BETHLEHEM, Pa. — The Lehigh Valley is preparing for its first official heat wave of the year, with a stretch of 90-plus-degree temperatures expected.
The National Weather Service has issued a heat advisory in effect from 11 a.m. Thursday to 10 p.m. Friday, with heat index values up to 104 expected.
- The Lehigh Valley is preparing for its first official heat wave of the year
- A heat advisory is in effect from 11 a.m. Thursday to 10 p.m. Friday
- Heat index values above 100 degrees may be possible again Saturday
An excessive heat watch is in effect Friday for the urban corridor, where heat indices may reach or exceed 105 degrees.
Heat index values up to 100 degrees may be possible again Saturday, the advisory said.
The heat kicks off Wednesday
Strong July sunshine is expected Wednesday, with high temperatures forecast to be near 90 degrees at most locations.
We should experience a gradual increase in cloud cover overnight, according to the weather service, with low temperatures likely ranging from the upper 60s to mid 70s.
A buildup of dangerous heat and humidity is expected on Thursday, continuing into Friday, the latest weather service forecast discussion said.
With a persistent south to southwest breeze, dew points will rise into the low to mid 70s with the southerly flow and this will result in heat index values reaching the upper 90s to low 100s in the afternoon.
Records in jeopardy
Near-record breaking heat is forecast for Thursday night through Friday night, forecasters warn, with Friday likely to be the hottest day of the week and potentially of the year.
Forecasters have made no changes to the forecast or messaging, expecting widespread high temperatures in the mid-90s. With dew points continuing in the low- to mid-70s, heat index values of up to 100 to 105 degrees are expected.
Records for climate sites (data from the National Weather Service) are:
Site | July 28 Warmest Low Record/Year | July 29 Warmest High Record/Year | July 30 Warmest High Record/Year |
Severe weather possible
The Storm Prediction Center has highlighted most of the area in a slight risk (2 out of 5) for severe weather for Thursday through Thursday evening.
1:03am CDT #SPC Day2 Outlook Slight Risk: FOR THE NORTHEAST INTO PARTS OF THE MID-ATLANTIC STATES https://t.co/Y1WiOd8TQQ pic.twitter.com/3UFaftTPVv
— NWS Storm Prediction Center (@NWSSPC) July 26, 2023
There is potential for any storms to bring damaging winds and large hail, though uncertainty exists regarding how extensive any coverage will be, the NWS forecast discussion said.
As far as timing, the SPC said a band of storms is expected to consolidate by the late afternoon/evening and push east off the coast by mid-evening.
