Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 421 PM EDT Thu Sep 07 2017 Valid 00Z Fri Sep 08 2017 - 00Z Sun Sep 10 2017 ...Hurricane Irma will begin impacting Florida this weekend... ...Widespread shower activity expected across the Southwest and Four Corners region the next few days... ...Temperatures will be below normal over the eastern half of the nation while temperatures should remain above normal for much of the Western U.S.... Showers and thunderstorms will be possible across Florida Thursday night into Friday as the tail end of a cold front that pressed off the Eastern Seaboard stalls and lingers across the Sunshine State, but then attention will shift into tropics as Hurricane Irma tracks northeastward towards the Bahamas. Strong winds, heavy rains, and dangerous storm surge from the approaching powerful storm should begin impacting portions of southern Florida by Saturday. For the latest information on Irma, please refer to the National Hurricane Center (www.nhc.noaa.gov). The combination of above normal moisture and an upper trough moving inland into the Western U.S. should bring widespread shower activity to the Southwest and portions of the Four Corners region the next few days. The greatest chance for precipitation will be during the late afternoon/early evening hours, and locally heavy rainfall could cause runoff concerns, especially Friday into Saturday. Strong surface ridging spreading over the the eastern half of the nation will keep conditions cool and dry through the end of the week, with the exception of the Great Lakes and Northeast where light to moderate showers will be possible and locations in the Southeast which are expected to be impacted by Hurricane Irma. Out West, temperatures will remain above normal beneath an upper ridge, but the axis of highest temperature anomalies should slowly shift eastward from the Rockies to the High Plains as the ridge axis shifts eastward ahead of the upper trough moving inland over the Western U.S.. Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php