Sunday, July 29, 2012

ECMWF Digs Strong Disturbance; Accompanying Severe Threat Possible

The ECMWF continues to show the prospect for a potential severe weather event in the first week of August, projecting a deepening disturbance over the western Great Lakes area.

This ECMWF solution seems pretty solid. A strong high pressure ridge remains over much of the southwestern US, and this does not look to go away anytime soon. If anything, expansion eastward seems probable. At the same time, a negative NAO currently in place is likely to persist into August, bringing the likelihood of a disturbance swinging down into the Great Lakes/Northeast regions in accordance with the buckling of the jet stream as is typical in a negative NAO.

If such deepening of a disturbance were to occur, an area of instability would be potent over the Midwest as a cold front attached to the back end of the disturbance would likely swing south and may ignite some strong to severe storms across the Midwest area. However, let's not jump to that conclusion just yet. It remains unknown where any cold front may set up, and if any instability could fuel any thunderstorms. Further analysis of the ECMWF at the same forecast hour reveals lower level winds in place over the Midwest, signaling a favorable thunderstorm atmosphere. However, jet stream winds look to be displaced to the east, which would diminish a tornado threat.


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