GaWx

Followup: It turned out that several bands of rain, sometimes moderate or heavy, continued to come in from the SE over this area. There was heavy near and soon after midnight. And then while I was sleeping, this occurred, still another FF warning for still another band of heavy:BULLETIN - EAS ACTIVATION REQUESTED FLASH FLOOD WARNING NATIONAL WEATHER SERVICE CHARLESTON SC 156 AM EDT MON AUG 11 2025 THE NATIONAL WEATHER SERVICE IN CHARLESTON HAS ISSUED A * FLASH FLOOD WARNING FOR... CHATHAM COUNTY IN SOUTHEASTERN GEORGIA... JASPER COUNTY IN SOUTHEASTERN SOUTH CAROLINA... * UNTIL 400 AM EDT. * AT 156 AM EDT, DOPPLER RADAR INDICATED AN LARGE BAND OF SHOWERS AND THUNDERSTORM WITH TORRENTIAL RAINFALL JUST OFF THE COAST OF CHATHAM COUNTY. THIS BAND WILL MOVE ACROSS MUCH CHATHAM COUNTY INTO PARTS OF JASPER COUNTY THROUGH 4 AM. THIS INCLUDES MUCH OF THE SAVANNAH METRO AREA. AS MUCH AS 1 TO 3 INCHES OF RAIN COULD FALL OVER A VERY SHORT PERIOD. THIS WILL RESULT IN URBAN FLOODING AND FLASH FLOODING. ROAD CLOSURES ARE POSSIBLE, ESPECIALLY ACROSS DOWNTOWN SAVANNAH. HAZARD...FLASH FLOODING CAUSED BY THUNDERSTORMS. SOURCE...RADAR INDICATED. IMPACT...FLASH FLOODING OF SMALL CREEKS AND STREAMS, URBAN AREAS, HIGHWAYS, STREETS AND UNDERPASSES AS WELL AS OTHER POOR DRAINAGE AND LOW-LYING AREAS. * SOME LOCATIONS THAT WILL EXPERIENCE FLASH FLOODING INCLUDE... POOLER, BLUFFTON, TYBEE ISLAND, MIDTOWN SAVANNAH, DOWNTOWN SAVANNAH, HUTCHINSON ISLAND, HUNTER ARMY AIRFIELD, WINDSOR FOREST, WILMINGTON ISLAND AND COFFEE BLUFF.————————Then this statement was issued:CHATHAM GA-JASPER SC- 326 AM EDT MON AUG 11 2025 ...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 4 AM EDT EARLY THIS MORNING FOR CHATHAM AND JASPER COUNTIES... AT 326 AM EDT, DOPPLER RADAR INDICATED MODERATE TO LOCALLY HEAVY RAIN FALLING OVER MUCH OF CHATHAM COUNTY. WHILE THE MOST INTENSE RAIN HAS SHIFTED NORTH OF THE AREA, THE RISK FOR FLOODING CONTINUES. AS MUCH AS 1 TO 2.5 INCHES OF RAIN HAS FALLEN IN SOME AREAS SINCE 2 AM. HAZARD...FLASH FLOODING CAUSED BY THUNDERSTORMS. SOURCE...RADAR INDICATED. IMPACT...FLASH FLOODING OF SMALL CREEKS AND STREAMS, URBAN AREAS, HIGHWAYS, STREETS AND UNDERPASSES AS WELL AS OTHER POOR DRAINAGE AND LOW-LYING AREAS. SOME LOCATIONS THAT WILL EXPERIENCE FLASH FLOODING INCLUDE... POOLER, BLUFFTON, TYBEE ISLAND, MIDTOWN SAVANNAH, DOWNTOWN SAVANNAH, HUTCHINSON ISLAND, HUNTER ARMY AIRFIELD, WINDSOR FOREST, WILMINGTON ISLAND AND COFFEE BLUFF.

0Z UKMET for what may be first AEW behind 97L: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 150 HOURS FORECAST POSITION AT T+150 : 16.0N 49.7W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 17.08.2025 156 17.0N 51.1W 1010 27 0000UTC 18.08.2025 168 18.4N 53.9W 1011 24

After having no rain throughout the daytime of 8/10, which allowed me to go to Tybee with some friends, rain showers (some heavy) coming off the ocean moving NW started at 11:30PM. It looks like per radar that periods of rain may last til after midnight. Edit: Before this, I was already way up at ~9.9” of rain for August!

Just what we don’t need, still another batch of moderate to heavy rain moving in at 1PM. Edit: This and other rain on 8/9 plus other rains after midnight on 8/10 during the late night added to ~0.9”. That put me up to 9.9” MTD!

After this, I got several more rounds of rain through the evening of 7/8 adding to that gotten yesterday afternoon adding up to a total of ~1.3”. After emptying that, I then through the early morning hours (7/9) received heavy showers coming off the ocean with the heaviest 5-5:30AM. I estimate 2” from the late night through now (7:40AM) with light rain still falling. All of this is on top of the 6” I got Aug 1-6! So, I’m at ~9.3” Aug 1 through 7:40AM of Aug 9!My water table is ridiculously high. Fortunately though due to the rains being spread out enough, I’ve yet to have any garage flooding this month despite heavy puddling of rain sitting just outside the garage. However, more heavy rains are possible over the next few days.Not one but two flash flood warnings were up for the county since late afternoon yesterday (8/8)!#1:BULLETIN - EAS ACTIVATION REQUESTED FLASH FLOOD WARNING NATIONAL WEATHER SERVICE CHARLESTON SC 353 PM EDT FRI AUG 8 2025 THE NATIONAL WEATHER SERVICE IN CHARLESTON HAS ISSUED A * FLASH FLOOD WARNING FOR... CHATHAM COUNTY IN SOUTHEASTERN GEORGIA... * UNTIL 700 PM EDT. * AT 353 PM EDT, DOPPLER RADAR INDICATED THUNDERSTORMS PRODUCING HEAVY RAIN ACROSS THE WARNED AREA. BETWEEN 1.5 AND 2.5 INCHES OF RAIN HAVE FALLEN. ADDITIONAL RAINFALL AMOUNTS OF 1 TO 2 INCHES ARE POSSIBLE IN THE WARNED AREA. FLASH FLOODING IS ONGOING OR EXPECTED TO BEGIN SHORTLY. HAZARD...FLASH FLOODING CAUSED BY THUNDERSTORMS. SOURCE...RADAR INDICATED. IMPACT...FLASH FLOODING OF SMALL CREEKS AND STREAMS, URBAN AREAS, HIGHWAYS, STREETS AND UNDERPASSES AS WELL AS OTHER POOR DRAINAGE AND LOW-LYING AREAS. * SOME LOCATIONS THAT WILL EXPERIENCE FLASH FLOODING INCLUDE... POOLER, DOWNTOWN SAVANNAH, HUTCHINSON ISLAND, HUNTER ARMY AIRFIELD, MIDTOWN SAVANNAH, WINDSOR FOREST, SAVANNAH INTERNATIONAL AIRPORT, GARDEN CITY, PORT WENTWORTH AND THUNDERBOLT. CITY OF SAVANNAH EMERGENCY MANAGEMENT REPORTS THAT NUMEROUS ROADS IN THE SAVANNAH AREA ARE BEGINNING TO FLOOD. ADDITIONAL RAINFALL OVER THE NEXT HOUR WILL CONTINUE TO WORSEN ONGOING FLOODING.—————————-#2:BULLETIN - EAS ACTIVATION REQUESTED FLASH FLOOD WARNING NATIONAL WEATHER SERVICE CHARLESTON SC 520 AM EDT SAT AUG 9 2025 THE NATIONAL WEATHER SERVICE IN CHARLESTON HAS ISSUED A * FLASH FLOOD WARNING FOR... CHATHAM COUNTY IN SOUTHEASTERN GEORGIA... * UNTIL 715 AM EDT. * AT 520 AM EDT, DOPPLER RADAR INDICATED A BAND HEAVY RAIN EXTENDING FROM DOWNTOWN SAVANNAH TO THE SAVANNAH RIVER ENTRANCE AND EXTENDING OFFSHORE. THIS BAND WILL CONTINUE TO PUSH WEST ACROSS PORTIONS OF THE SAVANNAH METRO AREA. UP TO A INCH OF RAIN HAS ALREADY FALLEN IN SOME AREAS THIS MORNING. AN ADDITIONAL 1 TO 2 INCHES OF RAIN COULD FALL THROUGH 7 AM, RESULTING IN AREAS OF URBAN FLOODING AND FLASH FLOODING. FLOODED ROADWAYS ARE LIKELY WHICH MAY RESULT IN CLOSURES. HAZARD...FLASH FLOODING CAUSED BY HEAVY RAIN. SOURCE...RADAR INDICATED. IMPACT...FLASH FLOODING OF SMALL CREEKS AND STREAMS, URBAN AREAS, HIGHWAYS, STREETS AND UNDERPASSES AS WELL AS OTHER POOR DRAINAGE AND LOW-LYING AREAS. * SOME LOCATIONS THAT WILL EXPERIENCE FLASH FLOODING INCLUDE... POOLER, TYBEE ISLAND, MIDTOWN SAVANNAH, DOWNTOWN SAVANNAH, HUTCHINSON ISLAND, HUNTER ARMY AIRFIELD, WILMINGTON ISLAND, WINDSOR FOREST, FORT PULASKI NATIONAL MONUMENT AND GARDEN CITY.

My analysis had nothing to do with date of formation. It was strictly based on date of Conus landfalls.

MJO phase (whether inside or outside the circle) 1975-2024 Jul-Sep on day of 67 CONUS hurricane hits 1: 7 (10%) 2: 17 (25%) 3: 7 (10%) 4: 7 (10%) 5: 10 (15%) 6: 6 (9%) 7: 2 (3%) 8: 11 (16%) ——————— MJO phase (whether inside or outside the circle) 1975-2024 Jul-Sep on day of 23 CONUS MAJOR hurricane hits 1: 3 (13%) 2: 9 (39%) 3: 2 (9%) 4: 2 (9%) 5: 2 (9%) 6: 2 (9%) 7: 0 (0%) 8: 3 (13%) Analysis: When considering just MH hits, phase 2 has easily had the most hits of any one phase. You may wonder (and I wondered at first, myself) if that’s because there were far more days in phase 2 than any other phase during Jul-Sep 1975-2924. Answer: 16.8% or 1 in 6. So, it had somewhat more than an avg share, which is 12.5%. But that’s not nearly enough to fully explain the high phase 2 #s for MH. **Edited Conclusion: So, phase 2 really has had by a good margin the highest frequency of MH CONUS hits per days in that phase during Jul-Sep since 1975. Regarding all H when considering that phase 8 had only 10.1% of the days, phases 8 and 2 are neck and neck for the highest hit freq. per day. Phase 5 has the 3rd highest. Sources: I looked at the following sources and did the calculations: 1. MJO phase: http://www.bom.gov.au/clim_data/IDCKGEM000/rmm.74toRealtime.txt 2. H classification/hit dates: NHC archives 3. For Katrina and Ian, I counted only the day of the more intense hit to determine MJO phase. For Andrew, both hits were during phase 6.

Showers, some heavy, (no thunder so far) are now moving in here in a WSW direction. Edit 4PM: More heavy rain falling again from a band of showers moving SW.

“Prediction remains on track for above-normal Atlantic hurricane season” Forecasters from NOAA’s National Weather Service updated the number of expected named storms to 13-18 (with winds of 39 mph or greater), of which 5-9 could become hurricanes (winds of 74 mph or greater), including 2-5 major hurricanes (winds of 111 mph or greater). The adjusted ranges are for the entire season from June 1 though November 30, and are inclusive of the four named tropical storms that have already formed. In the Atlantic basin, a typical hurricane season will yield 14 named storms, of which seven become hurricanes and three become major hurricanes. The likelihood of above-normal activity is 50%, a 35% chance of a near-normal season, and a 15% chance of a below-normal season. This updated prediction is similar to the initial outlook issued in May. https://www.noaa.gov/news-release/prediction-remains-on-track-for-above-normal-atlantic-hurricane-season —————— I’ve never been a fan of these wide ranges, especially 2-5 MH in this case, but otherwise I appreciate the availability of their predictions.

I think that’s a good guideline, but I feel there are exceptions. For example, due to good model support (most importantly including ensembles) for a strong western Atlantic hurricane from it, I feel that the thread for the AEW still in W Africa, despite it not yet being an invest and it not even being on the TWO, is already easily warranted. It will almost definitely be made an Invest and will make the TWO soon. I just posted the rather ominous looking 6Z Euro ensemble for it. I see no problem with already having posts about it siphoned off to its own thread so as to allow this main thread to not be as cluttered. Also, should it end up being a storm, we’d then have posts from further back in time all in one thread to look back at to see how it evolved on the models early on.

Since Atlantic ACE is considered to be a winter forecast factor: TSR just updated their forecast from last month…. -ACE increased markedly from 126 to 144. This compares to the CSU’s 145 and the Euro seasonal’s ~155. -The # of NS/H/MH increased slightly from 15/7/3 to 16/8/3. -However, US impacts remained the same at 4 NS/2 H. https://www.tropicalstormrisk.com/docs/TSRATLForecastAugust2025.pdf

TSR just updated their forecast from last month: -ACE increased markedly from 126 to 144. This compares to the CSU’s 145 and the Euro seasonal’s ~155. -The # of NS/H/MH increased slightly from 15/7/3 to 16/8/3. -However, US impacts remained the same at 4 NS/2 H. https://www.tropicalstormrisk.com/docs/TSRATLForecastAugust2025.pdf

2025 ACE, which is now 3.5, has just moved ahead of both 1998 and 1999 as of this date. Neither of those years had another storm til Aug 18/19. And yet they each ended up with ACE of 181 and 176, respectively. I’m not predicting that’s going to happen again. But I am saying that it isn’t a remote possibility that the season end up active (say 140+) just because it was only at 3.5 as of 8/6. Edit: Fwiw in the spring I predicted a slightly above 1991-2020 avg of 139 for 2025 ACE in the contest, and I wouldn’t change that even if I could.

A small thunderstorm has just popped up overhead this evening. I can’t tell if this is likely going to amount to much. I heard one clap of thunder. Temp is 80. Edit 8:25PM: That cell amounted to about nothing. However, it suddenly started raining heavily at 8:20 PM soon after a new 75 mile long SW to NE line of very heavy showers had just popped up with my area on the NE edge. It’s pouring! Edit: It poured for only a short period the evening of August 6th. Thus, I ended up with only ~.0.25” for the day, putting me at 5.25” for 8/1-6!

CSU 8/6/25 update: 145 total ACE vs 140 in last month’s forecast, vs 122, which is 1991-2020 average, and vs the new Euro seasonal’s ~155: FORECAST OF ATLANTIC SEASONAL HURRICANE ACTIVITY AND LANDFALL STRIKE PROBABILITY FOR 2025 We have maintained our forecast for a slightly above-normal 2025 Atlantic basin hurricane season, although noting lower-than-normal confidence with this outlook. Sea surface temperatures across the eastern and central Atlantic have anomalously warmed over the past few weeks and are now somewhat warmer than normal. Multiple indicators anticipate likely cool ENSO neutral conditions during the peak of the Atlantic hurricane season. Warm sea surface temperatures and ENSO neutral conditions typically provide a more conducive dynamic and thermodynamic environment for hurricane formation and intensification. The primary reason for the uncertainty in the outlook is the high observed Caribbean shear over recent weeks. Typically, high levels of Caribbean shear in June July are associated with less active hurricane seasons. We anticipate a slightly above- average probability for major hurricanes making landfall along the continental United States coastline and in the Caribbean for the remainder of the hurricane season.

CSU 8/6/25 update: 145 total ACE vs 140 in last month’s forecast and 122, which is 1991-2020 avg, and the new Euro seasonal’s ~155: FORECAST OF ATLANTIC SEASONAL HURRICANE ACTIVITY AND LANDFALL STRIKE PROBABILITY FOR 2025 We have maintained our forecast for a slightly above-normal 2025 Atlantic basin hurricane season, although noting lower-than-normal confidence with this outlook. Sea surface temperatures across the eastern and central Atlantic have anomalously warmed over the past few weeks and are now somewhat warmer than normal. Multiple indicators anticipate likely cool ENSO neutral conditions during the peak of the Atlantic hurricane season. Warm sea surface temperatures and ENSO neutral conditions typically provide a more conducive dynamic and thermodynamic environment for hurricane formation and intensification. The primary reason for the uncertainty in the outlook is the high observed Caribbean shear over recent weeks. Typically, high levels of Caribbean shear in June July are associated with less active hurricane seasons. We anticipate a slightly above- average probability for major hurricanes making landfall along the continental United States coastline and in the Caribbean for the remainder of the hurricane season.

The latest Euro Weeklies (yesterday’s run) remain quite active vs active 20 year climo base ACE (>200%) through ~8/24. Then they cool down to close to active avg 8/25-31 (100%). The first stab at 9/1-7 is slightly below the active climo (80%). I wonder if this is MJO related. Regarding absolute ACE, the very active Aug 18-24 is the most active week through Sept 7. As per what I’ve recently posted, the EW progs did fairly well in general last year overall looking out several weeks when they were consistent for, say, 7 days in a row. They’ve been consistent regarding well above 20 year climo levels of activity for 8/11-8/24 for at least that long. Regarding 8/25-31, they’ve been near that 20 year climo for 3 runs. So, I still want to see how the rest of this week’s runs look before giving too much weight to its 8/25-31. Of course, 9/1-7 is a total crap-shoot right now with that slightly below 20 year climo being just its first prog.

Strong thunderstorms here moving in now! It looks like twilight! ..A STRONG THUNDERSTORM WILL IMPACT EFFINGHAM JASPER AND CHATHAM COUNTIES UNTIL 530 PM EDT... AT 453 PM EDT, DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM OVER BLOOMINGDALE, MOVING NORTHEAST AT 5 MPH. HAZARD...WIND GUSTS OF 50 TO 55 MPH. SOURCE...RADAR INDICATED. IMPACT...GUSTY WINDS COULD KNOCK DOWN TREE LIMBS AND BLOW AROUND UNSECURED OBJECTS. LOCATIONS IMPACTED INCLUDE... POOLER, RICHMOND HILL, SAVANNAH INTERNATIONAL AIRPORT, GODLEY STATION, I-16/I-95 INTERCHANGE, DOWNTOWN SAVANNAH, HUTCHINSON ISLAND, RINCON, GARDEN CITY AND PORT WENTWORTH. ———— .***Upgraded to severe:BULLETIN - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE CHARLESTON SC 508 PM EDT TUE AUG 5 2025 THE NATIONAL WEATHER SERVICE IN CHARLESTON HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR PORTIONS OF... CHATHAM COUNTY IN SOUTHEASTERN GEORGIA... EFFINGHAM COUNTY IN SOUTHEASTERN GEORGIA... JASPER COUNTY IN SOUTHEASTERN SOUTH CAROLINA... * UNTIL 615 PM EDT. * AT 508 PM EDT, A SEVERE THUNDERSTORM WAS LOCATED OVER POOLER, MOVING NORTHEAST AT 10 MPH. HAZARD...60 MPH WIND GUSTS. SOURCE...RADAR INDICATED. IMPACT...EXPECT DAMAGE TO ROOFS, SIDING, AND TREES. * LOCATIONS IMPACTED INCLUDE... POOLER, SAVANNAH INTERNATIONAL AIRPORT, I-16/I-95 INTERCHANGE, GODLEY STATION, DOWNTOWN SAVANNAH, HUNTER ARMY AIRFIELD, HUTCHINSON ISLAND, WINDSOR FOREST, MIDTOWN SAVANNAH AND COFFEE BLUFF. ———- Edit: I ended up with ~0.4” from this severe thunderstorm on Aug 5, which brings my Aug 1-5 rainfall up to a whopping 5”! The CTG lightning was frequent. Highest wind gusts likely exceeded 40 mph. The Pooler area of Chatham county (NW of here) was harder hit with flooding rains as high as ~3” in spots, highest wind gust at 60 mph at KSAV, and even some pea sized hail!

The BoM released 8/2/25 has -0.2 for ASO and then rises to near 0.0 for the winter: Colder boat needed here too probably.

Thanks, Mitch. This is slightly cooler than the July run, which had ~-0.1 (ASO through NDJ): This new one has ~-0.3 for August and has trimonths through DJF at ~-0.2. So, it’s ~steady from now through winter though it still tends to have a bit of a warm bias even this late. The implied RONI low would be ~~-0.5 ignoring this warm bias. @Stormchaserchuck1

Lol, Aug-Nov doesn’t need to be anywhere near the most active ever to get 2025 to ~155 ACE and certainly wouldn’t even require close to 2005’s ACE the rest of the way, which was 179. We’re now at 2.5, which means 152.5 is needed to get to 155. 2005/1998/99/2017/2004/1961/1995 had 179/178/173/220/216/177/207 more ACE still to go. So, the most active the rest of the season since 1951 (2017’s 220, 2004’s 216, and 1995’s 207) would be 55-67 higher than the 152.5 needed this year to get to 155. Where are you getting your info?

Chuck, I didn’t look at ENSO yet.

Maybe but not just the finish. The Weeklies have quite an active August.

Since ACE is discussed here as a winter forecast factor, the new Euro monthly seasonal forecast has substantially increased from the near 30 year normal of last month’s forecast, which had ~125 ACE, to today’s ~155. The 155 incorporates the 1.5 prior to August, the well AN ~40 that the latest Weeklies have for August, and the well AN 130% of 1993-2024 based climo that today’s new Euro has for Sept+.

For those wanting a relatively quiet season (including me), the new Euro seasonal NATL forecast is not what you want to see. It has substantially increased from the near normal of last month’s forecast, which had ~125 ACE, to today’s ~155. This is estimated by taking its 130% of normal for Sept+ and adding the 1.5 prior to Aug and its latest Weeklies forecast for Aug, which is now at ~40, well AN. The implied total seasonal # of NS has risen from 15 to ~17-18. The # of H has risen from 6 to ~7.5. The concentration of tracks at/near the Conus has risen from very slightly BN to AN.