US Day 3-7 Hazards Outlook NWS Weather Prediction Center College Park MD 323 PM EDT Thu May 23 2019 Valid Sunday May 26 2019 - Thursday May 30 2019 Hazards: - Heavy rain across portions of the Plains, the Mississippi Valley, and the Great Lakes, Sun-Wed, May 26-May 29. - Heavy rain across portions of the Central Rockies and the Northern/Central Plains, Mon-Tue, May 27-May 28. - Severe weather across portions of the Central/Southern Plains, Sun, May 26. - Severe weather across portions of the Plains and the Middle/Lower Mississippi Valley, Tue, May 28. - Severe weather across portions of the Northern/Central Plains and the Upper/Middle Mississippi Valley, Mon, May 27. - Flooding possible across portions of the Northern/Central Plains, the Northern Great Basin, the Upper/Middle Mississippi Valley, the Great Lakes, and the Ohio Valley. - Flooding occurring or imminent across portions of the Plains, the Mississippi Valley, the Great Lakes, and the Ohio Valley. - Flooding likely across portions of the Northern/Central Plains and the Upper/Middle Mississippi Valley. - Excessive heat across portions of the Southern Plains, Tue-Thu, May 28-May 30. - Excessive heat across portions of the Southeast, the Mid-Atlantic, the Lower Mississippi Valley, the Southern Appalachians, and the Tennessee Valley, Sun-Wed, May 26-May 29. - Enhanced wildfire risk across portions of the the Southern Rockies, the Southern Plains, and the Southwest, Mon, May 27. - Heavy precipitation across portions of mainland Alaska, Sun-Mon, May 26-May 27. Detailed Summary: A front extending from the Northeast roughly westward to the Central High Plains, on Sunday, will develop a wave of low pressure over the Central High Plains on Monday that will move northeastward to the Upper Mississippi Valley by Wednesday. The low will continue to move northeastward into Quebec by Thursday, with a front trailing southwestward from Northern New England to the Southern High Plains. The eastern portion of the boundary will move off the Northeast/Northern Mid-Atlantic Coast by Monday. A warm front from the Great Lakes roughly southeastward to the Southern Mid-Atlantic, on Tuesday, will lift northward into Northern New England by Wednesday. Moisture from the Gulf of Mexico will pool along the boundary and lift associated with the front will aid in making the air mass unstable producing severe thunderstorms along and ahead of the boundary over parts of the Southern/Central Plains into Middle Mississippi Valley/Southern Plains into Monday and Tuesday. In addition, the moisture pooling along the front and upper-level dynamics will aid in producing an area of heavy rain over parts of the Plains, Central High Plains, and Mississippi Valley into parts of the Upper Great Lakes on Sunday through Wednesday. The heavy rain will be over different areas in particular from day to day but generally over the same region taken as a whole. First the heavy rain will develop over parts of the Central Plains/Middle Mississippi Valley on Sunday into Monday morning. As the wave of low pressure develops and The front extends east-west oriented into the Ohio Valley, on Monday, the heavy rain will develop over parts of the Central Plains/Central High Plains, with another region of heavy rain developing over the Middle Mississippi Valley into parts of the Upper Mississippi Valley/Upper Great Lakes on Monday into Tuesday morning. On Tuesday into Wednesday morning, the axis of heavy rain will become northeasterly to the Southern Plains northeastward to the Middle Mississippi Valley. For Thursday into Thursday night the area of heavy rain is too uncertain to narrow down to one area. Upper-level ridging over the Southern Plains eastward to parts of the Southern Mid-Atlantic/Southeast and with maximum temperature anomalies in a range from +10 to +15 degree range will aid in producing an area of excessive heat over parts of the Southern Mid-Atlantic/Southeast into the Eastern Gulf Coast/Tennessee Valley Sunday into Thursday. There will also be an area of excessive heat over parts of the Lower Rio Grande Valley from Tuesday into Thursday. For simplicity purposes, the hazards outlook area for excessive heat focuses across the Southeast where these types of temperatures would be the highest experienced thus far this year. Low pressure near the Aleutians, on Sunday, will lose it's associated front by Tuesday then gets absorbed into another area of low pressure over the Aleutians by Thursday. A plume of moisture extending from near Hawaii into parts of the Aleutians, on Sunday, will dissipate Monday evening. An area of heavy precipitation will develop over the area on Sunday from the South Mainland Alaska Coast that will slowly move eastward to near Yakutat by Monday. Ziegenfelder