Windspeed
-
Posts
4,164 -
Joined
-
Last visited
Content Type
Profiles
Blogs
Forums
American Weather
Media Demo
Store
Gallery
Everything posted by Windspeed
-
NW periphery of 97L's wave axis is now moving through the Windward Islands of the Lesser Antilles. Nothing immediately eye-opening yet. Convective showers and storms embedded in strong easterly flow around the wave. If something within the axis begins to fold, it's likely to be a tick east and not coming into range of radar until later this evening.
-
Nice post by Todd Kimberlain. My takeaway here would be AL98 staying relatively weak regardless of TCG until it begins to approach the Lesser Antilles. Lower steering flow will begin to align more with upper steering flow, which would likely allow the system to stack better vertically. The GFS has been a little wonky with convective feedback over the EPAC in the long-range, given some of the oddball convective spin-ups after Genevieve considering the shift of upper 200 hPa vorticity eastward; yet it continues to show a mighty large upper ridge / anticyclone developing over the Caribbean and GOM late in the period, which could spell trouble if a hypothetical TC is moving through the region. There is also a strong STJ that splits flow and ejects eastward over the Southern CONUS. That would seemingly decrease upper level westerlies over the NW Caribbean and GOM downstream. Again, this all means squat if there is no TC there to take advantage. I am still apprehensive of the GFS right now. So take the strong fantasy Caribbean runner with a grain of salt until we actually have a TC to track.
-
2020 East & Central Pacific Hurricane Season
Windspeed replied to jgf's topic in Tropical Headquarters
Actually I take that back. There is never an easier Category 5 call with a TC at TS intensity even with SHIPS values this ridiculous. The evolution of the vortex will still have most sway on how rapid it can accelerate spin. This is most dependent on convective structure; therefore, if the cyclone is faster at forming a very organized eyewall band versus prolonged competing convective cells, it might reach Cat 5. The issue is Genevieve only having roughly 60 hrs before atmospheric conditions decrease its MPI. So even though intensity modeling is very rapid with intensification, Genevieve may still not have time to iron out the internal structure of its vortex to fulfill an MPI above Category 4 before shear increases. I.e., atmospheric conditons may be near perfect out ~60 hrs, but Genevieve's structural evolution might still not be fast enough. At any rate, Cat 5s are never easier to forecast unless you already have a well-developed hurricane, adequate time and rapid intensification is already underway. -
2020 East & Central Pacific Hurricane Season
Windspeed replied to jgf's topic in Tropical Headquarters
That output is just ridiculous. Don't ever recall seeing 100% values for such large gains in a 48 hr period. Shear does increase in the late forecast period ~72 hrs; however, MPI is so high this may be one of those easier calls for a Cat 5. Hopefully it stays away from the southern Baja. -
In the short-term, the wave just east of the Lesser Antilles does have weak vorticity and increasing convection, especially on its SW axis. Some of last night's EPS showed potential development of this disturbance, though today's 12z ECMWF operational keeps this open into central America. The 12z UKMET and GEM operationals are much more forgiving and do want to produce a TC as it traverses the deep Caribbean. No need to mention the 12z GFS since @Idub23 has that covered into September. [emoji6]
-
12z ECMWF now runs a TC, presumably the AEW that just exited Africa, just north of the Antilles through the Florida Straits and deep into the Gulf. Extends WAR and builds heights. Obviously this is way out in fantasy long range, but we now have a major operational model coming into line with its ensembles. Was only a matter of time. Now we'll just have to be patient and see how TCG occurs and where. Additionally how the upper pattern will unfold as any potential systems reach the WATL. We are too far out to know if any particular potential TC will aligned under a favorable or unfavorable setup. A lot of variables and a lot depends on downstream TUTT evolution, split and where those upper heights build specifically. Overall takeaways should just be increased potential for a long-tracking TC out of the MDR and notable WAR extension.
-
-
Josephine's low-level center has finally succumbed to strong southwesterly shear and convection is now decoupled.
-
Long range European ensemble continues up...
-
Andy commenting on the EPS and Caribbean potential in the ~200 hr range. Note the powerful upper ridge being modeled over the Caribbean. Granted, the operationals do not have a TC under this feature yet. They may of course never. However, the EPS ensembles do and also have that upper ridge. Depending on TC placement, of course, that would support a powerful TC from the S. Bahamas to the NW Caribbean barring land interaction. Obviously this doesn't mean Jack Squat if there's no TC. But that's why you watch the ensemble packages for potential vorticity. At any rate, with MJO coming aboard in that range, this is all we've got until the ops do eventually start getting into closer range to better resolve something and we can see how those runs will start panning out.
-
You don't really focus on strength, you focus on signatures. That there are numerous possible tropical lows means potential increases for something to be somewhere favorable or unfavorable. At ~200 hrs all your looking for are potential low placements. Then you go back and analyze the possible upper environments for those areas. At some point an operational will start picking up on any one sig. At that range it is still a crapshoot, however. You're just looking for more potential area of interest and then analyze the pattern to keep looking for something to rear its ugly head in the ops.
-
Speaking of ensembles... [emoji102]
-
Then you would be failing to see or underselling the favorable atmospheric conditions that were developing over Hanna and over the western GOM. It just ran out of time to see that potential through.
-
Southwesterly flow is too strong in a few days. Josephine likely gets decoupled and dissipates. So I'd say those chances are slim to zilch.
-
That already occurred the last week of July and first week of August. We had a two week stretch that had two hurricane landfalls. Were conditions perfect for a major? No, but Hanna would have been a major given 6 to 12 more hours over the western GOM. It was a very well-developed hurricane intensifying right up to landfall with a symmetrical eyewall. Would that being a major hurricane at landfall really change the conversation about this quieter stretch? Not really in my opinion. We'd still have some struggling systems until conditions flip to more favorable in the coming weeks. Again, it's August 13th.
-
Are you seriously asking that question? Do you even read this thread? lol... Hell.... Kill me...
-
TAFB/NHC has issued a code yellow for a weak disturbance near the North Carolina coastline that is forecast to move ENE in the coming days with 20/30 probs. It does have weak mid-level vorticity and could take on more tropical characteristics in the coming days as the system moves out into the open Atlantic. ZCZC MIATWOAT ALL TTAA00 KNHC DDHHMM Tropical Weather Outlook NWS National Hurricane Center Miami FL 200 PM EDT Thu Aug 13 2020 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: The National Hurricane Center is issuing advisories on recently upgraded Tropical Storm Josephine, located over the tropical Atlantic Ocean several hundred miles east of the Lesser Antilles. 1. A low pressure area over eastern North Carolina is expected to move east-northeastward across the north Atlantic well to the south of New England and the Canadian Maritime provinces for the next several days. This system could acquire some subtropical or tropical characteristics during the next two to three days while it moves over warm sea surface temperatures. * Formation chance through 48 hours...low...20 percent. * Formation chance through 5 days...low...30 percent. Forecaster Beven
-
Has anyone said it was? Seems like most, including myself in recent posts, have gone to great lengths to cite the differences. Yet, ACE is still more than double climatological average for this date. It's also just Aug. 12th and we've had two hurricane landfalls in 2020 in addition to an ongoing TCG during an unfavorable period. You keep harping a specific operational model, in this case the GFS in the long-range, over and over again. I am uncertain why you are trying to climb upon this hill which to die. It's premature to do so a month prior to climatological peak. Counter arguments already established in this thread that we are in a less active period. It is too early to be locking down on a 240+ long-range operational output to make heads or tales of what will or will not occur versus just utilizing climatological modeling tools that such scenarios are better intended and better suited, such as ensemble precipitation guidance, long-range pattern and oscillation modeling, which do suggest a ramp up of activity across the Atlantic Basin in a few weeks.
-
Strong mid-level flow that has been tilting and displacing Josephine's mid-level vort from the low-level is forecasted to weaken this evening. There is already evident banding within the eastern MCS cloud canopy that is extending slightly more east of the vortex. Therefore, this strong flow may be beginning to back down now. A period of light shear should ensue the next 24 hours, some of that perhaps favorable to allow for some intensification before southwesterly shear increases over the system. Whether that buys enough time for more significant strengthening remains to be seen. Josephine does have a shot a Cat 1 intensity if it can establish a well-developed core over night. But it may not hold on to hurricane strength very long. Still, a nice little MDR TC to track until its inevitable demise in a few days.
-
000 WTNT41 KNHC 131453 TCDAT1 Tropical Storm Josephine Discussion Number 8 NWS National Hurricane Center Miami FL AL112020 1100 AM AST Thu Aug 13 2020 A just-received ASCAT overpass showed an area of 35-40 kt winds about 70 n mi north of the center of Tropical Depression Eleven, and based on this the cyclone is being upgraded to Tropical Storm Josephine with an initial intensity of 40 kt. Satellite imagery shows that the convective pattern associated with Josephine has become a little better organized since the last advisory, with a ragged central convective feature and a weak band in the northern semicircle. The initial motion is now west-northwestward or 295/13 kt. Josephine should continue this motion for the next several days as it moves toward a weakness in the western portion of the Atlantic subtropical ridge. The global models forecast the western end of the ridge to weaken even more after 72-96 h, which should cause the cyclone, or what is left of it by that time, to turn northwestward. The track guidance is tightly clustered, and the new forecast track lies a little to the right of the previous track and a little to the left of the consensus models. Some additional strengthening appears likely during the next 24- 36 h as Josephine moves through an environment of light vertical wind shear. After that, the cyclone is expected to encounter moderate to strong southwesterly shear as it approaches an upper-level trough over the southwestern Atlantic, which should cause at least some weakening. The new intensity forecast is adjusted upward for the first 72 h based on the current intensity. After 72 h, it shows weakening similar to the previous forecast, but not as drastic as the global models that show the storm degenerating to a tropical wave before 120 h. Josephine is the earliest tenth tropical storm of record in the Atlantic, with the next earliest tenth storm being Tropical Storm Jose on August 22, 2005. FORECAST POSITIONS AND MAX WINDS INIT 13/1500Z 13.7N 49.2W 40 KT 45 MPH 12H 14/0000Z 14.5N 51.1W 45 KT 50 MPH 24H 14/1200Z 15.8N 53.6W 50 KT 60 MPH 36H 15/0000Z 17.1N 56.3W 50 KT 60 MPH 48H 15/1200Z 18.5N 58.9W 50 KT 60 MPH 60H 16/0000Z 19.9N 61.3W 45 KT 50 MPH 72H 16/1200Z 21.3N 63.6W 40 KT 45 MPH 96H 17/1200Z 24.0N 67.0W 30 KT 35 MPH 120H 18/1200Z 27.0N 68.0W 25 KT 30 MPH $$ Forecaster Beven
-
Last night's ECMWF ensembles were picking up on a AEW in the 7-10 day range and developing it near the Northern Leeward Islands. To be honest, the operationals have not been the greatest this year on TCGs. The GFS op even ghosted a CA monsoonal gyre last week and went so far to produce a fantasy GOM hurricane over many consecutive runs. Odd fantasy TCGs aren't unusual, but entire monsoonal gyres are. They also have not handled positioning of upper 200 hPa vorticity well for convection. So the GFS may've just had that too far displaced east over the Caribbean. WPAC TCG has been off as well in the operationals. At any rate, complaining aside, I'm not sure if it's a lack of global flight data or just bad luck. We're still in the long range for improving pattern and environmental factors in the 10+ day range, however. You want to focus more on ensembles in the long-range and ops for short-term TCG. But even in the short-term, the ops haven't been great.
-
Isaias was a fast mover and the depth of the 26° isotherm is very anomalous off the SE CONUS this year. It's been a very hot Summer with limited cloud cover and few stalled boundaries, especially over the past 30-40 days. Everything on the shelf is above 26°C now based on AOML; and since the shallow layer for SSTs is only 25-30 meters at depth, it essentially is anomalously warm right up to the shoreline. Though keep in mind, the isotherm map isn't on the same scale, as the shallow shelf is only 50 meters deep at interaction with the Gulf Stream, where, at that point, it drops well below 100 meters on a much higher gradient extending ESE. This may also be throwing off the TCHP map as depth of 26ºC isotherm is one of the data sets along with immediate surface layer temperature profiles. In past years, the shallow shelf was hardly represented by the 26º isotherm. Perhaps in recent years this was changed in the way data was displayed; however, if the entire shelf is above that isotherm, it should still be represented in the immediate surface layer at ~30 meter estimate. Though Isaias' low level circulation was amplified by a tropical low level southerly jet on its eastern semicircle due to trough interaction, it was really moving too fast and had too small an RMW to do anything but perhaps upwell and push ~28°C water from 50+ meters depth down the shelf near the Gulf Stream. The immediate landfall area did cool a few degrees, but that appears to be rebounding fast due to hot days + clear skies. Also recall that Isaias only managed to regain hurricane intensity very near the South Carolina shoreline. Additionally, it remained rather devoid of convection on its southern semicircle and struggled to mix down higher winds until interaction with the coast. Its windfield only expand near landfall with influence of the low level jet and baroclinic enhancement up the Mid-Atlantic coast. In comparison, Hanna was a slow mover with a much broader low level circulation as it traversed the Central GOM and had a large region of persistent intense multi-convective systems that did a number on the shallow layer heat content, not to mention some extended upwelling. But that's been several weeks ago and, unsurprisingly, the Central and WGOM immediate shallow layer is running ~29-31°C again.
-
In a meteorological sense, it's called oceanic lag time. The ocean heat content always lags behind atmospheric mean temperature gain. It also takes time, even in the most favorable large scale patterns, for hurricane season to reach fruition.
-
If I read you right, you're calling for 2 hurricanes and 1 major hurricane the remainder of the season? I mean that's fine but you realize it's August 12th? Climatological favorability across the basin doesn't normally kick in until around August 20th-26th even in active years. I think a lot of folks fail to realize how quickly an unfavorable synoptic and environmental pattern can transition to favorable. Shear issues appear to be short-term. The hostile westerly upper level flow across the Caribbean is due to the current convective outbreak in the Eastern Pacific. However, more favorable upper 200 hPa vorticity will shift to over the Atlantic Basin by August 20th. Westerly windshear will decrease as the EPAC swings into a more suppressed regime. Likewise the strong easterly 700 hPa windbursts that have driven SAL will back down as Azores SPHP shifts into a more SER/WAR extended pattern (as is typical does this time of year). As such, the MDR will moisten for the September run. Sub-800 hPa to sea level pressures have already been running lower than climatological mean. All these factors within consideration, I think some folks are going to be taken surprise during the peak regardless of the active to hyperactive forecasts.
