UPDATE 3:30 PM: The band of showers indicated by the models this morning is moving through the I-77 corridor now, approaching the New River Valley. It will likely cross the New River and Roanoke valleys between now and 6 p.m. with mostly light rain. The main rain band is still well west in Kentucky. Radar linked here. END UPDATE
UPDATE 9:20 AM: Some forecast guidance brings a band of showers through our region at mid-afternoon, moving eastward by trick-or-treat time, but close enough of a call to go for “maybe some showers” rather than “probably dry” for early evening. It’s not likely to be a washout — the heaviest rain is still not expected to arrive til near midnight or later — but keep an eye on radar and grab the umbrella if you’re planning to take kids around the neighborhood this evening. Also of note is the wind advisory from 4 p.m. to 7 a.m., mainly for 50 mph gusts above 2,500 feet in elevation. END UPDATE
Trick-or-treat time (I’m thinking roughly 5-8 p.m. Thursday evening) will probably stay dry for the Roanoke and New River valleys. There is a small chance of showers, greater the farther west you go. But it appears likely it will be midnight or after when the bulk of rain arrives. What will be quite noticeable if you remember bundling up for last year’s Halloween is the remarkably different temperatures. Halloween 2012 saw highs of 48 for Roanoke and 42 for Blacksburg — and these temperatures were warmer than those the previous couple of days, as we were in the cold backside rotation of Superstorm Sandy. Highs on Thursday will be similar to Wednesday’s 72 for Roanoke and 67 for Blacksburg, and won’t drop much during the early evening. Normal highs for the last day of October are in the low-mid 60s.
Early Friday looks to be wet and windy . It’s a very similar setup to what we saw Sept. 21 and Oct. 7, with a strong cold front pushing west to east into warm, moist air. The air will not be as juicy as it was with Tropical Storm Karen’s injection on Oct. 7, so we probably won’t see as many 1-2-inch rainfall amounts. Most amounts will likely be under an inch, with a few greater than an inch, as the showers with some rumbles zip through the area. There is a lot of strong wind and spin in the air layers above the surface, and some of the downdrafts with the showers and any storms that occur could bring some of these stronger winds to the surface for locally damaging wind gusts. However, the front is arriving at entirely the wrong time of day to maximize the instability that could lead to a more serious severe weather situation, as daytime heating in the pre-dawn and morning hours to produce instability will be almost nil over Southwest Virginia. The two aforementioned similar setups spawned strong downburst winds and a few storms rotating enough for tornado warnings to be issued EAST of the Blue Ridge, so this is something worth keeping an eye out for on Friday.
Behind the front, the weekend gets windy and colder — not quite as cold as this past one, with highs staying mid 40s-mid 50s and lows 20s to low 30s. A few snow showers may blow over from West Virginia, but this looks to stay mostly west of I-81 and in higher terrain, and not be as noticeable as last week’s dusting in some spots along the Blue Ridge south of Roanoke. Next week looks to have a similar flow to the past several days: A gradual warmup, a day or two of much-above-normal temperatures, and then a slamming cold front with more windy rain and colder temperatures behind it late next week or during the following weekend.