Forecast Discussion
— Short Range
Discussion
Valid 12Z Sat Jul 18 2026 - 12Z Mon Jul 20 2026
...Daily monsoonal showers and thunderstorms continue across the Western U.S. this weekend; stormy weather expected over parts of the Northern Tier and Eastern U.S.
...Air quality alerts span from the Upper Midwest Great Lakes to New England; some relief in sight...
...Hot weather to build over the Central U.S. this week...
This weekend features a fairly active weather pattern along the Northern Tier of the Nation as an amplifying trough begins to pivot across the Upper Great Lakes, in turn sending a frontal system through the Northeast and Ohio Valley today. A moist and unstable airmass surging northward ahead of this system will set the stage for showers and thunderstorms capable of widely scattered severe weather and flash flooding later this morning and afternoon across these regions. By tomorrow, the front is expected to sink southward into the lower Mid-Atlantic, which will focus thunderstorms near the Carolinas. South of this activity, the eastern Gulf Coast can also expect unsettled weather as a disturbance south of the Florida Panhandle gradually develops over the next 24-36 hours. The National Hurricane Center shows a low chance of tropical cyclone potential with this disturbance, although isolated instances of flash flooding from this feature are possible near the Florida Panhandle today and tomorrow. In contrast to the Northern Tier, a slow-moving weather regime continues across the Southern Tier states where a persistent upper-level low in west Texas is slowly retrograding towards the Desert Southwest. This feature could enhance monsoonal thunderstorms over the Four Corners and Desert Southwest today and tomorrow, leading to widely scattered flash flooding as soils are sensitive from recent precipitation.
Rainfall aside, the approaching frontal system should simultaneously scour out smoke in the Northeast and Mid-Atlantic while ushering in cooler air from the north. Unfortunately, upstream areas in the Midwest and Upper Great Lakes will likely contend with poor air quality at least through tomorrow as northwesterly flow ushers in another smoke plume from Ontario. Hot and humid conditions are expected to spread from the Northern Plains into the Lower Mississippi Valley beneath a broad upper-ridge to close out the weekend. In advance of the heat, scattered Heat Advisories are noted across the Central U.S. where heat index readings could exceed 110 degrees in some locations.
Asherman
000 FXUS01 KWBC 180722 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 321 AM EDT Sat Jul 18 2026 Valid 12Z Sat Jul 18 2026 - 12Z Mon Jul 20 2026 ...Daily monsoonal showers and thunderstorms continue across the Western U.S. this weekend; stormy weather expected over parts of the Northern Tier and Eastern U.S. ...Air quality alerts span from the Upper Midwest Great Lakes to New England; some relief in sight... ...Hot weather to build over the Central U.S. this week... This weekend features a fairly active weather pattern along the Northern Tier of the Nation as an amplifying trough begins to pivot across the Upper Great Lakes, in turn sending a frontal system through the Northeast and Ohio Valley today. A moist and unstable airmass surging northward ahead of this system will set the stage for showers and thunderstorms capable of widely scattered severe weather and flash flooding later this morning and afternoon across these regions. By tomorrow, the front is expected to sink southward into the lower Mid-Atlantic, which will focus thunderstorms near the Carolinas. South of this activity, the eastern Gulf Coast can also expect unsettled weather as a disturbance south of the Florida Panhandle gradually develops over the next 24-36 hours. The National Hurricane Center shows a low chance of tropical cyclone potential with this disturbance, although isolated instances of flash flooding from this feature are possible near the Florida Panhandle today and tomorrow. In contrast to the Northern Tier, a slow-moving weather regime continues across the Southern Tier states where a persistent upper-level low in west Texas is slowly retrograding towards the Desert Southwest. This feature could enhance monsoonal thunderstorms over the Four Corners and Desert Southwest today and tomorrow, leading to widely scattered flash flooding as soils are sensitive from recent precipitation. Rainfall aside, the approaching frontal system should simultaneously scour out smoke in the Northeast and Mid-Atlantic while ushering in cooler air from the north. Unfortunately, upstream areas in the Midwest and Upper Great Lakes will likely contend with poor air quality at least through tomorrow as northwesterly flow ushers in another smoke plume from Ontario. Hot and humid conditions are expected to spread from the Northern Plains into the Lower Mississippi Valley beneath a broad upper-ridge to close out the weekend. In advance of the heat, scattered Heat Advisories are noted across the Central U.S. where heat index readings could exceed 110 degrees in some locations. Asherman Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$