Mid-August Hurricane Development Region Sea Surface Temperature Anomaly Update

According to the NOAA National Hurricane Center, there are two low pressure systems in the tropical North Atlantic with good chances of becoming tropical storms. See Figure 1. In fact, in the eastern part of the main development region, Tropical Depression 5 has formed.

UPDATE: In the time it took me to write this post, the NHC upgraded TD5 to Tropical Storm Erin. (Thanks, Ric Werme.)

atl_overview

Figure 1

This post illustrates that in early August 2013 there is nothing unusual about the sea surface temperatures we’re presently experiencing in the hurricane development regions. And, of course, since there are many other factors that impact tropical storms, this post allows you to comment on them in general and provide links to the monitoring and discussion websites you find noteworthy.

DATASET

We’re presenting the weekly Reynolds OI.v2 data–that is, the data for last week, centered on Wednesday. Reynolds OI.v2 data are available through the NOAA NOMADS website. There they use 1971-2000 as base years for anomalies.

Seasonal sea surface temperatures have been above the 26 deg C threshold of hurricane development for a couple of months, so there’s no reason to present absolutes, other than the map in Figure 2.

Figure 2

Figure 2

If you’re looking for longer-term illustrations of sea surface temperature anomalies for the following regions, see the May 19, 2013 post here.

CARIBBEAN ANOMALIES (10N-20N, 84W-60W)

One of the low pressure systems formed in the Caribbean. Sea surface temperatures there, Figure 3, are elevated (above the 1971-2000 reference), but they are not unusually warm.

Figure 3

Figure 3

MAIN DEVELOPMENT REGION ANOMALIES (10N-20N, 80W-20W)

The same could be said for the sea surface temperature anomalies of the Main Development Region, Figure 4, where Erin formed.

Figure 4

Figure 4

GULF OF MEXICO ANOMALIES (21N-31N, 98W-81W)

The National Hurricane Center is forecasting that the Caribbean storm will reach the Gulf of Mexico by Friday (tomorrow). Gulf of Mexico sea surface temperature anomalies are quite volatile, as shown in Figure 5. They were quite low earlier this year, but have since rebounded. And again, there’s nothing exceptional about their temperature anomalies last week.

Figure 5

Figure 5

EXTRATROPICAL U.S. EAST COAST (24N-40N, 80W-70W)

Sea surface temperature anomalies along the east coast of the U.S. interest people in the wake of Sandy. As shown in Figure 6, sea surface temperature anomalies there are slightly below normal.

Figure 6

Figure 6

As discussed last November, the sea surface temperatures for the extratropical portion of Sandy’s storm track have cooled over the past 70+ years. See the posts here and here. And we also discussed Sandy in the post here. We showed that lower troposphere temperature anomalies, specific humidity and precipitable water also haven’t increased along Sandy’s path for decades.

ENSO

El Niño events in the tropical Pacific suppress hurricane formation in the tropical North Atlantic. NOAA is forecasting ENSO-neutral conditions through the fall of 2013.

Sea surface temperature anomalies in the NINO3.4 region are a commonly used index for the timing, frequency and duration of El Niño and La Niña events. As illustrated in Figure 7, values there are slightly below zero. That is, we’re well within the +/- 0.5 deg threshold of El Niño/La Niña conditions.

Figure 7

Figure 7

YOUR TURN

What’s the story elsewhere?

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23 thoughts on “Mid-August Hurricane Development Region Sea Surface Temperature Anomaly Update

  1. TD 5 already has a name, Erin. See http://www.nhc.noaa.gov/ . From Public advisory 2A:

    DISCUSSION AND 48-HOUR OUTLOOK
    ——————————
    SATELLITE IMAGES INDICATE THAT TROPICAL DEPRESSION FIVE HAS
    STRENGTHENED AND IS NOW TROPICAL STORM ERIN.

    AT 800 AM AST…1200 UTC…THE CENTER OF TROPICAL STORM ERIN WAS
    LOCATED NEAR LATITUDE 14.5 NORTH…LONGITUDE 25.6 WEST. ERIN IS
    MOVING TOWARD THE WEST-NORTHWEST NEAR 16 MPH…26 KM/H. THIS
    GENERAL MOTION IS EXPECTED TO CONTINUE WITH SOME DECREASE IN
    FORWARD SPEED DURING THE NEXT COUPLE OF DAYS. ON THE FORECAST
    TRACK…THE CENTER OF ERIN WILL BE MOVING AWAY FROM THE CAPE VERDE
    ISLANDS LATER TODAY.

    MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 40 MPH…65 KM/H…
    WITH HIGHER GUSTS. SOME ADDITIONAL STRENGTHENING IS FORECAST DURING
    THE NEXT COUPLE OF DAYS.

    TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 35 MILES…55 KM…
    FROM THE CENTER.

    THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB…29.71 INCHES.

  2. El-Nino events supress hurricane formation… however, ENSO is neutral.

    So the question is, since hurricanes so far this year seem to have been suppressed: despite ENSO being neutral, can we take this as a sign that a new el-nino is setting in? And what does that mean for the rest of the hurricane season?

  3. Otter says:
    August 15, 2013 at 5:00 am

    El-Nino events supress hurricane formation… however, ENSO is neutral.

    So the question is, since hurricanes so far this year seem to have been suppressed: despite ENSO being neutral, can we take this as a sign that a new el-nino is setting in? And what does that mean for the rest of the hurricane season?

    No. El Niño is associated with increased wind shear, differing wind speed with height. That tends to blow off the tops of thunderstorms and reduces convection.

    If there’s been suppression of TS development this year, (June and July often have minor storm activity, especially in the Cape Verde area where Erin formed), the best thing to blame is dust coming from the Sahara. It blocks sunlight, thereby warming the upper air and slowing heating of the sea surface. That reduces convection and hence suppresses development. Further west of there, we’ve had a lot of dry air, which also suppresses development.

    To get a major hurricane, you really need to have all the attributes lined up. It can be amazing to see a Cat 5 storm ingest low level dry air and collapse down to Cat 1 or 2 within a day. That sort of event clobbers convection through the whole storm and has greater impact than wind shear.

  4. Erin will likely end up as Dorian 2.0. Heading into a stable and then hostile environment. Likely to peak in 48-60 hours as a moderate TS and decline thereafter. It might do something down the line in a week or so, but I wouldn’t bet on it. It has a long path through hostile territory. Not sure the entity in the NW Carib survives to get a name. Appears the mid level center will head north while any low level vorticity heads roughly west. I guess if the low level center festers long enough, it could get a name, but environmental conditions won’t get better for a few days. We’ll have to wait until later this month to start seeing legitimate threats to land masses.

  5. Normal water temperatures will create a normal event, which this time of year will be a normal hurricane which will do the normal thing, which is to intensify and take normal routes, one of which is normally up the east coast. However do not expect the media to treat it as anything that is normal. The headline “Things Normal” does not sell papers.

  6. Hmm, the additional links are pretty useful.

    I didn’t realize that the [Atlantic] tropical storms so far were not hurricanes. Reading and listening to the usual media outlets (poor practice, of course) the impression was a lot different.

    However, I did listen to a Joe Bastardi radio interview, and was a voice of reason regarding, I think, Dorian (living on the SE coast, hurricane watching is a pastime, but I’ve been lax this year).

  7. SJWhiteley says:
    August 15, 2013 at 5:42 am

    Yeah, the major outlets love ‘we’re all going to die’ headlines. It sells much better than “meh, pretty normal” so you’re going to get ‘We’re all going to die’ descriptions of even below normal events. Remember the ‘Year of the Shark’? If you read news stories it would have appeared that sharks had declared war on humans and the number of shark attacks were ‘unprecedented’ when, in actuality, the number of shark attacks that year were fewer than the years before. Again, ‘below normal shark attacks’ just isn’t going to generate a lot of clicks.

  8. Very off topic but worth a giggle

    UK Daily Telegraph
    “Climate change affecting apples’ taste
    Climate change may be affecting the taste and texture of apples by altering temperatures and rainfall levels, according to a new study. ”

    Reader Comment
    I’ve noticed several phenomena in recent years which can only be explained by AGW.
    My breakfast egg takes several seconds more to be just right, because the polar ice cap is melting, flowing down to us, and making tap water colder. I even had a bit of decaying polar bear come out of the shower head yesterday.
    Then, my car is becoming more difficult to start; my wife’s hair has gone grey (probably worrying about the homeless polar bears), and it’s rained three times today, and…………..

  9. The two most reliable models, IMO, are the GFS and ECMWF. The GFS is a product of NCEP and can be found all over the web, put why not go to the source:

    http://mag.ncep.noaa.gov/model-guidance-model-area.php

    The European model is harder to find in a user-friendly format, but this site has a nice display:

    http://moe.met.fsu.edu/tcgengifs/

    This site also has a real nice display of the GFDL and HWRF hurricane models that combines the track and wind intensity forecast in one graphic. I wouldn’t put a lot of stock in either one, but when they both agree, there accuracy is much higher.

    When I want a lot of information quickly, I go to http://www.spaghettimodels.com/

    But my first stop is always the National Hurricane Center:

    http://www.nhc.noaa.gov/

    These folks are still the best in the business. They have the most experience and best resources. Their discussions hit the important points quickly and their forecast track is almost always better than any individual model over the course of a season. They do, however, have a ‘big picture’ focus, meaning that they don’t concern themselves with the little wobbles and internal fluctuations that can have a big impact on any given location during a landfalling storm. That focus goes to the local forecasters and specialists.

    The NHC also has the best collection of tropical satellite imagery in about every format and color representation you could want:

    http://www.nhc.noaa.gov/satellite.php

    Enjoy!

  10. Ric Werme says:
    August 15, 2013 at 5:14 am

    Otter says:
    August 15, 2013 at 5:00 am

    ###

    Thanks for the wonderful answer to our mustalid friend’s question. I had the same one. Now I have another one, sorry if its stupid. Why are El Niños associated with increased wind shear? Now that I think about it, it seems that an El Niño condition would produce a region of warm moist (dense?) air. Is this correct and a factor?

  11. El Dorado Weather is a nice website. I’m able to zoom in on weather radar/sat here in the YYZ area using a combination of Buf doppler and the King City site north of Toronto. Covers the other gaps along the Canada/US border. Lots of other info links to the wider world.

  12. Naming anything that spins… got to love it…

    Can someone tell me when they changed criteria on naming storms?

  13. Solar activity governs the equator-pole gradients that dictate terrestrial circulation.

    Multidecadal Atlantic hurricane rates are controlled by the changing length of time-streaks during which sunspot numbers persist above & below a threshhold:

    (±40 SSN using annual SSN for this illustration)

    This is a simple measure of changes in how long the northern hemisphere maintains circulatory configurations that vary in central limit with the solar cycle.

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