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.

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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.
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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.

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Water temperatures up to 28-30 degrees C (82-86 F) over the main development region for the Eastern Pacific Basin.
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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

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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.

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Flash flood warnings along US-281 west of Corpus Christi this evening.
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Training rainfall over Galveston Island and inland east of Houston this evening. Some flooding possible from the rainfall if this persists.
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Graphic by the National Weather Service – Weather Prediction Center indicating likelihood for training rain bands and elevated flash flooding potential this evening.
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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

Flooding Rains Impacting Coastal Texas

Heavy rainfall and flash flooding continue to impact parts of Southeast Texas and the far northeast region of Mexico as tropical moisture sourced from the Caribbean shifts over the area.

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Lower atmospheric water vapor image showing deep tropical moisture streaming into Southeast Texas and northeast Mexico around a broad mid-level circulation (located over South Texas) Tuesday night. White to green is higher moisture content.
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Flash flood warnings in and north of Corpus Christi, TX Tuesday night as rainfall “trains” over the same areas for hours.
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Storm total rainfall (likely in the past 36 hrs) over the same region. Some areas have received up to an estimated 4-8 inches of rainfall.
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Storm Total Rainfall over the Houston Metro and surrounding areas. A core of heavy rainfall occurred today over far southeast Texas and southwest Louisiana. The Lake Charles radar (not shown) which is closer to this core and provides are more accurate estimate shows isolated 5-6 inches of rainfall in the area.

Corpus Christi International Airport has seen over 4.5 inches of rain since Monday night. Endinburg, TX has also seen about 4.5 niches since Monday morning where the heavy rain began earlier. Victoria, TX has seen close to 2 inches since Monday morning. More locally heavy rainfall and possible flash flooding is possible through Wednesday as further tropical moisture spreads over the region.

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One model forecast for precipitable water over much of Southeast Texas and western Louisiana during the day Wednesday. This is total of amount of liquid in the water column if all the water was precipitated out of the atmosphere. High values with available lift in the atmosphere to form precipitation indicates a high heavy rainfall potential.
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One model forecast showing total rainfall through midnight CDT Thursday. It indicates areas of heavy rainfall along the south-central Texas Coast. Where the heaviest bands of rain set up ultimately is unknown because of very fine scale variability, although areas near Corpus Christi appear to be the most favored, risking further flash flooding. Some areas could receive an additional 3-5+ inches of rain Tues night-Thursday.

Please avoid flooded roads as fast moving currents in unexpectedly deep water can sweep a vehicle away easily and roads may be washed out and unseen under the water. Keep track of the latest weather in your area prior to and while traveling as well.

–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.

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Hurricane Bud seen this morning by the GOES-16 satellite.
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A close up view of Hurricane Bud this morning after sunrise in the Mountain and Pacific time zones.
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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.

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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 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.

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

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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