NAO index continues to slide but Jury is still out on exact Track and # of Storms

Negative NAO

Bottom Line Up Front:  The exact forecast track of next weeks storm is still unknown at this time as some of the ensembles show an inland track and others show one closer to the coast.

Another very interesting development this afternoon is that the models this evening are suggesting that there may be two storms, the first on Tuesday afternoon/overnight and a second one coming up the coast Wednesday into Thursday.  Could the Tuesday storm be rain and the second storm on Wednesday into Thursday be our snow event?

Those of you who are weather geeks like me keep reading below:

The NAO index forecast continues to slide:  The latest forecast run of the GFS (image below courtesy Weatherbell) shows the NAO potentially falling to a negative 2 around the 27th of February.

gfs_nao_bias

European NAO index forecast is also trending negative around the 27th of February:

ecmwf_nao_bias

European Ensembles: The next four images (courtesy weatherbell) show that there is still a great deal of uncertainty in exact storm track.

Tuesday 12 Noon –  High pressure over northern New England trying to hold on as an area of low pressure is positioned somewhere in the deep south.

eps_slp_lows_ma_18

Wednesday 7AM – notice how scattered the “red L’s” (possible locations of where the area of Low pressure forms) are on the map across AL, GA, SC, TN, KY.  You can also see some “L’s” off of our coastline.

eps_slp_lows_ma_21

Wednesday 7PM – Inland storm? Coastal storm?

eps_slp_lows_ma_23

Thursday 7 AM – Storm system should at least be passing to our north and east.

eps_slp_lows_ma_25

European Ensembles: Potential snowfall accumulation through Noon on Thursday February 25th

As you can see the majority keep the heavier snow well west of DC.  However, until the energy that is responsible for how the pattern is going to evolve reaches the northwest coast on Sunday evening — we can’t rule out a winter storm in the DC Area just yet.

eps_snow_25_washdc_26 eps_snow_50_washdc_26

In Review:

  • Forecast Model Ensembles are not in 100% agreement on eventual track of the storm(s) next Tuesday morning through Wednesday night.
  • Recent models suggest there may actually be two storms, one on Tuesday/Tuesday night and secondary storm Wednesday into Wednesday night
  • NAO continues to trend more negative with each run! Even if we don’t get a big snow in DC Tuesday through Wednesday night, the overall pattern (ridge out west and negative NAO) is a black swan that an east coast snow storm for the big cities (DC to Boston) may pay us a visit during the next 7 to 12 days.

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One Reply to “NAO index continues to slide but Jury is still out on exact Track and # of Storms”

  1. Thanks again for such an informative post! I had more or less given up on next week, but at least there is still some hope.

    Like

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