quality weather can be expected for the northern tier states behind the cold front. Elsewhere, isolated to scattered convection can be expected each afternoon over the Four Corners region with the monsoonal moisture in place. Afternoon sea breeze convection is likely over the Florida Peninsula each afternoon. It will remain hot and humid over the Deep South states and into Texas, which are expected to remain south of the main frontal zone. The heat wave has prompted the issuance of widespread heat advisories and a few excessive heat warnings. Heat indices may approach 110 degrees in some of these areas with temperatures in the upper 90s to low 100s, along with high dewpoints. Hamrick Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php