The potential for the year's first 80 degree reading is definitely on the increase and Thursday may end up being the best chance for the region to cross that threshold. The combination of warmth aloft, optimal positioning of high pressure to our south near Cape Hatteras, and a west-southwest breeze in the atmosphere will help push temperatures towards record territory for some locations.
The GFS guidance, below, shows the 5 PM forecast position of a cold front (where the lines shift from a NW-SE direction to a WSW-ENE direction) across the Northeast. The wind shift is not an on-shore shift on Thursday so there wouldn't be much potential for sea breeze development and with the front coming in from the north during the afternoon, those west and southwest winds will create downsloping conditions for us and help boost our temperatures.
This could be the best chance to knock a record out. Friday looks warm as well but not quite as warm as the influence of the Hatteras high pressure system wanes a bit more in the wake of the cool front pushing through Thursday night. It might be a day where we "only" get into the middle 70's. Records on Friday are a touch cooler in Philadelphia -- 78 -- so if the front's passage is delayed a bit we could again flirt with a record. However, Thursday's ingredients look more promising for a record run.