Just today I was looking into information for record cold summer days in the PNW. I had never known about the July 18, 1987 event, but records indicate that it was a pretty extreme anomaly. The largest cold anomalies hit the area just east of the Cascades between Madras and Susanville from the looks of it. Here are some daily high temps and anomalies:
Portland - 69ºF (-12ºF - certainly cool for summer, but not the most extreme the area has seen for sure. The cold snap did not hit NW Oregon nearly as hard, from the looks of it)
Madras - 55ºF (-32ºF)
Redmond - 55ºF (-32ºF)
Bend - 47ºF (-36ºF)
Wickiup Dam Station - 46ºF (-37ºF)
Chemult - 47ºF (-37ºF)
Crater Lake NP - 36ºF (-34ºF)
Klamath Falls - 53ºF (-32ºF)
Lava Beds National Monument - 45ºF (-41ºF)
Cedarville - 54ºF (-35ºF) recorded on 7/19 (no data exists for 7/18, but it likely would have been even colder)
Several places west of the Cascades were hit hard as well:
Sexton Summit - 45ºF (-31ºF)
Medford - 61ºF (-34ºF)
Ashland - 55ºF (-34ºF)
Yreka - 56ºF (-37ºF)
Does anyone have more information on this massive cold snap? Regional anomaly maps, anything? At most if not all of these stations, it is far lower than most of the other daily cold records for that month. Very interesting event.