WxWatcher007

Tropical Storm Colin Discussion Number 1 NWS National Hurricane Center Miami FL AL032022 500 AM EDT Sat Jul 02 2022 A small area of low pressure formed along a surface trough just offshore of Savannah, Georgia, yesterday morning and moved inland across the Lowcountry of South Carolina by the evening. Deep convection formed near the low center as it was moving inland and has persisted and become better organized over the past 6 to 12 hours. In addition, surface observations and ASCAT data from 02-03 UTC indicated that an area of sustained 35-kt winds had developed offshore and near the coast of South Carolina. As a result, and rather unexpectedly, Tropical Storm Colin has formed near the South Carolina coast, centered just inland a bit to the northeast of Charleston. Colin is moving northeastward just inland of the coast with a motion of 045/7 kt. A low- to mid-level area of high pressure is located over the western Atlantic, and Colin is expected to move northeastward and then east-northeastward around that high during the next 48 hours. The bulk of the available track guidance suggests that Colin's center will move along or just inland of the coasts of South and North Carolina during the next 36 hours, and the NHC track forecast is generally a blend of the GFEX and HCCA consensus aids. Northwesterly shear of roughly 15-20 kt is expected to continue affecting Colin during the next 36 hours or so, with that shear increasing to 30 kt or more by 48 hours. As a result, strengthening is not anticipated, and Colin is expected to remain a sheared tropical storm while it moves across coastal areas of the Carolinas, with tropical-storm-force winds primarily limited to the southeast of the center. Colin is likely to dissipate over the western Atlantic soon after 48 hours. KEY MESSAGES: 1. Tropical storm conditions are expected within the warning area along the northeastern coast of South Carolina this morning and will spread northeastward within the warning area along the North Carolina coast this afternoon into Sunday. 2. Areas of heavy rainfall may result in localized flash flooding across portions of coastal South and North Carolina through Sunday morning. FORECAST POSITIONS AND MAX WINDS INIT 02/0900Z 33.2N 79.5W 35 KT 40 MPH...INLAND 12H 02/1800Z 33.9N 78.6W 35 KT 40 MPH...INLAND 24H 03/0600Z 34.8N 77.3W 35 KT 40 MPH...INLAND 36H 03/1800Z 35.7N 75.7W 35 KT 40 MPH...OVER PAMLICO SOUND 48H 04/0600Z 36.8N 72.9W 35 KT 40 MPH...OVER ATLANTIC OCEAN 60H 04/1800Z...DISSIPATED $$ Forecaster Berg

60% now… Near the South Carolina Coast: Surface observations and satellite-derived wind data indicate that the small low pressure system located along the coast of South Carolina is producing sustained tropical-storm-force winds primarily to the southeast of its center over water and near the immediate coast. In addition, shower and thunderstorm activity has persisted near the area of low pressure over the last 6 to 12 hours. If the associated showers and thunderstorms persist and continue to become better organized, then this system could become a tropical storm later today while moving northeastward along the South Carolina coast, and then reaching the North Carolina coast by tonight. Regardless of development, this system is expected to produce heavy rains, which could cause flash flooding across coastal portions of the Carolinas over the weekend. See products issued by the Weather Prediction Center and your local National Weather Service forecast office for more details. Further information on the system, including offshore gale warnings, can be found in High Seas forecasts issued by the National Weather Service. * Formation chance through 48 hours...medium...60 percent. * Formation chance through 5 days...medium...60 percent.

Thanks! Yes, the crossovers are pretty uncommon.

Some good storms over NY right now. That one near Pittsfield was a good one too.

NHC taking note. This is a really impressive invest for having this much land interaction. With a weak LLC over the coast and deep convection firing offshore with obvious rotation, this one could pick up a name as it moves northeast. Special Tropical Weather Outlook NWS National Hurricane Center Miami FL 1150 PM EDT Fri Jul 1 2022 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: Special outlook issued to update discussion of the low pressure system along the South Carolina coast. Active Systems: The National Hurricane Center is issuing advisories on Tropical Storm Bonnie, located near the Nicaragua/Costa Rica border. Near the South Carolina Coast: Updated: Recent surface observations indicate that a small low pressure system located just inland to the west of Charleston, South Carolina, is producing localized areas of winds to tropical storm force along the South Carolina coast. This system is expected to move northeastward along the South Carolina and North Carolina coasts over the weekend, and a tropical depression or tropical storm could form if the center of the low remains close enough to the Atlantic waters during that time. Regardless of development, this system is expected to produce heavy rains, which could cause flash flooding across coastal portions of the Carolinas over the weekend. See products issued by the Weather Prediction Center and your local National Weather Service forecast office for more details. * Formation chance through 48 hours...medium...40 percent. * Formation chance through 5 days...medium...40 percent.

It’s cool. It’s easy to do. Just go to the original post and hit edit in the menu on the top right. You can just change to Tropical Storm Bonnie, and when it becomes a hurricane change it again to note its maximum intensity.

Now that’s incredible.

96L along the SC coast is now producing TS wind gusts.

Wow, starting to see gusts over 40kts now. This invest is the real deal lol.

Recon confirms nascent eyewall trying to close off before landfall. Product: Air Force Vortex Message (URNT12 KNHC)Transmitted: 2nd day of the month at 1:38ZAgency: United States Air ForceAircraft: Lockheed WC-130J Hercules with reg. number AF97-5304Storm Name: BonnieStorm Number: 02 (flight in the North Atlantic basin)Mission Number: 9Observation Number: 20 ( See all messages of this type for this mission. )A. Time of Center Fix: 2nd day of the month at 1:22:20ZB. Center Fix Coordinates: 11.01N 83.38WB. Center Fix Location: 298 statute miles (479 km) to the WNW (298°) from Panama City, Panama.C. Minimum Height at Standard Level: 1,432m (4,698ft) at 850mbD. Minimum Sea Level Pressure: 998mb (29.47 inHg)E. Dropsonde Surface Wind at Center: From 185° at 10kts (From the S at 12mph)F. Eye Character: Open in the eastG. Eye Shape & Diameter: Circular with a diameter of 10 nautical miles (12 statute miles)H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 35kts (40.3mph)I. Location & Time of the Estimated Maximum Surface Wind Inbound: 4 nautical miles to the NW (318°) of center fix at 1:21:00ZJ. Maximum Flight Level Wind Inbound: From 61° at 50kts (From the ENE at 57.5mph)K. Location & Time of the Maximum Flight Level Wind Inbound: 6 nautical miles to the NW (318°) of center fix at 1:20:30ZL. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 40kts (46.0mph)M. Location & Time of the Estimated Maximum Surface Wind Outbound: 4 nautical miles to the E (82°) of center fix at 1:24:00ZN. Maximum Flight Level Wind Outbound: From 140° at 46kts (From the SE at 52.9mph)O. Location & Time of the Maximum Flight Level Wind Outbound: 10 nautical miles (12 statute miles) to the ENE (58°) of center fix at 1:26:00ZP. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 15°C (59°F) at a pressure alt. of 1,517m (4,977ft)Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 1,523m (4,997ft)R. Dewpoint Temp (collected at same location as temp inside eye): 14°C (57°F)R. Sea Surface Temp (collected at same location as temp inside eye): Not AvailableS. Fix Determined By: Penetration, Radar, Wind, Pressure and TemperatureS. Fix Level: 850mbT. Navigational Fix Accuracy: 0.02 nautical milesT. Meteorological Accuracy: 1 nautical mileRemarks Section: Maximum Flight Level Wind: 50kts (~ 57.5mph) which was observed 50 nautical miles (58 statute miles) to the ENE (61°) from the flight level center at 1:20:30Z

This one may not get classified given how close it is to the coast, but it has really delivered some big rainfall totals along the SC and GA coastline. Just south of Charleston is getting hit hard. 4+ inches of rain in the last two hours. Looks like the center is meandering right at the coast.

Can we also get a thread name change please?

It took forever, but Bonnie is finally looking like a legit system. Fortunate for Central America because this one is really getting it together as it closes in on landfall. Evidence of an eyewall on microwave imagery.

Very interesting day in the tropics. 96L on the SE coast could have been a TD with less land interaction, and Bonnie (below) is really cooking as it approaches landfall.

That’s definitely tropical. Not a lot of wind, but the structure is excellent for a developing system. We’ll see if it’ll meander on the coast or just offshore the next 24 hours. 50 miles more offshore and this would have been a TD.

Not high odds but interesting nonetheless. The radar appearance has deteriorated since earlier, but convection continues to fire as it drifts near the coast.

I love this stuff, and it has been a boring start to the season so it's nice to have a close to the coast opportunity. I feel like I learn the most about the elements of TC genesis from the under the radar disturbances, even if they don't develop.

10% odds from the NHC. I think that's reasonable. Let's see if this area can stay persistent and offshore. No matter what, cool to watch (for me at least).

I love TC genesis near the coast because you can really follow things on radar. While convection looks pretty disorganized on IR, the radar shows the apparent banding near the center, which is quite compelling IMO. It's drifting offshore too rather than moving toward the coast, meaning for now at least, there is time for additional organization. I haven't seen anything impressive in the way of velocities or pressure drops based on radar and buoy data, but this really just popped a few hours ago. I think this is worth some odds at 2pm.

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. In the vicinity of this low, cooling cloud tops are occurring just offshore, with a stripe of enhanced upper diffluence noted in the GOES-E WV imagery stretching from northern GA into eastern NC. The 12Z U/A sounding out of KCHS measured a PW of 2.11 inches, above the 90th percentile for the date, with a freezing level approaching 15,000 ft and a mean 700-500mb lapse rate of 5.5C/km. These together with MUCAPE around 1000 J/kg imply efficient warm rain processes, and radar-estimated rain rates from KCLX have been over 1.5"/hr this morning. As the low continues to move slowly northeast along the coast through this aftn, it is likely to consolidate and at least subtly strengthen. As this occurs, pinched flow northeast of the center will help push the 850mb LLJ to 20 kts out of the southeast. This will originate near the Gulf Stream, transporting the warm, more moist and unstable air onshore, helping to resupply favorable thermodynamics to the area through the aftn. The combination of increasing convergence on the nose of the LLJ, any frictional convergence near the coast, and broad upper diffluence will drive pronounced ascent, leading to increasing coverage of showers and thunderstorms. With the thermodynamics likely to remain extremely favorable, this will support an intensification of rain rates which could exceed 2"/hr at times as shown by the HREF probabilities and HRRR sub-hourly precipitation forecasts. The heaviest rainfall is likely along the immediate coast northeast of the low, which could receive more than 3" of rainfall. This is where the best training potential of these heavy rates exists as upwind propagation vectors become increasingly opposed to the mean flow. This indicates the likelihood for backbuilding of cells into the offshore instability with these subsequently training onshore. However, additional heavy rain is likely near and just west of the low center where storm motions will slow to less than 5 kts, while still containing impressive rain rates. The FFG across the area is generally 2-3"/1hr and 3-4"/3hrs, which the HREF indicates has a 20-30% chance for exceedance through late this aftn, suggesting at least isolated flash flooding in urban areas or where the most efficient training occurs. While this MPD is only valid through early evening, additional MPDs may be needed for the continued flash flood threat into tonight as the low continues to trek up the coast.

They've designated far worse lol. In all seriousness though, I don't think it's unreasonable to give this some official odds, given the well defined center that seems to be staying offshore for now, persistent convection, and banding structure that seems to be developing. That said, it needs to be persistent. If it can push a little further offshore it may have a chance. Interesting looking at the long range radar as it looks like the original convection ejected an LLC.

While all of the areas of interest in the Atlantic have underperformed, thanks to @nwohweatherI can weenie out on this. This is actually from the Bahamas MCS that slowly drifted up the coast over the last few days.

That looks better than former PTC Two and 95L ever did lol

Great info, thanks for sharing! I remember that NYC event. People thought the aliens finally arrived lol.

Right on cue Tropical Storm Bonnie Tropical Cyclone Update NWS National Hurricane Center Miami FL AL022022 915 AM EDT Fri Jul 01 2022 ...DISTURBANCE BECOMES A TROPICAL STORM... Data from an Air Force Reserve Hurricane Hunter aircraft indicate that the disturbance has now become Tropical Storm Bonnie over the southwestern Caribbean Sea with maximum winds of 40 mph (65 km/h). SUMMARY OF 915 AM EDT...1315 UTC...INFORMATION ---------------------------------------------- LOCATION...11.2N 80.5W ABOUT 230 MI...370 KM ESE OF BLUEFIELDS NICARAGUA MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...W OR 260 DEGREES AT 20 MPH...31 KM/H MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES $$ Forecaster Cangialosi/Hogsett