US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
351 PM EDT Mon Aug 05 2019
 
Valid Thursday August 08 2019 - Monday August 12 2019
 
Hazards:
- Heavy rain across portions of the Central Plains, the Lower Mississippi Valley, the Tennessee 
Valley, the Middle Mississippi Valley, the Southern Plains, and the Ohio Valley, Thu-Fri, Aug 8-Aug 
9.
- Heavy rain across portions of the Central Plains, the Middle Mississippi Valley, the Upper 
Mississippi Valley, and the Northern Plains, Sun-Mon, Aug 11-Aug 12.
- Heavy rain across portions of the Northern Plains, Fri, Aug 9.
- Flooding occurring or imminent across portions of the Northern Plains.
- Flooding likely across portions of the Northern Plains.
- Excessive heat across portions of the Lower Mississippi Valley and the Southern Plains, Thu-Mon, 
Aug 8-Aug 12.
 
Detailed Summary:

It looks like the main threat for hazards during this upcoming Day 3-7 period will be focused over 
central sections of the CONUS. The upper level ridge that's currently centered near the Four 
Corners region will slide east-southeastward over the next few days and become centered over the 
south-central Plains and lower Mississippi Valley late this week through the weekend. Under this 
ridge, weather conditions will be hot and mostly dry, though some scattered daily 
showers/thundershowers are possible over the lower Mississippi Valley. High temperatures will range 
from the upper 90s to low 100s, and combined with dew points in the 70s will result in heat indices 
approaching 105-110 degrees over much of this region, though upwards of 115 degrees over 
southeastern Texas.

Across the central Plains and mid-Mississippi Valley, short wave energy embedded in the northwest 
flow along the northern periphery of the abovementioned ridge will interact with deep Gulf of 
Mexico moisture pooling along a surface front to bring organized heavy rainfall late this week. The 
greatest amounts are likely during Thursday and Thursday night from eastern Kansas eastward across 
southern and central Missouri where widespread totals of 1-3 inches are likely, with higher amounts 
in areas with with repeat storm activity that could bring localized flash flooding. This area of 
rain will track southeastward into the Tennessee Valley on Friday, but weakening convergence along 
the surface front should reduce the threat for excessive rainfall.

Farther north, another short wave cresting the ridge will support surface low development along a 
stationary boundary draped across the northern High Plains during Friday. Current model guidance is 
in reasonable agreement that this feature will trigger an organized area of showers/thundershowers 
Friday evening and during the overnight hours across North/South Dakota. Rainfall totals will 
mostly range from 1-2 inches, with locally higher amounts potentially causing isolated flash flood 
problems. Later in the forecast period, the closed low that is now spinning off the Pacific 
Northwest coast will push inland across the northern Rockies into the northern Plains while 
gradually weakening as it works to flatten out the southwestern U.S. ridge. The associated surface 
front moving out into the Plains will tap into deep moisture east of the Rockies and bring a chance 
for organized convection on Sunday and Monday to portions of the north-central Plains and mid-upper 
Mississippi Valley. There is a lot of uncertainty with this feature, though, as models differ with 
speed at which the short wave energy moves across the northern tier of states. While we have decent 
confidence that heavy precipitation will impact some part of this region, confidence in the 
placement of the hazard area is very low, so it's likely to undergo significant modifications over 
the course of this week.

Elsewhere, monsoonal moisture flowing into eastern Arizona and the Four Corners region could cause 
locally heavy rainfall and localized flooding and flash flooding as afternoon and evening showers 
and thunderstorms continue through the week. With the ridge in the Southwest weakening late in the 
period, monsoonal precipitation may become lighter and more scattered/isolated by Sunday and Monday.

No hazards are currently forecast for Alaska during the Day 3-7 period.

Klein