Hey, folks!! Just a quick reminder: This is Zach Robinson, filling in for Kevin Myatt as he takes some well-deserved time off. After a winter/spring (was there a difference this year?) like we had, it is certainly a well-earned break. I will be filling in today through Wednesday, offering what insight I can about the weather and the fun it brings. Please feel free to comment and engage in active discussion! I look forward to it.
Now onto the weather: If you are not familiar with Southwest Virginia weather, you may be a little curious as to what exactly my blog title is referring to. If you are a bit more familiar, you should know all too well the consequences of an onshore flow. At its most basic level, when the surface winds blow from the East, they bring moisture off the Atlantic and bank it up against the mountains. This is known also as a “wedge” or a “dam.” The pattern is frequent enough to be a significant player, but rare enough for us to take note when it sets up.
The Blue Ridge plays a key role in the setup, allowing for the air at the surface to get trapped along and east of the Appalachians. The high ridges act as a dam for the cool moist air. The result is what you are seeing now (coupled with a shortwave trough digging through): Days of fog/drizzle and on-again, off-again rain. This pattern is similar to the primary pattern in the Pacific Northwest. The prevailing westerly flow brings in Pacific moisture, dams it up against The Cascades, and causes the wet weather that region is known for (hence, the blog title).
This particular onshore episode looks to be fairly prevalent for several days. Growing up right along the Parkway, I’ve seen this type of pattern hold for five to seven days. I don’t think this event will be that strong, but foggy/drizzly mornings are almost certain Monday and Tuesday and possible beyond that. As daytime heating occurs, some of the low clouds will begin to burn off, so don’t be surprised to see some sun as early as late this afternoon and late Tuesday. Winds should also turn more south than east after noon today, so the wedge will begin to weaken. Depending on the timing of any sun, temps could spike into the upper 60s/low 70s. Basically the further away from the Parkway you get, the better chance you have of seeing some warmer temps. West of Grayson, Western Wythe, and Bland Counties, down into Far SWVA (Michael in Washington County, I’m talking to you) should reach the mid 70s today and close to 80 on Tuesday (pic on left is Tuesday high temps – notice the 69 in Roanoke but 80 in Charleston).
I think the majority of our rain is done. Showers/drizzle will linger, but the heavier stuff is for the most part done (NAM projected rainfall through Monday Evening). Storms while not likely need to be watched, especially on the western fringes of the wedge, as instability here tends to be higher, and air is moist.
Let me know what conditions y’all are experiencing, and please comment and engage in discussion! Enjoy your Monday!