GaWx

1. That was the crazy 0Z GFS. 2. 0Z Euro: for 1st run since the one from 48 hours ago, the model not surprisingly based on history/climo totally abandoned the come back to lower SC or GA NW move and instead is a more normal from that position NNE move from the ocean to the SC/NC border and then up the E coast to MD followed by a move offshore. It never moves even just W of due N the entire time once out of the Gulf except when it barely did so hours 96-102. That leaves only the GFS and the last CMC with the funky trek NW to WNW back into the SE. I’ll be looking for those to also abandon this craziness. Let’s see what the next runs of these models do.

0Z UKMET: LF slightly E of prior runs in W Big Bend; then to SC GA to SE of Augusta, then E/NE to NE SC, E NC, NC coast, Newfoundland; once again, UKMET moves much more quickly than GFS/Euro and gets to NC by 108…so again not the huge flood threat of GFS/Euro on this much more common path: TROPICAL STORM DEBBY ANALYSED POSITION : 23.5N 83.2W ATCF IDENTIFIER : AL042024 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 04.08.2024 0 23.5N 83.2W 1006 31 1200UTC 04.08.2024 12 26.6N 84.1W 1003 45 0000UTC 05.08.2024 24 28.4N 84.3W 1000 46 1200UTC 05.08.2024 36 29.8N 84.2W 1000 39 0000UTC 06.08.2024 48 31.0N 83.6W 1002 34 1200UTC 06.08.2024 60 33.0N 82.3W 1000 41 0000UTC 07.08.2024 72 33.0N 81.6W 996 40 1200UTC 07.08.2024 84 34.0N 79.4W 994 40 0000UTC 08.08.2024 96 34.4N 77.6W 993 39 1200UTC 08.08.2024 108 35.6N 75.4W 995 45 0000UTC 09.08.2024 120 38.9N 73.4W 997 39 1200UTC 09.08.2024 132 41.4N 69.8W 996 43 0000UTC 10.08.2024 144 45.5N 61.7W 997 39 1200UTC 10.08.2024 156 48.9N 50.0W 996 39 0000UTC 11.08.2024 168 52.5N 32.8W 992 39

Once again, the GFS goes offshore and then comes back to the coast (5th run in a row), this time just S of me (furthest S yet I think) giving me TS wind gusts combined with the very heavy rain probably causing many uprooted trees. I need a generator.

Tropical Storm Debby Discussion Number 7 NWS National Hurricane Center Miami FL AL042024 1100 PM EDT Sat Aug 03 2024 NOAA and Air Force Reserve Hurricane Hunter aircraft have been investigating Debby during the past few hours and have found that the winds have increased slightly and the central pressure has fallen. The NOAA P-3 plane reported SFMR measurements of 35-40 kt east of the center over the Straits of Florida, and dropsonde data indicate that the central pressure has fallen to 1003 mb. The initial intensity is therefore raised to 40 kt. Debby is gradually turning toward the right and slowing down, and the initial motion is northwestward, or 320/12 kt. A large mid- to upper-level trough over the eastern United States has created a break in the subtropical ridge, which will cause Debby to move northward over the eastern Gulf of Mexico and approach the Florida Big Bend region over the next day or two. The track guidance is in good agreement during this period, and the NHC track has only been shifted slightly east to account for a slight relocation of the initial position based on the aircraft data. After 2-3 days, the steering currents around Debby collapse, and the cyclone is expected to creep northeastward at less than 5 kt across northern Florida to near the coasts of Georgia and South Carolina by day 5. While there is model disagreement on exactly where Debby will end up on day 5, there is high confidence that the storm will not be moving very fast, and this slow motion will have major implications for the associated hazards, particularly heavy rainfall and flooding. Low vertical shear and very warm waters (as warm as 32 degrees Celsius within Apalachee Bay) are likely to support additional strengthening while Debby approaches the Florida Big Bend. The intensity guidance has increased a bit on this cycle. Most of the regional hurricane models are showing Debby reaching hurricane strength before it reaches the coast, while the statistical-dynamical SHIPS and LGEM models have increased to the 75-80-kt range. In addition, the Rapid Intensification indices are showing a 1-in-3 chance of a 45-kt increase in intensity over the next 36 hours. Based on these model data, the NHC intensity forecast has been increased to 75 kt in 36 hours, just before the center of Debby is expected to reach the coast. Weakening is anticipated after landfall, but Debby's intensity on days 3 through 5 is highly uncertain and is dependent on whether the center moves over the Atlantic waters and for how long. FORECAST POSITIONS AND MAX WINDS INIT 04/0300Z 24.4N 83.6W 40 KT 45 MPH 12H 04/1200Z 25.9N 84.2W 50 KT 60 MPH 24H 05/0000Z 27.8N 84.3W 60 KT 70 MPH 36H 05/1200Z 29.3N 84.0W 75 KT 85 MPH 48H 06/0000Z 30.3N 83.3W 55 KT 65 MPH...INLAND 60H 06/1200Z 31.0N 82.4W 40 KT 45 MPH...INLAND 72H 07/0000Z 31.2N 81.5W 40 KT 45 MPH...INLAND 96H 08/0000Z 31.6N 80.2W 45 KT 50 MPH...OVER WATER 120H 09/0000Z 33.0N 80.5W 40 KT 45 MPH...INLAND

Tropical Storm Debby Advisory Number 7 NWS National Hurricane Center Miami FL AL042024 1100 PM EDT Sat Aug 03 2024 ...DEBBY A LITTLE STRONGER... ...HURRICANE AND STORM SURGE WARNINGS IN EFFECT FOR THE BIG BEND REGION OF FLORIDA... SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION ----------------------------------------------- LOCATION...24.4N 83.6W ABOUT 50 MI...80 KM WSW OF THE DRY TORTUGAS ABOUT 260 MI...415 KM SSW OF TAMPA FLORIDA MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...NW OR 320 DEGREES AT 14 MPH...22 KM/H MINIMUM CENTRAL PRESSURE...1003 MB...29.62 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Storm Surge Warning is in effect for... * Florida coast from Aripeka northward to Indian Pass A Storm Surge Watch is in effect for... * Florida coast from Bonita Beach northward to Aripeka, including Tampa Bay and Charlotte Harbor A Hurricane Warning is in effect for... * Florida coast from the Suwannee River to the Ochlockonee River A Hurricane Watch is in effect for... * Florida coast west of the Ochlockonee River to Indian Pass * Florida coast south of the Suwannee River to Yankeetown A Tropical Storm Warning is in effect for... * The Florida Keys west of the Seven Mile Bridge including the Dry Tortugas * Florida coast south of the Suwannee River to East Cape Sable * Florida coast west of the Ochlockonee River to Indian Pass A Tropical Storm Watch is in effect for... * The Florida Keys north of the Seven Mile Bridge to the Channel 5 Bridge * Florida coast west of Indian Pass to Mexico Beach At 1100 PM EDT (0300 UTC), the center of Tropical Storm Debby was located near latitude 24.4 North, longitude 83.6 West. Debby is moving toward the northwest near 14 mph (22 km/h). A turn toward the north is expected on Sunday, followed by a slower motion toward the northeast on Monday and Tuesday. On the forecast track, the center will move across the eastern Gulf of Mexico through Sunday night and reach the Florida Big Bend coast Monday morning. The center is then expected to move slowly across northern Florida and southern Georgia Monday and Tuesday. Data from NOAA and Air Force Reserve Hurricane Hunter aircraft indicate that maximum sustained winds have increased to near 45 mph (75 km/h) with higher gusts. Additional strengthening is forecast, and Debby is expected to become a hurricane by Sunday night, before it reaches the Florida Big Bend coast. Weakening is expected on Monday and Tuesday after Debby moves inland. Tropical-storm-force winds extend outward up to 140 miles (220 km) from the center. Wind gusts to 49 mph (80 km/h) and 48 mph (78 km/h) were recently reported at the Key West Naval Air Station and Key West International Airport, respectively. The minimum central pressure based on dropsonde data is 1003 mb (29.62 inches).

Sudden pop-up resulting from an outflow boundary giving me heavy rain. Not at all what I need in advance of Debby. I ended up with ~0.5”, bringing me to ~0.75” MTD.

I’m quite concerned here, especially due to the threat of 10”++ of rainfall over a several day period, especially after having received 9” over the last 15 days. Besides flooding, even TS force winds could lead to many uprooted trees due to an already wet ground. In all of my years of following models of tropical systems coming to the area, this is among the wettest I’ve seen on so many runs, especially Euro and GFS. But a good portion of the extreme rainfall progs would depend on the crazy left turn back to the NW. If that doesn’t happen, we probably wouldn’t be as bad off. Edit: Just what I don’t need in advance of Debby, I’m now getting a heavy shower from convection that just popped up along an outflow boundary.

Thanks. Keep in mind that I’m only talking about TCs that earlier crossed NW FL.

That’s not what I’m saying. I’m saying sharply turning around NW back into the SE coast like the 18Z GFS, earlier GFS/Euro, and many GFS/Euro ensemble members do. But you’re right about what you said.

I looked over past tracks of TCs back to 1851. Of those that moved from the GOM inland over W FL N of Tampa through the panhandle, I couldn’t find even one that then moved offshore SE US followed by a curl back NW back into the SE coast like the last few Euro/GFS runs. The closest I could find is Easy of 1950, which could have done it had it first gone offshore FL before curling back: So, whereas climo doesn’t tell me a curl back NW into the SE coast a la GFS/Euro can’t happen, it does tell me to not be surprised if that ends up not happening and to almost expect it to not.

These and others suggest 12Z Euro has just about as bad a huge rainfall total for SAV-CHS (15”+) (slightly lower most of corridor but still with insane max ~22”centered on HHI/Beaufort). Also, again a cat 1 H hits CHS.

True and that is encouraging although CC has favored increased max rainfall due to combo of some slowdown in avg speed of movement and higher dewpoints. Thinking about Harvey, Florence, Allison, etc.

Our saving grace would be for a UKMET type of movement, which has it already in NC by 120.

12Z UK: similar to 0Z with LF just E of Apalachicola; then NNE move to WC GA, then ENE/E to CHS, then turns up coast NNE into E NC followed by NE through VA, NE US, SE Can: not as bad flood threat vs other models due to less slowing SE US followed by accel. with it already in NC at 120 vs near GA/SC border GFS/CMC/0Z Euro: TROPICAL DEPRESSION 04L ANALYSED POSITION : 21.9N 81.3W ATCF IDENTIFIER : AL042024 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 03.08.2024 0 21.9N 81.3W 1010 27 0000UTC 04.08.2024 12 24.2N 84.0W 1007 31 1200UTC 04.08.2024 24 26.2N 84.7W 1005 40 0000UTC 05.08.2024 36 27.8N 84.9W 1002 46 1200UTC 05.08.2024 48 29.1N 85.1W 1002 45 0000UTC 06.08.2024 60 30.3N 84.6W 1003 30 1200UTC 06.08.2024 72 32.0N 83.9W 1003 37 0000UTC 07.08.2024 84 32.6N 82.4W 997 38 1200UTC 07.08.2024 96 32.6N 80.2W 996 37 0000UTC 08.08.2024 108 33.0N 79.4W 995 40 1200UTC 08.08.2024 120 34.6N 78.8W 996 43 0000UTC 09.08.2024 132 35.8N 78.1W 998 36 1200UTC 09.08.2024 144 37.7N 76.2W 1000 44 0000UTC 10.08.2024 156 42.2N 72.2W 999 36 1200UTC 10.08.2024 168 47.2N 66.3W 996 35

0Z Euro: similar track to 12Z but stronger with it coming back into CHS at 986 mb vs 989 on 12Z; biblical rainfall amts of 20-24” mainly over ~72 hr period SAV-CHS and inland to 50 miles Lowcountry

0Z UK: landfall just E of 12Z’s Apalachicola; then goes inland further W into C GA then turns E to CHS, goes up SC coast and then well inland into NC; flooding threat many areas: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 24 HOURS FORECAST POSITION AT T+ 24 : 23.5N 83.7W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 04.08.2024 24 23.5N 83.7W 1007 28 1200UTC 04.08.2024 36 25.7N 84.8W 1006 34 0000UTC 05.08.2024 48 27.4N 85.5W 1004 43 1200UTC 05.08.2024 60 28.8N 85.3W 1003 42 0000UTC 06.08.2024 72 29.9N 84.4W 1002 35 1200UTC 06.08.2024 84 31.4N 84.2W 1001 36 0000UTC 07.08.2024 96 32.5N 83.3W 997 37 1200UTC 07.08.2024 108 32.5N 81.1W 996 41 0000UTC 08.08.2024 120 32.8N 79.9W 994 43 1200UTC 08.08.2024 132 33.8N 79.5W 996 41 0000UTC 09.08.2024 144 35.3N 78.4W 998 39 1200UTC 09.08.2024 156 36.4N 78.5W 1001 38 0000UTC 10.08.2024 168 37.4N 76.6W 1002 36

Ok. Yes, you’re correct. 1007 mb into Big Bend. Strongest yet into Big Bend.

No, I see 989 at CHS. I don’t know what you’re looking at.

I agree that the very heavy rain threat is as of now the biggest danger from this. But even if you have just TS winds, the tree uprooting would be very bad.

It took awhile but it’s just started raining here with CTG lightning pretty closeby. But it didn’t last long. Thus I ended up with only 0.25”.

12Z Euro says not just a H hit at CHS but also a rainfall flooding disaster quite possible SAV to Georgetown, SC, with 10”+ amounts and inland a bit especially SC Lowcountry. Keep in mind that that area has had well above normal rainfall the last 2 weeks. Hopefully this run is way off.

12Z Euro, which is strongest yet into the FL Big Bend, goes offshore at Brunswick and then becomes the strongest in many runs offshore the SE US with a 988 mb H. Then it turns back W and hits CHS, SC, on THU as a 989 mb H before going well inland and weakening.

The 12Z Euro is a bit stronger (strongest of all runs into NW FL) and still has a FL Big Bend landfall.

It may not be fully relevant, but fwiw the CMC was too far left for the longest before finally changing from a MX final landfall for Beryl.

Thunderstorms already popping up all around this area. This is much earlier than most days of recent weeks. Been hearing thunder the last 10 minutes or so. Will it rain? So far it has been hit and miss pop ups and so that remains to be seen. The NWS has only 20% chances. Also, the dewpoints/HI are very high with upper 70s/108! Temps are in the low 90s. All conducive to the pop-ups.