EWR Local Controller described possible directive infraction during LAHSO operations when wind conditions increased beyond limitations; but after both involved aircraft were completing landing.

Narrative

While working the local control position; VMC and calm to light winds from the north prevailed. ILS Runway 4R approach was advertised on the ATIS with LAHSO and Runway ILS 11 approach traffic. An E145 was issued clearance to land on Runway 4R and hold short of Runway 11 for landing traffic; another E145; wind was calm according to our Information Display System (IDS4). Traffic landing Runway 11 was advised of traffic landing Runway 4R and holding short of their Runway (11) and of traffic holding in position on Runway 4L. Calm winds prevailed; but as the Runway 4R landed; touchdown and began rollout; the wind changed from calm to a Southwesterly direction; around 290 degrees at 5-6 KTS. Our national order states that in order to use LAHSO; there shall not be a tailwind; which has been taught to be between 310 and 130 degrees for Runways 4R and 4L. A go-around to either aircraft was not possible at the time the potential wind change was noticed since both aircraft were on the ground. The aircraft landed Runway 4R completed rollout about 5000 to 6000 FT from the intersection of Runway 11 and exited Runway 4R prior to the intersection. The aircraft landing Runway 11 completed rollout between 3000-4000 FT down the runway and exited prior to both the intersections of Runways 4R and 4L. The ASDE-X system was in full core alert for local control position with safety logic on Runways 4L/R and 11. It did not sound an alert at any time. The wind returned to 'calm' shortly after rollouts were completed.