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2020 Hurricane Season (Atlantic & East Pacific)

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  • Registered Users Posts: 4,497 ✭✭✭auspicious


    High ocean heat content, low shear, humid mid levels. Perfect conditions for intensification, but shear is increasing now.

    Ah just spotted this reply.
    Thanks.


  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    auspicious wrote: »
    Thanks.
    I'm guessing the average temperature of the gulf in August year on year is around the same as it is today 30c. So that would be a commonality of nearly all previous hurricanes in the region. Does this mean that the low wind shear is actually the main catalyst driving the intensity?

    It's a very delicate balance of everything

    It's not so much the temperature of the sea surface but more the depth of the warm water, measured as something called Ocean Heat Content or Tropical Cyclone Heat Potential (kJ/sq. cm). This is a measure of how deep the 26-degree isotherm is. The deeper it is, the higher the OHC value and the lower the chance that the storm will churn up colder water from below, killing off its energy supply. Below is the OHC map for when Laura was undergoing rapid intensification. In general, values need to be >50 for RI to occur. You can see the colder pool east of its track, partly caused by TS Marco's presence a few days ago, but there are always warm and cold gyres of OHC present in the Gulf and so the exact path of a cyclone has a large effect on its strength.

    2020al13_ohcnfcst_202008260000.gif

    Windshear also has a large effect and is what killed off Marco in nearly the same area just a couple of days ago and most of the other storms this season too. The MJO moving to Phase 1 (Africa/Indian Ocean) has now reduced shear over the Atlantic in general, helping Laura and also probably leading to the development of the next named system, Nana, from a wave just coming off western Africa right now.


  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Cat 4 Laura made landfall a while ago near Cameron, LA, with max winds 130 kt/150 mph.


  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Lake Charles Airport. 74 gust 111 knots. It seems to have stopped reporting since.

    METAR:
    KLCH 270618Z AUTO 08074G111KT 1/2SM RA BKN009 OVC014 25/ A2867 RMK AO2 PK WND 070111/0612 LTG DSNT NE PRESFR P0013 T0250 $


  • Registered Users Posts: 32,634 ✭✭✭✭Graces7


    Cat 4 Laura made landfall a while ago near Cameron, LA, with max winds 130 kt/150 mph.

    Thank you; we have dear friends in Texas so are watching this closely.


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  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Graces7 wrote: »
    Thank you; we have dear friends in Texas so are watching this closely.

    I have family in Houston but they dodged the bullet. Winds are currently light there, no rain. A balmy night.


  • Moderators, Sports Moderators Posts: 15,656 Mod ✭✭✭✭dfx-


    Judging by the state of the tall buildings in Lake Charles, it could've destroyed Houston.

    It didn't really weaken at all in the end


  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Wow
    Hurricane Laura Tropical Cyclone Update
    NWS National Hurricane Center Miami FL AL132020
    300 AM CDT Thu Aug 27 2020

    ...EYEWALL OF LAURA PUSHING INLAND ACROSS SOUTHWESTERN LOUISIANA...
    ...CATASTROPHIC STORM SURGE, EXTREME WINDS, AND FLASH FLOODING
    ONGOING...

    The eyewall of Laura will continue to move inland across
    southwestern Louisiana during the next several hours. TAKE COVER
    NOW! Treat these imminent extreme winds as if a tornado was
    approaching and move immediately to the safe room in your shelter.
    Take action now to protect your life!

    The safest place to be during a major landfalling hurricane is in a
    reinforced interior room away from windows. Get under a table or
    other piece of sturdy furniture. Use mattresses, blankets or pillows
    to cover your head and body. Remain in place through the passage of
    these life-threatening conditions.

    A National Ocean Service tide station at Calcasieu Pass, Louisiana
    observed a water level rise of 9.19 ft Mean Higher High Water
    at 100 CDT.

    In Lake Charles, Louisiana, the airport reported a sustained wind of
    98 mph (158 km/h) with a gust to 132 mph (212 km/h) and a University
    of Florida observing tower reported sustained winds of 95 mph (153
    km/h) and a gust to 132 mph (2012 km/h) within the past couple of
    hours.

    A Weatherflow site in Cameron, Louisiana reported sustained wind of
    92 mph (148 km/h) and a gust to 117 mph (188 km/h) in the southern
    eyewall of Laura after the eye has passed overhead.


    SUMMARY OF 300 AM CDT...0800 UTC...INFORMATION
    LOCATION...30.2N 93.4W
    ABOUT 15 MI...25 KM WNW OF LAKE CHARLES LOUISIANA
    MAXIMUM SUSTAINED WINDS...130 MPH...210 KM/H
    PRESENT MOVEMENT...N OR 350 DEGREES AT 15 MPH...24 KM/H
    MINIMUM CENTRAL PRESSURE...946 MB...27.91 INCHES


  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Max reported gusts (mph)

    524440.JPG


  • Registered Users Posts: 6,675 ✭✭✭ronnie3585


    Have been watching Jeff Piotrowski and Reed Timmer stream all morning from Lake Charles. Scary stuff.


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  • Registered Users Posts: 1,386 ✭✭✭aidanodr


    Could we in any way end up with the tail end of Laura?


  • Registered Users Posts: 4,497 ✭✭✭auspicious


    ronnie3585 wrote: »
    Have been watching Jeff Piotrowski and Reed Timmer stream all morning from Lake Charles. Scary stuff.

    Furniture blowing out of wrecked skyscrapers "20/30 stories up...".


  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Surface station reports right at landfall this morning. Maximum measured mean wind I saw reported was 94 knots.

    sfcplot_13L_2020082706.png

    SFMR wind just at landfall was 113 knots at 05:41Z. The NHC has it at 130 knots at landfall from radar data.

    recon_AF300-2513A-LAURA_timeseries.png


  • Registered Users Posts: 1,386 ✭✭✭aidanodr




  • Registered Users Posts: 10,460 ✭✭✭✭MJohnston




  • Registered Users Posts: 17,822 ✭✭✭✭silverharp


    The authorities came out with a brilliant piece of persuasion , they told people if they didnt evacuate that they were to put their details and next of kin on paper and put in a zip lock bag and put in their pocket. Im sure that saved lives, very visual.

    A belief in gender identity involves a level of faith as there is nothing tangible to prove its existence which, as something divorced from the physical body, is similar to the idea of a soul. - Colette Colfer



  • Posts: 25,611 ✭✭✭✭[Deleted User]


    I have family in Houston but they dodged the bullet. Winds are currently light there, no rain. A balmy night.

    It might not happen in my lifetime but with how Houston has expanded the next really big one that hits it will cause incredible devastation.


  • Registered Users Posts: 17,797 ✭✭✭✭hatrickpatrick


    There are now two tropical waves in the Atlantic being watched for development. One of the reasons I've been predicting an active season this year is that there's a large area of suppressed convection off the African coast, which has the effect of delaying cyclogenesis (and thus northward curving) until the waves are further West. This was one of the main factors which caused the 2005 season to be so dangerous - tropical formation was suppressed in the East Atlantic and as such, waves didn't develop until they were either in or North of the Caribbean and under the influence of the Bermuda High, thus preventing them from curving harmlessly out to sea.

    One potential effect of this is that we might be a lot less likely to get an Ophelia / Lorenzo redux this year - conditions in that area of the Atlantic for storms to curve northward early enough to reach us before undergoing extratropical transition are too hostile at the moment. Of course, that could easily change as we go through the season (and both of those systems formed later in the year so that is not without precedent) but at the moment it looks less likely than in other recent years.


  • Registered Users Posts: 32,634 ✭✭✭✭Graces7


    I have family in Houston but they dodged the bullet. Winds are currently light there, no rain. A balmy night.

    Thank you for this. I just heard the same this morning. And they have a well-equipped and sturdy cellar.


  • Registered Users Posts: 9,230 ✭✭✭sdanseo


    The Atlantic is starting to look very busy with all these disturbances. Still the remnants of Laura knocking about around 40N as well not accounted for.

    SSTs at or above 28°C just about everywhere south of 35N as well.

    799583a236c9dd4a29bf74f70639a4ed.png
    9c588ac1922d04b740a1eeae8a5b707a.png


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  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    The recent activity has been due to a strong MJO pulse moving to Phase 1/2, which has formed anomalous low-level westerly winds across the Atlantic, reducing wind shear. The MJO is forecast to become weaker as it moves to Phase 3 in the coming days, which means less conducive conditions may fight against what is about to be the climatological peak of the season in the next two weeks.

    524827.JPG

    Overall, the northern hemisphere is running at around half the seasonal average of activity, and that's with the active Atlantic. The NW Pacific has been at only around 25-35% with regard to hurricanes and overall ACE.

    524828.JPG


  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    TD Fifteen has formed just off the Carolina coast but looks set to not amount to anything as it meanders generally northeastwards or eastwards over the next few days. Increasing windshear could cause it to dissipate sooner.
    Tropical Depression Fifteen Discussion Number 1
    NWS National Hurricane Center Miami FL AL152020
    500 PM EDT Mon Aug 31 2020

    Satellite images indicate that the area of low pressure offshore of
    the Carolinas has had convection organized in bands since before
    dawn, and scatterometer plus an Air Force Reserve Hurricane
    Hunter mission data confirm that the circulation is closed. Thus,
    this is now a tropical depression, and the initial wind speed is
    set to 30 kt in accordance with 25-30 kt ASCAT-A data plus buoy
    42001 readings which earlier had an adjusted 10-m peak of 30 kt.

    The depression is moving northeastward at about 10 kt. The system
    should gradually turn toward the east-northeast by Wednesday due to
    it moving around the northwest side of the subtropical ridge, then
    move eastward in a few days around the flat ridge. By late week,
    the cyclone could slow and eventually turn back toward the northeast
    around a rather strong mid-latitude high pressure system over the
    northeast Atlantic. There is considerable spread in the guidance,
    which really seems to depend upon whether the system stays coherent,
    like the official forecast, or would become a shallow low-level
    swirl by 120h and end up slower and south of forecast track. This
    forecast is near the corrected-consensus guidance, leaning toward
    the ECMWF-based models, and it should be considered of low
    confidence.

    Gradual strengthening is expected over the next day or so while the
    depression remains in a low-to-moderate shear environment. Although
    the depression is expected to be traversing the warm Gulf Stream for
    the next several days, wind shear is expected to greatly increase by
    Wednesday, which should limit intensification. In fact there's
    some chance the system could decay and lose any deep convection in
    rather strong shear in a few days. However, since it likely will be
    moving near the Gulf Stream, I suspect it will continue to pulse
    thunderstorm activity and stay alive throughout the period. The NHC
    intensity forecast is near or just above the model consensus on
    that reasoning, closest to the HWRF model. The cyclone could
    become extratropical (or a remnant low) by the end of the forecast,
    but this is very uncertain.


    FORECAST POSITIONS AND MAX WINDS

    INIT 31/2100Z 32.6N 76.5W 30 KT 35 MPH
    12H 01/0600Z 33.8N 75.0W 35 KT 40 MPH
    24H 01/1800Z 34.9N 72.4W 40 KT 45 MPH
    36H 02/0600Z 35.8N 69.7W 40 KT 45 MPH
    48H 02/1800Z 36.7N 67.0W 40 KT 45 MPH
    60H 03/0600Z 37.6N 63.7W 35 KT 40 MPH
    72H 03/1800Z 38.2N 60.5W 35 KT 40 MPH
    96H 04/1800Z 39.0N 55.0W 35 KT 40 MPH
    120H 05/1800Z 41.5N 49.5W 35 KT 40 MPH...POST-TROP/EXTRATROP


  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Potential Tropical Depression 16 is now being monitored and could briefly become Tropical Storm Nana as it moves westwards through the Caribbean this week, making landfall somewhere near Belize/Honduras.
    Potential Tropical Cyclone Sixteen Discussion Number 1
    NWS National Hurricane Center Miami FL AL162020
    1100 AM EDT Tue Sep 01 2020

    An Air Force Reserve reconnaissance aircraft is currently
    investigating the vigorous tropical disturbance located south of
    Jamaica that the NHC has been tracking the past few days across the
    Caribbean Sea. An earlier report of 35 kt winds this morning from
    ship MAOR4 is the basis for the 35-kt initial intensity on
    Potential Tropical Cyclone Sixteen. (PTC-16)

    The initial motion estimate is an uncertain 285/16 kt, based mainly
    on past scatterometer surface wind data and passive microwave
    satellite fix data. A strong deep-layer to the north of the system
    is expected to build slowly westward over the next few days,
    keeping the disturbance moving in a general west-northwestward to
    westward direction through 48 hours, followed by a turn toward the
    west-southwest shortly thereafter when the system will be inland
    over Central America. The NHC official forecast track lies close
    to a blend of the simple consensus models TVCN and GFEX, and the
    corrected-consensus model HCCA.

    The disturbance has already developed an upper-level anticyclone,
    with outflow only restricted in the northeastern quadrant due to
    northeasterly shear of about 15 kt. This modest northeasterly to
    easterly vertical wind shear is expected to gradually subside to
    less than 10 kt by 48 hours, which should allow for at least some
    slow but steady strengthening, given that sea-surface temperatures
    (SST) will be 29.5-30.5 deg C along the track. Occasional intrusions
    of dry mid-level air might hinder development for the next 24-36
    hours, but model guidance shows that the atmosphere is expected to
    moisten thereafter and right up until landfall. The official
    intensity forecast is similar to the consensus of the intensity
    guidance through 24 hours, and then is a little above the consensus
    at 36 h and 48 h due to the very warm waters, moistening atmosphere,
    and low shear conditions. The statistical SHIPS guidance suggests
    that the cyclone could reach hurricane strength just prior to
    landfall. This alternate scenario will be evaluated on the next
    advisory cycle.

    Due to the system's expected proximity to the north coast of
    Honduras and Roatan Island, a Tropical Storm Watch has been
    issued for those areas. Additional watches and possible warnings
    will likely be required later today for Guatemala, Belize, and the
    southern portion of the Yucatan Peninsula.


    FORECAST POSITIONS AND MAX WINDS

    INIT 01/1500Z 16.1N 77.5W 35 KT 40 MPH...POTENTIAL TROP CYCLONE
    12H 02/0000Z 16.4N 79.6W 35 KT 40 MPH...TROPICAL STORM
    24H 02/1200Z 16.6N 82.3W 40 KT 45 MPH
    36H 03/0000Z 16.7N 85.1W 45 KT 50 MPH
    48H 03/1200Z 16.8N 87.4W 50 KT 60 MPH
    60H 04/0000Z 16.5N 89.6W 25 KT 30 MPH...INLAND
    72H 04/1200Z 15.7N 91.7W 15 KT 15 MPH...POST-TROP/REMNT LOW
    96H 05/1200Z...DISSIPATED


  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    TD Fifteen has been named TS Omar but is expected to be short-lived as shear incresaes tomorrow, causing Omar to dissipate in the mid-Atlantic within 48 hours or so. Omar is the earliest 15th named Atlantic system on record, beating the previous one (Ophelia, 2005) by a week.

    Meanwhile, PTD Sixteen above has been named TS Nana as it moves westards to the southwest of Jamaica. Decreasing shear may get it to hurricane strength before landfall in Belize early Thursday.
    Tropical Storm Nana Discussion Number 3
    NWS National Hurricane Center Miami FL AL162020
    500 PM EDT Tue Sep 01 2020

    Although convection has waned somewhat since the previous advisory
    due to mid-level dry air entrainment, Nana still has enough deep
    convection over and surrounding the low-level center to keep the
    intensity at 45 kt. Upper-level outflow has continued to improve,
    with the associated anticyclone becoming more symmetrical. Another
    reconnaissance mission is scheduled for this evening.

    The initial motion estimate is 275/16 kt. There are no significant
    changes to the previous track forecast or reasoning. A pronounced
    deep-layer to the north of Nana is forecast to remain intact and
    even build westward over the next few days, keeping Nana moving in a
    general westward direction for the next 36 hours or so. Thereafter,
    the aforementioned ridge is expected to build west-southwestward
    across southern Mexico, driving the cyclone west-southwestward as
    well across northern Central America. The new NHC forecast track is
    similar to the previous advisory track, and lies close to a blend of
    the simple consensus models TVCN and GFEX, and the corrected-
    consensus models NOAA-HCCA and FSSE.

    The current northeasterly 15 kt of vertical wind shear and dry air
    intrusions should inhibit development for next 24 hours or so.
    However, the GFS and ECMWF models both forecast the shear to
    gradually decrease during the next 48 hours, becoming near 5 kt by
    36 hours. The lower vertical shear, coupled with the already
    impressive outflow pattern, sea-surface temperatures of 29.5-30.5
    deg C, and a moistening mid-level environment should allow for
    gradual strengthening for the next 24 hours, followed by more
    significant intensification thereafter, which will continue right up
    until landfall occurs. The NHC official intensity forecast is a
    blend of the simple consensus intensity model IVCN, and the
    corrected-consensus models NOAA-HCCA and FSSE.

    A Tropical Storm Warning and Tropical Storm Watch have been issued
    for the southern portion of the Yucatan Peninsula and the
    Caribbean Sea coast of Guatemala, respectively.

    KEY MESSAGES:

    1. Tropical Storm Nana is now forecast to be a hurricane as it
    approaches the coast, and interests in Honduras, Guatemala,
    Belize, and Yucatan should closely monitor the progress of this
    storm. Strong winds, dangerous storm surge and very heavy rainfall
    causing flash flooding are becoming more likely from Nana.


    FORECAST POSITIONS AND MAX WINDS

    INIT 01/2100Z 16.8N 79.3W 45 KT 50 MPH
    12H 02/0600Z 17.1N 81.5W 50 KT 60 MPH
    24H 02/1800Z 17.3N 84.7W 55 KT 65 MPH
    36H 03/0600Z 17.2N 87.3W 65 KT 75 MPH
    48H 03/1800Z 16.9N 89.4W 45 KT 50 MPH...INLAND
    60H 04/0600Z 16.5N 91.7W 20 KT 25 MPH...POST-TROP/REMNT LOW
    72H 04/1800Z...DISSIPATED


  • Registered Users Posts: 6,235 ✭✭✭Oneiric 3




  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Omar has now weakened into a tropical depression, though its structure has been torn apart overt the past 24 hours and it resembles nothing like a TD. It should become a remnant low in 24 hours or so.

    TS Nana is battling 15 knots of northerly shear and has not strengthened as expected. It is not not likely to reach hurricane strength before making landfall in Belize in about 8 hours. It's a small storm, with tropical force winds only extending max 60 nautical miles out from the centre.


  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    Nana just about made hurricane strength before landfall in Belize earlier this morning, though no actual hurricane-force winds were measured (62 knots max SFMR, 72 knots 700 hPa flight level). A dubious call but I suppose good for bumping up the seasonal stats.

    There are two tropical wave disturbances being watched at the moment. One is mid-way between Africa and the Windward Islands and has a low (30%) chance of developing into a tropical depression in the next 5 days. The other is just south of Cabo Verde and has a high (70%) chance of development.


  • Registered Users Posts: 17,797 ✭✭✭✭hatrickpatrick


    Getting busy out there, another tropical wave currently drifting over Africa has been added to the tropical weather outlook, and the development potential for the tropical wave midway between Africa and the Caribbean has just been upgraded as well. Still a week away from the peak, I'd expect the Atlantic to run out of names and begin using the Greek alphabet for only the second time in recorded history before the end of September at this point.

    aW329nw.png


  • Registered Users Posts: 8,219 ✭✭✭Gaoth Laidir


    The mid-level remnants of Nana crossed into the eastern Pacific and a new low-level circulation has formed there, named Tropical Storm Julio. Only the ECMWF model has picked up on this. Julio should not amount to much as it moves northwestwards and should dissipate in a few days.


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  • Registered Users Posts: 14,279 ✭✭✭✭M.T. Cranium


    In terms of total storm numbers, we are going to be ten days ahead of 2005's record pace when they name the Cape Verde system (it will get the R name, they skip Q). In 2005 Rita hit the Gulf coast in late September, after coming into existence on the 18th, ten days later than our likely R storm tomorrow, September 8th. Paulette broke Philippe's record (also 2005), by ten days.

    In terms of total hurricane activity, the season is almost a dud, five going on six if one of these two makes hurricane, and only one major (Laura).

    This is one of the lowest ratios of hurricanes to named storms of any season on record, especially in the higher portion of named storms, a low ratio is more typical of weak seasons in general.

    Note for anyone following the race with 2005, after the season an additional hurricane was added to the list between Stan and Tammy (the "Azores hurricane") so this year's T storm will be compared to that added one (Oct 4th), while this year's V storm (U is also skipped) will be compared with Tammy (Oct 5th), etc. The only letters in use after V are W then the Greek letters. The W storm is actually the 21st storm except that the one time it was needed (1933 pre-name-era would have run out at V) for Wilma, there was the eventual revision, so Wilma was the 22nd storm of 2005. Greek letters took that season to 28 named storms (it was 27 in real time before the Azores hurricane was inserted into the list).

    There is some possibility that we will arrive at the confusing scenario where this year's first Greek letter storm will come earlier than 2005 (Oct 22), but not earlier than Wilma (Oct 17th).

    As of 0300z 8th our count became 17/5/1 ... the only year that had a final count resembling that was last year, 2019 ended 18/6/3 ... only two years (1933 and 2005) made it much past 18 and their eventual counts were 28/15/7 (2005) and 20/11/6 (1933)... 1995 ended 19/11/5, 1887 was 19/11/2, 2011 19/7/4 and 2012 19/10/2/ and 1969 was 18/12/5. Worth noting that the average of those very active seasons (not incl 2019) was 20/11/4.5 ... so these strong seasons tend to average half their storms as hurricanes and almost half of those as majors.

    The only years with a lower ratio of majors to named storms is already all those with no majors -- since 1945, the only years with no majors were 1946, 1962, 1968, 1972, 1986, 1994, and 2013.

    At the point where this season might reach 18/6/1, the ratio of hurricanes to named storms will be 1/3. Back in 2013 a real futility record of 14/2/0 sets the benchmark, but otherwise, besides 2019, the only other seasons since 1981 to have the same (2013 was one in seven) hurricane to named storm ratio, one third, are low total seasons 1982 and 2009. (If we were to reach 18/5/1 we would be lower than all but 2013 but I suspect either Paulette will also be a hurricane or the S storm will be, then if Rene is a hurricane as predicted we would reach 18/7/1 or even 18/8/1).


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