GaWx

New thread for Invest 96L:

Tropical Weather Outlook NWS National Hurricane Center Miami FL 200 PM EDT Fri Jul 1 2022 1. Near the Southeastern US: Satellite and radar images along with surface observations indicate that a low pressure system has formed just off the coast of Savannah, Georgia. Surface pressures are high in this region, and development, if any, of this system should be slow to occur while it drifts northeastward along the southeast U.S. coastline during the next day or so. Regardless of development, this system is expected to produce heavy rains, which could cause flash flooding across portions of southeastern Georgia and the Carolinas through tonight and into Saturday. See products issued by the Weather Prediction Center and your local National Weather Service forecast office for more details. * Formation chance through 48 hours...low...10 percent. * Formation chance through 5 days...low...10 percent.

Being that I'm not too many miles from the coast and thus am subject to major disruption to my family and myself from strong TCs, I'm fine with them nearby as long as they stay pretty weak! This is now Invest 96L by the way.

^The aforementioned low now has a 10% chance for tropical development as it moves slowly NE per the 2 PM TWO: (now is Invest 96L and thus this has its own thread in the tropical section) Tropical Weather Outlook NWS National Hurricane Center Miami FL 200 PM EDT Fri Jul 1 2022 1. Near the Southeastern US: Satellite and radar images along with surface observations indicate that a low pressure system has formed just off the coast of Savannah, Georgia. Surface pressures are high in this region, and development, if any, of this system should be slow to occur while it drifts northeastward along the southeast U.S. coastline during the next day or so. Regardless of development, this system is expected to produce heavy rains, which could cause flash flooding across portions of southeastern Georgia and the Carolinas through tonight and into Saturday. See products issued by the Weather Prediction Center and your local National Weather Service forecast office for more details. * Formation chance through 48 hours...low...10 percent. * Formation chance through 5 days...low...10 percent.

Kudos for being on top of this! I'm not saying I'm expecting imminent tropical development, especially with it not too far offshore, but obviously there's plenty of moisture at multiple levels and SSTs are conducive in the area with 82-84 F. So, although conditions for development are far from ideal with areas of moderate+ shear nearby and it not being far from shore, a TD forming from this wouldn't be shocking assuming it stays offshore. It should continue moving very slowly N and then probably NE near or just offshore SC. Regardless of whether or not it becomes a TC, this is interesting to watch spin around and it has and will likely continue to be a significant wx maker in terms of heavy rainfall potential in the coastal Carolinas as it was here earlier today.

Due to a coastal low/trough and the associated deep Atlantic moisture, I've received 4" since midnight (so all of it counts for July) with 3.5" of that during just midnight-3AM causing significant street flooding. This is the heaviest daily rainfall here since way back on 9/20/21, which wasn't from a tropical cyclone as that was due to converging surface flow off the Gulf and Atlantic (although moisture may have been enhanced by the remnants of Nicholas). The low center, which is getting a bit better organized and now is 30 miles ESE of Tybee Island/ESE of here (see radar image below), is now far enough north to reduce the heavy rain potential here due to not as much Atlantic moisture as earlier. The wettest flow was when the low was further south of our latitude earlier today giving us a SE/direct flow off the ocean. Now the flow is light from the north (land). It remains to be seen whether or not any more significant rain falls here today considering that the low is slowly moving north. The heaviest rainfall accumulation threat/flooding for the rest of today should be NE of here over coastal SC although it wouldn't surprise me if I were to get some short periods of heavy rain in showers. -------------- From the recent MCD Mesoscale Precipitation Discussion 0423 NWS Weather Prediction Center College Park MD 1224 PM EDT Fri Jul 01 2022 Areas affected...Coastal Lowcountry of Georgia and South Carolina Concerning...Heavy rainfall...Flash flooding possible Valid 011623Z - 012200Z Summary...Coastal low pressure will bring heavy rain to the coasts of Georgia and South Carolina through this evening. Rainfall rates of 1-2"/hr will likely train onshore, leading to instances of flash flooding. Discussion...An area of low pressure is clearly evident on the regional radar mosaic this morning as a closed swirl of reflectivity just east of Tybee Island, GA. This circulation has become better organized this morning along an inverted trough, and is responsible for heavy rainfall exceeding 4 inches that fell near Chatham, GA overnight.

Due to this coastal low/trough and the associated deep Atlantic moisture, I've received 4" since midnight with 3.5" of that during just midnight-3AM causing significant street flooding. This is the heaviest daily rainfall here since way back on 9/20/21, which wasn't from a tropical cyclone as that was due to converging surface flow off the Gulf and Atlantic (although moisture may have been enhanced by the remnants of Nicholas).

I got 0.15" yesterday to finish June at 7.0". After being in drought conditions for quite a long time and being about the driest of anywhere in the SE from mid November through May 20th, things have suddenly turned around here since then. Hoping many of the still dry areas in the SE have better luck in July. My June hottest was 102.7 early afternoon on June 23rd, the hottest for any day in at least several years! After midnight tonight, my area unexpectedly got slammed. But the details of that will have to wait for the July thread.

This means that during the last nine days vs the average of the last 15 years, 2022 has had a pretty dramatic 380K downturn from +240K to -140K (just over 40K/day). Recap of current vs avg. of last 15 years as of: 6/15/22: +70K 6/16/22: +120K 6/20/22: +240K 6/22/22: +140K 6/29/22: -140K

This SOI update suggests that a third in a row La Niña fall or winter peak is quite possible, if not likely, and that El Niño won't happen: - June 2022 SOI of +15.7 is the most positive June SOI since 1950 and second most positive June of last 100 years - Apr-June 2022 SOI of +18.1 is the second most positive on record by a good margin (back to 1876) with only 1917's +19.2 being higher - The last time a three calendar month SOI was more positive for ANY three month period than the current +18.1 was the strong La Niña of 2010-11, when it peaked at +22.4. - Prior to that, the only more positive three calendar month SOI periods of the last 100 years for ANY part of the year were the upper teens to low 20s leading up to or during the strong La Niñas of 1988-9, 1975-6, and 1973-4! Before that, one has to go all the way back to the lead up to the moderate La Niña of 1917-18, when the 3 calendar month hit an all-time record high of +29.5 during July-Sept. Prior to that, you have to go back to the +21.0 of the borderline mod/strong La Niña of 1889-90 and the +20.1 of the lead up to the borderline weak/moderate La Niña of 1879-80. - The highest 3 month +SOI lead up periods (April-June or later) to the 49 El Niños back to 1876-7 were the +12.9 of Jun-Aug of 1900, the +10.2 of May-July of 1968 and the +10.1 of Apr-June of 1904. Compare those to the current +18.1. - June-Aug of 1950 was +18.0 and lead up to a cold neutral. Jul-Sep of 1878 was +14.9 and also lead up to a cold neutral. Thus, neutral, especially cold, is still a reasonable possibility, especially considering the recent warming of both Nino 3.4 to -0.6 and the OHC. - I like to include the SOI in the mix for ENSO predictions because it, especially the 90 day, often is a decent leading (as opposed to lagging) indicator of general trends and the hard data goes back ~150 years making for good opportunities for analysis. - All of this fwiw because ENSO predicting isn't for the faint of heart as ENSO actuals will surprise you when you least expect it. Monthly SOI back to 1876: https://data.longpaddock.qld.gov.au/SeasonalClimateOutlook/SouthernOscillationIndex/SOIDataFiles/MonthlySOIPhase1887-1989Base.txt

^ Interesting stat. Here is that record tying 10th PTC advisory: Potential Tropical Cyclone Two Advisory Number 10 NWS National Hurricane Center Miami FL AL022022 1100 PM EDT Wed Jun 29 2022 ...CENTER OF THE DISTURBANCE APPROACHING THE GUAJIRA PENINSULA... SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION ----------------------------------------------- LOCATION...12.0N 70.6W ABOUT 65 MI...105 KM ESE OF NTHRN TIP OF GUAJIRA PNSULA COLOMBIA ABOUT 890 MI...1435 KM E OF BLUEFIELDS NICARAGUA MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...W OR 275 DEGREES AT 21 MPH...33 KM/H MINIMUM CENTRAL PRESSURE...1009 MB...29.80 INCHES

Potential Tropical Cyclone Two Advisory Number 9 NWS National Hurricane Center Miami FL AL022022 500 PM AST Wed Jun 29 2022 ...HURRICANE AND TROPICAL STORM WATCHES ISSUED FOR PORTIONS OF NICARAGUA AND COSTA RICA... SUMMARY OF 500 PM AST...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...11.6N 69.0W ABOUT 50 MI...80 KM S OF CURACAO ABOUT 180 MI...285 KM ESE OF NTHRN TIP OF GUAJIRA PNSULA COLOMBIA MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...W OR 280 DEGREES AT 21 MPH...33 KM/H MINIMUM CENTRAL PRESSURE...1009 MB...29.80 INCHES ------------------------- Potential Tropical Cyclone Two Discussion Number 9 NWS National Hurricane Center Miami FL AL022022 500 PM AST Wed Jun 29 2022 The system has changed little in organization today, and in fact has taken on a more elongated appearance. Most of the heavier showers and stronger winds are occurring in a long band over the northern portion of the disturbance. Reports from a NOAA Hurricane Hunter aircraft and a Dvorak classification indicate that the current intensity remains near 35 kt. High-resolution visible satellite images suggest that the system may trying to close off a center to the south of the ABC Islands, but the surface observations are still not very conclusive. Radar images from Curacao also do not yet show a definite center. The system could make the transition to a tropical cyclone at any time. The initial motion continues to be rapidly westward, or 280/18 kt. There is not much change in the track forecast reasoning. The flow on the southern side of a large mid-tropospheric ridge to the north of the system should maintain a mainly westward track for most of the forecast period. The latest HCCA prediction shows a slightly more southern track after 1-2 days than before, likely due to the input from the ECMWF model. The new NHC forecast is not much different from the previous one, but is only a little farther south after 36 hours or so. Since the system is expected to remain in a low-shear environment, it is likely to strengthen after it moves away from the influence of the South American land mass. The system is expected to approach hurricane strength over the southwestern Caribbean, and a Hurricane Watch has been issued for a portion of the Caribbean coast of Nicaragua. After some expected weakening from crossing Central America, the system should regain strength over the eastern North Pacific basin. KEY MESSAGES: 1. Heavy rainfall is expected to spread westward across the ABC Islands, portions of northern Venezuela, and northeast Columbia through Thursday morning, and reach Nicaragua and Costa Rica by Friday. Areas of flash flooding are expected, along with the potential for mudslides. 2. Winds to tropical storm force are expected over the ABC Islands for the next few hours. Tropical storm conditions are expected along the northwestern coast of Venezuela and the northeastern coast of Colombia tonight and early Thursday. 3. Hurricane conditions are possible within the Hurricane Watch area along the Caribbean coast of Nicaragua by late Friday, with tropical storm conditions possible by Friday afternoon. FORECAST POSITIONS AND MAX WINDS INIT 29/2100Z 11.6N 69.0W 35 KT 40 MPH...POTENTIAL TROP CYCLONE 12H 30/0600Z 11.8N 71.8W 35 KT 40 MPH...TROPICAL CYCLONE 24H 30/1800Z 12.0N 75.6W 40 KT 45 MPH 36H 01/0600Z 11.7N 79.4W 50 KT 60 MPH 48H 01/1800Z 11.4N 82.4W 60 KT 70 MPH 60H 02/0600Z 11.1N 85.1W 35 KT 40 MPH...INLAND 72H 02/1800Z 11.2N 87.7W 35 KT 40 MPH...OVER WATER 96H 03/1800Z 12.3N 92.7W 50 KT 60 MPH 120H 04/1800Z 13.5N 98.5W 65 KT 75 MPH $$ Forecaster Pasch

For the first time in 2 weeks (6/14), I'm getting a big dousing from thunderstorms. Been getting them for the last 1.5 hours (since 1:20 PM) and will thus add up nicely. There is some street flooding. I'll provide the total later. Until today, most of my rain this month fell 6/8-14. I got a modest amount yesterday (0.25") bringing me to 4.35" MTD before today's dousing. Recent radar: Edit for Flood advisory issued 1/2 hour ago and also this report in the area of 2.48" in only one hour: 0312 PM HEAVY RAIN 1 NNE VERNONBURG 31.98N 81.11W 06/29/2022 M2.48 INCH CHATHAM GA It looks like 2.5" has fallen IMBY, which brings me to 6.85" MTD (slightly above the longterm mean for all of June). This makes it the heaviest for any one day since way back on 11/6/21, when a similar amount fell. That amount is as much as I got in all of May.

Potential Tropical Cyclone Two Discussion Number 6 NWS National Hurricane Center Miami FL AL022022 1100 PM AST Tue Jun 28 2022 Satellite imagery suggests that the disturbance is slowly getting better organized, with gradually increasing convective banding in the northern semicircle. However, surface observations from Trinidad, Tobago, and Grenada indicate that the system has not yet developed a closed circulation. Therefore, it still has the status of a potential tropical cyclone. The initial intensity remains 35 kt based on the various surface observations. The disturbance is forecast to be in an environment of low shear and warm sea surface temperatures if it remains offshore, and this should lead the system to become a tropical cyclone in 12-24 hr. Strengthening is likely to be slow until the system moves away from the coast of South America after 36 h, at which time a faster development appears likely. The new intensity forecast is similar to the previous forecast and calls for the system to reach hurricane strength over the southwestern Caribbean Sea by the 72 h point. Later in the forecast period, the global models still suggest that the cyclone's low-level circulation will remain intact after crossing Central America and this is also shown by the NHC forecast. The system is moving a little faster with the initial motion now a somewhat uncertain 285/23 kt. A general westward motion near or just north of the coast of South America with some decrease in forward speed is expected during the next day or two due to the presence of a low- to mid-level ridge to the north. A south of west motion may occur for a time while the system is over the southwestern Caribbean Sea. The new forecast track is similar to the previous track is lies close to the various consensus models. KEY MESSAGES: 1. Heavy rainfall is expected to spread westward across the Windward Islands and parts of northern Venezuela tonight through late Wednesday night. Localized flash flooding will be possible. 2. Winds to tropical-storm-force are expected over portions of the southern Windward Islands for a few more hours, over Islas Margarita Wednesday morning, and over the ABC Islands by Wednesday evening. Tropical storm conditions are possible along the northeastern coast of Venezuela tonight and early Wednesday. 3. There is a greater-than-normal uncertainty in the system's forecast intensity once it reaches the southwestern Caribbean Sea late Thursday and Friday, which will depend on how much it interacts with land from tonight through Thursday. FORECAST POSITIONS AND MAX WINDS INIT 29/0300Z 10.9N 62.8W 35 KT 40 MPH...POTENTIAL TROP CYCLONE 12H 29/1200Z 11.3N 65.5W 35 KT 40 MPH...POTENTIAL TROP CYCLONE 24H 30/0000Z 11.8N 69.2W 35 KT 40 MPH...TROPICAL CYCLONE 36H 30/1200Z 12.3N 72.9W 40 KT 45 MPH 48H 01/0000Z 12.3N 76.6W 45 KT 50 MPH 60H 01/1200Z 12.2N 80.2W 55 KT 65 MPH 72H 02/0000Z 12.0N 82.9W 65 KT 75 MPH 96H 03/0000Z 12.0N 87.9W 35 KT 40 MPH...OVER PACIFIC OCEAN 120H 04/0000Z 13.5N 93.5W 25 KT 30 MPH $$ Forecaster Beven

Tuesday 6/28 was the first day in 1.5 months with it not colder than normal north of 80N: