But still some hot spots, in mid-town Savannah, GA, 95F 58% humidity, for a heat index of only 114 F. Better than the 120+ we spiked Friday/Saturday. Nothing in the tropics, a few earthquakes (including an 8.2 in Alaska the other day, fortunately no tsunami), so using the “break” for doing some long overdue computer maintenance like vacuuming all the @#$%! cat hair out of the computer intake fans :O
So there’s one or two heat warnings and advisories up this morning …
… and a lot of talk about the Heat Index. Let’s take a closer look. First off while the temperatures are above normal, at least here in coastal GA/SC they won’t be threatening the historical record highs. The air temperatures are going to be high Friday/Saturday, but won’t set any records. The average for July 30th is 92, the records this time of year are over 100 (101-103), and forecast highs in downtown Savannah are 97 today and 96 Saturday. The problem is that humidity is way above normal. That is due to the pattern of air flow over the region is keeping moist Gulf and Atlantic air “trapped” over us (recall the low pressure system that NHC was looking at earlier this week, AL90, wandered over us, then off of North Florida before drifting back over us). And it’s the humidity that’s the problem.
The Heat Index has an interesting history, and there are several versions. The method currently in use by the US National Weather Service is not a complex equation, if you want to see it look here:
The TLDR is that the “heat index” is supposed to represent how hot if feels, given that the higher the humidity, it “feels” hotter because your body can’t cool itself as efficiently. The technical reason is because we cool ourselves by sweating (ewww), and the evaporation of that sweat cools us down, since it takes energy – heat – to convert water from the liquid to gas states. The evaporation rate depends temperature and humidity – the higher the humidity, the less moisture evaporates, and the less heat is transferred from your body to its surroundings. Drier air means that evaporation works better, so it “feels” cooler (although that can be misleading), thus all the jokes about a Dry Heat …
Either way, especially if you are not adapted to it, the heat can be dangerous (and in the ranges expected today, even if you are). By the way, the NWS has different criteria for when to issue heat advisories around the country, depending on normals. So a heat advisory in Vermont is issued at much “cooler” temperatures than in Savannah.
To sum up, technically speaking, it’s not that it’s so hot, it’s because it’s kinda hot and really humid … it would be uncomfortable at 97, but all that humidity today will make it feel like it’s well over 110, maybe as high as 120 in parts of town where the temperature and humidity gang up. So if you can avoid working outside this afternoon, don’t, and if you absolutely have to, drink lots of fluids, protect yourself, and be careful.
Update: at 2:30pm, in midtown Savannah the air temperature was 93, the humidity 70%, which adds up to a heat index of 120F :O
Tropical Depression 09W slowly organizes as it moves in the general direction of Okinawa. The Joint Typhoon Warning Center forecast today is for a weaker storm tracking further south than yesterday. Here’s the “plain language” impact estimate based on their 5am ET forecast:
The objective guidance has it barely at hurricane strength at that time at worst. So it may not be more than some strong winds and rain on Okinawa. After that, the storm is likely to head for Mainland China, but it’s too early to estimate impacts there.
Elsewhere, a big weather story are the floods in Europe, particularly Germany (this link goes to Deutsche World live updates). The Netherlands and Belgium have also been hit hard.
A lot of the bad flooding is around Bad Neuenahr-Ahrweiler, Germany. The Ahr river flows through the town. . In looking at the period where we have really solid modeling for comparison with the climate models (1980-present), the peak total rain that ended up in the Ahr River fell on July 14th, and was 31% higher than the second highest value on record (which was in 2014). Worse, the Fifth highest daily value was on the 13th – and it was only about 5% lower than 2014. So two of the five highest total rainfall amounts in the last 40 years fell on back to back days.
The totals this last week were epic – 40% higher than the 2014 floods which came in at number two. Statistically it’s a well over 100 year event, maybe pushing a 200 year event. The rains on the 13th and earlier meant the soils were totally saturated (in fact soil moisture levels were at record highs on the 13th). So all of the water that fell on the 14th just ran off into the rivers and over the landscape. Also note that long ago (say 100 years) the flooding wouldn’t have been this bad with the same amount of rain due to development, impervious surfaces, etc.
This really was an epic amount of water. Fortunately it looks like there will be several days of clear weather, hopefully things dry out some before the next rains fall in 5-6 days. You’re probably hearing a lot about this being due to climate change. We’re in a difficult place right now data-wise. We are starting to see evidence of climatic changes that we would expect given anthropogenic changes to the atmosphere. Is this particular flood caused or made worse by human caused climate change? I think that’s impossible to say based on the data we have. But these kinds of disasters (floods, heat waves such as out west) are expected to become more frequent – and by the time it happens, it’s really too late to do anything except get out of the way. More on that in an upcoming post.
TLDR: it doesn’t really matter much if the NHC starts advisories or raises warnings in terms of impacts, the physical effects are going to be about the same: rainy afternoon and overnight, “landfall” this evening. Maybe some localized street flooding with over an inch of rain, winds don’t look bad at all right now, maybe a bit higher in South Carolina, and you might see some gusts and branches down, that sort of thing.
Here’s the details … The system moving towards the Georgia coast hasn’t organized much overnight, so the National Hurricane Center hasn’t started official advisories or raised any warnings as of 6am. Here is what it looks like on satellite (water vapor band, with surface analysis map overlay so you can see where the “center” is located – the L symbol):
The Charleston radar (which is really in Hampton, SC, about half way between Charleston and Savannah) is showing the outer rain blobs (not really bands at this point if ever) approaching the coast:
At the moment the impacts of this thing don’t look so bad. Could get some heavy rain, totals of an inch or more in the Savannah/Hilton Head/Beaufort area. It’s moving fairly fast so while there is some potential for minor flooding, flash flooding isn’t too likely. Winds look well below tropical storm strength; if it does organize enough to reach depression criteria, the winds should stay confined to the coast (the islands) but even then not really a big threat. On the beaches there is a rip tide caution, and any time these things come ashore there is a chance of waterspouts or weak tornadoes (EF0/1). So keep your weather radio on just in case. Serious rain should kick in around noon, and be gone by tomorrow morning.
Here is one last rant and some additional perspective on the sensationalist, fear mongering reports in several USA TODAY network newspapers this week. In 2019, 42 people died from tornadoes. That same year 47,511 committed suicide. In other words, reducing suicides by JUST ONE PERCENT would have saved ten times as many lives (475) as completely eliminating tornado deaths. On average, there are 132 suicide deaths PER DAY – more than the last two years of tornado deaths combined (117), and nearly twice the average annual tornado death rate (69/yr). Now, given that perspective, is this front page justified?
To be sure, any premature death is a tragedy, and weather causes a significant amount of death and destruction, a lot of it preventable. But we have made tremendous strides in warning and mitigation, especially in the area of hurricanes. The articles had some good points – but the melodrama and fear overwhelmed whatever valid points were to be made. I’ve made it my life’s work to try to reduce the impact of natural hazards, so obviously I think this work is important and valuable – but you have to keep it in perspective. Consider: over 6,000 Military Veterans are thought to die due to suicide every year – at least eighty six (86) times the annual average deaths from tornadoes. If I had the skills and knowledge to help reduce that horrific figure I’d drop what I’m doing in a second and change careers.
It’s important to realize that the most insidious and toxic thing about this kind of “reporting” is that factually the article is almost entirely “true” – as noted in the previous post, tornado activity might be shifting, and “The South” is more vulnerable than the Midwest. It just the reports lack context. I can do a screaming headline about “Every Surface In Your Home Is Coated in Bacteria,” show gross pictures of people with necrotizing fasciitis accompanied by sob stories from their families, and without any falsehoods make you afraid to touch your kitchen counter. But in context, all that bacteria isn’t really a major problem for most people with some common sense. I could have used many other examples of things more dangerous or impactful on everyday life than tornadoes, but I just got a note on Veteran suicide so it’s on my mind.
The bottom line is that while tornadoes are scary, by any rational measure we’re afraid of and worried about the wrong things – and “journalism” like this a big reason why.
Is Tornado Alley shifting, “spreading to the South, leaving a trail of DEATH AND DESTRUCTION” as this morning’s local Savannah newspaper dramatically blared? And is coastal Georgia at greater risk? Let’s see what grumpy cat has to say:
There has been a series of articles on potential changes in tornado climatology in the last few weeks, and the local paper in Savannah, as part of the USA TODAY network, has run a couple of dramatic front page articles on the subject including a front page Sunday feature that happened to coincide with some tornado potential from the passage of Tropical Storm Claudette, and another dramatic front page spread this morning (Wednesday). As I read these articles, I saw a lot of red flags, especially for being in the local paper and not pointing out that a lot of what was said did not apply to the Savannah area (including a local supplemental article supposedly focused on Georgia). It has been about 10 years since I was involved in active tornado research, and while I do try to keep up with things, it’s always possible to miss something, so I spent a fair bit of time the last couple of days catching up before writing this post. The bottom line is that while it had some great points about changing population and demographics, the implication that tornado activity is changing in some drastic way and that the risk was dramatically changing in the south – and particularly the implication that the local Coastal Georgia/South Carolina area has changed – was simply misleading.
The biggest technical issues are around the reliability of the historical data and the way the overall scenario was presented. However there are wider issues. This kind of overly dramatic reporting isn’t helpful in providing perspective, and are fueled by wider availability of raw data sets that anyone can download and manipulate, combined with scientists who naturally want to see their research publicized but often don’t get to see the final articles before they reach the public, and a sound-bite driven culture that has permeated even what should be more thoughtful long form pieces. These articles are a (cough) perfect storm, coming together to create a misleading train wreck. This is a complex topic, so will have to take some time to work through this to get a more balanced perspective.Continue reading
For those in the coastal Georgia and South Carolina Low Country, while there is some uncertainty there seems to be two bands of potentially severe weather on the way today. The first is a Quasi Linear Convective System (QLCS), which is a fancy term for a line of thunderstorms, interacting with a warm front late this morning. The second is a squall line that is shaping up to push through during the peak energy time, late this afternoon and early evening. Overall, heavy rain (up to 3″ in the Savannah area, maybe near high tide, so expect street flooding!), gusty winds, and according to the Storm Prediction Center a 10% chance for a tornado … so keep your weather radios on and be aware we could get some heavy weather today. You can see stuff shaping up to our southwest in this radar composite as of 7:30am …
Some severe weather is expected in the US this afternoon – here is the warning graphic from the US Weather Prediction Center (WPC):
An active and dangerous day of weather is set to unfold across theFrom WPC Discussion as of 8am ET, 25 March 2021
Mid-South today, highlighted by a High Risk of severe weather issued by
the Storm Prediction Center. The primary weather driver of this impending
tornado outbreak is a strengthening area of low pressure out ahead of a
sharp and intense upper level trough tracking into the middle Mississippi
Valley and Ohio Valley this evening. Powerful thunderstorms are forecast
to blossom in the South this afternoon and track into the Ohio and
Tennessee Valleys tonight. These intense thunderstorms are may contain a
myriad of hazards that include violent long-track tornadoes, damaging wind
gusts, and large hail. In addition to the severe threats, hydrologic
hazards are also a serious concern from northern Alabama and Mississippi
to the Tennessee Valley and southern Appalachians. Torrential rainfall
rates in these areas that also contain overly saturated soil is a recipe
for flash flooding. As a result, a Slight Risk of excessive rainfall is in
place with a Moderate Risk located over northern Alabama, northwest
Georgia, and southeast Tennessee. Residents in these areas should have a
plan of action if severe weather threaten their respective locations. In
addition, high winds from the lower Great Lakes to the northern
Mid-Atlantic Thursday night into Friday morning. High Wind Watches are in
place for portions of these regions as strong winds may result in downed
trees and power lines.
None of this is expected to make it into the coastal GA/SC area. In Savannah GA for example, there is only a slight chance of thunderstorms Friday afternoon, and again Sunday into Sunday night.
The storm system that has already spawned tornadoes across the south continues to sweep eastward this morning …
Inland areas of Georgia are likely to see strong thunderstorms today, with the potential for more tornadoes. It’s going to be a busy weather day. But, being self centered, what about the coast? TLDR: be prepared, hopefully you have a weather radio handy for alerts. There is a good potential for strong winds and intense thunderstorm cells, and some potential for tornadoes. For Savannah/Hilton Head, arrival times look to be at 3pm, with the main line passing through Savannah around 4pm. Here is the latest (6am) High Resolution Rapid Refresh model forecast for 3pm EST:
The strongest storms should stay west (inland) of I-95, and there is an area to the north of the Hampton SC area that has some potential for stronger storms and tornadoes. In the above model run you can see that area of severe storms approaching stretching up to Walterboro. But the entire region should pay attention to this event and be prepared to take shelter from any tornadoes that form. Here are some tornado preparedness tips from FEMA/DHS.
As for the details, like most things it’s complicated. As a start, while forecasts are much better, with high resolution tools running hourly to update the forecasts, this is still a dynamic situation with some uncertainty. It seems the risk along the coast is lower based on the latest data, however, here is what the National Weather Service’s office in Charleston has to say:
IMPORTANT MESSAGE: After much internal collaboration with the SPC and neighboring WFOs this morning, the earlier “moderate risk” has been replaced with an “enhanced risk” for given the continued uncertainty on how stability profiles will evolve through the day. This action SHOULD NOT be misconstrued as a lowering of the severe risk for the area as conditions still remain favorable for a potential outbreak of severe tstms some of which could produce a few strong tornadoes. It is simply an attempt to better message the uncertainty with how widespread today`s severe weather will be. Media partners are asked to helpFrom NWS Forecast discussion as of 622 AM EST, Thursday 18 March 2021
convey this critical message today.
It will be interesting to see how local media handles this request. Asking local weather forecasters to continue to push a message that things have the potential to be bad is likely to be successful 😛 . But … it also needs to be clear that despite the need for vigilance, these storms might well break up as they reach the coast. I’ve seen some comments that they never come here. Well, sometimes they do … so be prepared.
There is a typical winter storm forming up over the US, bringing gusty winds and rain to the Southeast, and snow to the Northeast. Because, um, it’s winter 😛 …
Fortunately there is enough other news that everyone other than that weather channel are too preoccupied with other “breaking” news to blow this out of proportion, although adjectives like “major” are being thrown around. But it’s a strong storm, so here’s that cool swiper thingee so you can see the radar and precipitation type by grabbing the pointer with your mouse (finger on a touch screen) and slide between views.
The usual impacts from this kind of storm, nothing catastrophic in store if people use common sense (well, I can hope!). Tomorrow will be a messy start to the week, I see that some cities like New York are taking precautions like closing schools and shifting to on-line instruction (a sad consequence of COVID is kid’s don’t get snow days so much any more). There is another storm system hitting the Pacific as well, that has washed out a chunk of the Pacific Coast Highway (caution: link goes to insufferably preachy news source, but does have drone footage).