Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 401 AM EDT Mon Jul 15 2013 Valid 12Z Mon Jul 15 2013 - 12Z Wed Jul 17 2013 ...Heat wave to build into the Ohio Valley and eastern U.S. early this week... ...Cool and wet weather with possible flooding from the Southern High Plains to the Southwest... A very anomalous pattern is in place over the U.S. for mid-July, with a large upper level ridge centered over the upper Ohio Valley and a deep closed upper level low over the Texas/Oklahoma border. Beneath the upper ridge/trough, temperatures will remain atypically hot/cool, respectively. Across the northwestern U.S., an upper level disturbance will skirt eastward across southern Canada, which will slowly drag a cold front across the northern U.S. The upper level low over Texas/Oklahoma is forecast to slowly drift west, reaching New Mexico by Wednesday morning. Moderate to locally heavy rainfall rates are expected to continue near and south of the low as it drifts west over the next couple of days, with the upper low's slow movement leading to potentially excessive rainfall. The greatest risk of flooding rain exists from central Texas to the New Mexico/Arizona border through Tuesday night. Due to increased cloud cover and rainfall near the upper low, high temperatures will be run 10 to 20 degrees below mid-July averages. Across the East, temperatures will warm well into the 90's as the upper ridge slowly drifts westward. While isolated to scattered thunderstorms will be possible during the afternoon/evening east of the Mississippi River, the majority of locations beneath the ridge will stay rain free. 90's will also reach the Midwest and portions of the northern plains for Tuesday and Wednesday, feeling quite seasonal for the middle of summer. As low pressure tracks northeastward from southwestern Canada, it will take a cold front slowly across the north-central U.S. but the front will do little to cool off locations in its wake. Scattered thunderstorms are expected near the boundary in and around the upper Mississippi Valley today and Tuesday where the greatest moisture and instability will be present, but widespread heavy totals are not forecast. Otto Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php