Jump to content

a.salt

Members
  • Posts

    76
  • Joined

  • Last visited

Posts posted by a.salt

  1.  Mesoscale Discussion 1854
       NWS Storm Prediction Center Norman OK
       1257 PM CST Wed Dec 16 2020
    
       Areas affected...Northeast West Virginia...northern
       Virginia...western Maryland...and central to eastern Pennsylvania
    
       Concerning...Heavy snow 
    
       Valid 161857Z - 170000Z
    
       SUMMARY...Heavy snowfall rates around 2 inches per hour are expected
       to increase in coverage through the mid to late afternoon hours
       across portions of the Mid-Atlantic. Heavy snowfall will likely
       continue into the overnight hours for portions of
       eastern/northeastern Pennsylvania.
    
       DISCUSSION...Precipitation continues to gradually increase in
       coverage across much of the Mid-Atlantic region within a broad swath
       of strong warm air advection between 850-700 mb (per recent RAP
       soundings and mesoanalysis). Mixed precipitation types continue to
       be reported within the precipitation transition zone along the
       Roanoke to Fredericksburg, VA line. While a wintry mix, including
       pockets of freezing rain, will continue in the near term, this zone
       should become more limited spatially through the mid/late afternoon
       hours. Further north, moderate, to at times heavy, snowfall rates
       have been observed (as evidenced by visibility reductions to
       one-quarter mile and observed snow rates around 2 inches per hour
       for some locations in northeast WV). 
    
       Heading through the afternoon, the low that is currently advancing
       northward along the Carolina coast will continue to deepen. As this
       occurs, mid-level winds will strengthen and begin to tighten the
       850-700 mb baroclinic zone and augment warm advection across the
       region. As isentropic and frontogenetical lift increase, snowfall
       rates will see a corresponding uptick in intensity. Lift within the
       dentritic growth zone and weak instability closer to the coast will
       help further augment snowfall rates. Widespread snowfall rates above
       1 inch per hour over the region are likely, and the potential for
       widespread snowfall rates exceeding two inches per hour will
       increase through 00 UTC as the potential for organized
       frontogenetical/deformation-driven snow bands increases.

    mcd1854.gif

    • Like 4
  2. From LWX (4:33 AM)

    .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
    Low pressure will traverse the area Friday. It`s weak, but there`s
    notable warm advection in the 850-700 hPa layer, tucked under a
    modest coupled upper jet structure and mid-level PVA. Given the cold
    temperatures, any precipitation that falls will be snow and have no
    trouble sticking. East of the mountains, lift is focused in the
    dendritic snow growth zone, so despite low-level dry air believe
    there should be at least some steady light snow in the I-81 corridor
    and near/north of US-50. Along and north of I-70, moisture and lift
    are a bit better and this is where the best chance for plowable snow
    exists east of the mountains.
    
    As far as the ridges of the Allegheny Highlands go, lift here is
    actually a bit below the dendritic snow growth zone. Cold
    temperatures should yield ratios close to 18:1, but with low
    inversion heights and less than ideal wind trajectories, current
    most likely forecast is for sub-warning level snow (solid advisory,
    3-6"). Therefore, have opted not to go with a watch at this time.
    Advisories will likely be needed over the mountains and in northern
    Maryland (especially given the cold ground and potential impact) for
    Friday, if current forecast projections remain on course.
    

     

     

    StormTotalSnowWeb1.png

    • Like 2
  3. From LWX:

     

    Here are the current rankings for wettest year on record
    (through November 15th):
    
    Baltimore MD area (BWI)
    1. 63.01 inches (2018)
    2. 62.66 inches (2003)
    3. 62.35 inches (1889)
    4. 58.98 inches (1979)
    
    Weather records for the Baltimore MD area have been kept at
    what is now Baltimore-Washington International Thurgood Marshall
    Airport (BWI) since 1950. Precipitation records observed
    downtown extend the period of record back to 1871.
×
×
  • Create New...