Sunday, April 4, 2010

Severe Weather - Apr. 4

A true convergence of air masses will lead to severe weather potential stretching from extreme eastern Kansas to the northeast across northern Missouri, southeast Iowa and Illinois.  A cold front will slowly drift southeastward during the day today, at the same time a strong southerly flow will continue the return of warm air and moisture to the Central Plains.  By late this afternoon or early this evening a good bulk of warm air and moisture will begin to bisect the cold front, aiding in destabilization and convergence along the front.  A meager shortwave is shown in model forecasts, and should give at least a glancing blow to aid in storm initiation this evening, especially along the northeastward extent of the front in northeast Missouri and adjacent areas of IA/IL.  Further southwest, instability should be higher due to slightly higher moisture return by this evening, with SBCAPE values of 1000-1500 J/kg and MUCAPE values even higher (~2000 J/kg).  This may be enough when combined with the convergence along the front to initiate storms this evening which may be surface based for a short time as well.  If surface based storms can develop, they will be able to take advantage of some low level shear which will aid in the organization of supercells.  This may open up a small window of opportunity for a tornadic storm or two, however those risks at the moment seem quite low.  More likely scenario will be for elevated storms to develop along the front this evening over northern Missouri as the low level jet provides additional lift and support to parcels ~1km above the surface.  Elevated supercells are possible across northern Missouri, with the potential for large hail and a few damaging wind gusts.  Individual storms will move east/northeast oriented with the cold front, thus the potential will also be there for training storms capable of some localized flooding concerns.  The cold front will drift slowly southward overnight continuing the risk of thunderstorms into central Missouri and adjacent areas, before lifting back to the north Monday morning.

As I've mentioned before I work throughout the weekend and into next week, thus no chasing is planned.  For a local chase today I would suggest a target in northern Missouri, perhaps along a Macon to Moberly line dependent on where the front is when initiation occurs.  A brief update may be posted around Noon, otherwise any additional updates will be later tonight.

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