ITHACA, N.Y. — It’s been no secret that we’ve been running a bit drier than we otherwise should be. Which is why the week of rain and thunderstorms ahead isn’t as terrible as it sounds. Though we wouldn’t stop you if you call it a miserable ball of mugginess.
We’re at about the warmest point of the year, climatologically speaking. The average low maxes out around 58 °F, and the average high at about 80 °F. July’s running a couple degrees above average according to the Northeast Regional Climate Center, but now over halfway through the year, we’re running modestly cooler than the 1981-2010 climatological average thanks to the unseasonable cold of March and April.
From a precipitation standpoint, we were running close or slightly above average for the year up until early June, and since then, it’s been pretty darn dry as a pronounced dome of hot, dry air squelched most frontal systems from penetrating into the region, leaving up with slim pickings from the convective pop-up showers and thunderstorms that could bubble up on the more unstable, muggier days. As of Saturday the normal was 19.79″ of precipitation year-to-date, and we had 17.13″, about 87% of normal – dry, but not enough to raise serious drought alarms. The airport picked up 0.18″ over the weekend, and the Game Farm Road weather station the climate center utilizes picked up a less generous 0.08″ Sunday morning.
We’ll see if we can make a bigger dent in our precipitation deficit this week, because the larger-scale weather pattern is certainly accommodating for a wet week ahead.
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The big drivers of this week’s weather will be a stacked and powerful low pressure area over the Ohio River Valley and Southeastern United States, and since it’s cut off from the jet stream (a.k.a. a cutoff low) it’s like an eddy in a creek, and will move very slowly. Meanwhile, a ridge of high pressure, the one that passed through last week, is now off the East Coast. That strong low’s counterclockwise circulation will tap into tropical moisture down around the Gulf of Mexico, and bring it up over the East Coast, its flow further enhanced by the clockwise flow of the high pressure area offshore. This will lead to a deep southerly flow of unstable, moisture-laden air, and with shortwave pulses of energy riding along the low and triggering showers and storms, it will be a very unsettled setup for the week ahead.
Interestingly, that low will draw down a lot of unseasonably cool air from Canada, but the cool air advection will be far enough so as to not really affect us – in fact, with the channeling of that warm, moist air northward will give us temperatures near to slightly above normal for the week ahead. With frequent bouts of rain and summery temperatures, it’ll certainly feel tropical at times.
Most of us are starting off with a muggy, wet, showery morning, and that pattern should continue throughout the day. For your Monday, bring an umbrella, as rounds of showers and thunderstorms are interspersed with cloudy and briefly dry periods. Highs will be in the low 80s, but with dewpoints in the low to mid 70s, it’ll feel a little warmer. A stiff southern breeze won’t do much to dry things out, and rainfall totals will likely be 0.25-0.5″, with more in places that experience heavy downpours.
One thing to be mindful is that it will be possible for showers and thunderstorms to “train”, repeated cells of heavy rain over one location in a short period of time, like cars of a train coming down a track. The high water content of the area means a lot of rain can fall in a short time, so flash flooding will be a concern.
For tonight, it’s a “sleep with the windows closed” kinda night. The high humidity means temperatures won’t fall park, with most of the county staying above 70 °F. Rainfall chances will diminish somewhat without the heat of the day to provide instability, but plan for some scattered showers if you’re out tonight.
Tuesday will be another wet, muggy day, as the southerly flow of unstable, moist air continues. A grey day will be broken up by periods of showers and embedded thunderstorms, with heavy downpours possible. Highs will be in the low 80s, with 1-2″ of rain likely, more in places where training storms develop. Tuesday night will be more of the same, cloudy with frequent showers and thunderstorms, downpours possible, and a low around 70 °F.
Wednesday may be the worst day because a pulse of energy will trigger widespread and heavy precipitation, and many areas will have already been thoroughly soaked, meaning no room for new rainfall and a higher risk of flooding. Keep an eye out for warnings and advisories. Highs will be around 80 °F.
After sunset Wednesday night, the humid air mass should have pushed east just enough to allow us to start drying out and clearing out. Wednesday night will be muggy and with some remnant showers early on, but the clouds should begin breaking up by morning. Lows will be in the upper 60s.
Thursday will be better, if still fairly muggy. Partly cloudy skies will prevail, with highs in the low 80s. Thursday night will be mostly cloudy with maybe an isolated shower or two, and lows in the mid 60s.
Friday will be unsettled as a cold front advances into the region. A surge of moist air ahead of it will feed the development of showers and thunderstorms, and highs will reach into the low 80s. Friday night should see some drying out as temperatures fall back into the upper 50s under mostly cloudy skies, and the weekend is looking seasonable and on the quiet side with partly cloudy skies and highs in the upper 70s. A new rainmaking event may arrive late in the weekend, however, so watch those Sunday plans.
Graphics courtesy of the NOAA Climate Prediction Center.
For the start of August, it’s looking wet. Thanks to the strong low pressure area firmly in place over the central part of the country, we’ll continue to see a flow of warm and very moist air into the Northeast. The influence of the cold air dragged down by the low vs. where the warm southerly flow is more dominant will result is near-normal temperatures overall. Meanwhile, those heading out to Kansas city can expect temperatures 20+ °F below normal, which sounds bad but is much more tolerable in July than it is in January.