A trend towards milder temperatures will take hold in the Finger Lakes for the second half of the week and the weekend.
Northwestern portions of the Finger Lakes will return to the 50s today, while areas further south and east remain locked in the low and mid 40s.
The disparity in temperatures will be caused by two factors. First, an area of low pressure to our south is trying to spread precipitation northward into the southern half of the region. The radar shows precipitation over the area this morning, but it does not appear as though much, if any, is reaching the ground.
The precipitation is evaporating as it falls, which is a process that cools that atmosphere. This evaporative cooling will counteract the daytime warming, holding temperatures down in these southern areas.
Second, south-southeast winds will blow steadily today. These winds will come from the higher elevations in the south and flow downslope to the lower elevations of the Lake Ontario plains. Downslope flowing air is a warming process.
In the absence of these two phenomena, our region would probably see uniform temperatures in the mid and upper 40s. Instead, southern areas will be cooler than that, while northern areas get a slight boost.
Skies will be cloudy throughout the day but should break up tonight. Sunshine is likely for a good portion of Thursday before clouds and a few showers move in for the afternoon. The rain that falls tomorrow should be brief and come mainly after 5 PM.
Those showers will be triggered by a low pressure system to our northwest. South winds ahead of the low will result in a mild day throughout the region. Low 60s are likely in the northwestern quadrant, with most of the remainder of the area settling near 60 degrees. Higher elevations in Central New York will top out in the upper 50s.
Additional rain will be possible Thursday night and very early Friday, mainly for the counties that border Pennsylvania. Even they may stay mostly dry, though.
Morning clouds will then give way to sunshine, with mostly clear skies continuing into Friday evening.
Friday’s winds will be from the north behind Thursday’s low pressure, so temperatures will not be quite as warm. Still, most areas should reach the low or mid 50s. The north wind coming off the cold waters of Lake Ontario will keep the coastal counties in the 40s.
Thin clouds will work in from the south Friday night and Saturday. At first, the sun should be able to shine through the clouds early Saturday, but the clouds should thicken through the morning.
Rain is now not expected to arrive until late Saturday afternoon or Saturday night as a warm front lifts north. Even ahead of the front, though, temperatures Saturday should reach the low and mid 50s.
If the front moves in quicker and precipitation tries to make inroads earlier, another evaporative cooling situation similar to today could evolve, which would hold temperatures in the 40s.
The warm front should lift through Saturday night with a period of heavier rain. Gusty winds will develop behind the front and continue into Sunday. A couple rumbles of thunder cannot be ruled out, either.
Temperatures Sunday will depend on how the precipitation evolves and the track of the low. Most likely, highs will be in the upper 50s or low 60s. Some areas could get warmer though, especially if any sun comes out between showers.
Cooler air will work in for much of next week behind Sunday’s system, with daily highs mainly in the 40s.