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December 26-27 Winter Storm Part 2

Hoosier

By Hoosier,
in Lakes/Ohio Valley

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SpartyOn

SpartyOn

Posted
Posted

DTX issued an update.

Winter storm to impact southeast Michigan on Wednesday as upper level energy/trough is tracking through the west coast at the present time. The key to the forecast appears to be the upper level low over Ontario retrograding to the west, allowing for the weakness over central/eastern Great Lakes for the gulf coast storm system to track far enough to the north. Otherwise, bit concerning for the low to deepen so rapidly along the gulf coast states, with 500 mb low struggling to make it much farther north than the southern Ohio Valley. A solution calling for a miss, like the 12z Canadian suggests can not be discredited at this juncture. However, preference will be with the majority of the models and bank on the system being negatively tilted and keeping a northern stream attachment, allowing trowal structure to arch back into our forecast area late Wednesday. Still, the 00z NAM clearly shows the system unraveling a bit, with one surge of upper level PV emanating from the center, with secondary development taking place along the coast as initial surface low dissipates before even reaching pittsburgh.

NAM cross section shows about 3.5 g/kg of specific humidity at 750 mb level reaching M-59 corridor. EPV above 0.25 throughout the entire column below 500 mb, so not terribly unstable. One of the biggest hindrance of this system for us is the progressive/relatively short lived good lift ( less than 9 hrs ). With those considerations and using GFS/UKMET/Euro output in the equation as well, expecting a 3 to 5 inch snowfall across most of southeast Michigan, with half a foot coming in and around Monroe-detroit to the eastern Thumb region. Probably looking at a decent northwest gradient/cutoff to the snow shield, and suspect tri-cities region will be on the lower end. None-the-less, there still is room for a northwest jog of the system, or southeast for that matter, as 00z Canadian remains on the southern fringe of solutions. Regardless of snow amounts, northeast winds look to be rather strong, .20 to 30 mph. Assuming there is sufficient snowfall..blowing snow and reduced visibilities below 1/2sm will be possible.

Positively tilted upper level trough will slide through the central Contiguous U.S. on Friday, and east of the Mississippi River on Saturday. Another similar storm track advertised, with lead low dissipating with secondary coastal storm taking over. This system does not look as strong or organized at first glance.

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Chicago WX

Chicago WX

Posted
Posted

Assuming the flatter solutions we've seen in today's 12z models is in fact a trend, gotta give credit to yesterday's 18z GEFS. They were the first to sniff it out.

edit: of course, credit also due to the UKIE/GGEM, which although at first were too suppressed, never went overboard like the EURO/NAM/GFS.

Too early for model congratulations.

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michsnowfreak

michsnowfreak

Posted
Posted

DTX issued an update.

Winter storm to impact southeast Michigan on Wednesday as upper level energy/trough is tracking through the west coast at the present time. The key to the forecast appears to be the upper level low over Ontario retrograding to the west, allowing for the weakness over central/eastern Great Lakes for the gulf coast storm system to track far enough to the north. Otherwise, bit concerning for the low to deepen so rapidly along the gulf coast states, with 500 mb low struggling to make it much farther north than the southern Ohio Valley. A solution calling for a miss, like the 12z Canadian suggests can not be discredited at this juncture. However, preference will be with the majority of the models and bank on the system being negatively tilted and keeping a northern stream attachment, allowing trowal structure to arch back into our forecast area late Wednesday. Still, the 00z NAM clearly shows the system unraveling a bit, with one surge of upper level PV emanating from the center, with secondary development taking place along the coast as initial surface low dissipates before even reaching pittsburgh.

NAM cross section shows about 3.5 g/kg of specific humidity at 750 mb level reaching M-59 corridor. EPV above 0.25 throughout the entire column below 500 mb, so not terribly unstable. One of the biggest hindrance of this system for us is the progressive/relatively short lived good lift ( less than 9 hrs ). With those considerations and using GFS/UKMET/Euro output in the equation as well, expecting a 3 to 5 inch snowfall across most of southeast Michigan, with half a foot coming in and around Monroe-detroit to the eastern Thumb region. Probably looking at a decent northwest gradient/cutoff to the snow shield, and suspect tri-cities region will be on the lower end. None-the-less, there still is room for a northwest jog of the system, or southeast for that matter, as 00z Canadian remains on the southern fringe of solutions. Regardless of snow amounts, northeast winds look to be rather strong, .20 to 30 mph. Assuming there is sufficient snowfall..blowing snow and reduced visibilities below 1/2sm will be possible.

Positively tilted upper level trough will slide through the central Contiguous U.S. on Friday, and east of the Mississippi River on Saturday. Another similar storm track advertised, with lead low dissipating with secondary coastal storm taking over. This system does not look as strong or organized at first glance.

That wasnt an update that was their morning discussion.

EDIT nevermind Im late to the party, you already noticed that :lol:

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snowstormcanuck

snowstormcanuck

Posted
Posted

Yikes, latest LSX WRF is an unmitigated disaster for STL-LAF. 4km WRF isn't looking hot either. Both are using the meso-low from the convection to drive the system further east, though.

Might as well ask a pro: did you think either the NAM or GFS were suffering from gridscale convective feedback? Nothing jumped out at me, but what the hell do I know.

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csnavywx

csnavywx

Posted
Posted

Might as well ask a pro: did you think either the NAM or GFS were suffering from gridscale convective feedback? Nothing jumped out at me, but what the hell do I know.

Not really, had more to do with their handling of the jet streak and resulting depth of the downstream trough over the Pacific. The cut-off high over Canada had a part to play as well, but less so.

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hm8

hm8

Posted
Posted

A lot of the hi-res models have been showing a sorta squashed look to the deform band as it tries to make its way into MI...which is believable since this is exactly when the system begins to transfer east. I'm going with 4-8" for SEMI, obv. with the higher amounts in the SE and lower as you go NW.

Some images from the 12z 4km NAM

cld60.gif

snow60.gif

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