MARCH-MAY 2024 90-DAY OUTLOOK
1858 PM EDT Tue. Mar. 5, 2024

Atmospheric patterns, 700 MB and 500 MB height anomalies, statistical data, and various models such as the ECMWF monthly, NMME, IMME, and the CFSv2, along with observed cases from past such months, data from 1895-2000 were used in this forecast.

During January, above-normal sea surface temperatures continued across most of the equatorial Pacific Ocean. Sea surface temperature anomalies weakened slightly in the eastern and east-central Pacific, as indicated by the weekly Niņo index values. However, changes were more pronounced below the surface of the equatorial Pacific Ocean, with area-averaged subsurface temperature anomalies returning to near zero. Although above-normal temperatures persisted in the upper 100 meters of the equatorial Pacific, below-normal temperatures were widespread at greater depths. Atmospheric anomalies across the tropical Pacific also weakened during January. Low-level winds were near normal over the equatorial Pacific, while upper-level wind anomalies were easterly over the east-central Pacific. Convection remained slightly enhanced near the Date Line and was close to average around Indonesia. Collectively, the coupled ocean-atmosphere system reflected a weakening warm episode.

The most recent IRI plume indicates a transition to neutral ENSO during spring 2024, with a cold episode potentially developing during summer 2024. Even as the current El Niņo weakens, impacts on the United States could persist through April 2024.

In March, the Polar Vortex seems to be trending more to wave-2 that could favor a Polar Vortex split. Models seem to be deciding on whether the PV will split or not. It appears a split may occur with one over Europe and the other over the U.S. Most of the models predict a cold pool over the polar stratosphere. The Canadian is predicting a most a negative AO and NAO for the stratosphere. If it verifies it could be supportive of a negative surface AO and NAO. We shall see.

The ECMWF monthlies depict above normal heights near the Aleutians, a trough with below normal heights across western North America. Heights are above normal across Greenland and across eastern North America for March. In April, A trough is forecast near the Aleutians with above normal heights from Greenland west, southwest into the West. Below normal heights over the Atlantic. In May, below normal heights are depicted in the East. The C3S forecast depicts above normal heights across much of North America. The SEA5 is similar.

The ECMWF monthlies depict above normal heights near the Aleutians, a trough with below normal heights across western North America. Heights are above normal across Greenland and across eastern North America for March. In April, A trough is forecast near the Aleutians with above normal heights from Greenland west, southwest into the West. Below normal heights over the Atlantic. In May, below normal heights are depicted in the East. The C3S forecast depicts above normal heights across much of North America. The SEA5 is similar.

The CS3 and the SEAS5 depict above normal temperatures across much of North America. THE ECMWF depicts below normal temperatures in the West and above normal temperatures in the East for March then trending above normal temperatures in April and May.

TEMPERATURES

Yeloow-2-4°F

Orange-4-6°F

Red-6-8°F or Greater

Light Blue 2-4F Below

Mediam Blue 4-6F Below

Dark Blue-6-8F or Great Below

Above normal temperatures are forecast for the southern Rockies, southern Plains, the Mississippi Valley to the Atlantic Coast. Anomalies are forecast to be near 4°F. The remainder of the nation is expected to average near normal with no significant deviation from normal climatology.

PRECIPITATION

Yellow=-35% Below

Brown-35-45% Below

Dark Brown-45-55% Below

Light Green-30-35% Above

Green-35-45% Above

Dark Green-45-55%Above

Below normal precipitation is forecast for a portion of the Southwest and the southern Plains. The probability of below normal precipitation in this region is 35 percent. Above normal precipitation is forecast for northeast Montana, most of the northern Plains. A portion of the Plains to the Atlantic Coast. The probability of occurrence is 35 percent. The remainder of the nation is expected to average near normal with no significant deviation from normal climatology.


Jim Munley Jr.
http://www.jimmunleywx.com

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