Forecast thoughts

Se Michigan remains lodged within a deep/moist and progressively destabilizing southwest flow late
this morning. Several hour window of nearly full insolation certainly helping this process, although
the northern extension of the remnant cloud debris attached to the leftover weak PV filament
streaming into west-central Ohio will begin to filtering the heating component slightly heading into
midday. However given current trends, high temperatures of lower to middle 80s certainly are
attainable. This projects to roughly 1500 j/kg of mlcape for this afternoon. 

Despite this emerging low level instability gradient, delineating both the location and scale of
convective development, both upstream and locally, remains a challenge for the afternoon and evening
period. 12z DTX sounding and recent model guidance suggest some degree of capping remains in place,
albeit not nearly as strong as noted yesterday. Convective initiation may become tied to additional
weak shortwave energy and on the lead edge of an expanding differential heating zone working across
Missouri and into southern Illinois. Recent hi res model guidance provide few clues, suggesting a
window for isolated/scattered discrete cell development in that favored 19-22z period. Given a solid
background thermodynamic environment to maintain updraft strength, the presence of a supportively
deep layer wind field will maintain a risk of damaging winds and hail with any cells that can
organize through the peak heating cycle. 

Minor update issued already to readjust pops through the evening and tweak temperatures based on
recent trends. 

. . posted at 1013 AM EDT Tuesday May 21 2013


Remaining Commentary on the forecast - Wednesday through Monday

Despite a mid level shortwave and support from the low level jet, morning convection has not held
together well as it has travelled through southeast Michigan this morning. As the 06z runs come in
they are keeping additional convection to the north and south of the area where the better dynamics
are, in stark contrast to the 00z runs which blanketed the area with rain all day. Water vapor
imagery shows some validity to this thinking as the jet stream to the north pulls storms over the
northern Great Lakes and activity to the south shows signs of staying over the south. It appears
southeast Michigan could be in between activity to the north and south today the way water vapor
imagery is shaping up. Given these factors will tone down pops from categorical to likely, however
going below this threshold would be a mistake with the amount of instability that is forecast to
develop during the afternoon hours. Further adjustments to the forecast will be made as necessary.

. . posted at 738 AM EDT Tuesday May 21 2013
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