WEATHERAmerica Newsletter, Sunday, April 12, 2026; MEDIUM RANGE OUTLOOK

[Larry Cosgrove]

MEDIUM RANGE OUTLOOK

(Four To Ten Days From Now)

 

The "Number Two" Severe Weather Outbreak May Chase A Heatwave Out Of Dixie And The Eastern Seaboard

METEOBLUE

TwisterData (4)

ECMWF (4)

TrueWx.Com (4)

UQAM Meteocentre (4)

College Of DuPage Weather Laboratory (2)

The proverbial "one-two punch" is a major factor in the course of weather across the lower 48 states.

A sequence of three storms visible on satellite imagery will proceed from below the Aleutian Islands into the western USA, then recurve through the lower Great Lakes into the Gulf of St. Lawrence. It is the second impulse in the series that may produce the most havoc in the lower 48 states, starting with heavy rain and mountain snow in the Pacific Northwest and then setting up the same Texas/Great Plains to Midwest/Northeast heavy rain and severe weather scenario around April 19-21. The alignment between the oncoming storm and the heat ridge over Florida could set up impressive heat and humidity from Dixie up along the Eastern Seaboard before the arrival of low pressure and its frontal structure. I slowed down the progression of the cyclone by about a day since the upper component will take on a closed core of cold air and negative tilt as it moves from the Mississippi Valley into Ontario/Quebec and the Northeast.

The ECMWF model suite has been very consistent with the structure and intensity of the second disturbance, creating a heat wave replaced by high amounts of vorticity and cold air aloft. This is the type of set-up that can lead to a major severe and tornado outbreak that follows an astonishing rise in temperature. The approach of the third and final storm in the series should work quickly to kick out any cold air, so only a day or two of nocturnal chill is likely over the eastern half of the U.S.

That system will create another window for strong warm advection east of the Rocky Mountains that should last well into the 11-15 day period.