ROCHESTER, NY (WROC) — We are forecasting for Rochester’s overnight low temperatures to drop into the lower and middle 20s. This will challenge the record of 22° set in 1943. Remember that the coldest part of the day is often right before dawn. Sunrise for the 16th of April is 6:25 am, so the coldest part of Thursday will be right around 6 am. Average low for the 16th is 37°.
While March was the top 20 warmest on record for Rochester, April has swung back to normal with temperatures through the 14th only 0.4° above normal. This mid-month cold stretch will likely bring the average below the climatological average as we near the end of the month.
THE SETUP FOR COLD:
A large trough of colder air will sweep into the Great Lakes and Western New York that turns the surface winds out of the northwest. A storm system to the south may even bring light snow showers south of the thruway Wednesday night into Thursday.
A light coating of snow can help warmer air radiate away from the cold and bright surface versus a warmer, darker surface. Once this system clears out after midnight, skies will clear and winds calm. That “opens the door” to quick cooling at the surface. Lack of surface moisture will also allow temperatures to drop down to the dewpoint. All this in combination is known as radiational cooling.
The above is a forecast model output for 5 am Thursday morning showing zero cloud cover over Western New York. This will lead to a chilly start to the day! There will likely be frost around to start. Below is the RPM forecast for lows. Note the potential for teens in some areas of the Southern Tier. This forecast is even lower than the current News 8 forecast seen above.