Important: GDP is reported at a seasonally adjusted annual rate (SAAR). A 15% annualized increase in GDP is about 3.6% quarter-over-quarter (QoQ). Also, a 15% annualized increase would leave real GDP down about 7.5% from Q4 2019. A 25% annualized increase in Q3 GDP, is about 5.7% QoQ, and would leave real GDP down about 5.5% from Q4 2019.
For comparison, at the depth of the Great Recession, real GDP was down 4.0% from the previous high.
Also, even if activity is flat in Q3 compared to June, GDP will show a significant increase in Q3 over Q2 because of the sharp decline in April.
From Merrill Lynch:
2Q GDP tracking remains at -32.6% qoq saar. We expect 3Q GDP growth of +15%. [August 14 estimate]
From the NY Fed Nowcasting Report
The New York Fed Staff Nowcast stands at 14.8% for 2020:Q3. [August 14 estimate]
And from the Altanta Fed: GDPNow
The GDPNow model estimate for real GDP growth (seasonally adjusted annual rate) in the third quarter of 2020 is 26.2 percent on August 14, up from 20.5 percent on August 7. [August 14 estimate]