Forecast Models Struggling with Central/East Hot/Dry Weather Forecasts.

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08/05/2022, 10:33 am EDT
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Highlight: Forecast models struggling with Central/East hot weather forecasts.

Charts of the day: Past 14 days Central U.S. hot/dry model bias is too strong.

Discussion: Not convenient is the developing hot/dry bias by the GFS (and all models are showing this problem) during the past 2+ weeks for the Central/Midwest U.S. Maximum temperatures are hot at times but nowhere near 2-meter forecasts offered primarily by the GFS. During July streaks of historic rainfall roared across parts of the Midwest to central Appalachia not well-forecast in the 6-10-day period. The temperature/precipitation error appears in a high-profile agriculture zone as analysts weight drought risk to corn and soybeans for mid-to-late summer. This region is a source of heat for the PJM-Wet/PJM-East energy markets so the model bias is also an issue for electricity markets. The exact cause of this error is likely an over estimation of the hot influence regional dry soils has on climate. Midwest U.S. soil moisture analysis (during the past 14 days) may be initialized (by the model) as too dry leading to hot/dry medium-range bias. That opinion is very preliminary.

Medium-range 6-10 Day Forecast Valid August 6-10, 2022 (24-hour change right)

Medium-range 11-15 Day Forecast Valid August 11-15, 2022 (24-hour change right)

Discussion: The least “bad” temperature bias in the 6-10-day period is offered by the ECM ENS. So…we’ll rely on the ECM ENS for today’s medium-range forecast. ECM ENS lingers very warm temperatures across the Northwest U.S. with hot weather in the Great Plains and also the Northeast Corridor. Any caveat forecasts would likely be cooler. During the past 24 hours, ECM ENS is warmer in New England, Oklahoma and the Northwest. In the 11-15-day forecast, the clear direction is hot weather in the Central U.S. to Montana with marginal heat California and into the Northwest U.S. plus the Mid-south States. The Northeast U.S. looks temperate in the 11-15-day period. The ECM ENS trends cooler across the northern states.

%Normal Precipitation forecast for the Medium-range

Discussion: ECM ENS maintains a wet monsoon pattern in the West with wet weather more-established in the Ohio Valley 6-10-day outlook followed by a drier outlook in the extended-range. The northeast Gulf of Mexico requires monitoring for tropical development.

The Extended-range Day 16-20 forecast Valid August 16-20, 2022

Discussion: The ECM 16-20-day forecast is available later today. The NCEP CFS V2 version is cool in the Central U.S., a dramatic change from what is expected. Meanwhile, the GFS ENS projects widespread heat for the Northwest and Central U.S. Both models are too extreme. The actual forecast is somewhere in-between likely biased toward the hotter GFS but trending cooler.