Category: Tropical weather

Last week, we discussed how 2020 had started off tremendously fast but slowed a bit. We’re coming out of that lull now, but thankfully what we are amassing is mostly curiosity rather than any serious impacts.

Tropical outlook in a sentence

While another system is possible off the East Coast, the Gulf is not expected to deliver any action over the next 1 to 2 weeks, as summer roasts much of Texas.

Edouard sets another 2020 superlative

With Tropical Storm Edouard being named on Sunday night, the Atlantic has now set a new record for the earliest 5th storm on record. The previous record holder was Emily back in 2005, which formed on the 11th of July. We typically do not see our 5th storm until the end of August, so we are off to the races right now. We’ll discuss 6th storm records in just a moment.

Again, there’s a huge difference between utilizing number of named storms and accumulated cyclone energy (ACE) to characterize the start to a season. Please see last week’s post for an explanation of the value and shortcomings of ACE. From the named storm standpoint, we’re at late August levels already. From an ACE standpoint, we’re at July 20th levels, not super abnormal.

While named storms are up to typical late August levels already, accumulated cyclone energy (ACE) is only running about two weeks ahead of schedule right now, which is probably a more reasonable way to characterize the 2020 season thus far. (Colorado State)

Just to put this into a little perspective: In 2005, the year we keep beating for earliest storm, by the time the 5th storm dissipated on July 21st, we had amassed an ACE of 56, or what is normal for September 14th. As I’ve told some people, 2020 thus far is about quantity, not quality.

East Coast bias

Of this year’s five storms so far, four of them have formed near or off of the East Coast. Could our next system come from that area? It very well could. A disturbance dubbed “Invest 98L” moved ashore on the Florida Panhandle on Sunday night. It is currently over northern Georgia and projected to lift to the north and east over the next few days.

Invest 98L is disorganized over Georgia today, but it does have about a 40% chance of developing as it pushes off the coast later this week. (Tropical Tidbits)

Right now, the National Hurricane Center is giving this about a 40 percent chance at becoming a tropical system over the next few days as it lifts north and east off the East Coast. If it does become a tropical storm, it would be named Fay, and it would break the record for earliest 6th storm (Franklin on July 21, 2005). This disturbance should produce heavy rain on the coast of the Carolinas, but at this point, it is not expected to cause much serious trouble before rolling out to sea.

Saharan dust

We continue to see the bulk of the Atlantic basin littered with dust today.

Widespread dust continues to hold over most of the Atlantic Basin, but it has eased up in density and coverage a bit. (University of Wisconsin CIMSS)

Dust, while widespread, is beginning to ease up a little relative to late June. The good news for us in Texas is that the quantities of dust reaching the Gulf are slowly diminishing, so we’re not expecting quite as ugly of an impact from dust over the next 10 days as we saw in late June up through this past weekend. Still, as dust rolls west across the basin, it’s always possible we see some in our area. But we do have something extra working in our favor by this weekend.

Heat in Texas keeps the Gulf closed

Look, some of us like the heat this time of year. Many of us deride as just something we have to accept about living here. Sometimes the heat can be good for something, and in our case, it would seem that it will help shield us from any Gulf happenings, including Saharan dust over the next week or two. To be clear, we don’t really expect any Gulf happenings, but in the off-chance something could form, strong high pressure over Texas would most likely deflect anything back to the east or well south into Mexico. Below, you will see the GFS ensemble mean forecast for days 6 through 10 (Sunday to Thursday next week), which shows high pressure in the upper atmosphere oriented just right to keep Texas protected.

The upper air forecast for days 6 through 10 shows a rock solid, strong high pressure system over Texas, which should be enough to keep the region “shielded” from any Gulf impacts. (Tropical Tidbits)

Of course, that will come with a cost, assessed in triple digit temperature risk and heat index values. But as long as high pressure can hold over Texas, we’ll be pretty safe from the Gulf. We don’t expect that to last forever, but for the next week or two, it is expected to be quiet, albeit dry.

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The 2020 Atlantic hurricane season got off to an early and fiercely active start back in May and early June, which had many people justifiably on edge wondering what was to come. Now, here we are on June 30th and we’ve had one additional storm since Cristobal made landfall in Louisiana at the beginning of June. Things have thankfully slowed down a bit. We’re going to aim to provide sort of a broad overview of the state of the tropics every Tuesday here at Space City Weather, just to keep you apprised of things we don’t make time or space for in the morning updates.

Tropical outlook in a sentence

While we will be watching the potential for some kind of hybrid system to develop off the Florida or Georgia coast early next week, we do not see any threats to the western Gulf for the foreseeable future.

Active start, sort of

Our most recent named storm was Dolly, which briefly threatened some fish in the north Atlantic back on June 23rd. Dolly just missed being the earliest “D” storm on record by 3 days. For those of you scoring at home, the earliest “E” storm was 2005’s Emily, which formed on July 11th.

We normally don’t get to the letter “D” storm until mid-August. (NOAA)

But interestingly, even though we’re running about 45 days ahead of schedule in terms of named storms, when you look at cumulative intensity, it’s less impressive. We like to sometimes look at what we call “accumulated cyclone energy,” or ACE to really hammer home how active a season has been to place it in better historical context. We can name more storms now because we have superior technology to even 10 or 20 years ago that allows the National Hurricane Center to name something borderline that might have slipped through the cracks in the past. Stronger storms likely would not have been missed in the past, so ACE provides a good way to almost compare apples to apples better than number of storms would.

So what is ACE? We said there would be no math, so I won’t go into the details of how it’s calculated. Read the Wikipedia article here for more (yes, it’s legitimate and accurate). Essentially, it’s just an equation that factors the length of time a storm had particular sustained winds. The stronger the winds, the longer it maintains strong intensity, the higher the ACE. Since it only factors in wind, by no means is it perfect. For instance, Hurricanes Harvey, Andrew, and Katrina won’t crack the top 25 list of storms that have generated the most ACE because they didn’t last long enough. So in that respect, the calculation is imperfect, but overall it’s a pretty good gauge of where a season stands historically. You can track seasonal ACE in real time here.

The accumulated cyclone energy for this season so far is running about 3-4 weeks ahead of schedule. (Colorado State)

So back to 2020: We have amassed 6.1 units of ACE this season so far. This is normal for about July 20th, so 3 or 4 weeks ahead of schedule instead of 45 days.

Regardless of how you want to slice it, we’re off to a fast start, so this pause is welcome.

Tropical outlook

Things won’t stay quiet forever, and it appears the next opportunity for a system will be sometime later this weekend or early next week, and in true 2020 fashion, it will occur in a peculiar manner. An upper level low over the Northeast looks to exit over the next couple days, but it seems like a weak little lobe off the south side either stays trapped over or drifts into the Southeast. Here’s the latest 500 mb GFS Ensemble mean view through next week, looking at what’s happening 20,000 feet up. Note the light blue color over the Southeast. This is showing an upper level disturbance of some type by the weekend.

The upper level pattern shown here by the GFS and also by the European model suggests shenanigans are possible off the Southeast coast early next week. (Tropical Tidbits)

From here, we start to see <waves hands> things happening. It appears this may gradually transition to a surface low as it drifts eastward, off the Georgia or Carolina coast and it’s plausible to think it could become tropical on its exit out to sea. While this will likely have limited impact to any land mass, we have a legitimate shot at having our earliest E/5th storm on record this year.

The European ensemble is particularly enthusiastic about a risk for a depression or weak tropical storm to from from the transitioning disturbance over the Southeast early next week. It likely will move steadily out to sea. (Weathernerds.org)

But that’s it; that’s the tropical update for the next 10 days or so. The overall background state of the Atlantic is one that has become more favorable in recent days. I won’t delve too much into the meteorology here, except to say that we’ve had some shifts in the atmosphere over the tropics that should, in theory, allow for a few more waves. But you’ve seen the Saharan dust here in Houston. It’s out there, and it’s widespread.

Yellow, orange, red, Saharan dust is all over. (University of Wisconsin CIMSS)

Anywhere you see yellow, orange, or red on that satellite image is an indication that dust is present. It’s all over the Atlantic basin right now, not necessarily abnormal for this time of year. But where you have dust, you have drier air and a less hospitable environment for tropical development. Suffice to say, with this all over, conditions right now are not ideal for tropical development in the Atlantic basin. In addition, you still have a good bit of shear as well. So the basin isn’t completely immune to storms, but it’s rather inhospitable.

Is there anything happening in fantasyland on the models? Nope. Things look quiet right now as we head through early or mid-July. Short of something rogue like this thing off the Southeast coast next week, we don’t expect much through mid-month. So breathe easy here in Houston for the time being. We’ll check back in on things in a week.

Tropical Storm Cristobal made landfall on Sunday evening in southeastern Louisiana, bringing winds, waves, and heavy rainfall to the northern Gulf of Mexico coast. This seems as good of a time as any to take stock of a frenetic start to the 2020 Atlantic hurricane season, and assess what it means for the rest of the year.

Busy start

Cristobal formed on June 2 in the Southern Gulf of Mexico, and this was the earliest ever point in the Atlantic season that the third named storm has formed in a given year. (However imperfect, the Atlantic basin has records dating back to 1851). The previous earliest “C” storm was Colin, on June 5, 2016. Arthur and Bertha, which were both relatively weak and short lived storms, formed this year even before the season officially began on June 1.

This may seem like an ominous beginning to what seasonal forecasters have predicted to be a busy season. But according to hurricane scientist Phil Klotzbach, there is little correlation between early season storms and the total activity (in terms of number of storms and their overall intensity) for the remainder of the year. In fact, the correlation is slightly negative.

Correlation between seasonal activity and first named-storm formation. (Phil Klotzbach)

What this means is that we’re not really going to know the full tale of the 2020 season until about August, when activity in the tropical Atlantic Ocean—known as the Main Development Region—gets fired up. This is the period of summer when we start to watch tropical waves spin off the western coast of Africa, and develop into tropical systems as they migrate westward across the Atlantic Ocean toward the Caribbean Sea. We’re still about six to eight weeks from the opening of this period.

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Good morning. Houston is seeing warm and humid conditions this week, as one would expect in June. However, we still have a ways to go in terms of summertime heat, and the region should reach the mid-90s by Saturday. The question remains about what happens after that, and it almost entirely depends on what happens with Tropical Storm Cristobal. At the moment, it still appears as though the storm and the bulk of its effects will probably stay east of Houston, but we’re far from being able to make a definitive call on that.

Wednesday

Today should produce the region’s best chance of showers and thunderstorms until at least Sunday. A combination of daytime heating, ample moisture in the atmosphere, and only moderate high pressure should allow for some storms to fire up this afternoon before fading this evening. High resolution models offer a mixed bag of solutions, bit given our recent pattern I’m fairly bullish on at least some moderately strong storms firing up closer to the coast and pushing inland later today. Areal coverage of these storms will probably be in the 30 to 50 percent range, so not everyone is going to get wet. Otherwise, expect partly sunny skies with highs of about 90 degrees.

Expect high temperatures to push into the mid-90s by Saturday. (Pivotal Weather)

Thursday, Friday, and Saturday

As high pressure settles into the area we should see a warming trend, with partly to mostly sunny skies through Saturday, and highs rising into the mid-90s. Under such a pattern we normally would expect only slight afternoon rain chances along the sea breeze.

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