February 29, 2020

The Rare Meteorological Phenomenon "Snow Firehose" Is Neither Rare Nor A Phenomenon

Poor CBS News. The more I write about their weather coverage, the more it just feels like bullying. The radar started spinning off the pedestal in 2014. First, there was CBS's infamous "sideways tornado," which was not a tornado. A year later, CBS discovered a 'massive' tornado that was perhaps massive to several ant colonies and no one else. They responded to criticism of that coverage by issuing a correction that the storm had the potential to turn into a massive tornado, just like I have the potential to turn into Andrew Walker.

A few months later, CBS reported on a "Monster 'Freak' Storm" (wrong) that brought 230 MPH winds to Iceland (wronger). Two years after that, CBS reported Hurricane Nate "touched down" (wronger-er) on the northern Gulf Coast, bringing flooding to the Mississippi River community of Mobile (wrongest).

And then there's Maude!

Today we learned about a "rare meteorological phenomenon" known as a "snow firehose."

Who knew?

I've used plenty of cheeky hyperbole in my oddball blogging adventures. I peppered The Vane with dorky phrases like "wind bagel," "dangerous sky onion," and "Polar Flortex" to describe annular hurricanes, large hail, and a storm off Florida, respectively. It was meant to be hokey!

But CBS News, bless its heart, isn't in on the joke. We've graduated from sideways tornadoes to a snow firehose. Granted, I'll give the reporter the benefit of the doubt that somewhere in his reporting, a meteorologist may have analogized the thick, intense band of lake effect snow plastering northern New York as akin to a firehose.

Nowhere, though, is it ever an actual term used for actual events. Go ahead. Google it. If you filter out February 27-29, it's nearly impossible to find any mention of "snow firehose" that doesn't loop back to CBS's report on Friday.
The band of lake effect snow over Watertown, New York, on February 28, 2020. (Gibson Ridge)

Lake effect snow can occur when wind blows cold air over relatively warm waters. The warmth of the water warms up the air immediately above the surface of the lake. This warm air rises through the colder air above through convection, creating bands of snow that blow ashore. The resulting lake effect snow can develop as thin bands that produce a broad swath of accumulation (common on Lake Michigan), or it can form into a solid band that traverses the length of the lake and plasters a small area with a lot of snow, which is common on Lakes Erie and Ontario.

The latter process, called single-band lake effect snow, is what we've seen in northern New York for the last couple of days. A long, cold fetch across an ice-free Lake Ontario allowed an intense band of snow to ride up the Tug Hill Plateau and drop several feet of snow. In fact, the orientation of the winds allowed for several bands of snow to set up across Lakes Superior, Huron, and Ontario, giving the appearance on radar that it was a single band of snow stretching from one body of water to the next.

Single-band lake effect snow is relatively common and it's often intense, dropping several inches of snow an hour and occasionally producing lightning. This was a particularly hefty band that dropped four feet of snow in some higher elevations. There's a reason northern New York isn't exactly known for sunbathing in the wintertime.

It's okay to refer to this as a "snow firehose" as an analogy to explain it, but it's not a term anyone uses seriously as the report reports. News organizations have got to be more precise and accurate in their reporting of events like lake effect snow. Meteorology is a science, after all, and goodness knows we don't need another ripe-for-TV buzzword at the expense of the facts.

[Screenshot: CBS News]

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February 21, 2020

Nothing Happened Today

There was no weather.

Weather is possible again tomorrow.

[Satellite Image of Nothing: NOAA]

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February 20, 2020

North Carolina Could See A Li'l Thump Of Snow On Thursday

A fast-moving storm will develop over the southeastern United States on Thursday, potentially dropping a couple of inches of snow across the eastern half of North Carolina and the Virginia Tidewater. There's still some uncertainty around the storm right now—oh, little things like "how much snow will fall?"—but it's likely that the season's first (and only?) snowfall is on the way.

This isn't going to be a mammoth storm, but it will drop a shovelable snow in areas that can go a few winters without seeing much snow at all.

Right now, most meteorologists in the state expect at least an inch of snow across most of North Carolina. The latest forecast from local National Weather Service offices shows the thinking. Forecasters don't expect the system to be a bangin' rock fest like the short-range models keep trying to spit out, though there's a 10 percent chance that the "high-end" totals grow problematic east of Raleigh. The position and movement of heavy bands of snow within the storm leave open the possibility that some towns in eastern North Carolina could see half a foot of snow or more.

Snow should begin in western North Carolina on Thursday morning, spreading east toward the coast through the afternoon hours. The evening rush hour, should there be one, looks messy for just about every part of N.C. and southeastern Virginia.

The storm will clear out to the Atlantic by Friday morning, leaving behind an icy mess that will make it tough to get around on untreated surfaces. Above-freezing temperatures and sunny skies should take care of most roads by Friday afternoon.

This is one of those uncomfortable situations where the final forecast will come down to the wire in a few spots. Some towns will see more snow than they were expecting, while others wind up with little to no snow at all. That's the nature of southern snowstorms.

Charlotte meteorologist Brad Panovich laid it out in plain terms on Wednesday. These flaky southern snowstorms rely entirely on minuscule changes in temperature and moisture throughout the atmosphere. If it's even just a little bit warmer than predicted, snow will change to sleet or freezing rain and the entire forecast is blown to smithereens. Dry air can chomp away at snow like a snack. If the storm moves five or ten miles farther north or south than expected, that also nudges the heaviest bands of snow right along with it.

Forecasters had a tough time getting a handle on this storm until Wednesday morning. Short-range regional models like the NAM, which is great for forecasting thunderstorms but not so much when it comes to snow, have been incredibly bullish on the threat for snow across N.C., consistently painting a swath of double-digit snowfall totals along and east of I-95. Global models like the GFS and European have been less impressed by the storm, lurching back and forth between a few inches and hardly a flurry.

Like many of its neighbors, North Carolina hasn't seen much of a winter so far this winter. It's as if the end of October started skipping and nobody bothered to jiggle the CD player. The coldest we've gotten in Greensboro this season is 20°F—potentially setting us up for the first winter on record without a low in the teens—and most of North Carolina has gotten this far without any measurable snow to speak of, another unusual feat for areas sees at least a dusting or two by the middle of February.

While winter storms aren't out of the question in the southeast in March, encroaching warmth from the south and the increasing angle of the sun makes it more difficult for wintry precipitation to fall with each passing day.

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February 6, 2020

A Drenching Storm Could Bring Severe Storms, Flash Flooding To The Southeast Thursday

An unusually juicy storm for early February will drench the southeastern United States on Thursday, carrying a moderate risk for flash flooding and an enhanced risk for severe thunderstorms. The sprawling system is so large that it'll produce significant snows in northern New England at the same time it's bringing heavy rain to the southeast.

Flash Flooding

Precipitable water on Thursday afternoon, per the GFS model (Tropical Tidbits)

Widespread flash flooding is a distinct possibility along and east of the Appalachian Mountains on Thursday as a surge of moisture moves north from the tropics.

The above model image shows precipitable water (PWAT) on Thursday afternoon. PWAT is a measure of how much moisture is available in the atmosphere. If the PWAT value for Podunk is 1.00", it means that 1.00" of rain would fall if you were to wring out all the moisture in the atmosphere over that particular spot.

Higher PWAT values indicate a greater potential for heavy, flooding rains. Models indicate a potential PWAT of 1.50" (roughly 40 mm) or more across the interior southeast on Thursday, which is extremely unusual this far north at the beginning of February.

The heaviest rain and highest totals are likely in thunderstorms and along the eastern side of the Appalachians where orographic lift enhances the rainfall rates.

A moderate risk for flash flooding exists along and east of the Appalachians in Georgia, South Carolina, and North Carolina, according to the Weather Prediction Center's update on Wednesday night. It won't take much heavy rain to send waterways over their banks and overwhelm man-made drainage systems in populated areas.

The flooding threat here is similar to what we'd see from the remnants of a landfalling tropical cyclone. Thursday's weather is more common of the warm season than February 6—but it's also felt more like April for much of the winter, so why not?

Some areas could see more than 5.00" of rain as a result of the heavy and persistent rain. The Weather Prediction Center's latest rainfall forecast paints a widespread area of 4"+ of rain across the Southeast, with even higher totals possible along the eastern side of the Appalachians and where thunderstorms enhance rainfall rates.

Severe Thunderstorms

It's not just flooding that we have to worry about. The influx of warm, moist air, combined with extremely strong winds not far above the surface, will allow lines of strong or severe thunderstorms to develop and move across the southeast on Thursday.

Thunderstorms that fire up won't have to work hard to produce damaging winds, isolated tornadoes, and occasional instances of large hail.

An enhanced risk for severe weather is in effect on Thursday across much of the southeast from Florida's Big Bend through central North Carolina, including the cities of Tallahassee, Columbia, and Charlotte. Slight risk and marginal risk areas radiate out from there, covering just about everyone between Mobile and the Virginia suburbs of D.C.

It's likely that a portion of the severe weather will occur after dark, ratcheting up the threat as people tune out for the evening and go to sleep.

The best way to prepare for this kind of severe weather and flooding threat is to make sure the wireless emergency alerts are activated on your smartphone. I know it's repetitive to bring it up in every one of these posts, but lots of folks shut off the alerts after one ill-timed interruption. The push alerts are proven lifesavers, and it's possible for tornado warnings to catch you off-guard at home (it's even happened to me!) and it's even more common to unknowingly drive into an area experiencing flash flooding.


It's worth mentioning that the northern fringe of this storm will bring significant snows to northern New England. This storm is large enough that it'll produce significant winter weather around the U.S./Canadian border at the same time it's drenching the southeast with flooding rains and severe thunderstorms.

This will be a long-duration event for northern parts of New York, Vermont, New Hampshire, and Maine, with some areas seeing a foot-and-a-half of snow by this weekend. The National Weather Service's latest snowfall forecast is shown above. Some areas to the south of the snow could see a glaze of ice from freezing rain that could lead to slick surfaces and spotty power outages. 

The storm left a decent blanket of snow across the southern Plains in its infancy on Tuesday night. This was the first significant winter storm to hit the area in a while. Oklahoma City measured its first inch of snow since January 19 of last year, and this was the first measurable snow in Midland, Texas, since December 8, 2016.

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February 3, 2020

The Weather Should Mostly Cooperate For Monday's Cumbersome Iowa Caucus

Weather shouldn't hinder Iowans heading out to caucus on Monday night in the first contest of the 2020 presidential election. The lengthy and rigid nature of caucuses makes this type of voting more susceptible to dampened turnout than traditional elections. Most of Iowa can expect a typical February evening with subfreezing temperatures and a breeze that makes it feel even colder. Freezing drizzle might make for some slick roads in the southwestern part of the state.

Iowa's Democrats and Republicans will begin their caucuses at 7:00 PM CST. Temperatures will struggle to climb much above the 30s across most of Iowa during the day on Monday, allowing temperatures to quickly fall once the sun sets. The National Weather Service expects most of Iowa (except the southeastern counties) to fall below freezing by the start of the caucuses.

Patchy drizzle and freezing drizzle is possible across the southern half of Iowa during the evening hours, especially east of Omaha, which could make roads and sidewalks slippery in some places. Any icing issues could deter voters from heading out to caucus, but it's unlikely that the drizzle will become a big deal. Overall, it should just be cold and windy for the election's first voters.

Caucuses are a lengthy process compared to traditional elections. Rather than casting ballots, voters arrive at their voting precincts at a set time and physically gather in different sections of the room in support of their preferred candidate. Officials conduct a headcount for each candidate's section and tabulate the results. In the Democratic contest, supporters of candidates who don't win enough support have the opportunity to caucus for a different candidate or persuade others to come to their side before the second count. The final tally is used to calculate delegates at the state and national level.

Monday night's bearable conditions across Iowa should remove the one natural barrier to this otherwise obstacle-laden process. The involved nature of caucuses makes the event last about an hour, though a contested race or a heavily attended caucus can stretch it out even longer.

This kind of rigid time commitment—aside from making caucuses difficult to attend or flat-out inaccessible for parents, low-income workers, disabled individuals, those who are sick, those without transportation, or those for whom a public and confrontational voting process may be ill-advised due to social, domestic, or mental pressures—means that foul weather can easily dissuade potential caucusgoers from venturing into rain or snow or extreme temperatures. Political scientists have found that foul weather depresses turnout, and it stands to reason that the effect is even more pronounced in an involved caucus than it would be in a traditional election.

The 2020 presidential nomination process will feature less than half the number of caucuses we saw during the 2016 cycle. Democrats in 14 states held a caucus during the 2016 election, compared to just three traditional caucuses (IA, NV, and WY) this time around.

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