Hot, humid. As temperatures climbed to the 90s in most parts of the metro area this afternoon, dewpoints were in the muggy low 70s at many locations. Dulles reached 92° by 3pm, and the humidity was producing a heat index as high as 96° the following hour. Although prolonged hot spells are relatively rare in September, at some point in the past National has observed temperatures in the 90s on every day of the month, and the all-time monthly high of 104° occurred on this date in 1881.
On this 12th consecutive rainless day, however, precipitation prospects from a possible developing tropical system are diminishing.
The area of storms lurking off the southeastern Atlantic coast has become more concentrated today, and a Hurricane Hunter flight investigated the situation this afternoon. As of 5pm, it had not found a closed circulation at the surface, but it was continuing to collect data. If a depression or tropical storm does develop, the most likely scenarios at this point are for it to move northwestward, weaken and dissipate over eastern North Carolina or for it to be swept out to sea ahead of a cold front moving eastward on Sunday.
The scheduled topic for this weekend's Forecast Earth on The Weather Channel (5pm Saturday and Sunday) is "Paying For Climate Change", but the broadcast may be pre-empted for tropical coverage.