The dry weather is over. The high pressure system that had given us very comfortable weather for the past few days has moved out to sea. With the resulting southerly breeze the dew point temperature has risen from the pleasant low 60s to the stickier upper 60s. The increased humidity will give us a mostly cloudy afternoon with a high near the mid-July normal of 84.
A surface trough, a line of lower pressure that's not quite a low pressure system or a cold front, will sit along the coast from New England down to the Mid-Atlantic states by late this afternoon. That should be enough of a disturbance to get the humid lower atmosphere churning and producing showers or thunderstorms, especially north of the city. We will have a better chance of rain tomorrow as the heat and humidity increase. Look for Thursday's high to be in the sticky upper 80s.
The humidity is expected to drop a bit on Friday as the winds start coming out of a more southwesterly direction. The drier air should let us warm into the lower 90s on Friday. A cold front late Friday night should set us up for a pleasant summer weekend. Saturday and Sunday are shaping up to be mostly sunny and not overly humid with highs in the mid 80s.
