Storms pass Friday; record heat, ozone warning linger
Less than 24 hours after severe weather prompted a tornado watch and flood advisory in the Lehigh Valley, record-setting heat is expected to blanket the area on Saturday.
The roller coaster of conditions began Friday afternoon, when severe thunderstorms moved across the area, bringing torrential downpours, high winds and even some hail.
A tornado watch, issued for the Lehigh Valley and surrounding region around 11:30 a.m. Friday, was canceled at 4:30 p.m. while a flood advisory was in effect from 4 to 7 p.m.
Also Friday, the state Department of Environmental Protection declared a Code Orange Air Quality Action Day for ozone for Saturday in the following areas of Pennsylvania:
The Philadelphia area, which includes the counties of Bucks, Chester, Delaware, Montgomery, and Philadelphia.
The Lehigh Valley-Berks Area, which includes the counties of Berks, Lehigh, and Northampton.
The Susquehanna Valley Area, which includes the counties of Cumberland, Dauphin, Lancaster, Lebanon, and York.
The U.S. Environmental Protection Agency’s Air Quality Index provides standardized color codes for forecasting and reporting daily air quality. Orange represents unhealthy pollution levels for sensitive groups of people.
In its latest forecast discussion, Empire Weather, which provides localized forecasts for The Morning Call, said Saturday remains poised to “easily be our hottest day of the season so far.” High temperatures in the mid to upper 90s are expected, with heat index (or “feels like”) values in the upper 90s or around 100 degrees in most areas.
Temperatures will be high enough to be record-breaking in some areas, and a heat advisory has been issued for portions of the region on Saturday. This includes both the I-95 corridor and some areas outside the urban corridor, with high confidence in the heat index reaching triple digits.
“It does seem like splitting hairs a bit to leave out areas such as the Lehigh Valley or the remainder of northern New Jersey, but [we] have to give some deference to the established criteria. Regardless, it will certainly be hot everywhere,” meteorologist Jonathan O’Brien said in the forecast discussion.
The established criteria means a heat advisory is issued with an expected heat index of at least 105 degrees but less than 115 degrees for less than 3 hours per day, or nighttime lows above 80 degrees for 2 consecutive days.
The hot and humid air mass will stick around for Sunday, with thunderstorms expected to develop ahead of a cold front moving in Sunday afternoon or evening.
Forecasters say scattered to potentially widespread storms are possible, but the chance for stronger storms may be west of the Lehigh Valley area.
A much cooler pattern is expected next week, with daily highs in the 70s and dry weather expected through Wednesday.
If you’re making plans for Memorial Day weekend, forecaster say longterm guidance suggests rain chances should arrive later in the week and perhaps put a damper on outdoor activities.