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National Weather Service
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
221 AM EDT Mon Jun 29 2026
Valid 12Z Thu Jul 02 2026 - 12Z Mon Jul 06 2026
...Significant, dangerous, and record breaking heat wave expected next week for the Central to Eastern U.S...
...Pattern Overview...
The period begins Thursday with a strong ridge anchored over the eastern half of the country, supporting a significant and dangerous heat wave. Meanwhile an amplified trough will be over the West to start the period, with some energy working to suppress the Eastern ridge slightly by next weekend as a shortwave slides into the Great Lakes. Ridging may build back across the south-central Plains by later in the period as well. Showers and thunderstorms will be most likely over the Upper Midwest/Great Lakes, the Gulf Coast, and eventually across the East next weekend and early next week.
...Guidance/Predictability Assessment...
Good agreement continues amongst the latest guidance for at least the large scale pattern, but the details remain uncertain across the West and specifically the evolution of energy as it progresses northeastward and finally breaks down the eastern ridge. Confidence and predictability is high for the large upper ridge centered over the East to start the period, with basically all guidance showing a closed 594dm contour that persists through at least Friday. Out West, a shortwave over the Northwest by Thursday will drift eastward with time, eventually working to break down the ridge over the East. Some of the guidance shows gradual amplification of this feature as well which should allow for ridging to build back upstream over the south-central and Southwest U.S.. Confidence is increasing that the ridge should weaken by the end of the period, but the timing of when this begins is still quite uncertain. The guidance is mixed on how strong this shortwave will be as it moves into the Great Lakes/Midwest early next week. There is also some timing uncertainties on another trough entering the Northwest late period as well.
The WPC fronts/pressures forecast for tonight used a blend of the deterministic guidance for the first half of the period, gradually increasing weighting of the ensemble means to 60 percent of the blend by the latter half. Generally maintained good agreement with the previous WPC forecast, with sensible weather adjustments to the NBM needed primarily for Max T and afternoon Dewpoints.
...Weather/Hazards Highlights...
The most impactful weather hazard during the medium range period will be a long lasting heat wave affecting much of the central to eastern U.S. spanning the short to medium range period, peaking around Thursday or Friday of this week. Widespread and daily record breaking maximum temperatures into the 90s to low 100s, combined with high humidity, will result in heat indices approaching or exceeding 105-110 in many places. Some of these values may break all time records as well. This equates to widespread Major to Extreme HeatRisk from the Midwest/MS Valley eastward to the East Coast. Overnight lows will also be quite warm, with numerous record high minimums possible, bringing little to no relief from the heat in the nighttime hours. Heat may finally begin to abate from west to east this weekend, with upper temperature limits possibly restricted by clouds/convection. Above normal temperatures should expand westward into the Southern and Central Plains as well, with temperatures out West near to below normal underneath of the upper trough.
Rain and thunderstorms associated with a slow moving frontal boundary will impact parts of the Northern Plains to Upper Midwest and Great Lakes into next weekend. Moisture anomalies and instability within fairly weak flow may support at least a localized flash flood threat. WPC highlights much of this region within a Marginal Risk for both the Day 4/Thursday and Day 5/Friday Excessive Rainfall Outlooks. Some of this activity will likely make its way into parts of the Northeast as well as it rounds the northern periphery of the mid/upper level ridge.
Elsewhere, diurnally driven showers and storms are expected from the central Gulf Coast to Florida with moisture increasing south of the upper ridge. Showers may increase across parts of the Ohio Valley and East by next weekend as the upper ridge slightly weakens and upper level energy intrudes into the region.
Santorelli