Update on the Eastern Pacific Tropics

The North Pacific and North Atlantic appear to be fairly quiet as far as significant ocean storms. However, I wanted to make note of a likely developing tropical cyclone in the Eastern Pacific Basin (east of 140 W longitude). The US National Hurricane Center has pegged it with a 80% chance of development over the next 2 days before it moves northward toward much colder waters after Monday. It should be no threat to land at this time.

Developing tropical cyclone over the Eastern Pacific late-Saturday afternoon. Much cooler waters exist to the north, which can be noted by the thick layer of low clouds (known as “stratocumulus”) to the north of the red circle. These signify a “stable” atmosphere near the surface, not conducive for deep thunderstorm activity which tropical cyclones need to survive.
Saturday afternoon graphic by the National Hurricane Center showing the likely development region for the future tropical system during the next two days.

A couple of other tropical waves are ongoing east of the one mentioned above; one south of mainland Mexico, another offshore Central America. Numerical models indicate the two waves may merge and possibly form a tropical cyclone the second half of next week (after Tuesday). There’s also appears to be a favorable signal for elevated tropical cyclone development in the Eastern Pacific starting mid-week going into early the following week. Details become sketchy that far out of course, beyond the general pattern set up. The active pattern signals forecasters look for are 1) active monsoon trough…the convergence zone for abundant thunderstorm activity from Central America out over the very warm waters of the Eastern Pacific, 2) active Central American Gyre which provides thunderstorm complexes with mild spin as they move from land over open water, and 3) a low wind shear environment over the open ocean for systems to form without disruption. And with more cyclones means greater risk for landfall impacts as were seen with Bud and Carlotta. Waters over the basin continue to be abnormally warm (1-1.5 C/2-3 F above normal generally) relative to mid to late-20th century norms.

Water temperatures up to 28-30 degrees C (82-86 F) over the main development region for the Eastern Pacific Basin.
Water temperatures are running roughly up 1-1.5 C (2-3 F) above normal across the main development region of the Eastern Pacific. This is relative to the 1961-1990 baseline which I reference as global warming has warmed the oceans significantly since the mid to late-1970s.

So something to watch later next week for more significant impacts to either Mexico or the Southwest US for remnant moisture yet again.

–Meteorologist Nick Humphrey


Heavy rain and areas of flash flooding continue in Southeast Texas

Brief update. Parts of Southeast Texas continue to face locally heavy rain this evening. Things should begin to improve tomorrow, but more of the same through tonight unfortunately. Hidalgo County, TX along the border with Mexico (in the Rio Grande Valley) suffered significant flooding in multiple communities, including Weslaco and Mercedes. The Weather Channel showed live footage this afternoon of people wading in the water and cars driving through flooded roads (please do not ever do that!). See their news story on the events in Texas HERE. Rainfall is currently impacting portions of far south Texas and near Houston and Galveston which have yet to receive significant heavy rainfall.

Flash flood warnings along US-281 west of Corpus Christi this evening.
Training rainfall over Galveston Island and inland east of Houston this evening. Some flooding possible from the rainfall if this persists.
Graphic by the National Weather Service – Weather Prediction Center indicating likelihood for training rain bands and elevated flash flooding potential this evening.
Continental US - Longwave Window - IR
Thermal infrared image showing coldest (and therefore tallest) cloud tops over South Texas and the southeast Texas coast, where the strongest thunderstorms and heaviest rainfall is currently located (as of 7:30 pm CDT).


–Meteorologist Nick Humphrey

Major Hurricane Bud continues movement offshore Pacific Coast of Mexico; watching for tropical development near Central America

Hurricane Bud strengthened to a Category 4 hurricane on the Saffir-Simpson Wind Scale with maximum sustained winds of 130 mph overnight. The update released at 8 am PDT by the National Hurricane Center has now downgraded back to Category 3 with 125 mph winds. With ocean heat content (which accounts for warmth with depth) dropping off quickly farther to the north, Bud has likely begun a weakening trend which will likely take it below major hurricane status by tonight and weaken it to a minimal hurricane by tomorrow.

Hurricane Bud seen this morning by the GOES-16 satellite.
A close up view of Hurricane Bud this morning after sunrise in the Mountain and Pacific time zones.
Rapid drop-off in oceanic heat content as the Hurricane Bud moves north, closer to the Baja California Peninsula. Although surface waters in this region are running ~2 C above 1961-1990 averages, the depth of warm water is not supportive for a strong hurricane this early in the year.

As Bud approaches the southern tip of Baja on Thursday, rainfall and high surf will increase over the area. I expect tropical storm watches to be put up over southern Baja California Peninsula by this evening. The biggest threat to southern Baja will be locally heavy rain from rain bands and high surf. The system will likely be a dying tropical storm by the time it arrives near Cabo San Lucas Thursday night.

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Heavy rainfall from Bud will spread over the southern Baja Peninsula and into the southern Gulf of California Thursday evening thru Friday evening.

Again, still expecting a moisture surge up the Gulf to generate increasing monsoon showers and thunderstorms into northern Mexico and Southwest US this weekend. Watch out in these areas for potential flash flooding concerns.

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One model depiction of precipitation through sunrise Sunday. Depending on track, precipitation axis may be a bit farther west than this model predicts. Locally heavier showers and storms likely in southern Arizona and southwest New Mexico as well as mountainous terrain farther north in the Four Corners. Rainfall expected to increase Friday afternoon from Mexico.

Checking in on the Atlantic…there’s a very slight chance of tropical development in the western Caribbean during the next 5 days (20% according to the National Hurricane Center). However, regardless of development, it appears a pattern is setting up for a significant surge of deep moisture from the Caribbean into Texas early next week, potentially bringing significant rainfall and possibly flooding. Texas is currently facing growing drought conditions.

9-km ECMWF USA Cities Texas Total Precipitation 156
One model forecast for total rainfall through Monday evening. Much of the rain which falls in Southeast TX and Southwest LA will fall beginning Saturday. There’s a slight possibility it could be in association with a tropical system, so details may change among models, but more likely an “atmospheric river”, a connection of deep tropical moisture from the Caribbean moving into the region. Certainly flooding is a possibility, even with the drought or abnormally dry conditions spreading into Southeast and south-central Texas.
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High precipitable water plume expected to move from the tropics into Texas and Louisiana as forecast this weekend.

I’ll keep an eye on things, but regardless, I would be mindful of heavy rainfall in the forecast later this weekend and early next week if you live in Southeast Texas into Louisiana and perhaps farther north. I’ll keep an eye on things!

–Meteorologist Nick Humphrey.

Bud in the Eastern Pacific becomes a major hurricane well-offshore Pacific Mexico; threat to Baja late-week.

Hurricane Bud has continued its robust intensification, as expected, now a Category 3 hurricane (at 8 am PDT) based on satellite intensity estimates with maximum sustained winds of 120 mph and gusts to 150 mph.


The hurricane continues to show strong blow ups of thunderstorms with very cold cloud tops in its inner core region known as the “central dense overcast” or CDO Region indicating that it is continuing or organize and additional strengthening may occur during the day today into this evening.


As mentioned last night, given the thermodynamic environment (abnormally warm waters below unstable air above for air to rise), low wind shear (winds not increasing in speed with height so the low pressure system remains “vertically stacked”) and favorable poleward outflow (air from the surface low being sent up upper atmosphere and blown off generally northward and away, allowing surface low to intensify further), there’s little to stop Bud from strengthening further, except for the system itself. Unpredictable structural changes in its eyewall could inhibit further strengthening, but for now that doesn’t appear to be imminent. However, by tomorrow, the steering currents are forecast to slow down somewhat and its own powerful inner core may act as a “negative feedback” and cool the waters under it as a result of upwelling of colder water from greater depths not as well heated by sunlight. This will likely result in a gradual weakening. After this, it will also begin to traverse somewhat lower temperature waters already on the surface itself, limiting any opportunity for re-intensification as it approaches the Baja California Peninsula late-week. So an overall weakening trend should begin after Tuesday.144123_5day_cone_no_line_and_wind

It appears the hurricane’s tropical storm-force wind field will largely stay offshore the Pacific coast of mainland Mexico, although gusts of 40+ mph are certainly possible in gusts as the rain bands hug the coast line near Manzanillo and points with a couple hundred miles north and south over the next 48 hrs. The system should pull away from land the tropical storm watch area after Tuesday and the threat of locally heavy rain and gusty winds will diminish (rip currents and heavy surf will continue) and the threats will shift and increase for the Baja CA Peninsula. There has been a trend in some numerical models to track the to system more toward the southern tip of Baja or slightly towards the Gulf of California. Any track farther away from the open Pacific waters would mean more of its circulation over warmer waters (compared to the more open Pacific) for more thunderstorm activity to keep the system stronger in terms of winds, wave action and heavy rain. So far, given the decrease in ocean heat content and increasing wind shear, this still looks far more like a tropical storm event than a hurricane event for Baja and the possibly the southern Gulf waters. But this would still mean areas of heavy rain, flash flooding and landslides over mountainous terrain and wave hazards along coastal areas. In addition, if Bud moves more toward the Gulf, this may induce a stronger moisture surge up into the Southwest US, enhancing the monsoon flow pattern change and increasing thunderstorm activity.

9-km ECMWF USA Cities undefined undefined 168
One model depiction of the total precipitation over the Southwest US between Sunday evening (6/10) and next Sunday evening (6/17) local time. Much can change and will depend on the track of Bud, but if the system approaches the southern tip of Baja or moves into the Gulf of California a strong low-level moisture surge would result, bringing an unstable air mass for abundant thunderstorms to much of the Four Corners States over the weekend. Virtually all the US rain on this map and much of northern Mexico is forecast to fall beginning Friday night from the south.

While *again*, amounts will change depending on the track of Bud, some monsoon-related switch in air flow pattern is expected and if the moisture is as abundant as possible with a very abnormally warm Gulf + remnant moisture from Bud, folks living in the Four Corners region should watch forecasts specifics related to possible thunderstorms and locally heavy rainfall this weekend. Given the extreme to exceptional drought conditions in this region, the soils are likely very dry and hard and heavy rain which falls will not be absorbed as quickly as it would be otherwise (rainfall will help, but too much too soon is bad for rapid runoff). So details can only be found in future forecasts, but it’s something to keep in mind at the moment.


Follow updates as I get them on my Twitter and Facebook!

–Meteorologist Nick Humphrey

PS: I was just asked a question about the Eastern Pacific Hurricane Climatology compared to how things are going thus far in 2018. Numbers of systems thus far are listed with days, late or normal listed in parentheses). The normal values are based on 1971-2009 baseline. Still very early in the season and early season activity doesn’t necessarily provide clues to future activity.

Tropical Storms: 2 (2nd storm formed 16 days earlier than normal).

Hurricanes: 2 (2nd hurricane formed 34 days earlier than normal).

Major Hurricanes: 2 (2nd major hurricane formed 69 days earlier than normal).

For the North Atlantic, which is quiet at the moment (based on 1966-2009 baseline):

Tropical Storms: 1 (1st storm formed 45 days earlier than normal).

Hurricanes: 0 (normal until August 10th)

Major Hurricanes: 0 (normal until September 4th)


Bud Now a Hurricane and a Threat To Pacific Coast of Mexico

Bud is now a hurricane (Category 1 on the Saffir-Simpson wind scale as of this post) and expected to intensify as it moves over waters in the mid-80 F (28-29 C). With these very warm waters and weak vertical wind shear, I expect robust intensification during the next day or two. Steering currents will take take the system much closer to Mexico, making direct impacts by wind, wave action and rainfall likely vs. Aletta which stayed completely offshore. As a result, the government of Mexico has issued a tropical storm watch for a portion of the mainland Pacific coast from Manzanillo to Cabo Corrientes.

Hurricane Bud with its eye offshore Mexico rapidly intensifying at the 8 pm PDT hour.


The tropical storm watch covers the possibility that the tropical storm force wind field…with sustained winds of 39 mph or greater…may graze the coastal communities late-Monday through late-Tuesday. Based on the as the track suggests, the system could also threaten Baja California by the end of the week. The system will likely go through its period of robust intensification through the next 24-36 hrs. Based on satellite trends tonight and the upper-level environment, I think it becoming a Category 4 hurricane (130 mph+) is not out of the question. Satellite estimates suggests the system may be approaching Category 2 (96-110 mph) status already. A stronger hurricane could mean a larger wind field and higher waves threatening more of the Pacific coast.

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Model Forecast Total Precipitation through 5 am PDT Wednesday. One depiction showing potentially 10+ inches of rain impacting the tropical storm watch area the first half of the week.

While it is still too early to determine the full impact that Bud will have on the Baja Peninsula, given the abnormally warm waters, it will likely be an organized cyclone with rain bands and some wind, but yet likely to weaken thanks to increasing vertical wind shear farther north. Although there’s a likelihood Bud will become a major hurricane, its slow forward motion over the next few days may induce cold upwelling, inducing earlier weakening than would otherwise occur. I think the likelihood of a Bud bringing hurricane-force winds to the Peninsula as low at this time.

So anyone traveling to the mainland areas, be mindful of locally heavy rainfall, rip currents and strong winds in the tropical storm watch area Monday-Tuesday. The southern tip of Baja California will know more about their threats by Tuesday.

–Meteorologist Nick Humphrey

Tropical Storm Bud forms in Eastern Pacific Basin; Maliksi to move east of Japan

Tropical Storm Bud formed in the Eastern Pacific basin offshore Southwest Mexico Saturday afternoon. The cyclone is moving over sea surface temperatures in the mid-80s F (28-30 C) allowing for robust thunderstorms and modest vertical wind shear environment (winds are not increasingly rapidly with height). As a result, strengthening is expected over the coming 2-3 days and Bud is forecast by meteorological models to have a chance to become a hurricane early this week.



Tropical Storm Bud at 1:30 am CDT.

Unlike Aletta, which became a powerful, but harmless major hurricane out in the open ocean, Bud may be an unusual June threat to the Baja California Peninsula by the end of the week. Water temperatures are running a couple of degrees C above normal near the tip of the Peninsula and some models have suggested Bud may be a fairly strong system as it approaches. However, this is still very early and much depends on the track forecast. Flooding rainfall is certainly a more serious threat and I would give additional mention to an increasing likelihood of early initiation to the US Southwest monsoon caused by the tropical cyclone remnants surging moisture northward from the Gulf of California beginning next weekend. We’ll know more on the hazards to both Baja and the Southwest US by mid-week.

6-10 day Precipitation Outlook showing the probability for below, near, or above normal precipitation. The Southwest US in the middle of an ongoing extreme to exceptional drought.
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Hurricane Aletta as a Category 4 storm with maximum winds of 140 mph on Friday June 9, 2018.

Quick mention on a system in the Western Pacific. Tropical Storm Maliksi, which formed on June 8th, is forecast to move well offshore Japan through early this week. It may strengthen to a Category 1-equivalent typhoon Sunday (sustained winds as of this post, currently at 70 mph as analyzed by the Joint Typhoon Warning Center). In fact, it already appears to be nearing typhoon strength (74 mph+) based on its satellite presentation. Locally heavy rainfall from showers and thunderstorms in outer bands and high surf/rip currents likely the most significant hazards associated with the system as it advances offshore and becomes a non-tropical system.


Tropical Storm (possibly soon to be Typhoon) Maliksi due south of southern Japan Sunday afternoon local time (1:50 am CDT Sunday morning in the US).
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Heavy rain and tropical moisture surge from Maliksi forecast to mostly stay offshore and effect the coastal areas of Japan with moderate to locally heavy rain early this week.

–Meteorologist Nick Humphrey