ITHACA, N.Y. — In a month where half of the days have had recorded rainfall, a dry spell would be a welcome reprieve. It looks like this last weekend of July will grant that wish.
As an unusually winter-like storm system develops over the Mid-Atlantic and drops impressive rainfall amounts on the Washington D.C. and Philadelphia areas, conditions for the Southern Tier and Tompkins County should be generally okay, remaining dry with some mixed clouds and sun on Saturday and Sunday. High temperatures will be a tad below the climatological average for this time in the year, in the mid to upper 70s F, with lows in the mid 50s F, and possibly a few lows near 50 in the higher elevations Saturday night into Sunday morning. The rule of thumb this weekend will be, the further south and southeast one goes, the cloudier it will be, and the greater the chance for rain.
Thinking of the developing storm system in a winter context, normally with a big coastal event, the counterclockwise (cyclonic) circulation of northern hemisphere storms draws in cold air from Canada, often triggering lake effect, bitter chills and the latest round of gripes and moans. But placed in a summery environment, the region experiences comparatively cool but still mild temperatures. Another benefit is that this time of the year, the lake water is cooler than the air passing above, so instead of destabilizing the air to allow lake effect development, it does the exact opposite, stabilizing the air over Ontario and the Finger Lakes and limiting the formation of clouds over downstream shorelines.
The rain should stay well to the south of Ithaca as the storm strengthens and slowly but steadily heads eastward, over the open waters of the Atlantic. Some of rainfall amounts from D.C. and through South Jersey will exceed 5 inches, with isolated locations of 6″+ by the time the system has fully moved on. For comparison’s sake, Ithaca’s rainy July has totaled 6.57″ at the NRCC/Cornell Game Farm Road weather station. If all that comes in a 24-hour or 36-hour span, flooding becomes a high risk possibility. As if this area wasn’t aware of that.
Looking ahead, this rare stroke of pleasant weather should continue into the early part of next week. The jet stream aloft is holding firm in a wave pattern that creates a ridge of hot air over the Western continental U.S. (WCONUS), and a trough that lets cooler air flow down from northern climes and over the Eastern U.S. (ECONUS). This means that any heatwaves are unlikely for the next several days, and temperatures should be around normal, low 80s for highs and low 60s overnight. Later in the week, it’s looking like there may be a shortwave trough embedded in the larger upper-level weather pattern, in attendance with a modest near-surface cold front that could trigger some showers and thunderstorms later in the week.
Overall, we’re looking at quiet, seasonable and dry – perfect opportunity to make some summer memories in this otherwise waterlogged season.