cieldumort
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A vigorous tropical wave that has emerged off the coast of western Africa is attempting to merge with an active Monsoon Trof, and is poised to become a strong tropical low or tropical cyclone while tracking west to west-northwest at a fairly low latitude.
This feature has the backing of a wide array of TC genesis models, which is not surprising given its vigor, and the favorable environment it is in, and will likely continue to be in for the better part of its voyage west.
This wave has the potential to become a serious hurricane and should be monitored closely.
While not yet Invest tagged at the time of this entry, it will likely be assigned 90L or 91L within a few days, if not sooner. (Edit: This wave has been tagged as of 8AM Aug 13, 91L. Second edit: the original wave pictured above in the far eastern Atlantic has been reassigned 92L, and the westerner-most Low center assigned 91L.).
This is where to place best guesses on this wave's development potential. The sharing of medium to long range model output is also encouraged here.
At 10:30AM Aug 17 Invest 91L has become PTC NINE and the title has been updated. And at 5PM EDT Aug 17 NINE recon has found PTC9 is now a tropical storm, Harvey. - At the 5:00PM Advisory Aug 20, Harvey was declared a remnant wave. However, the wave of Harvey is entering a favorable region for regeneration.
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vpbob21
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The 00Z cycle of model runs seem to be trending weaker (although we haven't yet heard from the Euro). The does very little with it (although it really likes the wave behind it) and the 00Z is considerably weaker.
One thing that's a bit concerning is that the pattern in about a week should feature much more ridging in the western Atlantic than we have now with Gert so whatever kind of a system we have when it reaches 60-65W should have a chance to get much further west. Next couple days of model runs should be interesting to say the least.
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cieldumort
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Much confusion with what and where is 91L this morning. Forecasting this system is going to be a problem unless and until (more likely until) there is really something we can hang our hats on. And it also remains very possible that the most interesting parts of the broad area of low pressure that the original 91L wave is starting to merge with ends up being tracked as two distinct disturbances. (91L and 92L, for example).
NHC has shifted their initialization of 91L to the west this morning, now closer to the center of the low pressure trof, and less so the strong wave that just rolled off Africa, and which has not yet merged all that much with the trof. This will change subsequent model runs, probably not by a lot - but perhaps noticeably - from prior runs.
As of 7:45AM EDT, the '91L' wave axis was located near 24W from 05N to 21N, with low pressure centered along the axis near 13N 24W.
However, as of the 10:37AM EDT graphic update, '91L' was positioned at roughly 12N 30W.
And at 10:45AM EDT, had 91L centered at 12.5N 33.8W, and by the next graphical update, it could be this that is being tracked --- and this would be a very substantial repositioning of this Invest. Or, as noted above, we could have two separate Invests to track by this evening.
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cieldumort
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91L is now definitely being tracked as the westernmost Low center associated with the broad monsoon trof, with Invest 92L having just been assigned to the distinct wave to its east.
As of 15/14Z listed Invest 91L at 14.1N 41W with an estimated minimum surface pressure of 1011mb.
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doug
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the models have not really bitten on either 91 or 92L yet.
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doug
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doug
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GFS not interested in 91or 92L yet...others showing some development and solutions. Satellite representation does suggest that the time estimations for development rendered by NOAA are reasonable.
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doug
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cieldumort
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91L is looking better and better this afternoon. Since the upgrade last month, the 'new and improved' seems to be missing developments of systems that do develop, and over-hyping others that do not develop at all. I tend to think 91L is probably going to be another miss for the , despite it being historically one of the best genesis models.
When it comes to models so far this season, if a system has the DNA, I've paid more attention to the almost always bullish Canadian, because it is at least picking up on a cyclone, where others, including the , may have not.
12z Runs
The most recent run of the Canadian expects a TD by the time 91L crosses the Lesser Antilles, becoming a mid-grade trop storm by time 91L has traveled half-way across the Caribbean.
Of the hurricane specific models that tend to just run on the assumption that a feature has already, or will develop, the new and improved HWRF follows a similar track and intensity trend, while the new and improved HMON keeps 91L a sloppy Trop Storm through the Caribbean, at best.
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cieldumort
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WSI Calibrated EPS now showing a greater than 90% chance that Harvey regenerates.
While the runs should not yet be fully discounted, it is my personal opinion that the new (since the July 19 upgrade) has not performed as admirably with Atlantic tropical cyclones as might be desired, and even in the face of a dramatic convective resurgence this morning, the latest runs (20/0z, 20/06z and now the 20/12z) still do mostly nothing with now x-Harvey... maybe a TD crossing Belize, or forming in the extreme southern Bay of Campeche, at best. These runs now run entirely counter to the Euro, and defy the eyes.
Now awaiting the restarting of the TC-specific models HWRF & HMON. Run, runs, run.
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ftlaudbob
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Harvey looks alive and well.Should be an upgrade soon.
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Survived: 10 hurricanes in Rhode Island,Florida and the Yucatan of Mexico .
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ftlaudbob
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And just like that, it died out again.
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Survived: 10 hurricanes in Rhode Island,Florida and the Yucatan of Mexico .
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cieldumort
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Model consensus for south Texas this Friday is growing much more concerning. HWRF, HMON, , , GEM & Ensemble Members with almost 100% unanimity on a landfalling Texas hurricane Cat 1 to Major. Some runs hang it around just inland, others around the coast - with potential for very severe flooding if either of those scenarios verify (inland and/or coastal).
This is a few days out, and these runs can change. "Harvey" is not even yet a tropical cyclone again, so large shifts in track and intensity are quite possible. Image credits Tropical Tidbits.
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Prospero
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I'm starting to watch Harvey as a possibility to bring some weather to Tampa Bay. I know right now it doesn't appear to be likely, but the plots have been shifting our way more and more as time moves forward.
If nothing else we need rain. This is starting the time of year when almost the only rain we get is from tropical systems that visit.
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Gulfport Florida Webcam - Gulfport Florida Weather Station - Clearwater Beach Cams
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MikeC
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Been away for nearly two weeks, looking at Harvey it's really coming together quickly off the Yucatan, concerned it may slow down enough to increase a bit more than expected. Central Texas coastline (Matagorda?) appears the most likely for first landfall, I'd watch it as far east as New Orleans or mobile, but expect it a bit further west if it re-emerges in the Gulf.
I'm also watching 92L as a harbringer of where it may go as well.
It also may stall out over northeast Texas/Houston, which would bring a massive flooding event to the area.
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MikeC
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0Z has it landfalling near matagorda Saturday morning and slowly moving inland and curving east, dropping extremely large amounts of rainfall, slowly, though northeastern Texas to Alabama
0Z is stronger toward Brownsville.
A lot depends on the short term motion now that its in the gulf, more west now would indicate a south Texas landfall, more northerly would put it closer to Houston. With the center appearing a bit more north than the models initialized at, the latter seems a bit more likely.
Rainfall would be the big story, 24" of rain in some spots.
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MikeC
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Overnight model runs are extremely interesting, going to call out a few things not normally mentioned on this one.
6Z takes the system into Texas near Matagorda on Saturday morning as a cat 1 (although strengthening at landfall), and slowly meanders it around eastern Texas, near Houston on Monday morning, then scoots it along eastward into Louisana and MS dropping incredible amounts of rainfall. This model has only a single landfall and is rain heavy.
0z Euro takes the system in near the same place on Saturday, as a strong TS or Cat 1 hurricane, stalls it out over land, then back into the Gulf Sunday night where it restrengthens into a hurricane, it then crawls along the texas coast and is just offhshore of houston as a category 2 hurricane, again raining like mad in Texas, likely a cat 2 hurricane at the time, then landfalls near Port Arthur midday on Tuesday. Rainfall estimates are in excess of 20" in many areas of Texas.
landfalls in brownsville then hooks left into Mexico, seems less likely given current movement trends.
6z HWRF takes the system in as a 972mb hurricane (cat2), late Friday night, then basically stalls out over land in east Texas.
There is potential for rapid intensification before landfall with this system due to the position of the upper level low at the time (it's position relative to Harvey would enhance the spin)
The mesoscal model at the newer 3k resolution shows Harvey approaching the Eastern Texas coast as a category 5 (897mb) hurricane, https://www.tropicaltidbits.com/analysis...=0&ypos=342
Although the is not to be used as an intensity model and not a good tropical model, it is picking up the possibility that rapid intensification could happen.
In short from rainmaker to potentially major hurricane somewhere in Texas, slow moving (either on or offshore) would bring in crazy amounts of rain, and we hope it remains disorganized enough to not rapidly intensify before landfall. But those in Texas absolutely should be watching it, and for signs of strengthening, if RI were to happen there would not be much warning for it.
One good bit of news, most of the usual intensity models keeps the system below hurricane strength over the next 5 days. So the rainfall event is more likely than not, but the potential for intensification is there.
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MikeC
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12Z double landfall hit for Texas, first landfall north of Corpus, Saturday morning as a hurricane, loops through inland, slowly and exits back into the Gulf Tuesday, regains strength, another hurricane landfall near Galveston Wednesday morning, and raining still on Thursday.
rainfall though:
If its anything close to this it would be a disaster despite wind/surge.
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MikeC
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12Z Euro is slightly west, with landfall south of Corpus Cristi Saturday morning (cat 1/2 hurricane), then stall out just inland near San Antonio on Sunday, then exits back into the Gulf Monday, then crawls offshore of Texas and landfalls in Western Louisiana Wednesday Morning as a cat 3/2.
Ukmet 12Z takes it closer to Galveston,
12Z HWRF has a cat 2 landfalling near Corpus Cristi Friday night, then stalls it over San Antonio for days. HMON is similar.
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MikeC
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18Z so far, showing landfall as a cat 2 hurricane near Corpus Christi on Saturday morning, then moves inland south of San Antonio. (up to 102 hours out so far) This is a shift southwest a bit of earlier runs.
After this it slowly moves just south of the TX/MX border to the east and weakens, shifting the massive rain field a bit south, by Tuesday when the last run had it back over water, it still is over land in the 18Z run.
Toward Wednesday it's inland nearing the coast again, near the Tx/MX border. 180 hours out (next Thursday) it re-emerges into the Gulf, but it never really gets back together and another landfall occurs in Western Louisiana a week from Friday. Rainfall totals are still extremely high with this scenario as well.
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MikeC
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The hurricane models,
18z HMON has Harvey making landfall near South Padre Island as a category 3 (957mb) on Friday afternoon. This is a shift south from earlier runs.
18z HWRF shows Harvey making landfall near corpus Christi as a category 3 (958mb) on Saturday morning (pre-dawn hours) This is a shift north from earlier runs.
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MikeC
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0Z starting to come in, this one with a lot of recon data collected today.
Immediacy notice this change from earlier runs, it's a 985mb Hurricane by tomorrow night. Cat 2 by Friday morning (975MB) shifting a bit west then.
Landfall early Saturday morning as a cat 3 hurricane near Corpus Christi, possibly wobbling into Kennedy county. Then moving more northwest over Corpus Christi then inland, stalls out south of San Antonio until monday, (not as far west as the 18Z run) Early Monday it starts moving back east (slowly).
Tuesday morning it's back in the Gulf as a Tropical Storm, and slowly creeping northeast offshore goes back inland on Wednesday morning near port O'Connor. stays inland then moves into Louisiana Thursday. Lots of rain.
0z Canadian, stronger and further north than the prior run. landfall near S. Padre Island as a Cat 2 hurricane on Saturday morning.
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