US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
238 PM EDT Thu Aug 15 2019
 
Valid Sunday August 18 2019 - Thursday August 22 2019
 
Hazards:
- Flooding possible across portions of the Central Plains and the Middle Mississippi Valley.
- Flooding occurring or imminent across portions of the Northern Plains.
- Excessive heat across portions of the Southwest, Tue-Thu, Aug 20-Aug 22.
- Excessive heat across portions of the Southern Plains into the Lower Mississippi Valley, Sun-Mon, 
Aug 18-Aug 19.
 
Detailed Summary:

The medium range period (Sun - Thur) remains relatively quiet in terms of any widespread 
precipitation hazards. Most precipitation across the country along various frontal boundaries 
should be rather scattered in nature with no significant heavy rain threat. The only exception is 
from the Central Gulf Coast to the Southeast where pooling moisture along a stationary frontal 
boundary carried over from the short range period may result in localized areas of heavy rain. 
Briefly considered a small heavy rain area from New Orleans into southern Mississippi and Alabama, 
but there is enough uncertainty to keep something out at this time.

A generally warm pattern will persist over the southern tier of the U.S. with daytime highs 
averaging about 10 degrees above normal in some places underneath stubborn upper level ridging. 
There are two notable regions for excessive heat threats during the medium range. The first spans 
across much of Texas into central Oklahoma and northern Louisiana from Sun - Mon. This is based on 
heat indices between 105 and 110 degrees (mainly from eastern Texas into Oklahoma and northern 
Louisiana). Farther west across the High Plains, heat indices are not expected to be as warm due to 
lower humidity, but daytime highs near 100 degrees may approach record high temperatures in select 
locations with little recovery expected overnight. Thus, the excessive heat area from yesterday's 
chart was expanded to include central Texas into the High Plains. The heat shifts westward into the 
Desert Southwest Tue-Wed, where daytime highs are forecast to be around 110-115 degrees and 
overnight lows in the upper 80s to near 90. A second excessive heat area was included in this 
region.

In Alaska, heavy rainfall is possible across parts of the southern Panhandle region to start the 
period but amounts are borderline to include an area on the hazards chart, especially considering 
that most of this precipitation should fall near the end of the short range period. Across the 
Aleutians by Tues-Wed next week, a deep surface low approaches the island chain bringing the 
potential for windy and general unsettled weather to the region. At this point, the 
wind/precipitation hazard potential continues to be below criteria so no areas were included today, 
but this system will need to be monitored for future changes in the forecast.

Santorelli