The possibility of two hurricanes--or even one--in the Atlantic this week is diminishing, as the two tropical storms far out at sea are falling short of model projections and forecaster expectations. Meanwhile, two new systems in the Pacific could end up being significant, especially one in the Northwest Pacific that could threaten China and/or Taiwan as a typhoon next week.Karl now a depression
Downgraded on Wednesday morning after six days as a tropical storm, Tropical Depression Karl
is now clinging to life in the central Atlantic, still with some hope of strengthening. Located about 265 miles northeast of the Leeward Islands, Karl’s top sustained winds were just 35 mph as of the 11 am EDT Wednesday advisory
from the National Hurricane Center.Figure 1.
Visible satellite image of Tropical Storm Karl as of 1545Z (11:45 am EDT) Wednesday, September 21, 2016.
To say Karl has been unimpressive is putting it mildly. Karl’s peak winds since becoming a tropical storm on Thursday have yet to top 45 mph. Phil Klotzbach pointed out on Tuesday
that Karl was tied with Tropical Storm Dennis (1981) for having generated the least amount of accumulated cyclone energy (ACE) in its first five days for any Atlantic storm since satellite monitoring began in 1966. As we noted yesterday, Karl has been plagued by moderately strong wind shear and relatively dry air at middle levels of the atmosphere. Together, these have kept Karl’s showers and thunderstorms shunted well east of its low-level center, thus keeping the storm from gathering strength. For much of Karl’s life, wind shear had been stronger than expected--a frequent occurrence in the Atlantic this season. As NHC forecaster Lixion Avila put it
in a discussion this morning: “Global models have totally failed so far in forecasting the upper-level winds surrounding Karl. The upper-low near Karl which unanimously all models have been forecasting to weaken is still strong and producing shear over the cyclone.”
Karl is still expected to recurve toward the northeast around Friday, eventually accelerating toward an upper-level low in the North Atlantic. Our best track models now agree on keeping Karl southeast of Bermuda, most likely well to the southeast, where it may finally have a chance to intensify. Sea surface temperatures at that location are 1°C to 1.5°C above average
(1.8-2.7°F), and Karl will have left behind the tenacious upper low that’s hindered its growth. The official NHC forecast
brings Karl to hurricane strength for only a day, on Sunday, before it shoots northeast and becomes an extratropical storm. Less than half of the members of the 00Z Wednesday GFS and European model ensemble members bring Karl to hurricane strength, and I won’t be at all surprised if Karl never reaches that threshold. Figure 2.
Infrared satellite image of Tropical Storm Lisa as of 1445Z (10:45 am EDT) Wednesday, September 21, 2016. Image credit: NASA/MSFC Earth Science Office
.Lisa continues rolling through eastern Atlantic
Sprawling yet still fairly disorganized, Tropical Storm Lisa
is only slowly gaining strength in the eastern Atlantic, about 580 miles west-northwest of the Cabo Verde Islands as of 11 am EDT Wednesday
. Lisa’s top sustained winds are now 50 mph, with showers and thunderstorms scattered widely around its somewhat ill-defined center. Lisa continues on a well-predicted northwest track that will keep it safely away from land areas. Only a tiny fraction of ensemble members from the 00Z Wednesday GFS and European model runs bring Lisa to hurricane strength, and the official NHC forecast has Lisa peaking as a mid-strength tropical storm. Lisa’s location and satellite appearance on Tuesday bore a striking similarity to our last Tropical Storm Lisa, from 2010 (see embedded image at bottom).Figure 3.
Typical areas of tropical development in the Atlantic during October. Image credit: NOAA/NHC
.Elsewhere in the Atlantic: Quiet for now
There are no other areas of immediate concern in the tropical Atlantic. We’re now on the downswing of the Cape Verde season, so we can expect fewer systems to be traversing the region from Africa to the Caribbean. Recent runs of the GFS model have suggested that a low-latitude tropical wave could make this trek next week and strengthen in the Caribbean more than a week from now. As we head toward October, we’ll need to watch the Caribbean more closely, as this becomes a more favored area for development (see Figure 3 above).Figure 4.
Moisture from Post-Tropical Cyclone Paine (located just off the coast of Baja California) continues to funnel into southern California and Arizona, as shown in this visible satellite image from 1615Z (12:15 am EDT) Wednesday, September 21, 2016. Image credit: NASA/MSFC Earth Science Office
.Paine’s moisture heads into Southwest U.S.
With the headline “Paine goes away,” NHC discontinued advisories on former Hurricane Paine
on Tuesday night, as the rapidly decaying system continued on its northward path west of Baja California, Mexico. As of 11 am EDT Wednesday
, Post-Tropical Cyclone Paine was located near the central coast of Baja California, still bearing 35 mph sustained winds but lacking the showers and thunderstorms (convection) that would qualify it as a tropical depression.
Some of Paine’s moisture is feeding into the Southwest U.S., with additional moisture being shuttled into the area ahead of an upper-level trough. At 12Z (8:00 am EDT) Wednesday, the atmospheric sounding from San Diego, CA, showed 2.12” of precipitable water (the amount of water in a column of air over a particular point). This puts Wednesday morning in a tie for the largest amount of atmospheric moisture recorded in September at San Diego since soundings began in 1948. Welcome rains of 1” - 2”
have fallen in parts of Southern California’s high country since Monday. Even San Diego’s Lindbergh Field got in on the action, with 0.31” recorded
in the 48 hours through 8:00 am MDT Wednesday. It’s the heaviest rain observed there since May 5-6.Figure 5.
Infrared image of Invest 94E at 1600Z (noon EDT) Wednesday, September 21, 2016. Image credit: NOAA/NESDIS
.Next up in the East Pacific: 94E
The next in the seemingly endless string of systems in the East Pacific is Invest 94E
, located a few hundred miles southwest of Acapulco, Mexico. On its expected westward path over the next several days, 94E will benefit from warm SSTs (28-29°C) and a moist atmosphere (mid-level relative humidity of 70-75%), with light to moderate wind shear of 10 - 20 knots. As of Wednesday morning, 94E featured a large envelope of moisture and scattered convection but not much organization yet. Like Paine, 94E is likely to be pulled northward toward Baja California after a few days of westward motion. Another potential threat to East and Southeast Asia next week
Global models are suggesting that a tropical cyclone expected to form in the next day or two
several hundred miles east-southeast of Guam has a good shot at intensifying into a significant typhoon. This system is still a few days away from the Northern Philippines, Taiwan, and the South China coast. Any of these could be eventual targets, according to the 00Z runs of the UKMET, European, and GFS models. Further north, Japan was picking up the pieces after the departure of Typhoon Malakas
, which killed 2 people
and triggered widespread flooding and landslides across southern Japan.
We’ll be back on Thursday morning with our next update.
Bob HensonFigure 6.
Philippe Papin (University of Albany, State University of New York) says:
“#Lisa (2016) is a mirror image of Lisa (2010) occurring exactly 6 years ago in nearly the exact same location. Incredible. #tropics #dejavu”. Image credit: @pppapin