Friday, May 3, 2013

Severe Weather Prognosis - May 3, 2013

This discussion concerns the next week and how severe weather may evolve within that timeframe.

Madden-Julian Oscillation is predicted to strengthen and move into the middle phases as the next 7 days evolve. Current stage of MJO is in weak Phase 1 as the above image shows. The GFS Ensembles predict the MJO wave to move through Phases 2 and 3, both of which are known to ignite severe weather concerns. Phase 2 has been judged by multiple meteorologists to have an atypically high risk of tornado outbreaks. Main concern for this discussion is centered around the time that the MJO spends in Phase 3. Time spent in Phase 2 is of little interest, as unusual weather pattern involving a massive closed low in the Plains situates itself in the region for the period of time the MJO spends in Phase 2. By the time the Madden Julian Oscillation wave reaches Phase 3, the closed low will have moved out of the contiguous United States and another storm system will be forcing itself through the Southwest and Southern Rockies. It is this timeframe when our first severe weather risk arises.

Vorticity map shows closed low on the Eastern Seaboard and the next storm system pushing through the Southern Rockies. Future forecasts going into the overnight hours of May 8-May 9 include high instability values and extreme supercell composite values. Capping inversion will likely prove problematic should the current forecast pan out, but the event's details will be addressed in a future post.

Madden-Julian Oscillation will be in Phase 3 during this timeframe, and analogs were examined for springtime Phase 3 dates. These dates were gathered from 2011 to 2006, with candidate months including April through June. Storm Prediction Center storm reports from all dates in these five years were examined, and 17 of 19 analog days included a synoptic severe weather event. The conclusion indicates that Phase 3 of the MJO does include severe weather potential.

Concern then falls to the aforementioned May 8-9 potential severe weather event. Current forecasts have this event progged to be relatively significant, but further analysis is needed in coming days to assure or disprove this estimation. Not willing to examine any dates beyond the May 8-9 timeframe, uncertainty in both model predictions and MJO forecasts are too great to give any confidence.



Anonymous said...

Where are you expecting this severe weather? Will the Chicago area have any?

Andrew said...

This is just an overview, not looking at any outbreak. The details will be addressed in a future post.