A warm and mostly dry Halloween but then wildness could happen
Showers around the area this morning are courtesy of a warm front that is currently draped west to east across central Virginia.
Dewpoints north of this front are mostly in the 40s while south of the front they climb into the 50s (UMW weather station dewpoint is currently 48). Earlier this week I was concerned with the possibility of cold air damming suppressing this front south of Fredericksburg but such is not to be.
Later today this boundary will climb north of our area and usher in southerly winds and warmer temperatures. In fact, although today’s high will “only” reach the mid-60s tomorrow – Halloween – the thermometer will soar above 70 degrees!
Now, to address the burning question of parents and kids everywhere: will it rain during trick-or-treating time tomorrow? The short answer is no. The approaching cold front and its accompanying rain and possible wild weather (more on that in a moment) will hold off until later Thursday night as shown in this Weather Prediction Center forecast graphic for 8 p.m. tomorrow:
The green areas indicate areas of showers and steadier rain, and you can see that per this graphic Fredericksburg is still dry. Having said that I would still bring along an umbrella during trick-or-treating, but then I’m a weather geek who wants to be prepared for all contingencies.
Now, more on the previously mentioned potential wild weather. The surface low – red “L” – shown near Chicago in the above graphic is forecast to “bomb out” by Friday morning as it pushes north and east.
That is a term normally used for nor’easters that quickly intensify off the Atlantic coast, but this time it will happen over the continental U.S. The result will be a strengthening of the wind field around the low center and there could be potential impacts for Fredericksburg as the cold front approaches. The winds at the 850 mb level – about 5000 feet up – will be well over 60 knots Friday morning, which means that any convective cell building upward will reach into this wind field. The rainfall from such cells (can’t call them thunderstorms because there won’t likely be any lightning) could then drag down these winds to the surface.
The results would be very heavy rainfall early Friday accompanied by strong wind gusts that could cause localized damage. Additionally the shear – change of wind direction and speed with height – will be favorable for rotating updrafts to occur so a brief tornado or two can’t be ruled out across Northern Virginia.
To be fair the Storm Prediction Center doesn’t have Fredericksburg under a risk for severe weather Friday, but that may change as the next couple of numerical model runs become available. Thus between 3 a.m. and early afternoon Friday you will want to monitor either a weather radio, media outlets, or your emergency alert apps in case things get wild.
Behind the front the temperatures will cool off and the weekend looks sunny and calm at this point. We just have to get past the spooks and goblins Thursday evening and some potentially wild weather early Friday first!