Precipitation banding and advection

[icicleman]

In the Feb 18th OBS thread, Rainshadow said "I have to pay attention to these sw flow aloft events going forward if there is an orographic favoring of these bands along/northwest of the fall line.  This and the Super Bowl they almost fell one on top of the other."

My question:

Since the frontogenesis banding occurs so high (5000-10000 ft), does the wind speed and direction also affect the location of the resultant "surface accumulation band" where we actually measure the fallen precipitation?  It seems like the placement of this accumulation band could vary by tens of miles, depending upon wind profile.  Rt 202 and I-95 are only about 15-20 miles apart.  Or are the wind profiles not that different from storm to storm?  Thanks.

Edit on 2/23:

I did a layman's google search and found this paper from 2019:

https://journals.ametsoc.org/view/journals/mwre/147/11/mwr-d-19-0036.1.xml

They note that "Environments that accompany mesoscale snowbands in extratropical cyclones feature strong midlevel frontogenesis and weak symmetric stability, conditions conducive to vigorous ascent." (They use the term "lofting" to describe the ascent.)  They tried to answer "to answer the more fundamental question of how much spatial separation may occur between regions where snow crystals form and grow aloft, relative to where they reach the surface."

They find that "considerable horizontal displacement can occur between the locations of strongest ascent and heaviest surface snowfall."  

I don't understand mid and low level wind patterns enough to guess whether the horizontal displacement is consistent (in orientation and/or extent) for storms in our area.

[Bananashadow]

On 2/20/2021 at 10:57 AM, icicleman said:

In the Feb 18th OBS thread, Rainshadow said "I have to pay attention to these sw flow aloft events going forward if there is an orographic favoring of these bands along/northwest of the fall line.  This and the Super Bowl they almost fell one on top of the other."

My question:

Since the frontogenesis banding occurs so high (5000-10000 ft), does the wind speed and direction also affect the location of the resultant "surface accumulation band" where we actually measure the fallen precipitation?  It seems like the placement of this accumulation band could vary by tens of miles, depending upon wind profile.  Rt 202 and I-95 are only about 15-20 miles apart.  Or are the wind profiles not that different from storm to storm?  Thanks.

Edit on 2/23:

I did a layman's google search and found this paper from 2019:

https://journals.ametsoc.org/view/journals/mwre/147/11/mwr-d-19-0036.1.xml

They note that "Environments that accompany mesoscale snowbands in extratropical cyclones feature strong midlevel frontogenesis and weak symmetric stability, conditions conducive to vigorous ascent." (They use the term "lofting" to describe the ascent.)  They tried to answer "to answer the more fundamental question of how much spatial separation may occur between regions where snow crystals form and grow aloft, relative to where they reach the surface."

They find that "considerable horizontal displacement can occur between the locations of strongest ascent and heaviest surface snowfall."  

I don't understand mid and low level wind patterns enough to guess whether the horizontal displacement is consistent (in orientation and/or extent) for storms in our area.

The ascent vs where it fell with the 2/18/-2/19 event was displaced pretty far to the northwest.  Best predicted (we can never measure it) fgen forcing was down in Delmarva & SE NJ and also the snow growth area was way high around 500mb.

 

[icicleman]

Thanks! I am just starting to catch on to what is happening in these storms.  I wish there were a 3D recreation of storms (built from sensor data) that you could "fly through" and watch the storm evolve from any vantage point.  Thanks again and thanks for all of the information you pass on to the board.