US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
324 PM EDT Thu Aug 01 2019
 
Valid Sunday August 04 2019 - Thursday August 08 2019
 
Hazards:
- Heavy rain across portions of the Southeast and the Mid-Atlantic, Sun-Mon, Aug 4-Aug 5.
- Flooding possible across portions of the Central Plains and the Middle Mississippi Valley.
- Flooding occurring or imminent across portions of the Lower Mississippi Valley and the Northern 
Plains.
- Flooding likely across portions of the Upper Mississippi Valley and the Northern Plains.
- Heavy rain across portions of mainland Alaska, Sun-Tue, Aug 4-Aug 6.
- High winds across portions of northern mainland Alaska, Sun, Aug 4.
- High winds across portions of western mainland Alaska, Mon-Tue, Aug 5-Aug 6.
 
Detailed Summary:

The beginning of next week will start out with an overall upper-level pattern of ridging centered 
in the Four Corners, with troughing in the eastern U.S. Going into midweek, an upper low coming out 
of central Canada will help press the troughing south and westward into the north-central U.S., 
where a surface front should also pass through. This is expected to lead to rainfall that could be 
locally heavy as mesoscale convective systems are possible, moving from the Northern to Central 
Plains/Midwest during the beginning of the week and then into the Middle Mississippi Valley. At 
this point, any heavy rainfall looks localized enough that it precluded us from drawing hazard 
areas at this point. Did outlook a heavy rain area for portions of the Carolinas and Virginia early 
in the week as tropical moisture combines with a dying front. The GFS suite is more bullish with 
the amounts of rainfall here compared to other model guidance, and the most recent medium range WPC 
QPF followed the GFS more closely, so the Hazards Outlook did too. Additionally, monsoonal moisture 
flowing into the Four Corners region could cause locally heavy rainfall and localized flooding and 
flash flooding as showers and thunderstorms increase there. As the overall pattern is pretty 
typical for the beginning of August, no significant temperature anomalies are expected through the 
period.

A couple of upper troughs are expected to pass through Alaska next week, causing the potential for 
marginally high winds for this time of year as a surface low moves through. There is increasing 
confidence for heavy rainfall for parts of the west coast of the mainland on Sunday into portions 
of interior Alaska through Tuesday, and tried to compromise the axis of heavy rain drawn for the 
map between the farther south ECMWF and other models that were farther north.

Active weather is expected over Hawaii as Flossie approaches. While Erick should take a path south 
of Hawaii late this week, the current forecast track of Flossie from the National Hurricane Center 
takes the tropical storm north of the archipelago on Monday and Tuesday. Heavy rain, gusty winds, 
and high surf are all possible, with the magnitudes depending on the exact track Flossie takes.

Tate