Cooling Western North Atlantic Foreshadows Cooler East U.S. Coast Weather in May

Charts of the day: Is the cooling western North Atlantic basin a sign of cooler weather ahead for U.S. East Coast?

Discussion: The western North Atlantic basin has cooled to near normal during mid-spring. Most dramatic are waters just north of the Gulf Stream. Large areas of cooling SSTA can foreshadow cooling air aloft forcing presence of an upper trough which is indicated by the ECMWF during May. Note the 1-year change which is BOLDLY cooler for the western North Atlantic.

Week-2 Ahead Forecast valid May 5-11, 2024: Not as wet; East Coast likely cooler.

Discussion: Upper air pattern forecast projects two relatively bold trough patterns on each coast leaving a warm high-pressure ridge over Canada and the Central U.S. ECM is overstated with the warmth particularly on the East Coast where the trend will be cooler. Wet weather shifts northward.

Week-3 Ahead Forecast valid May 12-18, 2024: U.S. is temperate.

Discussion: ECM projects an upper trough off the Mid-Atlantic Coast. Consequently, the East U.S. is temperate or cooler than normal. In the West, an upper trough is located off the California Coast. The forecast trend is cooler. Wet weather is indicated for the Gulf States. Support for western Great Plains rainfall is weak.

Week-4 Ahead Forecast valid May 19-25, 2024: Pattern is not supportive of any significant rain.

Discussion: As the last third of May arrives, the East Coast remains susceptible to an upper trough. An upper ridge extends to the Northwest States. Support for marginal warmth across the northwest quadrant of the U.S. and temperate elsewhere. The pattern is not supportive of any significant rain.