West Hub's peak lands an hour earlier than Houston and South

The decision window runs Aug 27, 4 PM CDT to 11 PM CDT, covering tonight's net-load peak and the cleared curve's evening high.

Since the prior issue, West Hub's local RT-DA residual moved to $12.6/MWh, a swing of +$11.5/MWh outside its own calibrated band. Houston's eased to -$6.4/MWh, a change of -$7.4/MWh, and South's eased to -$6/MWh, a change of -$5/MWh, both outside their own bands, opposite West's direction.

The calculated capacity margin sits at -1,565 MW at the 8 PM CDT hour, soft but inside the recent range at the 11th percentile.

Three checks decide tonight: the cross-location median RT-DA spread holding between -$9.8/MWh and $8.8/MWh, West Hub's residual staying inside its threshold, and realized load tracking within 2,090 MW of the forecast vintage through the peak.

Every ERCOT hub settled real time far above its day-ahead award through last night's evening peak, and the shared convergence component driving that gap averaged $56.6/MWh across 24 joined hours. West Hub's raw real-time premium over its award reached $69.2/MWh, but after stripping out that common component its own local residual comes to $12.6/MWh, a swing of $11.5/MWh from the prior issue and the largest local deviation this issue carries against its own trailing-90-day pattern for any of the four hubs. West Hub's real-time price averaged $135.6/MWh and topped out at $591.9/MWh at 9 PM CDT, up sharply from the prior issue's $43.2/MWh average; its day-ahead award averaged only $66.4/MWh and peaked at $158.9/MWh in the 8 PM CDT hour. The other three hubs' real-time peaks landed an hour later: ERCOT Hub Average topped at $533.9/MWh, North Hub at $534.9/MWh, and Houston Hub at $525.3/MWh, all at 10 PM CDT, so last night's peak pricing spanned the 9 PM to 10 PM CDT window with West Hub leading. Tonight's cleared day-ahead curve prices West Hub's evening peak at $109.4/MWh for 9 PM CDT, well under last night's realized levels, so the award has not repriced the residual away. No West-specific driver in this dataset explains why West Hub's local residual widened while the shared convergence component held the same shape across hubs.

The watch item for tonight is whether the cross-location median RT-DA spread holds inside its calibrated band; a real-time print that again clears meaningfully above West Hub's $109.4/MWh cleared peak would extend last night's breakout rather than close it.

MetisCast prices ERCOT Hub Average -$13.6/MWh against the cleared day-ahead curve across 17 joined hours. Its P50 tops out at $61.1/MWh at Aug 27, 7 PM CDT while the market cleared $104.4/MWh at Aug 27, 9 PM CDT. The two agree on when the evening matters and disagree on what it pays.

West Hub's real-time price peaked at 9 PM CDT, an hour ahead of North Hub's $534.9/MWh high, Houston Hub's $525.3/MWh peak, and South Hub's peak, all landing at 10 PM CDT. Day-ahead awards split the same way: West and North Hub cleared their session highs at 8 PM CDT, North reaching $154.2/MWh, while Houston and South cleared two hours later, at 10 PM CDT.

Houston Hub's raw RT-DA spread averaged $50.2/MWh, below the shared systemwide convergence component that lifted every hub; its local residual is -$6.4/MWh, a change of -$7.4/MWh from the prior issue, still outside Houston's own calibrated band. South Hub's $50.6/MWh raw spread sits under the same convergence component, leaving a -$6/MWh residual, a change of -$5/MWh, also outside its band. North Hub's residual alone held inside its own band despite sharing Houston and South's later peak hour.

Watch whether West's early peak and North's contained residual repeat tonight, or the later Houston/South grouping reasserts across the 8 PM-11 PM CDT decision window.

Today's load path eases only slightly from yesterday's read: the cutoff vintage puts the gross-load peak at 89,045 MW for 5 PM CDT, elevated against the trailing 90 days but not breaking new ground. Solar carries the midday, forecast to reach 31,882 MW at 1 PM CDT, while wind's forecast high of 11,673 MW does not arrive until 9 PM CDT, after the sun has already left the net-load calculation. That sequencing, not the load number itself, is what turns the transition hours into today's ramp.

The outage picture is the fundamentals story worth carrying into the operating day. ERCOT's generation-outage snapshot at the Aug 27, 8 AM CDT read shows 16,314 MW out, 119 MW planned and 16,195 MW forced, well above the 9,357 MW peak the forward outage-capacity curve carries for 2 PM CDT today. If forced units stay down through the afternoon, the day runs against a higher outage base than the curve assumed. Grid event: ERCOT generation outage mix

RUC commitments climbed through last night's window from 927 MW at 11 AM CDT Aug 26 to a session high of 4,285 MW at 10 PM CDT Aug 26, tracking the same hours hub prices peaked; Houston and South still carry most of this morning's 1,582 MW commitment, a lingering signal rather than a resolved one. Grid event: 927 MW of RUC-committed capacity

MetisCast's evening path continues to sit below the cleared curve, averaging a $13.6/MWh P50 discount across 17 joined hours, widening to $53.8/MWh at the 10 PM CDT hour against a mean P10-P90 band of $48/MWh across the frozen horizon. Early post-midnight real-time prints near $81/MWh and near $65/MWh landed inside the range the curve already priced for that normalization window, a sign the rollover it assumed is holding into this morning. Real-Time Settlement Point Prices Display

Last night's West Hub local RT-DA residual carries forward into tonight's window. The cleared award for West Hub's evening peak sits at $109.4/MWh for the 9 PM CDT hour, and a real-time print that again clears meaningfully above that award would extend the same convergence pattern rather than close it. Houston Hub and South Hub RT-DA residuals moved the opposite direction overnight, easing while still outside their own calibrated bands.

Three checks define tonight's decision window: the cross-location median RT-DA spread holding between -$9.8/MWh and $8.8/MWh, West Hub's local residual staying inside its own $7/MWh threshold, and the 11 PM CDT to midnight rollover clearing without a real-time print above the remaining-day cleared day-ahead curve. Open the West Hub real-time versus day-ahead detail chart and the ERCOT hub real-time price comparison chart across the 8 PM to 11 PM CDT window; a break on any check keeps West Hub's RT-DA exposure live rather than resolved.

Forecast-vintage policy. Every input in this issue was published at or before the knowledge cutoff. Forecast series are the latest vintage available at that instant and are never revised after the fact; realized history used for percentiles is guarded by the same cutoff. The preceding issue's frozen vintage is stored with the issue, so a revision is measured against what was actually published, not against a later correction. Not covered by this issue's data: Residual dispatchable demand; Reserve, PRC and contingency coverage; Weather-to-market translation. Each limitation is stated where it applies rather than filled in by inference.

Source and quality note. 29 of 29 requested issue series were available; 16 longer-lookback series provided the historical baselines. 49 event records were known at cutoff and 2 unchanged records were suppressed. Knowledge cutoff: Aug 27, 8:00 AM CDT.