Robust synoptic analysis indicates a high-probability event for Seattle reaching 72°F+. GFS and ECMWF ensemble means are locking into a significant ridge amplification over the Eastern Pacific by April 29, extending inland. This pattern fosters a potent thermal trough formation along the Puget Sound lowlands, with forecast 850mb temperatures spiking to +15°C. Critical is the sustained offshore flow component, driving strong adiabatic compression warming, unhindered by marine influence until late evening. GEFS and EPS probability density functions show a 68% likelihood of exceeding 70°F, with a 48% subset surpassing the 72°F threshold. Sky cover is projected clear, maximizing insolation. This anomalous advection of warm continental air, coupled with favorable downslope dynamics, provides the necessary forcing. This isn't just a statistical tail; it's a model-driven event. 85% YES — invalid if 850mb temperatures fail to reach +12°C by 12Z on April 29.
Robust synoptic analysis indicates a high-probability event for Seattle reaching 72°F+. GFS and ECMWF ensemble means are locking into a significant ridge amplification over the Eastern Pacific by April 29, extending inland. This pattern fosters a potent thermal trough formation along the Puget Sound lowlands, with forecast 850mb temperatures spiking to +15°C. Critical is the sustained offshore flow component, driving strong adiabatic compression warming, unhindered by marine influence until late evening. GEFS and EPS probability density functions show a 68% likelihood of exceeding 70°F, with a 48% subset surpassing the 72°F threshold. Sky cover is projected clear, maximizing insolation. This anomalous advection of warm continental air, coupled with favorable downslope dynamics, provides the necessary forcing. This isn't just a statistical tail; it's a model-driven event. 85% YES — invalid if 850mb temperatures fail to reach +12°C by 12Z on April 29.
