The month of May was a relatively tranquil that featured abnormally dry conditions and several unseasonably cool stretches for many Northeast climate sites. Consequently, as rainfall deficits increased through the month, many areas finished well below average precipitation wise. This resulted in areas of drought across parts of the Mid-Atlantic and Pennsylvania. Furthermore, the month completely flipped the script from April in that severe weather was essentially nonexistent across the entire Northeast. In fact, most National Weather Service offices in the area did not issue a single severe warning for the entire month. Additionally, despite the ample sunshine that reigned supreme, you may have noticed bouts of hazy sunrises and sunsets through the moth which were due to smoke in the atmosphere originating from numerous wildfires in western Canada.
If anyone has noticed, the severe weather season has been slow to evolve across the region. Stats do not lie as our office did not issue a single Severe Thunderstorm Warning in May (last May this occurred was 1987). #MDwx #VAwx #DCwx #WVwx pic.twitter.com/asl9qEMCGw
— NWS Baltimore-Washington (@NWS_BaltWash) June 1, 2023
Graphic from NWS Baltimore-Washington highlighting the anomalous lack of any severe weather throughout May 2023.
May started out rather cool with temperatures generally running 5-10 degrees below average, and kicked off in the same unsettled fashion that April closed out on as an upper level low spun overhead. This kept plenty of rain showers around throughout the entire Northeast during the first week of the month. Then, following a few waves of light precipitation on the 8th and 9th across the Mid-Atlantic, high pressure built back in across the Northeast and largely dominated the weather pattern into mid-month which allowed for a prolonged stretch of drier weather for many as temperatures also trended much warmer. In fact, many daily record high temperatures in the mid-80s to around 90 degrees were set on the 12th across Northeast climate sites. After some showers and storms on the 13th across the Mid-Atlantic, the 16th brought the only notable bout of severe weather and flooding to portions of Virginia as a series of disturbances and frontal systems passed through. Overall, the majority of the severe reports were confined to the Kentucky and Tennessee River Valley regions, though a few strong storms also passed through Richmond during the evening which led to a few instances of downed trees / powerlines and a quarter sized hail report. Perhaps most notable reports from these storms were the repeated and torrential downpours that occurred across the Greater Richmond area with locally 3-4"+ of rain falling along and just south of the James River in a short while! This led to flash flooding in the area.
The passage of this cold front ushered in an unseasonably chilly airmass as we progressed into the latter half of the month. Temperatures generally ran 2-5 degrees below normal into the end of the month. Despite the mild daytime temperatures, the cooler air was especially felt at night and even led to some late season frosts and freezes across parts of New England and NJ / PA. Some daily record lows set the morning of the 18th included Trenton, NJ which had a low of 37 degrees, Allentown, PA (32 degrees), Providence, RI (33 degrees), and Mount Pocono, PA where temperatures dipped to 26 degrees, brrr !! And while the second half of the month still featured plenty of dry time and quieter stretches, there were some sporadic systems that impacted the Northeast. Most prominent was a coastal low on the 20th that led to a good soaking, but mainly across New England where swaths of 2-3" of rain fell. A cutoff low then impacted portions of the southern Mid-Atlantic during the last few days of the month which yielded a rather soggy close to May for parts of southern MD and VA.
Check out the very red sun rising over New York City. This is due to all of the wildfire smoke traveling above us from wildfires in Canada. How is the sun looking in your area? @EarthCam #NYwx #CTwx #NJwx pic.twitter.com/FjCLCIstM2
— NWS New York NY (@NWSNewYorkNY) May 22, 2023
Tweet from NWS New York of a hazy sunrise over Manhattan on May 22nd caused by wildfire smoke originating from Canada.
Overall, temperatures were variable, but highs and lows generally ran 1-3 degrees below average throug the month owing to the rather cool start and end to May. As for precipitation, was an abnormally dry month for most of the Northeast climate sites (barring some spotty exceptions to this such as Richmond). Consequently, many areas finished 1.5-3" below their normal monthly precip. As a testament to this dry weather, Philadelphia recorded a mere 0.24" of rain for the entire month !! Ultimately, this led to some areas of drought by the end of May, most notable across portions of eastern PA and MD which even until now, reside in a moderate drought.
