Update on Conversational Snow Event

Check out the gorgeous sunrise this morning here in the Nation’s Capital! (Image courtesy National Park Service)

National Capital, DC,Netherlands Carillon

National Capital, DC,Netherlands Carillon

This “storm system” really just didn’t come together with everything going right if you didn’t want accumulating snow.

The storm’s evolution according to this morning’s latest forecast models is showing very weak pieces of energy moving through instead of the original idea of a phased storm with a nice “deformation band” right over the 95 corridor (an area of intense lift on the NW side of a coastal storm).

Here are the latest forecast models (courtesy Weatherbell) showing the European, GFS, and Weather Prediction Center’s (WPC) models:

Latest European Snowfall Forecast –  Basically we have to accept that there could be zero accumulation in the metro area even if wet snow falls overnight tonight or Sunday evening.  The Euro is advertising a lull in the precipitation overnight tonight and on Sunday… so if the lull doesn’t occur then we could actually receive some light accumulations on grassy surfaces.

ecmwf_tsnow_washdc_12

GFS –  Light coating for some… northern Maryland and higher elevations could pick upwards of 2 to 4″. Highest elevations (above 2500 feet) could pick up 3 to 6″.  The GFS has less of a lull in the activity, hence higher totals.

gfs_6hr_snow_acc_washdc_9

Finally here are two images from the WPC showing the 50 percentile and 75 percentile (snow probability maps). 

Given that this is a late March system that is weak with very little cold air to work with, I’d consider the first image (50 percentile map) to be the bearish, realistic, outcome and the 75 percentile map (second image) to be the bullish outcome:

Bearish Snowfall Potential: Zero Accumulation for areas outside of extreme northern Virginia and northern Maryland.  This morning’s models are showing a lull in the precipitation tonight and on Sunday.. if this lull materializes then rain will be the predominant precipitation type for most areas outside of the higher elevations.

wpc_snow_72_50_washdc

Bullish Snowfall PotentialIf the precipitation comes down at a steady enough pace overnight tonight and Sunday evening and temperatures can cool into the middle 30s during those two time frames… then this these amounts could occur on grassy surfaces, trees and cars.  Again if there is no lull in the action tonight and tomorrow… these totals could be realized on grassy surfaces.

wpc_snow_72_75_washdcHave a good weekend!   I hope we are done with winter!

 


Latest Euro, Canadian and GFS Snowfall Accumulation Forecasts

The best chance of accumulation from this weekend’s snow event will be on grassy surfaces and trees.  Here are the latest forecast models (images courtesy Weatherbell):

Here is the latest 12z Operational European Snowfall Forecast: Generally a dusting in the urban heat island with one to three inches in the suburbs.

ecmwf_tsnow_washdc_13

Here is the latest European Ensemble which probably has the best idea: Again a general one to three inches with two to four inches the further north and west you go from the metro Area.

eps_snow_m_washdc_11

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European Model Shifts East in Track Overnight as Consensus Finally Builds

Bottom Line Up Front:

  • Latest operational run of the European (00z) from overnight shifted the storm track well to the east (talk about model whiplash!)
  • The European Ensembles are now in agreement with this shift in the operational track.  The GFS also has the more eastward track which means consensus is finally there that the heaviest snow will remain offshore.
  • Still some light snow will likely accumulate on grassy surfaces overnight on Saturday into the day on Sunday (read below for latest accumulation maps).

Here is the latest European Ensemble (image courtesy Weatherbell) showing clustering of “L”s more offshore than yesterday which explains why last nights operational model shifted east as well (those of you dreading a heavy march snow are probably cheering).

eps_slp_lows_ma_13

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