FXUS02 KWBC 051828

PMDEPD



Extended Forecast Discussion

NWS Weather Prediction Center College Park MD

228 PM EDT Wed Aug 5 2026



Valid 12Z Sat Aug 08 2026 - 12Z Wed Aug 12 2026





...Heat wave continues through the weekend for the Southwest, with

some expansion into the Intermountain West, Central U.S., and 

parts of the Southeast next week...



...Overview...



A strong and lingering upper high over the Southwest will bring 

hazardous heat concerns to the region through the weekend before it

finally begins to weaken a bit. Ridging will then expand eastward 

over the Central U.S. and the Southeast, bringing increasing heat 

concerns for parts of those regions later next week. Meanwhile, a 

progressive northern stream trough will carry a surface front 

across the northern U.S. into the East with moderate to locally 

heavy rainfall. The Bermuda high will help funnel tropical moisture

into the Southeast and Gulf Coast, continuing a wet and humid 

pattern through the period that will surge northward at times into 

the Mid-Atlantic/Ohio Valley.





...Guidance/Predictability Assessment...



Guidance continues to show good agreement on the overall large 

scale pattern and evolution, but with some disagreement in the 

details and timing of individual systems. There are some minor 

timing differences with energy rotating through the base of a 

trough through the Great Lakes and Northeast, and with energy as it

enters the Northwest early next week. Given the progressive flow, 

the differences were well within the normal ranges for the time 

period and most solutions were plausible. The trough into the 

Northwest though does increase uncertainty with how quickly the 

Southwest upper high/ridge erodes, and there's also question on the

extent and strength of a subtropical Atlantic ridge which may 

extend into the Southeast at times next week. 



The WPC forecast used a blend of the deterministic guidance for 

the first half of the period with increasing weighting of the 

ensemble means by days 6 and 7. This maintains good agreement with 

the previous shift as well.





...Weather/Hazards Highlights...



Going into next weekend, a slightly weaker upper ridge will allow 

for lessening HeatRisk across the Southwest compared to the short 

range period, though Moderate HeatRisk will still be widespread 

with isolated Major and Extreme values. Heat should build gradually

northward across the Intermountain West and Rockies to the High 

Plains, and eastward towards the Central Plains and Mississippi 

Valley next week as the upper ridge expands. Areas of smoke will 

also remain likely given active fires across the Western states. 

Increasing monsoonal moisture and a weakening upper ridge into the 

Southwest will also help dial back temperatures. Across the 

northern tier, temperatures should be near normal the whole period.

The East may be near or slightly above normal, with some major 

HeatRisk creeping into parts of the Southeast coast next week. A 

slight cooling trend is expected for the Pacific Northwest in the 

wake of a weak/dry cold front this weekend.



Interaction between a weakening front in the East and a stronger 

one into the northern Plains will allow for ongoing showers and 

storms across the Midwest to the East this weekend. A wet pattern 

looks to set up by the weekend and into early next week, especially

for the South and Southeast, as tropical moisture rounds the west 

side of the subtropical Atlantic ridge. More widespread, moderate 

to heavy rainfall is also looking increasingly likely across 

portions of the Upper Midwest/Great Lakes/Upper Ohio Valley early 

next week with additional energy moving through. Monsoonal moisture

is likely to continue through the period for Arizona and New 

Mexico, reaching portions of Utah and Colorado as well. The 

remainder of the West into the Northern Plains should be mostly dry

during the period.





Fracasso/Santorelli





Additional 3-7 Day Hazard information can be found on the WPC 

medium range hazards outlook chart at: 

https://www.wpc.ncep.noaa.gov/threats/threats.php



WPC medium range 500mb heights, surface systems, weather grids, 

quantitative precipitation forecast, excessive rainfall outlook, 

winter weather outlook probabilities, heat indices and Key Messages

are at:



https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif 

https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif 

https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html 

https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml 

https://www.wpc.ncep.noaa.gov/#page=ero 

https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 

https://www.wpc.ncep.noaa.gov/heat_index.shtml 

https://www.wpc.ncep.noaa.gov/#page=ovw







$$