US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
441 PM EDT Mon May 20 2019
 
Valid Thursday May 23 2019 - Monday May 27 2019
 
Hazards:
- Heavy rain across portions of the Middle Mississippi Valley and the Southern Plains, Thu-Fri, May 
23-May 24.
- Heavy rain across portions of the Central Plains and the Middle Mississippi Valley, Fri-Mon, May 
24-May 27.
- Severe weather across portions of the Central Plains, the Middle Mississippi Valley, and the 
Southern Plains, Thu, May 23.
- Flooding possible across portions of the Plains, the Mississippi Valley,and the Great Lakes.
- 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 Plains, the Lower/Middle Mississippi Valley, and the Great 
Lakes.
- Excessive heat across portions of the Lower Mississippi Valley, the Tennessee Valley, the 
Mid-Atlantic, the Southern Appalachians, the Southeast, and the Southern Plains, Thu-Mon, May 
23-May 27.
- Much below normal temperatures across portions of the Plains, the Central Great Basin, the 
Northern/Central Rockies, and the Southwest, Thu, May 23.
- Heavy precipitation across portions of mainland Alaska, Thu, May 23 and Sat-Mon, May 25-May 27.
 
Detailed Summary:

A deep upper-level low over the Western U.S. will move northeastward to Central Ontario while 
weakening by Saturday.  The associated cold front moving across the Central/Southern Plains, on 
Wednesday, will aid in producing severe thunderstorms over parts of the Central/Southern Plains.  
Moisture flowing northward out of the Gulf of Mexico will intersect the boundary over the Southern 
Plains producing an area of heavy rain over parts of Southern Plains on Thursday into Friday.  The 
boundary will stall out over parts of the Central Plains/Middle Mississippi Valley on Friday 
through Monday producing an area of heavy rain over the region.     

In addition, temperatures across much of the Western U.S. will remain below to much below normal 
underneath the upper-level low.  The highest anomalies should focus over parts of the Northern 
Rockies into the Great Basin early during the period on Thursday.  While minimum temperature 
anomalies are not overly impressive (which would typically be used as criteria for the hazards 
chart), daytime highs could be 20+ degrees below normal with overnight lows near freezing in some 
places. 

In the meantime, a building ridge across the Eastern U.S. will support warmer than normal 
temperatures from Thursday into Monday.  The main hazardous threat will be across the Southeast 
where daytime highs may reach into the upper 90s, with possible higher heat index values. Farther 
north into parts of the Mid-Atlantic and Ohio Valley, maximum temperature anomalies could be in the 
+10 to +15 degree range, but with less extreme heat indices.  A small area of excessive heat will 
also develop over parts of Southern Texas as the upper-level ridge builds over parts of the 
Southern Plains.  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 over the South-Central mainland of Alaska along with a plume of moisture extending 
from near Hawaii into parts of the Aleutians, but quickly diminishes by Thursday.  An area of heavy 
precipitation will develop over the area on Thursday.  By Saturday, a second low that was over the 
North-Central Pacific will move into the Aleutians that will dissipate by Monday along the 
Southwestern Coast of mainland Alaska.  Another plume of moisture, likewise, extending from near 
Hawaii to the Aleutians that will move into the Alaska peninsula on Saturday and into the Southern 
mainland of Alaska by Monday.  The moisture and upper-level energy will aid in producing an area of 
heavy precipitation along the Southwestern and South-Central mainland Alaska Saturday into Monday.  
  

Ziegenfelder