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The tundra and tropics will clash dramatically over our heads Friday, bringing a windy, soggy transition between a recent quick burst of summerlike warmth and a coming surge of winterlike cold for Southwest and Southside Virginia.
Nicole, on the edge between a strong tropical storm and a hurricane on Wednesday afternoon, is headed for an early Thursday landfall along the east coast of Florida. After that, with high pressure that has blocked any previous northward move by Nicole slipping eastward, and a strong cold front pressing in from the west with the coldest air of the season so far, Nicole will get pulled northward over the inland Eastern U.S., zooming across or very near Virginia on Friday.
The result for Virginia is likely to be a widespread soaking rain of 1 to 4 inches over all but perhaps the southeast corner of the state, with locally heavier amounts, especially where easterly wind flow rotating north of the storm center moves up and over terrain such as the Blue Ridge and other western Virginia mountain ridges, enhancing lift.
Two weeks ago in this column, focusing on the 10th anniversary of Superstorm Sandy, we discussed tropical systems being captured by polar troughs and becoming notable extratropical systems with a reach of rain and wind far away from palm-lined coastlines. Nicole certainly fits in that category, though likely not remotely in the same league as 2012’s Sandy or 1954’s Hazel.
Nicole began earlier this week as a subtropical storm, a hybrid system showing some characteristics of a tropical system fed by warm ocean water and some characteristics of a “regular” baroclinic low-pressure system powered by contrasting air masses.
Nicole has since become more recognizably tropical as it has moved west over very warm Atlantic Ocean water, but it will not take long for it to become a post-tropical cyclone as it is grabbed by the deep southward dip in the jet stream and slug northward rapidly over land. Its wind field will broaden but weaken while its rain shield will become more elongated and less firmly attached to the storm’s circulation center.
Even hundreds of miles in front of Nicole’s center of circulation, thick moisture will be transported on easterly trajectory winds, lifted by the gradually rising land from the ocean to the mountains, then more sharply by the mountain ridges. Rain may begin as early as Thursday evening over parts of Southwest and Southside Virginia, with gradually increasing persistence and intensity into Friday.
Nicole’s speed and prior dryness over a large part of the commonwealth east of the Blue Ridge will likely quell the chance of widespread, major flooding, but there could be localized flooding where especially heavy rain bands move over the same area repeatedly.
The rain will be accompanied by some wind gusts, possibly exceeding 40 mph at times in a few spots. This doesn’t look likely to be a major problem for damage or widespread power outages, but some sporadic power outages, or trees blown over in rain-soaked ground, may occur.
Some areas east and northeast of the track of Nicole’s circulation center might have a risk of tornadoes, especially if there is enough instability from daytime warmth to combine with abundant moisture and strong winds shifting in direction with height, often called shear.
While more likely in the eastern Carolinas toward Hampton Roads, a tornado risk could edge into Central and Southside Virginia, even as far west as the Blue Ridge if Nicole’s track is somewhat farther west.
Something to keep an eye on Friday is whether or not the rain turns into squally bands with breaks in between rather than a solid shield, with sunshine possibly poking out at times. If the more broken, banded rain develops with drier spaces in between, the tornado risk would likely ramp up, both from increased instability in warmer, partially sun-cooked air and atmospheric spin that can develop along boundaries between moist and drier air.
It appears most of Southwest and Southside Virginia will have temperatures in the 50s to lower 60s as it rains Friday, usually not that conducive for storm updrafts that could potentially spin. But just a little sun with temperatures pushing near 70 could change the calculus.
Rain will end like a faucet shutting off – some models show one last heavy burst then totally done – Friday night or perhaps very early Saturday morning, which may dawn with sunshine in many locations.
By Saturday afternoon, the circulation center of a very post-tropical Nicole will be in general vicinity of Maine, racing north-northeast, its identity quickly being fused into a strong low-pressure system moving east from the Great Lakes that will have spun up a midweek Northern Plains blizzard.
The wraparound flow from the Great Lakes storm-Nicole merging low-pressure system will propel an Arctic cold front rapidly across Virginia from west to east early Saturday. While Saturday will be a bit blustery with temperatures mostly in the 40s and 50s across Southwest and Southside Virginia, the mercury will drop into the 20s and lower 30s by Sunday morning, and widespread 20s with some localized teens will greet us for the start of a new work week on Monday.
Some snow showers may blow through the mountains of West Virginia, possibly crossing into Virginia in a few locations near the western border, over the weekend in stiff northwest wind gusts.
With highs only making the 40s Sunday and Monday, the temperatures across our region will resemble normal daytime temperatures for mid-January. That will be an extreme contrast to this past Monday, when all-time record November warmth in the low to mid 80s in the Roanoke and Lynchburg areas and across Southside was more like June.
Rather than a gentle season of colored leaves sifting to the ground, autumn is more frequently a ferocious push and pull between air masses from the tundra and the tropics, and quite often a rapid back-and-forth shift between summer and winter seasons rather than a gradual cooling.
Stats of the week
Monday highs of 84 at Lynchburg and 83 at Roanoke were the warmest it’s ever been in the entire month of November (a new record at Lynchburg, tying one at Roanoke) and the warmest it has ever been so late in the fall season. This and some other regional warmth records were covered in a special weather update on Cardinal News posted late Monday and linked here.
Snowfall contest on hold
Because of the need to discuss the effects of Nicole and the approaching cold front in this week’s column, I am delaying the start of the first Cardinal Weather snowfall prediction contest one week. I will introduce the contest on Wednesday, Nov. 16, and take entries through Friday, Nov. 25.
With some cold temperatures ahead, we’ll be more in the mood for snow talk next week anyway. (See next section.)
Looking ahead
Generally the weather looks cold and dry most of next week. But there are a couple of systems moving through the upper-air wind flow that could, theoretically, trigger precipitation mid to late next week. Some forecast model runs have shown this, ranging in time from Tuesday to Friday, though many keep it dry or else push precipitation well south or east of our region.
It might be cold enough that, if any precipitation did develop next week, it might not be entirely liquid, especially in higher elevations north and west of Roanoke.
For now this an outlier chance that probably won’t come to fruition, but just keep it in the back of your mind in case you hear whispers or rumors about snow next week. I’ll be following the potential on my @KevinMyattWx Twitter handle, and will post something here on Cardinal News if there are any dramatic developments that would lead to something significant and wintry in a sizable chunk of our Southwest/Southside region.
Journalist Kevin Myatt has been writing about weather for 19 years. His weekly column is sponsored by Oakey’s, a family-run, locally-owned funeral home with locations throughout the Roanoke Valley.