Friday Update on Nate

Tropical Storm Nate continues to strengthen and Hurricane Watches have been issued for portions of the Louisiana, Mississippi and Alabama coastline.  The forecast models are beginning to come into better agreement on Nate’s potential track and impact on our area as it begins to interact with an approaching cold front out of the Midwest late this weekend into early next week.

Latest European (ECMWF) and GFS Ensemble “Spaghetti Track” models:

Currently, a land falling Hurricane is likely across the north-central Gulf coast between the New Orleans Area and the Mobile Area.  How quickly the cold front tracks through the Midwest will have a direct impact on exactly where the majority of Nate’s leftover (much-needed rainfall) tracks on Monday.

Precipitation Ensembles:

– While the Washington DC Area will likely receive some rainfall, exactly how much is still in question and ultimately dependent on the exact track of Nate’s leftover center of circulation.

– A track well to the west of DC will increase the severe weather threat as wind shear in the atmosphere increases, however this track would produce lesser amounts of rainfall across our area.

– A track very near the DC Metro region would produce significant amounts of much-needed rainfall (possibly in the range of 2 to 5 inches)

– Finally a track to our south would offer lighter rainfall amounts and shift any severe weather threats to our south.

It has not rained in DC in over 20 days, the ground is parched, the trees are stressed. The ideal track for our region would be right across the Shenandoah Valley or spine of the Blue Ridge mountains as this would provide some widespread soaking downpours.

50 individual European Ensemble outputs for potential rainfall accumulation through Tuesday afternoon (notice the wide range of variance):

If you were to average all 50 European Ensemble members above:

The latest GFS Ensembles for potential rainfall amounts:

I will provide more updates this weekend as the eventual track of Nate’s leftovers become more clear.  For the folks living along the Gulf Coast, my hope is that this system remains weak and just provides some rainfall.

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