PTC1 on Saturday Morning (4 June)

Potential Tropical Cyclone One is still an unrealized potential, and shows no signs of organization before the associated mess of rain squalls moves past Florida. Here is what it looks like on InfraRed satellite (the sun isn’t up yet as I write this):

Click any image to embiggen.

There are actually several “centers” depending on how you define that, including the small convection-free swirl of clouds you can see in the center of the image. NHC thinks this mess will consolidate into a single center once it moves past Florida and The Bahamas, but they are off the hook for a real tropical storm. That doesn’t mean that some rain squalls with tropical storm force winds won’t pass by this morning, but more like the typical summer downpours and thunderstorms than a real tropical storm.

For being such a disorganized mess the track models and forecasts are remarkably consistent, taking it out parallel to the US Southeast coast towards Bermuda. There is still a chance that this will develop briefly in to Tropical Storm Alex before it gets there, but it will likely be short lived before conditions deteriorate and it becomes extratropical.

Raw spaghetti. Not for human consumption until cooked.

PTC1 still not a tropical storm

So far Potential Tropical Cyclone One can’t get it’s act together. It’s a very broad and disorganized system, and all of the rain and wind is displaced far to the east of the center, here from GOES East just before 5pm …

Click to embiggen

Here is the regional radar composite – Florida is getting a lot of rain already. It may well be that the rain will be ending before the storm itself actually passes over the state!

Multi Radar Multi Sensor composite at 5pm Friday,

The hurricane center is still thinking PTC1 will organize enough to become Tropical Storm Alex before landfall, which should just after noon tomorrow (Saturday). The biggest “threat” from PTC1, even if it does evolve in to Tropical Storm Alex, will be heavy rain. Here’s a link to NHC’s latest Key Messages regarding Potential Tropical Cyclone One (en Español: Mensajes Claves).

Elsewhere, just off the US east coast there is an area NHC is watching, but chances of development are small, and if something does spin up it seems at worst it would give Bermuda a windy day before moving out to sea.

Potential Tropical Cyclone One (AL012022) heads to #Florida

Potential Tropical Cyclone One is a large, disorganized system that is producing tropical storm force winds, but technically isn’t a tropical storm (more on that later). In terms of impacts, it should just be some wind and rain – here are NHC’s Key Messages regarding Potential Tropical Cyclone One. As a reminder, once a storm forms the “Key Messages” product is a nice summary of watches, warnings, and forecast. Here is my TAOS/TC impact estimate based on the 5am forecast. Bottom line is windy/rainy weekend for Cuba, south Florida and the northern islands of The Bahamas, minimal damage other than some trees down, scattered power outages, very scattered roof damage, that sort of thing. Economic impact should be transitory, under $100 million, and recovered quickly. Elsewhere the storm may cause rip currents along the Southeastern US coast next week.

Click to enlarge.

So what the heck is a “Potential Tropical Cyclone”? In the past these kinds of storms were not tracked and reported by the Hurricane Center until they met the formal criteria for being a tropical storm. That would mean a distinct (from other systems) warm core, closed circulation. The problem is that in some conditions a tropical storm can form from an otherwise disorganized disturbance before the system crosses land, and less than the normal time frame when watches are issued. This became more of an issue in 2010 when the lead time for a watch was increased from 36 to 48 hours, and a warning form 24 to 36 hours, and more storms were forming withing those time frames and people were not getting as much notice. So in order to give people warning and time to prepare, NHC starts advisories as a “Potential Tropical Cyclone” on systems that are forecast to become actual tropical systems. So like a lot of things in tropical meteorology, it’s a mix of actual meteorology, administrative issues, and emergency management needs.

Here is a handy reference to terms like PTC, tropical wave, tropical storm, etc., from the NWS Mobile, AL office. And here are the “new” (as of 2010) criteria for watches and warnings.

NHC Likely to start advisories, post watches for #Florida today for potential #tropicalstorm

Although still not well organized, and not in a great environment for development, the system off of Yucatan continues to move slowly northeast. Since it has a good potential to become at least a tropical depression or low end tropical storm, the hurricane center will likely start advisories and post watches later today as at least a “potential tropical cyclone.” At the moment the models aren’t terribly enthusiastic about the system, most keeping it at minimal tropical storm strength. Here is what the US GFS model shows for Saturday Morning at 8am, a disorganized minimal tropical storm …

850mb heights and winds (about 5000 feet above ground, a good indication of organization)

Some of the models don’t even form a coherent system (just a broad area of disturbed weather). In the map above you can see two distinct “centers” (the “L” symbols), indicating a very disorganized system. Here is what some of the models are showing as tracks, for a disorganized mess they are actually fairly consistent …

Computer Models as of 5am ET; click any image to embiggen. “Dispersion” is a measure of where a mix of models puts the storm each day. The tighter the ellipse, the better. The orientation shows the most likely direction of error.

Other than a lot of rain it’s not likely this storm will get organized enough to produce significantly damaging winds. Unless you’re just unlucky and a tree falls on your house, or something breaks that shouldn’t, this should be just a rain event for Cuba, Florida and The Bahamas. For the Southeastern US (Georgia and Florida), an approaching cold front that will bring rain Friday and early Saturday will have moved past, and the system (tropical storm or not) should stay far enough away to not cause any impacts other than perhaps waves and a risk of rip tides at the beach.

Start of official Atlantic hurricane season; tropical weather outlook

This morning’s Tropical Weather Outlook (TWO) from the US National Hurricane Center (NHC) is worth reading and, if you’re in a hurricane prone area, bookmarking. It should be your go-to reference for hurricane planning to get the “big picture”. Today’s TWO has a nice overview of NHC products (reproduced below). Here is the link: https://www.nhc.noaa.gov/gtwo.php?basin=atlc&fdays=5

There are two areas of disturbed weather being watched today. The one in the Bahamas isn’t likely to be much of a threat to anyone, the one over the Yucatan has a better chance of at least a tropical depression forming (70% according to the early morning update, up to 80% at the 8am update). The 06z (2am) GFS global weather model showed it staying pretty disorganized as it crosses over Yucatan and then Cuba, the Florida Keys, and Bahamas through next weekend. As the advisory states, people in those areas should “monitor the progress” of the system.

Sunrise over the Eastern Atlantic/Gulf of Mexico. IR (temperatures) on the left, visible on the right.
Click to embiggen.

As for Enki’s products this year, if there is something going in in any of the hurricane basins (not just the Atlantic, but the Pacific and Indian Ocean as well) I plan on doing a post between 6:00am and 7:30am Eastern Time with an overview and discussion of the potential impacts, as well as any interesting scientific or political points of interest for any active events. If a storm is threatening land, I’ll do an additional post in the mid to late afternoon (between 3:30pm and 5:30pm) with any important updates. It is vital to remember that weather analysis has a cycle of updates, and despite the efforts of the media to make you fixate on every wobble or update, the forecasts are only updated four times a day and it is rare they change that much from one to another. Generally speaking, checking once a day is fine for a storm more five days away from you, and twice a day until it passes or you are in/near a watch/warning zone, at which point more frequent checking is a good plan. Don’t worry about what models say: follow the official forecast for planning purposes. If you want to understand how those models become a forecast, that’s something I write about here, but don’t bet your life on a model (or, as I like to say, don’t eat raw spaghetti).

As promised, here is the product overview from the TWO for reference since it will be overwritten later today by an updated advisory …

Today marks the first day of the Atlantic hurricane season, which 
will run until November 30.  Long-term averages for the number of 
named storms, hurricanes, and major hurricanes are 14, 7, and 3, 
respectively.

The list of names for 2022 is as follows:

Name           Pronunciation    Name            Pronunciation
-------------------------------------------------------------
Alex           AL-leks          Lisa            LEE-suh 
Bonnie         BAH-nee          Martin          MAR-tin
Colin          KAH-lihn         Nicole          nih-KOHL     
Danielle       dan-YELL         Owen            OH-uhn  
Earl           URR-ull          Paula           PAHL-luh 
Fiona          fee-OH-nuh       Richard         RIH-churd
Gaston         ga-STAWN         Shary           SHAHR-ee
Hermine        her-MEEN         Tobias          toh-BEE-uss 
Ian            EE-an            Virginie        vir-JIN-ee
Julia          JOO-lee-uh       Walter          WALL-tur
Karl           KAR-ull

This product, the Tropical Weather Outlook, briefly describes 
significant areas of disturbed weather and their potential for 
tropical cyclone formation during the next five days.  The issuance 
times of this product are 2 AM, 8 AM, 2 PM, and 8 PM EDT.  After the 
change to standard time in November, the issuance times are 1 AM, 7 
AM, 1 PM, and 7 PM EST.

A Special Tropical Weather Outlook will be issued to provide 
updates, as necessary, in between the regularly scheduled issuances 
of the Tropical Weather Outlook.  Special Tropical Weather Outlooks 
will be issued under the same WMO and AWIPS headers as the regular 
Tropical Weather Outlooks.

A standard package of products, consisting of the tropical cyclone 
public advisory, the forecast/advisory, the cyclone discussion, and 
a wind speed probability product, is issued every six hours for all 
ongoing tropical cyclones.  In addition, a special advisory package 
may be issued at any time to advise of significant unexpected 
changes or to modify watches or warnings.

The Tropical Cyclone Update is a brief statement to inform of 
significant changes in a tropical cyclone or to post or cancel 
watches or warnings.  It is used in lieu of or to precede the 
issuance of a special advisory package.  Tropical Cyclone Updates, 
which can be issued at any time, can be found under WMO header 
WTNT61-65 KNHC, and under AWIPS header MIATCUAT1-5.

All National Hurricane Center text and graphical products are 
available on the web at https://www.hurricanes.gov. More information 
on NHC text products can be found at 
https://www.hurricanes.gov/aboutnhcprod.shtml, while more 
information about NHC graphical products can be found at 
https://www.hurricanes.gov/aboutnhcgraphics.shtml.

You can also interact with NHC on Facebook at 
https://www.facebook.com/NWSNHC. Notifications are available via 
Twitter when select National Hurricane Center products are issued.  
Information about our Atlantic Twitter feed (@NHC_Atlantic) is 
available at https://www.hurricanes.gov/twitter.php

#TropicalStorm near #Florida next Weekend (4 June)?

We have the first Magic Words(tm) of the Atlantic hurricane season! The latest (2pm Tuesday 31 May) NHC five day outlook shows an ominous red X and hashmark of doom pointed towards Florida …

Click to open NHC TWO page in another window.

As I frequently recommend, read the text for the graphic before getting too excited. Here’s what it says, with the “magic words” highlighted:

A large and complex area of low pressure is expected to develop near the Yucatan Peninsula and the northwestern Caribbean Sea in a couple of days, partially related to the remnants of Agatha from the eastern Pacific. Despite strong upper-level winds over the area, this system is likely to become a tropical depression while it moves northeastward over the northwestern Caribbean Sea and southeastern Gulf of Mexico late Thursday or Friday. Regardless of development, locally heavy rainfall is likely across portions of southeastern Mexico, the Yucatan Peninsula, Guatemala, and Belize during the next couple of days, spreading across western Cuba, southern Florida, and the Florida Keys on Friday and Saturday. Interests in the Yucatan Peninsula, western Cuba, the Florida Keys and the Florida Peninsula should monitor the progress of this system.

NHC’s Tropical Weather Outlooks follow a specific pattern. They tell you what the thing is (“A large and complex area of low pressure…”) then they will have the phrases Interests in <some place, in this case highlighted in red> should <do something, here in green>. So if you’re (someplace), do that thing – otherwise, don’t worry about it.

In this case the models seem to be showing, well, a large and complex area of low pressure, which are forecast to dump a lot of rain and maybe spin up some tropical winds. The latest GFS run did not form as clear of a center as it has previously, but any organization is still a couple of days away. Even if it does become a depression or minimal tropical storm, it probably won’t be a dangerous system until it is past the Bahamas as it treks northeast (and probably not then either). But we may get “Alex” out of it. As the TWO says, monitor the progress (if you’re in Florida) or enjoy the short work week (if you’re most other folks except me or another profession who works all the time on some crisis or another …).

#Agatha landfall; It Came from the Yucatan

Hurricane Agatha made landfall on the west coast of Mexico last night as a strong Category Two storm. Damage reports are starting to come in, and there is still a risk of flash flooding and mudslides as rain is dumped across the mountainous terrain. As with any storm there will be local stories of tragedy, and there will be people who need help, but Agatha should not have caused a widespread disaster with perhaps one million people in the zone of tropical storm conditions, and estimated impacts on the order of $150 million US Dollars. Here is the surface analysis from NOAA’s Tropical Analysis and Forecast Branch on top of an Infrared (IR – cloud top temperature) satellite image …

Click to embiggen.

IR satellite images are part of the basic tool kit of modern meteorology. These sensors measure the temperatures of the tops of the clouds. If you want to learn more about them, try this overview from the University of Wisconsin geared towards high school students (link). And to learn more about the squiggly lines and symbols, here is a page from NWS on how to read weather maps (link).

So what is the TLDR? The remains of Agatha are merging with an existing low pressure system lurking around the Yucatan. It is possible (NHC says 60% chance at the moment) that the resulting mess will consolidate and form a tropical depression by this weekend and move towards Cuba, the Florida Keys, and the Bahamas. Either way it should dump a lot of rain across that swath. So at the moment there is nothing specific to worry about, just a big blob of wet weather. Will be watching in case something does spin up …

Hurricane #Agatha making landfall in #Mexico today

The slowly moving Hurricane Agatha is making landfall on the west coast of Mexico this evening. Tropical storm force winds and heavy rain are already being felt on the Mexican coast, and conditions will worsen throughout the day. Here’s the latest impact forecast map using my TAOS/TC model, based on the official forecast:

Click to enlarge.

Agatha is a strong Category Two hurricane at 110mph (95 kt) winds. The forecast keeps it at that intensity, although it might barely make Cat 3 status before landfall. Either way that shouldn’t change the impact estimates much. Agatha is a small storm, but there are still around 1.5 million people in the potential damage swath. The economic impact estimate has decreased a little with the track and intensity forecast changes, now at about $200 Million USD.

It is not likely Agatha will survive long after landfall, and while some of the track models do take the remnants into the Gulf on the current track the dynamics of it being a recognizable storm just aren’t there. NHC is showing an area of potential development around the Yucatan Peninsula in a couple of days (the yellow blob on the five day outlook (link)). Some of the remnant moisture of Agatha might contribute to the development of that potential system. The GFS model has been persistent in forecasting a storm to spin up off the coast of Belize in three or four days, then track across Cuba and the Bahamas as it moves northeast, ending up between Bermuda and North Carolina in about 10 days. While of interest to modelers and long range forecasters, it’s WAY too early to speculate or get excited about it.

#Agatha rapid intensification

Wow, that changed quickly. This morning Hurricane Agatha (EP012022) has rapidly increased in organization and intensity …

Agatha – note the dark red (cold) cloud tops on the infrared image (left), and a swirl of an eye forming.
Click to embiggen.

Rather than landfall as a Category One hurricane, it is very possible it could be a Category Three storm as it hits between Puerto Escondido and Mazunte, in the Mexican State of Oaxaca. This has caused the forecast economic impacts to triple to almost $400 Million USD. Still seems unlikely for Agatha to survive to enter the Gulf of Mexico – it should stall out and rapidly decay over land. But with more energy/moisture available it’s more possible. Just goes to show that despite advances, these storms remain somewhat unpredictable, especially intensity forecasts.

Tropical Storm Agatha and #Mexico; Southwestern Gulf of Mexico

Agatha (EP012022) looks to make landfall near Puerto Escondido, Mexico tomorrow (Monday) evening as a minimal hurricane. There is some uncertainty in the intensity, the National Hurricane Center is being conservative and forecasting landfall as a 90mph storm but chances are it will be less than that. If the forecast holds it will affect around 1.5 Million people and have economic impacts of between $100 and $150 Million USD. Like many tropical storm hitting Central America, aside from the immediate coast the biggest risk is probably flooding and landslides from heavy rains. Here’s the latest (Sunday Morning) impact forecast:

Click to enlarge.

Elsewhere, NHC has flagged the southern Gulf of Mexico and the area just to the east of Belize as an area for the possible formation of a storm next week with the odds at 30%. This morning’s GFS run did show something developing off the coast of Belize in about 5 days, becoming a tropical system as it crosses Cuba, the Bahamas, and then exiting northeastwards towards Bermuda. It’s WAY too early to speculate about that – and notice that the NHC Five Day outlook does not have the magic words in it, so nothing to worry about at this point. It is important to keep in mind that while the longer range models are getting better, they still spin up imaginary storms far too often to get excited about them. Unless you are testing your new blood pressure medicine for hurricane season, then feel free 😛