We’ve been talking about this cut-off low since before I took my 3-day absence a week ago, so I’m quite ready to move on — and after 3 days of cool rainy days I’m sure most of you are too. Looks like we get to do that on Thursday, as it finally pushes northeastward away from us. The remaining residual effect may be some scattered afternoon showers and storms as highs push above 70, boiling up some of the moisture, plus any weak disturbances or boundaries that can rotate around the backside of the low. The Weather Prediction Center is showing very minimal amounts of rain for the next 24 hours. We likely get three consecutive days of highs in the 70s after six days in a row when it has failed to reach 70. A cold front pushes in Saturday, but it looks likes more like our typical spring cold front from the northwest, with a quick shot of showers and storms Friday night and/or Saturday rather than anything like the marathon rain we just experienced.
I’m going to go ahead and post this graphic — Tuesday morning’s projected lows on the 12Z GFS (courtesy Allan Huffman’s RaleighWx forecast models page) — even though it’s still a bit far out to get specific about this. The GFS has been consistent in showing lows dipping below freezing west of Roanoke and very near freezing to the east on Tuesday morning (and almost as cold on Monday morning). Behind this weekend’s cold front, high pressure may eventually settle right on top of us, which could lead to a clear, calm night or two in which radiational cooling will be maximized. The 32 on the graphic is very close to Roanoke’s position — a freezing temperature on May 14 would set a record for latest freeze if it occurred, the standing record being May 11, 1966 (nearly happened May 22, 2003, when it dropped to 33). A freeze occurred as late as June 11 in 1972 at Blacksburg, but the record low for May 14 is only 31, set in 1996. Next week will bring drier weather, so temperatures may shoot up from these cold morning lows well into the 60s and 70s in the afternoon. While it may not end up quite as cold as this model is showing, it’s important for us to keep this potential freeze/frost situation in mind because of its potential disruptive impact on gardening and agriculture throughout the region.