GaWx

1. Maybe wx recon something? Just guessing 2. The 18Z GFS is the weakest for the SW Atlantic since way back to the 6Z June 15th run as it has virtually no closed LLC.

BULLETIN Potential Tropical Cyclone One Advisory Number 1...Corrected NWS National Hurricane Center Miami FL AL012024 400 PM CDT Mon Jun 17 2024 ...LOW PRESSURE AREA OVER THE BAY OF CAMPECHE EXPECTED TO BRING HEAVY RAINFALL THREAT TO PARTS OF THE WESTERN GULF COAST... ...TROPICAL STORM WATCH ISSUED FOR PARTS OF THE COAST OF TEXAS AND NORTHEASTERN MEXICO... SUMMARY OF 400 PM CDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...20.3N 93.2W ABOUT 380 MI...615 KM SE OF LA PESCA MEXICO ABOUT 470 MI...755 KM SE OF BROWNSVILLE TEXAS MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...NNW OR 345 DEGREES AT 7 MPH...11 KM/H MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: A Tropical Storm Watch has been issued for the Texas coast from Port O'Connor southward to the mouth of the Rio Grande. The government of Mexico has issued a Tropical Storm Watch for the northeastern coast of Mexico south of the mouth of the Rio Grande to Boca de Catan. —————- Potential Tropical Cyclone One Discussion Number 1 NWS National Hurricane Center Miami FL AL012024 400 PM CDT Mon Jun 17 2024 Satellite, surface, and aircraft data show that the center of the large low pressure area is over the Bay of Campeche with a central pressure near 1001 mb. The system currently does not have the structure of a tropical cyclone, as the associated convection is poorly organized and the maximum winds are located about 200-250 n mi northeast of the center. The various global models forecast this band of stronger winds to start moving onto the western Gulf coast on Wednesday, and a Tropical Storm Watch is required at this time. Thus, advisories are being initiated on Potential Tropical Cyclone One. The initial motion is 345/6. This general motion should continue for the next 24 h or so, although there could be some erratic motion due to center reformation. After that, the cyclone is expected to turn west-northwestward and westward on the south side of a mid- to upper-level ridge over the northern Gulf coast. This should steer the system into northeastern Mexico between 48-72 h. While there are differences in details due to the disorganized nature of the system, the track guidance is in good agreement on this general scenario. The global models suggest that some deepening of the central pressure could occur, although none of them currently forecast the system to tighten up into a classic tropical cyclone. Based on that, the intensity forecast calls for only modest strengthening. There is a chance than a small-scale vorticity center inside the large cyclonic envelope may develop enough convection to form a tighter wind core as suggested by the GFS, and based on this possibility the forecast has the system becoming a tropical storm in about 36 h. However, there is a chance the system will never become a tropical cyclone. issued. FORECAST POSITIONS AND MAX WINDS INIT 17/2100Z 20.3N 93.2W 35 KT 40 MPH...POTENTIAL TROP CYCLONE 12H 18/0600Z 21.1N 93.4W 35 KT 40 MPH...POTENTIAL TROP CYCLONE 24H 18/1800Z 22.2N 93.8W 35 KT 40 MPH...POTENTIAL TROP CYCLONE 36H 19/0600Z 22.9N 95.0W 35 KT 40 MPH...TROPICAL CYCLONE 48H 19/1800Z 23.4N 96.4W 40 KT 45 MPH...TROPICAL CYCLONE 60H 20/0600Z 23.8N 97.7W 40 KT 45 MPH...TROPICAL CYCLONE 72H 20/1800Z 24.0N 98.9W 30 KT 35 MPH...INLAND 96H 21/1800Z 24.0N 101.4W 20 KT 25 MPH...INLAND 120H 22/1800Z...DISSIPATED $$ Forecaster Beven

Outside of the GFS/GEFS, which to me don’t look impressive, the 12Z model consensus has only an open wave. I continue to predict this won’t become a TD with 90% confidence. But I’ll still keep watching the models and satellite images as in my mind it’s ~10% rather than 0% as I haven’t totally written it off just yet.

12Z UKMET: still has a TS NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 30 HOURS FORECAST POSITION AT T+ 30 : 22.8N 91.4W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 19.06.2024 36 23.6N 92.6W 997 36 1200UTC 19.06.2024 48 23.6N 95.0W 997 36 0000UTC 20.06.2024 60 23.3N 95.2W 995 40 1200UTC 20.06.2024 72 25.1N 98.9W 998 39 0000UTC 21.06.2024 84 CEASED TRACKING

Looks broad on models but chances still increasing for a TC: Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 AM EDT Mon Jun 17 2024 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: Southwestern Gulf of Mexico: Satellite imagery and surface observations indicate that a broad area of low pressure is forming over the Bay of Campeche. Environmental conditions appear conducive for additional gradual development, and a tropical depression or tropical storm is likely to form by midweek while it moves slowly westward or west-northwestward toward the western Gulf coast. Regardless of development, several days of heavy rainfall are expected across portions of southern Mexico and Central America, and these rains are likely to cause life-threatening flooding and flash flooding. Locally heavy rainfall is also expected to spread over portions of the northwestern coast of the Gulf of Mexico by the middle of the week. In addition, gale warnings have been issued for portions of the Gulf of Mexico, and more information on those warnings is available in High Seas Forecasts issued by the National Weather Service. Interests along the western and northwestern Gulf coasts should monitor the progress of this system. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate the system later today. * Formation chance through 48 hours...high...70 percent. * Formation chance through 7 days...high...70 percent. *This is now Invest 91L.

0Z UKMET: a little further north than the 12Z run; still has a TS NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 54 HOURS FORECAST POSITION AT T+ 54 : 23.6N 94.4W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 19.06.2024 60 23.5N 94.7W 998 35 0000UTC 20.06.2024 72 23.4N 95.6W 997 39 1200UTC 20.06.2024 84 24.9N 97.9W 999 38 0000UTC 21.06.2024 96 CEASED TRACKING

Based on the weaker trend today for the potential SW Atlantic low including the brand new 0Z model consensus, it wouldn’t surprise me if the NHC were to lower the 7 day 30% lemon to 20% soon. I’ve seen enough to feel confident that there won’t be a TC from this. The 0Z ICON, GFS, CMC, and UKMET have no TC from it.

Columbus, GA, was the hot spot of all major reporting stations in/near the SE with 100 today.

The 12Z Euro is weaker than the prior 3 runs with an open wave at hour 108 offshore the Carolinas. The associated pretty unimpressive rain is headed toward N SC/NC.

12Z models so far for low off SE US coast: -ICON has the low further west and this leads to a further SW track into C FL. It is a tad stronger than prior run but is still weak/likely not quite a TD. -GFS similarly comes in further SW into C FL; similarly weak to 6Z with a TD vs the TS of the 0Z -GEFS further S, less active, and not as wet as prior two runs -CMC weaker than the already weak 0Z with nothing closed into SC (similar track to 0Z) -UKMET no TC just like 0Z and unlike the TD that forms on yesterday’s 12Z just offshore Brunswick on Fri moving N to GA/SC border

The UKMET, which did very well last year, is about the same as the prior (May) run with dip to ~-0.9 vs -1.0 in May. Add ~-0.5 for best guess at RONI conversion and you get -1.4/high end moderate. It has 1+2 slightly less cool, 3 about the same, and 4 the least cool with ~-0.2. I’d label this prog neither Modoki nor east based but rather in-between for autumn at least.

Thankfully, we’re in June rather than August/Sept. The strongest I’ve seen on any model so far (which is GFS) is lower end TS. Per history that I posted yesterday, there hasn’t been a June TS hit on the SE US from the E or SE since way back in 1909 though there was a late May TS hit (on SC) in 2020 and another late May TS hit (on Jacksonville) in 2012. 6Z update: ICON weaker than prior run and back to no closed low. GFS is also weaker than its prior run but still has a TD landfall at GA/FL border. *Edit: Oops, I somehow missed Danny of 2021, which hit S SC as a 40 mph TS. That is the only June TS back at least to 1851 (per records) to hit SC from the E or SE. I just edited yesterday’s list of May/June analogs to include this.

0Z Euro weaker than 12Z so far off SE coast. Edit: The 0Z GEFS is much more active and wetter for the offshore SE low than the prior runs.

The 0Z CMC, GFS, and ICON all have a TC off the SE coast. But the 0Z UKMET, which had a TD on the 12Z, doesn’t.

The ICON went from virtually nothing on the 12Z to a nearly closed off low on the 18Z to a TS on the 0Z. It landfalls as what I think is a TD due to slight weakening near Brunswick.

2. Southwestern Atlantic Ocean: An area of low pressure could form by the middle part of next week a few hundred miles northeast of the central Bahamas. Some slow development of this system is possible thereafter while the system moves westward or west-northwestward. * Formation chance through 48 hours...low...near 0 percent. * Formation chance through 7 days...low...20 percent. Forecaster Blake 12Z/18Z GFS/Euro, 12Z UKMET, and 18Z ICON all show something threatening a portion of the coast between FL and SC Thu/Fri. There is moderate support for a WNW moving TD to TS moving ashore among the GFS/EPS members. Go to Tropical thread for more info.

Good call on first alerting us to this area in the SW Atlantic two days ago. 18Z GFS, Euro, and ICON also have something though the ICON does not quite close off to a TD as of the end of the run at 120 just before NE FL landfall.

I’ll be watching. But despite what the 12Z GFS and 5 of the GEFS members show, I’m not worried about it at this point. The consensus of the 12Z GFS, Euro, UKMET (see below) has a TC somewhere along the SE coast late next week. History of TC landfalls from the E or SE to SE US May-June: - 1873 minimal TS GA/FL border 6/2 - 1909 low end TS Ft. Lauderdale 6/28 - 1972: minimal STS Alpha Brunswick 5/27 - 1984 TD 1 St. Augustine 6/13 https://en.m.wikipedia.org/w/index.php?title=1984_Atlantic_hurricane_season&diffonly=true#/media/File%3A1-L_1984_track.png - 2012 high end TS Beryl Jacksonville 5/28 - 2016: TD Bonnie Isle of Palms, SC 5/29 -2020 50 mph TS Bertha Isle of Palms, SC 5/27 *Edit I somehow missed this one: -2021: 40 mph TS Danny Pritchard’s Island 6/28 ———————————- 12Z UKMET has TD at 150 just off GA that moves NNE to Tybee/lower SC GLOBAL MODEL DATA TIME 1200UTC 15.06.2024 NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 150 HOURS FORECAST POSITION AT T+150 : 31.1N 81.1W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 22.06.2024 156 31.9N 80.9W 1012 24 1200UTC 22.06.2024 168 33.8N 80.3W 1014 25

12Z UKMET is similar with 90L and with nothing in the GOM TCGwise fwiw.

More on the accelerated SLR along the SE US: “The rate of sea level rise (SLR) along the Southeast Coast of the U.S. increased significantly after 2010. While anthropogenic radiative forcing causes an acceleration of global mean SLR, regional changes in the rate of SLR are strongly influenced by internal variability. Here we use observations and climate models to show that the rapid increase in the rate of SLR along the U.S. Southeast Coast after 2010 is due in part to multidecadal buoyancy-driven Atlantic meridional overturning circulation (AMOC) variations, along with heat transport convergence from wind-driven ocean circulation changes. We show that an initialized decadal prediction system can provide skillful regional SLR predictions induced by AMOC variations 5 years in advance, while wind-driven sea level variations are predictable 2 years in advance. Our results suggest that the rate of coastal SLR and its associated flooding risk along the U.S. southeastern seaboard are potentially predictable on multiyear timescales.” https://www.nature.com/articles/s41612-024-00670-w https://www.nature.com/articles/s41612-024-00670-w/figures/1

0Z UKMET has nothing (TCwise) in the Gulf but still has the one offshore the E coast though it is weaker than what the 12Z had: GLOBAL MODEL DATA TIME 0000UTC 14.06.2024 NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 30 HOURS FORECAST POSITION AT T+ 30 : 36.5N 70.5W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 15.06.2024 36 37.8N 68.9W 1007 38 0000UTC 16.06.2024 48 40.5N 63.0W 1005 39 1200UTC 16.06.2024 60 45.7N 54.6W 1003 34 0000UTC 17.06.2024 72 CEASED TRACKING

Extra interesting map from my perspective because only area E of Miss. River with >200% of mean snowfall is narrow strip from E FL Panhandle to Charleston, SC. That was entirely due to one very rare storm, the SE coastal storm of Jan of 2018, the biggest since Dec of 1989. Keep in mind that most winters in that area have no measurable snow/sleet.

For Bay of Campeche next week, 12Z UKMET: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 162 HOURS FORECAST POSITION AT T+162 : 19.7N 93.0W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 20.06.2024 168 19.9N 93.1W 1002 34

For Invest 90L, 0Z had actually dropped it but 12Z UKMET got it back: TROPICAL DEPRESSION 90L ANALYSED POSITION : 30.2N 78.1W ATCF IDENTIFIER : AL902024 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 13.06.2024 0 30.2N 78.1W 1011 27 0000UTC 14.06.2024 12 31.9N 77.8W 1009 31 1200UTC 14.06.2024 24 32.2N 76.6W 1007 35 0000UTC 15.06.2024 36 36.6N 72.2W 1005 40 1200UTC 15.06.2024 48 39.1N 68.7W 1000 42 0000UTC 16.06.2024 60 45.2N 60.3W 998 37 1200UTC 16.06.2024 72 52.2N 53.2W 993 32 0000UTC 17.06.2024 84 POST-TROPICAL

The UKMET tends to be too low with winds. But OTOH as you mentioned, highest winds tend to be lower for same pressure due to spreading out as latitude increases.