hawkeye_wx Posted September 2, 2020 Share Posted September 2, 2020 The convection keeps getting shoved south of the center by stiff northerly shear, preventing it from strengthening into a hurricane. Link to comment Share on other sites More sharing options...
NorthHillsWx Posted September 2, 2020 Share Posted September 2, 2020 Yep, shear is going to win on this one. Levi’s discussion last night about the northerly shear imparted on the system by the ULL was spot on. Center has become exposed. Link to comment Share on other sites More sharing options...
CheeselandSkies Posted September 2, 2020 Share Posted September 2, 2020 @ldub23 this season. TBH I'm starting to get there, too and so are some others based on the state of the season thread lately. 3 Link to comment Share on other sites More sharing options...
Windspeed Posted September 2, 2020 Share Posted September 2, 2020 [mention=14667]ldub23[/mention] this season. TBH I'm starting to get there, too and so are some others based on the state of the season thread lately. In a nutshell, mid-range modeling has sucked this year for upper pattern features. Look at this GFS shear forecast when 99L (pre-Nana) was developing in the eastern Caribbean and tell me what you see and do not see? Edit: Might help if I post the right image. At any rate, it's probably unwise to bank on smaller upper anticyclonic features versus larger regional upper ridging. You can easily get burned when a small upper trough or pinched PV is underdone. Clearly the northerly shear was underdone in this case when trying to figure out potential setup three days in advance for 99L versus just having an overall larger / regional upper 200 hPa ridge. Even those don't always go perfectly. See: Laura with strong backflow upper convergence on the TC as it moved south of the Cuban shoreline. The following image is from 12z Sunday. 1 Link to comment Share on other sites More sharing options...
ldub23 Posted September 2, 2020 Share Posted September 2, 2020 44 minutes ago, CheeselandSkies said: @ldub23 this season. TBH I'm starting to get there, too and so are some others based on the state of the season thread lately. Nana is running into the problems they have all had. A struggle against shear and dry air. If i was told in june that we would have 15 named storms by sept 02 i would have laughed at anyone saying ace would be under 50. I am quite confident ace will be below avg for the season. 1 Link to comment Share on other sites More sharing options...
hawkeye_wx Posted September 2, 2020 Share Posted September 2, 2020 The new recon has the pressure down to ~994 mb, but the wind is meager. Link to comment Share on other sites More sharing options...
ldub23 Posted September 3, 2020 Share Posted September 3, 2020 Doing a bit more than i expected. Link to comment Share on other sites More sharing options...
NorthHillsWx Posted September 3, 2020 Share Posted September 3, 2020 Hurricane Nana Link to comment Share on other sites More sharing options...
Windspeed Posted September 3, 2020 Share Posted September 3, 2020 000 WTNT41 KNHC 030252 TCDAT1 Hurricane Nana Discussion Number 8 NWS National Hurricane Center Miami FL AL162020 1000 PM CDT Wed Sep 02 2020 After the center of Nana nearly became exposed during the late afternoon, a new burst of convection developed near and to the south of the center which has resulted in strengthening this evening. Very recently received data from an Air Force Reserve reconnaissance aircraft has indicated that Nana has become a hurricane. The plane has measured a peak 700-mb flight-level wind of 72 kt to the north of the center, and peak SFMR winds of 62 kt earlier this evening. These data support an initial intensity of 65 kt, making Nana the fifth hurricane of the 2020 Atlantic basin hurricane season. Since Nana should make landfall along the coast of Belize within the next several hours, little additional strengthening is expected before the center crosses the coast. Rapid weakening will occur after landfall, and the new 12 through 36 hour intensity forecast reflects this. The low-level center is likely to dissipate over mountainous terrain within 48 hours, if not sooner. Nana is moving just south of due west at about 265/14 kt. A low- to mid-level ridge to the north of Nana should keep it moving on a west-southwestward motion during the next day or so. The guidance enveloped has shifted slightly southward and the new NHC track forecast has been adjusted accordingly. KEY MESSAGES: 1. Hurricane conditions and a dangerous storm surge will spread onshore along portions of the coast of Belize within the Hurricane Warning area through early Thursday. 2. Tropical storm conditions are expected in the tropical storm warning areas in Belize, the Bay Islands, Guatemala, and the Yucatan Peninsula of Mexico through early Thursday. 3. Heavy rainfall with isolated maximum amounts as high as 8 to 12 inches could result in flash flooding in Belize, Guatemala, and portions of southeastern Mexico and the Yucatan Peninsula. FORECAST POSITIONS AND MAX WINDS INIT 03/0300Z 17.0N 87.5W 65 KT 75 MPH 12H 03/1200Z 16.8N 89.2W 50 KT 60 MPH...INLAND 24H 04/0000Z 16.4N 91.6W 30 KT 35 MPH...INLAND 36H 04/1200Z 16.0N 93.9W 20 KT 25 MPH...POST-TROP/REMNT LOW 48H 05/0000Z...DISSIPATED $$ Forecaster Brown Link to comment Share on other sites More sharing options...
the ghost of leroy Posted September 3, 2020 Share Posted September 3, 2020 trying to pull an ernesto 2 Link to comment Share on other sites More sharing options...
NorthHillsWx Posted September 3, 2020 Share Posted September 3, 2020 3 minutes ago, WxWatcher007 said: Once again, while the models did have a signal for development, virtually every global not named the Para GFS failed to develop a truly coherent tropical cyclone in the days leading up to development. The models continue to struggle across the board with regard to TC genesis. Something to really pay attention to as we move into the next two weeks where there are a lot of impulses in the flow. NHC earning their pay this season. Every one of their forecasts defied the models up until the very end for Nana. They’ve been incredible this season 4 Link to comment Share on other sites More sharing options...
JakkelWx Posted September 3, 2020 Share Posted September 3, 2020 Nana did the thing! Link to comment Share on other sites More sharing options...
hawkeye_wx Posted September 3, 2020 Share Posted September 3, 2020 Nana was upgraded when a burst of convection fired over the center, but now the convection has been sheared back south. Recon just made a final pass and found the pressure up and the wind down. 1 Link to comment Share on other sites More sharing options...
the ghost of leroy Posted September 3, 2020 Share Posted September 3, 2020 2 minutes ago, hawkeye_wx said: Nana was upgraded when a burst of convection fired over the center, but now the convection has been sheared back south. Recon just made a final pass and found the pressure up and the wind down. 2020’ing 1 Link to comment Share on other sites More sharing options...
Orangeburgwx Posted September 3, 2020 Share Posted September 3, 2020 Nana was upgraded when a burst of convection fired over the center, but now the convection has been sheared back south. Recon just made a final pass and found the pressure up and the wind down.So it will be a Nana-cane in post analysis Sent from my LML212VL using Tapatalk Link to comment Share on other sites More sharing options...
Floydbuster Posted September 3, 2020 Share Posted September 3, 2020 Shame there is no Belize radar. Link to comment Share on other sites More sharing options...
hlcater Posted September 3, 2020 Share Posted September 3, 2020 Yea 90% certain that Nana gets downgraded in post. Link to comment Share on other sites More sharing options...
NorthHillsWx Posted September 3, 2020 Share Posted September 3, 2020 4 hours ago, hlcater said: Yea 90% certain that Nana gets downgraded in post. Idk it looked pretty robust coming ashore... Saw a 61 mph sustained wind report noted in the advisory. Being the system was tiny the chance of that being in the strongest winds seems very remote Link to comment Share on other sites More sharing options...
Yeoman Posted September 3, 2020 Share Posted September 3, 2020 Yay for Belize! Link to comment Share on other sites More sharing options...
KChuck Posted September 3, 2020 Share Posted September 3, 2020 Na-na-na-na, Na-na-na-na, Hey-hey, goodbye! :-/ 1 1 Link to comment Share on other sites More sharing options...
SnowLover22 Posted September 6, 2020 Share Posted September 6, 2020 technically the same storm so ill put it here, looks the storm has reformed in the Eastern Pacific. Link to comment Share on other sites More sharing options...
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