ITHACA, N.Y. — This weekend has been a less humid, sunny and seasonably pleasant departure from the storms and humidity that we’ve experiences for much of the past six weeks, but all good things must come to an end. A strengthening low pressure system will move across the and Northeast, bringing rain and muggy conditions for the first half of the week, with sunnier and seasonably warm temps as we head into next weekend.

Your Weekly Weather

It’s been a fairly pleasant, meteorologically carefree Sunday ash igh pressure moved eastward. However, we are starting to see cirrus clouds cover build in from the west as a low pressure storm system works its way up the Ohio River Valley and towards the Eastern Great Lakes.

This system will usher in ample moist, warm air from the southwest, which will not only increase the humidity for the next few days, but providing plenty of moisture for the destabilized atmosphere overhead, allowing for some fairly significant rainfall amounts and creating the risk for some flash flooding Monday and Tuesday. There will also be an elevated risk for severe thunderstorms with damaging winds and hail. Do take care to put anything lightweight outdoor objects into storage tonight, and make sure grass and lawn clippings aren’t clogging your storm drains. If you have outdoor plans tomorrow PM or Tuesday, you should probably move them indoors if possible.

For the rest of your Sunday, expect increasing clouds as we head towards sunset, but it will stay for dry for now, with temperatures receding from the mid 80s to the mid 70s by sundown. Sunday night will see rain move, especially after midnight as the warm frontal boundary of the low arcs into Tompkins County, with bands of showers and storms pinwheeling counterclockwise around the low over Michigan. Expect skies to become overcast with showers and thunderstorms in the early AM hours, and lows in the upper 60s. New rainfall amounts will be 0.10-0.25″ with higher amounts under stronger embedded storm cells.

Monday will experience a drier period during the late morning hours between bands of precipitation, but the next band will rotate in during the afternoon and evening, and the storms will be enhanced by daytime heating. In the warm sector of the low as it moves into Canada, it will be tropically muggy, with highs in the low 80s and dewpoints in the lower 70s. New rainfall amounts will be 0.10-0.25″ with higher localized amounts. Monday night will host heavier periods of rain before midnight, enhanced by the very moist atmosphere. Lows will be in the mid 60s with 0.25-0.50″ of rain expected.

The cold frontal boundary of the low will pass through Tuesday, Another 0.25-0.50″ of rain is likely during the day as the front pushes through, with overcast skies and highs in the upper 70s. Tuesday night will see rain taper off and decreasing clouds behind the low, with low temperatures around 60.

High pressure builds in from the Southern Appalachians Wednesday. Skies will be mostly sunny with highs in the low 80s. It will be rather humid, but the palpable effects will be tempered by the strong northwest breeze. Wednesday night will be mostly clear with lows around 60.

Another low pressure storm system, this one to the northwest over Canada, will begin to press towards Ithaca and Tompkins County later Thursday. This will be a quick moving system with less moisture available, so it’s impacts will be limited. It will be increasingly cloudy and rather muggy, with late afternoon/evening pop-up shower and storms. Highs will be in the low 80s. Thursday night will see the showers come to an end after midnight, with mostly cloudy skies and lows around 60.

High pressure from Canada will take the reins for Friday, though a shortwave low skirting by to its south will create an unsettled weekend for Upstate. Friday will be mostly sunny with highs in the low 80s, and Friday night will be partly cloudy with lows in the lower 60s. Saturday will see mostly cloudy skies, humid conditions with some scattered showers, and highs in the mid 80s. Sunday will be much the same with some scattered showers and highs in the low 80s.

Graphics courtesy of the NOAA Climate Prediction Center.

Extended Outlook

Looking into mid-August, the large-scale weather pattern calls for a trough in the jet stream over the Central U.S. and Upper Midwest, which will create a conveyor belt of instability and moisture into the Northeast. This will also channel some unseasonable heat into the area, though the vast majority will remain bottled up over the Southern United States. Houston’s looking at low 100s with lows around 80, and there isn’t any way you can convince me that’s going to be a dry heat. Anyway, it’s looking like an unseasonably hot and humid pattern for the Finger Lakes and Southern Tier as the kiddies make their plans to come back to Ithaca for the start of their fall semesters.

Brian Crandall reports on housing and development for the Ithaca Voice. He can be reached at bcrandall@ithacavoice.org.