Forecast Discussion
— ExtendedOverview
A strong upper ridge/high over the north-central U.S. will continue to cause dangerous heat across the northern Plains and Midwest late week. The eastern portion of the ridge likely joining up with a subtropical Atlantic ridge should lead to hot temperatures across the Ohio Valley to Mid-Atlantic Thursday and gradually shifting south through the period as an upper trough pokes into the Northeast. Energy to the south of the ridge will provide support for additional heavy rain and flooding potential in parts of Texas into Thursday. Monsoonal moisture is forecast to increase and produce diurnally driven showers and storms across the Southwest, Four Corners states, and northward into the northern Rockies/High Plains. Additionally, energies on the northern side of the ridge could also lead to rounds of rain and thunderstorms in the Great Lakes to East Coast.
Guidance/Predictability Assessment
Model guidance shows good agreement in terms of the 594+ dm upper high centered near the north-central U.S. at the start of the medium range period Thursday, providing high confidence for continued heat. Energy undercutting the ridge will be in place over the southern High Plains, continuing heavy rain into Thursday, but should gradually weaken late week. Meanwhile, model consensus is initially good for Great Lakes to Northeast troughing.
Into late week/weekend, models diverge with some details of the pattern. In general, the northeastern trough is forecast to gradually deepen over the weekend and early next week, which shunts the upper ridge axis westward a bit into the Intermountain West. However, shortwaves within the trough have been questionable, affecting the trough's depth as well as QPF and frontal placement. Recent 00Z guidance mostly shows a deeper trough compared to earlier guidance, due to a shortwave moving through the Great Lakes over the weekend. Meanwhile, models have struggled with an upper low in the eastern Pacific offshore of the Pacific Northwest. The 12Z AIFS and AIGFS had the feature meandering there through much of the period before finally moving into the Northwest early next week, while dynamical models were faster. However, now with the 00Z cycle, the GFS/CMC/UKMET are all much slower and align with those AI models. The 00Z ECMWF is generally alone in taking that low inland by Friday and tracking it across southern Canada. Elsewhere, will also note that the AIGFS/AIFS and many AIFS members are favoring a tropical low in the northeastern Gulf early next week, which bears watching.
The WPC forecast was based on a model/ensemble mean blend excluding the ECMWF given its issues with the Northwest low. Increased proportions of the means as the forecast progressed, reaching half Days 6/7.
Weather/Hazards Highlights
Hazardous heat is forecast to persist in the north-central U.S. into late week under the upper ridge. Continued well above normal maximum and minimum temperatures will lead to Major to Extreme HeatRisk in the northern/central Plains and Midwest. WPC continues to update Heat Key Messages for this event, which can be found on our homepage. The hot conditions should slowly ease in the northern states and shift southward into early next week. Farther east, warmer than average temperatures are likely for the Mid-Atlantic Thursday, shifting gradually southward as an upper trough pushes a cold front slowly south. The upper ridge potentially combining with subtropical ridging down to Florida will maintain warm temperatures and elevated HeatRisk there.
Meanwhile, the southwestern to south-central U.S. could see slightly below average temperatures as ample moisture leads to clouds and rain/thunderstorms. Increasing southerly flow around the western periphery of the central U.S. ridge will draw significant monsoonal moisture into the Southwest and Intermountain West to Rockies. This moisture will lead to diurnally driven scattered to numerous showers and thunderstorms with the potential to produce heavy rainfall and localized flash flooding. Sensitive places such as burn scars, steep terrain, etc., would be the most vulnerable to any flooding concerns that may develop. Broad Marginal Risks of excessive rainfall remain in place from the Southwest across parts of the Intermountain West north to Montana for Day 4-5 (Thursday- Friday), and monsoonal moisture should continue into next weekend. Farther east, Pacific and Gulf moisture should combine in the vicinity of a shortwave aloft over Texas, leading to further flooding concerns. A Slight Risk is in place for western/south- central portions of Texas into Thursday, and the flooding threat could be compounded by the likely rainfall in the short range period causing wetter antecedent conditions. The energy aloft should gradually dissipate into Friday and slowly ease the flooding threat. Some showers and storms should stretch into the Southeast. As energy moves through the northeastern upper trough, rounds of rain/thunderstorms are also possible from the Great Lakes to the Mid-Atlantic and Northeast, including potentially severe weather.
Tate
Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at:
000 FXUS02 KWBC 131815 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 215 PM EDT Mon Jul 13 2026 Valid 12Z Thu Jul 16 2026 - 12Z Mon Jul 20 2026 ...Dangerous heat continues across the north-central U.S. through the end of the week... 18Z Update: The models agree the most on the persistence of the upper level ridge/closed high that will be situated across Wyoming/Colorado/Utah, providing a continuation of above normal temperatures for many areas of the western U.S. and transport of deeper monsoonal moisture northward around the back side of the high, fueling daily afternoon and evening storms from the Desert Southwest to the northern Rockies. There is more model variance across the northern tier of the nation with shortwave energy tracking around the northern periphery of the high, and there are still some amplitude differences regarding the broad eastern U.S. trough that should be in place by the weekend after a heat wave here this week. A general deterministic model blend sufficed as a starting point for fronts and pressures, followed by a gradual increase of the ensemble means to about half by next Monday. There was a modest reduction in max temperatures across portions of Texas and also from eastern Montana to northern Minnesota where the NBM appeared a little higher than most of the deterministic guidance. The previous forecast discussion is appended below for reference. /Hamrick --------------------------- ...Overview... A strong upper ridge/high over the north-central U.S. will continue to cause dangerous heat across the northern Plains and Midwest late week. The eastern portion of the ridge likely joining up with a subtropical Atlantic ridge should lead to hot temperatures across the Ohio Valley to Mid-Atlantic Thursday and gradually shifting south through the period as an upper trough pokes into the Northeast. Energy to the south of the ridge will provide support for additional heavy rain and flooding potential in parts of Texas into Thursday. Monsoonal moisture is forecast to increase and produce diurnally driven showers and storms across the Southwest, Four Corners states, and northward into the northern Rockies/High Plains. Additionally, energies on the northern side of the ridge could also lead to rounds of rain and thunderstorms in the Great Lakes to East Coast. ...Guidance/Predictability Assessment... Model guidance shows good agreement in terms of the 594+ dm upper high centered near the north-central U.S. at the start of the medium range period Thursday, providing high confidence for continued heat. Energy undercutting the ridge will be in place over the southern High Plains, continuing heavy rain into Thursday, but should gradually weaken late week. Meanwhile, model consensus is initially good for Great Lakes to Northeast troughing. Into late week/weekend, models diverge with some details of the pattern. In general, the northeastern trough is forecast to gradually deepen over the weekend and early next week, which shunts the upper ridge axis westward a bit into the Intermountain West. However, shortwaves within the trough have been questionable, affecting the trough's depth as well as QPF and frontal placement. Recent 00Z guidance mostly shows a deeper trough compared to earlier guidance, due to a shortwave moving through the Great Lakes over the weekend. Meanwhile, models have struggled with an upper low in the eastern Pacific offshore of the Pacific Northwest. The 12Z AIFS and AIGFS had the feature meandering there through much of the period before finally moving into the Northwest early next week, while dynamical models were faster. However, now with the 00Z cycle, the GFS/CMC/UKMET are all much slower and align with those AI models. The 00Z ECMWF is generally alone in taking that low inland by Friday and tracking it across southern Canada. Elsewhere, will also note that the AIGFS/AIFS and many AIFS members are favoring a tropical low in the northeastern Gulf early next week, which bears watching. The WPC forecast was based on a model/ensemble mean blend excluding the ECMWF given its issues with the Northwest low. Increased proportions of the means as the forecast progressed, reaching half Days 6/7. ...Weather/Hazards Highlights... Hazardous heat is forecast to persist in the north-central U.S. into late week under the upper ridge. Continued well above normal maximum and minimum temperatures will lead to Major to Extreme HeatRisk in the northern/central Plains and Midwest. WPC continues to update Heat Key Messages for this event, which can be found on our homepage. The hot conditions should slowly ease in the northern states and shift southward into early next week. Farther east, warmer than average temperatures are likely for the Mid-Atlantic Thursday, shifting gradually southward as an upper trough pushes a cold front slowly south. The upper ridge potentially combining with subtropical ridging down to Florida will maintain warm temperatures and elevated HeatRisk there. Meanwhile, the southwestern to south-central U.S. could see slightly below average temperatures as ample moisture leads to clouds and rain/thunderstorms. Increasing southerly flow around the western periphery of the central U.S. ridge will draw significant monsoonal moisture into the Southwest and Intermountain West to Rockies. This moisture will lead to diurnally driven scattered to numerous showers and thunderstorms with the potential to produce heavy rainfall and localized flash flooding. Sensitive places such as burn scars, steep terrain, etc., would be the most vulnerable to any flooding concerns that may develop. Broad Marginal Risks of excessive rainfall remain in place from the Southwest across parts of the Intermountain West north to Montana for Day 4-5 (Thursday- Friday), and monsoonal moisture should continue into next weekend. Farther east, Pacific and Gulf moisture should combine in the vicinity of a shortwave aloft over Texas, leading to further flooding concerns. A Slight Risk is in place for western/south- central portions of Texas into Thursday, and the flooding threat could be compounded by the likely rainfall in the short range period causing wetter antecedent conditions. The energy aloft should gradually dissipate into Friday and slowly ease the flooding threat. Some showers and storms should stretch into the Southeast. As energy moves through the northeastern upper trough, rounds of rain/thunderstorms are also possible from the Great Lakes to the Mid-Atlantic and Northeast, including potentially severe weather. 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, 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 $$