ITHACA, N.Y. — The past several days have been quite the rainy deluge. Much of the county has received four inches or more of rain since the start of month, which is more than what the Ithaca area typically sees for the entire month of July.
Unfortunately, rain will remain the forecast for much of the week ahead, largely in the form of pop-up showers and thunderstorms as a hot and unstable air mass settles over the Southern Tier. This means that any heavy downpour as part of a thunderstorm could easily overwhelm the ground’s capacity to absorb water, since the soil is already saturated, and as a result potential flash flooding will remain a concern during the week.
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Some lingering light to moderate rain showers remain across the Southern Tier and Finger Lakes this afternoon, but the bulk of the moisture has shifted to the east, bringing prolonged heavy rains to an end across most of Upstate New York. Temperatures are in the low 70s with a dewpoint in the upper 60s, largely thanks to all the moisture that’s still hanging in the air. Some breaks in the clouds and highs in the mid 70s are to be expected as we head through the afternoon and evening hours, with continuing showers. In areas where the cloud coverage lessens more, temperatures may climb into the upper 70s, but the air remains fairly unstable, and the formation of pop-up thunderstorms is possible if more sun can break through and inject more energy into the atmosphere.
The loss of daytime heating should reduce the number of showers and thunderstorms as we head into tonight and the overnight hours, but the atmosphere will remain unstable as a weak short wave (pulse of atmospheric instability) pass through, and that will allow for showers to continue into Tuesday morning. It will remain humid, with mostly cloudy skies and lows around 70°F.
Tuesday will see a surge of hot, moist air from the Deep South northeastward into the Ohio River Valley and Eastern Great Lakes regions. The combination of moist air, enhanced by the saturated soils, will create an oppressively muggy environment on Tuesday, with dewpoints likely in the mid 70s and actual temperatures in the mid to upper 80s, though it will feel more like the mid to upper 90s with the ample humidity. Further to that, the highly unstable moist air made even more unstable by another passing short wave will allow for the development of numerous showers and thunderstorms, primarily in the afternoon and evening hours. Some of these storms could produce torrential downpours and damaging winds, and with the saturated soils, trees and power poles will be higher risk of being blown down, so keep an eye out for severe thunderstorm warnings.
As a frontal boundary begins to push in from the west Tuesday night, further instability will be injected into the local column of atmosphere, allowing showers and thunderstorms to continue overnight. Expect showers and thunderstorms to continue, tapering off somewhat after midnight, with mostly cloudy skies and lows around 70°F.
Wednesday will see the frontal trough push through during the day, with the most substantial rains likely during the afternoon hours, and numerous strong thunderstorms capable of producing heavy rain and flash flooding. Partly cloudy skies around sunrise will become mostly cloudy to near-overcast by the PM hours. Highs will be in the mid 80s with a heat index in the mid 90s due to tropically muggy conditions. Rain should rapidly come to an end as the trough passes Ithaca around sunset, ushering in a drier and more stable airmass. It will be dry overnight Wednesday, with a few passing clouds and lows in the mid 60s.
Thursday will be a drier day, though still quite hot and on the humid side as high pressure builds in from the southeast. Plan for partly cloudy skies and highs in the upper 80s. Thursday night will be partly cloudy and rather humid, with lows in the upper 60s.
Friday will once again see higher humidity as a developing storm system over the Western Great Lakes enhances the flow of hot, moist air from the Gulf of Mexico. Highs will be in the low 90s (it’ll feel more like 100°F, so heat advisories may be needed Friday) with scattered pop-up thunderstorms likely during the later afternoon and evening hours. Friday night will see pop-up showers and thunderstorms with lows around 70°F.
The weekend will be hot and unsettled as the storm systems lifts into Canada northwest of Tompkins County. Expected scattered showers and thunderstorms Saturday with partly cloudy skies otherwise and highs near 90°F. Saturday night will host a chance of showers and thunderstorms throughout the night, with mostly cloudy skies and lows in the upper 60s. Sunday will see more showers and thunderstorms as the system slowly moves away, with highs in the upper 80s.
All in all, expect at least another inch of rain from all the potential sources this week, with locally higher amounts possible. Between flash flood possibilities and heat advisories, it will continue to be an active and problematic weather pattern for the next several days.
Looking into the second half of July, the large-scale patterns favor continued hot and dry conditions over the Pacific Northeast and Upper Great Plains, which is concerning as drought conditions worsen and wildfires and brushfires are growing in quantity and severity across the region. The displacement of hot desert air into the northern Mountain West and Dakotas is allowing for Pacific air to slide into Arizona and New Mexico, creating wetter and cooler than normal conditions, and cooler and cloudier than usual conditions are expected around the Gulf of Mexico as well.