So IAD 0.7 then DCA. 0.14 then BWI 1.35”
Following this one time would not mean much but I see it 30 times per year starting about 15 years ago when ethanol became so prevalent
Moderate to the west, weakens right around DC beltway circle, restrengthens when moving east and north . It’s most prevalent in summer and winter and not fall or spring. A unified cold front in the summer is not so effected.
Just make scrupulous observations from now thru end of February and get back to me.