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This year has raced out of the starting blocks to an unprecedented warm start at many Southwest and Southside Virginia locations.
Through April 15, the year 2023 to date has the highest average temperature on record at Roanoke (49.9 degrees F), Danville (49.8) and Lynchburg (49.1), and it’s essentially a dead heat (pardon the pun) at Blacksburg (44.2), only a tenth of a degree behind leading 1949. (See some averages for other locations scattered around the region in the second section of this column.)
This should not be too surprising given it was the warmest February on record at all four locations, anywhere from fourth to 10th warmest January at each, March was 1 to 4 degrees above normal at each site despite a significant mid-month cold spell, and the first half of April has started 3 to 6 degrees above normal.
The next couple days of April will continue to show that warmth, with highs well into the 80s in most of the region, possibly scraping 90 at a spot or two, but then a weekend cold front brings a sharp turnaround into next week.
After some Saturday afternoon and evening rain and storms, northwest winds behind that front will bring in cold air from the northern latitudes, though tempered considerably by the lateness of the season and the modifying warmth of longer days and higher sun angle.
By Sunday morning, it will be cold enough with stiff northwest winds blowing up and over the Appalachians that upslope snow showers may develop, mostly in higher elevations west of Interstate 77 and near the West Virginia state line. Don’t rule out the possibility of seeing a few flakes into the New River Valley or the higher elevations along the Blue Ridge.
Windy and chilly 30s and 40s will be common across the entire region on Sunday morning, and even with emerging sunshine, most places won’t make it to 60, and some to the west won’t sniff 50.
As the cold air settles in early next week, freezing temperatures and frost will become a concern across much of the region, especially if one night can turn clear with calm wind.
Although temperatures will modify to something milder next week (most days will be in 60s even with cold mornings), there are some signs the cooler air relative to seasonal norms will recharge a time or two more later in the month, perhaps into early May.
This is happening because – as every snow lover could have cynically guessed was going to happen two months ago – an almost idealized pattern for mid-winter prolonged cold and snow potential is setting up too late on the calendar to deliver all that.
Arctic and North Atlantic oscillations (AO and NAO) are swinging strongly negative, which means high pressure blocking at the northern latitudes is forcing colder air south into the eastern U.S. Meanwhile, high pressure will build across the West, the positive phase of the Pacific-North America pattern (PNA).
It’s been hard to get these three things aligned in prior months, as just when a couple of them would set up strongly, the third would give way. Late December, early February and mid-March came the closest.
Snow showers in the mountains are not terribly unusual behind cold fronts in April, but given the mild winter we’ve just had and several recent warm days, including a couple more ahead, the chilly winds and any icy bits of white floating through the air will seem all the more out of place.
Seeing patterns like this developing may at least be something of a hint that some of the default setups of the prior winter are relenting as the atmospheric furniture begins being rearranged. More on that a couple of sections down.
Warm start to 2023
Beyond the National Weather Service’s designated major climate stations mentioned earlier, a quick look at a few other stations scattered around the region with at least 50 years of records shows the Jan. 1-April 15 period also had the highest average temperature on record at Abingdon (51.0 degrees), Appomattox (47.5), and the John H. Kerr Dam (50.6); fourth warmest at Hot Springs (41.6 degrees); fourth warmest at Wytheville (44.1); fifth warmest at Martinsville (46.8 degrees); and sixth warmest at Lexington (45.0).
While it hasn’t been the single warmest start to the year at every individual location, it ranks among the top few just about everywhere in our region.
That would go along with the National Climatic Data Center finding that the January to March period was the warmest first quarter on record going back 129 years for Virginia as a whole, along with every state to our south extending to Florida.
It is important to realize that this past winter was not a mild or snowless one nationally just because it was that way in our backyard. Large sections of the West and some of the northern tier of the nation experienced epic snowfall and frequent cold temperatures – still continuing in many of those areas, even following previous days of summerlike warmth in Minnesota.
The warm weather in the East was partially balanced by colder weather out West, with eight states having January to March periods that ranked among the coldest third on record – although none of those states had a first quarter among the 10 coldest on record. The intensity of cold in the West wasn’t quite the same level as that for warmth in the East.
But it’s also important to note that this wasn’t the only recent winter and early spring that has trended strongly toward the warm end of historic records in our region.
For Roanoke, the four warmest Jan. 1-April 15 periods have occurred in barely more than a decade, since 2012, for a record database that goes back to 1912. For Lynchburg, five of the 10 warmest such periods have happened during that same short timeframe for a record database that goes back to 1893.
And that raises the question about how much of what is being seen with recent mild winters is more systemic, large scale and long term rather than just seasonal atmospheric happenstance.
A warming global climate does not mean that every single year or season at a local or regional level will be progressively warmer than the year before. Various factors in shifting atmospheric patterns have always and will continue to cause average temperatures to bounce up and down quite a bit year to year, and between like seasons in consecutive years. (There is a slight bounce, rather than a purely linear climb, even on the global level.)
What it does mean is that, looking over the span of multiple decades, warmer seasons and years are expected to happen more frequently in most regions as global temperatures climb, while colder periods are generally expected to be not quite as cold, or not as cold for as long, as many have been in the past. This would tend to raise average temperatures in most regions and localities over time even with some dramatic variations in shorter time scales.
It would take a far more rigorous analysis than what can be conducted here to determine how much of the early 2023 warmth in our region is connected to long-term, global climate vs. transient atmospheric patterns specific to this season.
But these two things can be true at the same time: (1) A recent tendency for more frequent winter to early spring periods ranking near the top of historical averages is at least consistent with what would be expected with a warming global climate translated to a regional level. (2) A persistent southeast high-pressure ridge during this particular winter, often associated with La Niña patterns, can be more readily fingered as the likely most direct cause of the extreme warmth in the first quarter plus 15 days of 2023.
And that gets us to what might happen now that La Niña is behind us and El Niño has a strong chance of developing.
El Niño watch issued
The Climate Prediction Center has issued an El Niño Watch, signaling the likelihood that three years of La Niña conditions in the equatorial Pacific Ocean, or a stripe of cooler than normal sea surface temperatures, will soon be replaced by El Niño. or warmer than normal sea surface temperatures, by summer or fall and headed into next winter.
You may have already seen some discussion that a developing El Niño could mean that 2023, or possibly 2024, ends up as the new warmest year on record globally.
That’s because El Niño adds considerable warmth into the overall global circulation pattern, and global average temperatures in those years tend to be higher than in neutral or La Niña years.
The current warmest year on record globally is 2016, 1.9 degrees Fahrenheit above the 20th century average. That was the year of a strong El Niño. Every year since ranks second through fourth and sixth through eighth (2015 is fifth, 2014 is ninth; you don’t get to a non-21st century year until 16th-ranked 1998 – an El Niño year that was warmest on record up to its time.)
With recent years ranking very close to the top even during cooler-water La Niña, there is considerable expectation among climatologists that this expected El Niño may push the global temperature to new heights.
But the picture is murkier when we boil it down to what happens specifically in Southwest and Southside Virginia during an El Niño.
Snow lovers may find hope that four of our region’s last five snowstorms that dumped a foot or more on sizeable portions of Cardinal News territory happened in El Niño winters, in January 1998 (mostly west of I-81), December 2009, January 2016 and December 2018. But the 1997-98 and 2015-16 winters were mostly warm and wet on the whole (Appomattox County tornado in February 2016) and the 2018-19 winter didn’t really do much wintry after the early December snowstorm.
The 2009-10 El Niño winter, however, was the dream season for snow fans in much of our region, nightmare for winter haters, with multiple 6-inch-plus snows that took a long time to melt. The 2002-03 El Niño winter was also consistently cold with frequent small to medium snows, the abundant rain and snow from fall to spring pulling us out of a lengthy drought period to start the 21st century. Going farther back, the 1977-78 El Niño winter was the coldest on record at many locations in our region.
El Niño effects for our region vary widely based on how warm the sea surface temperatures are in the Pacific Ocean, whether those sea surface temperatures are warmer more to the east or west, and the interplay with numerous other atmospheric oscillations.
Typically, a moist west to east flow develops across the southern tier of states during the cooler months with an El Niño-influenced pattern, which tilts late fall to early spring toward often (but not always) being wetter than normal when El Niño is present. There usually is no dominant southeast high-pressure ridge, so cold air masses have a better chance to slide down to meet the moisture — except that sometimes during a stronger El Niño, the warmth from the southern branch of the jet stream spreads out more widely and overwhelms cold-air pushes. So there can be a sort of “feast or famine” nature to snowfall in El Niño winters.
El Niño also often dampens the Atlantic hurricane season a little bit. That can mean less chance for inland downpours and tropical stickiness for us in the fall, but of course, it only takes one big storm on a certain track to wreck a coastal city or move inland and flood us.
At this point, we still have spring and summer to get through before El Niño becomes a bigger factor, if in fact it does develop. Lots of time left to speculate.
Hasan Shamim of Sterling won the Cardinal Weather snowfall prediction contest, the results of which were discussed in the last weather column. Originally, his first and last names were reversed. That has since been corrected, but also wanted to note that for the record this week. A $25 gift card is on its way to Northern Virginia for his victory.
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.