12/13/17 - 300PM
Epilogue:
The forecast and clipper system behaved very well. In fact; the anticipated strengthening deeper than even the models projected came to pass with the central pressure diving to 992-994 MB. On much of the the 12z guidance 12/12/17, central pressure was deepening to around 996-997 MB. Snowfall forecast overall also went well issued 245 PM. Nit picking; I could have said areas of 8" and isolated higher amounts but I'm happy with the overall forecast outcome.
From original forecast below;
"This system has all the ear-marks of a possible over-achiever in the latest guidance compared to
the earlier runs. All models are leaning toward a bit of a wetter system considering the classic clipper system. This has me concerned and as we have seen; the past few have been achievers-overachievers. The Great Lakes are wide open which won't hurt and the dynamics /vorticity/ projections were notable and getting even stronger".
"At this point the max amounts of snow may very well be in the 6" to pockets of 8" totals with 3-6" encompassing that area."
Epilogue:
The forecast and clipper system behaved very well. In fact; the anticipated strengthening deeper than even the models projected came to pass with the central pressure diving to 992-994 MB. On much of the the 12z guidance 12/12/17, central pressure was deepening to around 996-997 MB. Snowfall forecast overall also went well issued 245 PM. Nit picking; I could have said areas of 8" and isolated higher amounts but I'm happy with the overall forecast outcome.
From original forecast below;
"This system has all the ear-marks of a possible over-achiever in the latest guidance compared to
the earlier runs. All models are leaning toward a bit of a wetter system considering the classic clipper system. This has me concerned and as we have seen; the past few have been achievers-overachievers. The Great Lakes are wide open which won't hurt and the dynamics /vorticity/ projections were notable and getting even stronger".
"At this point the max amounts of snow may very well be in the 6" to pockets of 8" totals with 3-6" encompassing that area."
Snowfall Map below: Courtesy of the NWS DTX
Individual amounts and more can be found here
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12/12/17 - 245PM
More snow will move into Southeast Lower Michigan during the forenoon hours of Wednesday. Generally speaking this system appears to have more "uumph" with it than the last one. Simply meaning; depending you location, the same or better amounts of snow than Monday night's & gusty winds while it's falling. In addition; the band of snow will orientate Northwest-Southeast as it moves into the region before leveling off again west-east like Monday night.
At this point the max amounts of snow may very well be in the 6" to pockets of 8" totals with 3-6" encompassing that area. Points further north-northeast will see the least with this system in the 1-4" range. I see no reason to deviate with the models upping amounts seeing the upstream wave impulse and projected track. This system has all the ear-marks of a possible over-achiever in the latest guidance compared to the earlier runs.
The main models are in remarkable agreement on the general snowfall with a snow to water equivalent averaging 2.0"/.15". I believe that's a bit low as the the environmental air initially is quite cold and dry; a 15/1 to 20/1 (2.0"/.10") doesn't seem too outrageous. Then however, one must account for evaporational cooling initially and moistening/saturating the column of air before the snowfall can accumulate much. All models are leaning toward a bit of a wetter system considering the classic clipper system. This has me concerned and as we have seen; the past few have been achievers-overachievers. The Great Lakes are wide open which won't hurt and the dynamics /vorticity/ projections were notable and getting even stronger.
Since the models are very close with this system and they look reasonable at this time with the track; I've decided to post the snowfall amounts generated by some of the pertinent ones. One caveat in the forecast would be main the track and its deviation from the track forecast. Further north, less snow south, more snow north; further south, less snow most areas except near Ohio border. Also of course; true available moisture and speed at which she tracks.will also affect the outcome.
