FXUS02 KWBC 261827

PMDEPD



Extended Forecast Discussion

NWS Weather Prediction Center College Park MD

227 PM EDT Thu Jun 26 2025



Valid 12Z Sun Jun 29 2025 - 12Z Thu Jul 03 2025



...Overview...



Fairly typical summertime pattern will be in place over the Lower 

48 next week, with warmer than normal temperatures for the 

Northwest and cooler than normal temperatures for the southern 

Rockies. Scattered showers and thunderstorms will focus along and 

east of the Rockies near the mostly progressive frontal 

boundaries, across the Southeast, and perhaps over the northeast

Gulf.





...Guidance/Predictability Assessment...



The latest 00/06Z guidance offered reasonable clustering through 

the period, though the 06Z GFS was notably quicker to lower heights

into the Northwest than the other models/ensemble means by next 

Wed/Thu. The ECMWF AIFS and AIFS ensemble were closer to the larger

ECMWF-led cluster, which formed the basis for the starting point 

of the surface fronts/pressures. 





...Weather/Hazards Highlights...



Thunderstorms are likely to form ahead of the broad but shallow 

upper trough and a surface frontal boundary in the Upper Midwest to

central Plains Sunday. Global models have already been showing 

high instability with MUCAPE 4000-6000 J/kg for this region, so 

strong storms are possible, and this will also support heavy rain 

rates that could cause flash flooding. A Marginal Risk is in place 

in the Upper/Middle Mississippi Valley back into the south-central 

Plains for the Day 4/Sunday ERO. By Monday the setup will be 

similar, but with the trough and cold front pressing southeast. A 

large Marginal Risk is located along and ahead of the front from 

the Ohio/Tennessee Valleys, Mid/Lower Mississippi Valley, and the 

south-central Plains where storms are likely in the moist and 

unstable airmass on Day 5/Wednesday. For both days, further 

refinements may be needed in future cycles, including possible 

embedded Slight Risks, but model agreement in the specifics remains

low for now. The front will continue to push eastward Tuesday, 

leading to a wet day in the Northeast/Mid-Atlantic before drying 

out midweek, and southward for thunderstorm chances across the 

Southeast Tuesday-Wednesday. Even before the front approaches, 

scattered thunderstorms are likely farther south in the broad warm 

sector as well. There will be less forcing for organization and 

sustaining of storms across the southern tier away from the upper 

jet, but instability could allow for heavy rain rates that may 

cause non-zero chances of localized flash flooding, but that are 

likely dependent on smaller scale boundaries and are less 

predictable at this point. One area of focus that the models show 

for some heavier rain is across the central to eastern Gulf Coast 

region. Will monitor if there will be flash flooding concerns there

but it would have to battle with very high flash flood guidance.



Monsoonal moisture is likely to increase next week in the 

Southern/Central Rockies and Plains with southerly flow under the 

upper ridge, thus increasing coverage of and rain amounts in 

storms. Marginal Risks are in place for the southern High Plains 

Day 4/Sunday and stretching north into eastern Colorado Day 

5/Monday as the back end of the front nears. Areas like the 

Sacramento Mountains, where the steep terrain and burn scars cause 

the area to be particularly sensitive to rain, are likely most 

vulnerable to rain causing potential flash flooding, especially 

with wet antecedent conditions there. 



Elsewhere, showers and storms may develop across parts of the 

Great Basin Monday and toward the Northern Rockies by Tuesday. Then

depending on a shortwave, rain chances are forecast to increase in

the north-central U.S. by midweek.



Temperatures are forecast to be around 5-10 degrees above average 

across the Midwest/Great Lakes early next week, while the southern 

half of the Plains to Southeast can expect typical summer heat. 

HeatRisk shows some Major (level 3 of 4) areas in these regions, 

indicating heat levels that affect anyone without effective cooling

and/or adequate hydration. Temperatures and dewpoints will 

decrease behind the cold front as it progresses southeast. Farther 

west, building heat is expected next week as an upper ridge takes 

hold. Temperatures in the Northwest are likely to be 10-15 (locally

20) degrees above normal, for highs nearing 100F. In the Desert 

Southwest, temperatures a few degrees above already high averages 

will equate to 100s and 110s. Moderate to Major HeatRisk is shown 

for much of the Interior West peaking Monday-Tuesday.





Fracasso/Tate





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 (QPF), excessive rainfall 

outlook (ERO), winter weather outlook (WWO) probabilities, heat 

indices, and Key Messages can be accessed from:



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









$$

