WEATHERAmerica Newsletter, Saturday, November 30, 2024; SHORT RANGE OUTLOOK

[Larry Cosgrove]

NEXT TEN DAYS

(Through December 10)

 

James Bay Vortex, "Clipper" Type Shortwaves Bring Snow Squalls And Warm West Vs. Cold East Pattern

METEOBLUE

ECMWF (4)

PivotalWeather.Com (4)

College Of DuPage Weather Laboratory (2)

Residents of the Great Lakes and middle/upper Appalachia may not want to read this, but....you are NOT done with heavy lake effect/related snow squalls. The strong ridge complex in the Gulf of Alaska and the Pacific Northwest is holding the southern branch storm over CA/BCN for the near term. But the James Bay cAk vortex will eject another shortwave through Manitoba into Michigan by Thursday. With a powerful surge of cold air and vorticity aloft (the disturbance takes on a closed off appearance while still moving), amounts of snow may exceed six feet again in the prone lee areas. The danger is that the Interstate 90 corridor, including Cleveland OH and Buffalo NY metros, will be involved in the squalls to an even greater degree than that seen this weekend. 

Rain may start to break out across the Lone Star State on December 3-4 as the upper low in the Southwest starts to move out of the Desert Regions. This feature appears stronger on every numerical model run, and could be a severe weather producer along the western Gulf Coast and Mississippi Delta. The harshest cold should be in sections of the Midwest into Onatraio and Quebec before migrating inyto the Mid-Atlantic and New England states.

Subtropical Jet Stream, Baja California Storm Combine To Bring Quick Warming And Significant Rain/Thunderstorm Event From The Great Plains To Eastern Seaboard

METEOBLUE

TrueWx.Com (4)

UQAM Meteocentre (4)

College Of DuPage Weather Laboratory (2)

The presence of an intense storm southwest of Alaska, and of a vigorous southern branch jet stream, warns of some very turbulent conditions in the eastern 2/3 of the USA in the medium range and longer term.

Timing the second system in this sequence will be difficult; I like the GGEM panels track sequence, but think that the system moves about a day slower than is depicted by the Canadian version. Moisture will be abundant, and the cold pool drawn in from Ontario will enable the lake-effect and lake-related snow machine to restart. Following on the heels of the James Bay vortex dive through the Great Lakes (see above), this will mark the third major interruption of transportation in the Midwest and Northeast. And while I think the cold advection may not be as strong as previous systems, there will be an effective drop in temperature all the way into Texas by December 10. A severe weather threat also looks likely for TX and the Deep South to the right of the storm track (Colorado/Trinidad "A").