Isaias

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Isaias

Post by Caribbean Traveler » Tue Jul 28, 2020 7:31 am

Tuesday Morning Update

Disturbance organizing

The Weather Situation
I suspect that we now have tropical storm Isaias east of the Lesser Antilles. A recon is scheduled for this afternoon. It will likely be named at that time or earlier if it looks "too good not to name" by NHC. Deep convection is much more organized today than yesterday. Yesterday there was a very large low level circulation with minimal convection.

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Re: Isaias

Post by Caribbean Traveler » Tue Jul 28, 2020 7:37 pm

Tuesday Evening Update

PTC 9 moving toward the Caribbean

The Weather Situation
The disturbance east of the Leewards has winds to 40 mph, but no distinct circulation yet. That is why it is a PTC or potential tropical cyclone in anticipation of formation. Regardless, heavy rainfall and gusty winds are likely in the northeastern Caribbean to the Dominican Republic as it moves through tomorrow and Thursday.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 8:00 PM AST PTC 9 was centered at 14.2 N / 58.7 W or about 340 miles SE of the Leewards. It was moving WNW at 25 mph. Officially top sustained winds are estimated at 40 mph. Pressure was estimated at 1007 hPa (mb).

Tropical Weather Forecast:
PTC 9 will likely be called a tropical storm soon. The track currently has low probability as a distinct center has not yet formed. The northern Caribbean and eastern U.S. coast should follow this tropical cyclone.

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Re: Isaias (PTC 9)

Post by Caribbean Traveler » Wed Jul 29, 2020 8:23 am

Wednesday Morning Update

PTC 9 in eastern Caribbean

The Weather Situation
The disturbance is now in the Caribbean with a recon currently investigating. As discussed last evening, it appears that the forming low center did indeed move farther southwest toward the deepest convection. This will take the track farther west.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 8:00 AM AST PTC 9 was centered at 15.1 N / 62.1 W or about 55 miles WSW of Dominica. It was moving WNW at 23 mph. Officially top sustained winds are estimated at 45 mph. Pressure was estimated at 1005 hPa (mb).

Tropical Weather Forecast:
PTC 9 will likely be called a tropical storm soon. The track currently has low probability as a distinct center has not yet formed. The northern Caribbean and eastern U.S. and Gulf coast should follow this tropical cyclone.

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Re: Isaias (PTC 9)

Post by Caribbean Traveler » Wed Jul 29, 2020 7:10 pm

Wednesday Evening Update

PTC 9 in eastern Caribbean

The Weather Situation
This morning's recon did not seem to fully investigate PTC9. It turned north instead of south where it could have possibly have found a closed circulation. There have been no additional recons today. I don't know if this is a mechanical issue or something else.

The most recent satellite imagery still seem to show a circulation. Convection in the meantime has decreased markedly. We'll see if there's another burst tonight.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 8:00 PM AST PTC 9 was centered at 16.0 N / 66.3 W or about 280 miles of Santo Domingo, Dominican Republic. It was moving WNW at 18 mph. Officially top sustained winds are estimated at 45 mph. Pressure was estimated at 1004 hPa (mb).

Tropical Weather Forecast:
PTC 9 will likely be called a tropical storm soon. The track currently has low probability as a distinct center has not yet formed. The northern Caribbean and eastern U.S. and Gulf coast should follow this tropical cyclone.

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Re: Isaias

Post by Caribbean Traveler » Thu Jul 30, 2020 7:05 am

Thursday Morning Update

New low forming

The Weather Situation
IMO Isaias had a circulation yesterday but at least by midday, but the recon did not investigate the whole system. The PTC was upgraded at 11 pm ast last night.

Isaias remains a complex storm. The low level circulation is south of the Dominican Republic whereas the most robust convection is well northeast of the center. This will now allow the track to jump a little east as a new low level circulation reforms north of Hispaniola.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 8:00 AM AST Tropical Storm Isaias was centered at 17.6 N / 68.5 W or about 105 miles ESE of Santo Domingo, Dominican Republic. It was moving NW at 20 mph. Officially top sustained winds are estimated at 60 mph. Pressure was estimated at 1003 hPa (mb).

Tropical Weather Forecast:
Isaias is forecast to move over Hispaniola then possibly reform after the circulation is disrupted. For now models have shifted a bit east again, but the track is still somewhat uncertain depending on what happens to the circulation after being disrupted by the high terrain of Hispaniola. Flooding rainfall is the main concern over Hispaniola at this time.

Interests in the Bahamas and U. S. east coast should continue to follow the progress of Isaias.

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Re: Isaias

Post by Caribbean Traveler » Thu Jul 30, 2020 6:48 pm

Thursday Evening Update

Isaias projected to become a hurricane

The Weather Situation
Isaias has essentially dodged the rough terrain of Hispaniola. This has allowed only a small disruption to the circulation. Because of this, there will be an opportunity for it to strengthen into a hurricane as it moves toward the western Bahamas.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 8:00 PM AST Tropical Storm Isaias was centered at 19.9 N / 71.2 W or about 155 miles ESE of Great Inagua Bahamas. It was moving NW at 20 mph. Officially top sustained winds are estimated at 60 mph. Pressure was estimated at 999 hPa (mb).

Tropical Weather Forecast:
Isaias is now forecast toward the western Bahamas then northward, just east of the Florida peninsula. It will then move close the the U.S. coast possibly all the way to the Northeast into the middle of next week. The track will become better known as the center reorganizes north of the Dominican Republic.

Interests in the Bahamas and U. S. east coast should continue to follow the progress of Isaias.

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Re: Isaias

Post by Caribbean Traveler » Fri Jul 31, 2020 7:41 am

Friday Morning Update

Isaias upgraded

The Weather Situation
Models this morning - GFS and Euro - are both more in line with continuity from last nights runs. The Euro may be a touch to the east from the previous run. Both are in the vicinity of the far northwestern Bahamas late Saturday afternoon. It was interesting to read NHC's discussion as they basically did not know what model was best and said we'll go with consensus.

Satellite imagery shows dramatic change from yesterday. Convection is going through another rebuilding phase after becoming disorganized last night. There still appears to be a channel of dry air west of the circulation keeping most of the deep convection near and east of the center.

A recon is currently investigating and has only found strong tropical storm force winds. There is still a lot of area to cover before the system is fully sampled. The center has been located northwest of the southern part of Great Inagua. This confirms that Isasis is sheared with most of the deep convection on the eastern side of the circulation.

Recon has found pressure up a bit at 993 mb.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 8:00 AM AST Hurricane Isaias was centered at 21.3 N / 73.9 W or about 30 miles NW of Great Inagua Bahamas. It was moving NW at 17 mph. Officially top sustained winds are estimated at 80 mph. Pressure was estimated at 990 hPa (mb).

Tropical Weather Forecast:
Isaias is forecast toward the western Bahamas then northward, just east of the Florida peninsula. It will then move close the the U.S. coast possibly make landfall over eastern North Carolina and all the way to the Northeast into Tuesday of next week.

Interests in the Bahamas and U. S. east coast should continue to follow the progress of Isaias.

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Re: Isaias

Post by Caribbean Traveler » Fri Jul 31, 2020 4:14 pm

Friday Evening Update

Isaias moves toward Florida east coast

The Weather Situation
Isaias appeared to weaken earlier today. Recon and satellite imagery now confirm that it is in a deepening phase again. Dry air and some SW wind shear will likely keep the heaviest rainfall and strongest winds on the eastern side of the circulation - over the water into the northwestern Bahamas. Storm surge of 1-4 feet is likely up most of the Florida east coast.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 5:00 PM AST Hurricane Isaias was centered at 22.6 N / 75.7 W or about 195 miles SSE of Nassau Bahamas. It was moving NW at 15 mph. Officially top sustained winds are estimated at 75 mph. Pressure was estimated at 991 hPa (mb).

Tropical Weather Forecast:
Isaias is forecast to make landfall on the Florida east coast late Saturday and likely move offshore again before moving over eastern North Carolina and then all the way to the Northeast into Tuesday of next week.

Interests in the Bahamas and U. S. east coast should continue to follow the progress of Isaias.

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Re: Isaias

Post by Caribbean Traveler » Sat Aug 01, 2020 7:03 am

Saturday Morning Update

Isaias battling dry air and shear

The Weather Situation
Dry air and westerly wind shear is keeping Isaias at bay. The western side of the hurricane is much weaker than the east with an upper air trough eating away at the structure. The recon is still finding winds up to 85 mph in a compact area near the core east of Andros Island.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 8:00 AM EDT Hurricane Isaias was centered at 24.3 N / 77.5 W or about 50 miles south of Nassau Bahamas. It was moving NW at 12 mph. Officially top sustained winds are estimated at 85 mph. Pressure was estimated at 987 hPa (mb).

Tropical Weather Forecast:
Isaias is now forecast to move very close to the east coast of Florida late today into Sunday. The latest models show the hurricane barely staying offshore. Wind shear and dry air should weaken Isaias before it approaches the coast of North Carolina late Monday night as a tropical storm.

Interests in the NW Bahamas and U. S. east coast should continue to follow the progress of Isaias.

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Re: Isaias

Post by Caribbean Traveler » Sat Aug 01, 2020 4:06 pm

Saturday Evening Update

Isaias weaker

The Weather Situation
Isaias crossed Andros Island this afternoon which basically destroyed its eyewall. Dry air and shear will continue to hamper redevelopment. Some deep convection is trying to north of the center. IMO Isaias is only about 60 mph, so I'm estimating a bit lower than NHC. Tweets today suggested that Isaias weakened to TS strength several hours ago.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 5:00 PM EDT Tropical Storm Isaias was centered at 24.3 N / 77.5 W or about 50 miles south of Nassau Bahamas. It was moving NW at 12 mph. Officially top sustained winds are estimated at 85 mph. Pressure was estimated at 987 hPa (mb).

Tropical Weather Forecast:
Isaias is now forecast to move very close to the east coast of Florida this evening into Sunday. The latest models show the tropical storm to move very close to the coast. Wind shear and dry air should weaken Isaias before it approaches the coast of North Carolina late Monday night as a tropical storm.

Interests in the NW Bahamas and U. S. east coast should continue to follow the progress of Isaias.

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Re: Isaias

Post by Caribbean Traveler » Sun Aug 02, 2020 7:55 am

Sunday Morning Update

SE Florida dodging Isaias

The Weather Situation
Dry air and shear continue to wreck havoc on Isaias. Florida has been protected with little effect from the tropical storm so far. Rough surf, breezes and an occasional rainband is what has been seen to this point. Strong winds and very heavy rainfall have been experienced in the western / NW Bahamas on the eastern side of the circulation.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 8:00 AM EDT Tropical Storm Isaias was centered at 26.5 N / 79.5 W or about 40 miles ESE of West Palm Beach, Florida. It was moving NW at 8 mph. Officially top sustained winds are estimated at 65 mph. Pressure was estimated at 996 hPa (mb).

Tropical Weather Forecast:
Isaias will move along the Florida coast today then move inland near South Carolina and inland up the east coast. The main effect will be heavy rainfall.

Interests on the U. S. east coast should continue to follow the progress of Isaias.

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Re: Isaias

Post by Caribbean Traveler » Sun Aug 02, 2020 4:10 pm

Sunday Evening Update

Isaias having little effect on Florida

The Weather Situation
Per my tweets today, it was apparent that Isaias had strengthened a touch. The east coast of Florida has seen very little of rainfall except for an occasional brief rainband. Winds have been well under tropical storm force. Satellite imagery shows an impressive burst and excellent outflow east of the circulation center. It's still possible that the TC could achieve minimal hurricane strength, but it is more likely to stay near 70 mph before shear weakens it.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 5:00 PM EDT Tropical Storm Isaias was centered at 27.8 N / 79.8 W or about 65 miles SE of Cape Canaveral, Florida. It was moving NNW at 9 mph. Officially top sustained winds are estimated at 70 mph. Pressure was estimated at 994 hPa (mb).

Tropical Weather Forecast:
Isaias will move just east of the north Florida coast this evening then move inland near South Carolina Monday night and inland up the east coast. The main effect will be heavy rainfall into the coastal Carolinas to Mid Atlantic.

Interests on the U. S. east coast should continue to follow the progress of Isaias.

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Re: Isaias

Post by Caribbean Traveler » Mon Aug 03, 2020 8:49 am

Monday Morning Update

Isaias heading to the Carolinas

The Weather Situation
Last evening on Twitter I suggested that Isaias had become a hurricane again. I still believe that It was a minimal hurricane for several hours late last evening. Radar showed an improved circulation with an eyewall forming and recon reported winds in the 75-80 mph range. Typically NHC uses the max winds found, but did not that time. They typically don't like to "flip flop" between intensities to avoid confusing the public.

This morning it appears that the tropical storm is a bit weaker it is also battling wind shear. I believe the tropical storm is a bit weaker than the official 70 mph, maybe 65 mph.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 8:00 AM EDT Tropical Storm Isaias was centered at 30.2 N / 80.1 W or about 250 miles SSW of Myrtle Beach, South Carolina. It was moving north at 13 mph. Officially top sustained winds are estimated at 70 mph. Pressure was estimated at 994 hPa (mb).

Tropical Weather Forecast:
Isaias will move inland near the northern South Carolina / southern North Carolina coast by this evening.... and inland up the east coast. The main effect will be heavy rainfall into the coastal Carolinas to Mid Atlantic.

Interests on the U. S. east coast should continue to follow the progress of Isaias.

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Re: Isaias

Post by Caribbean Traveler » Mon Aug 03, 2020 3:43 pm

Monday Evening Update

Isaias to make landfall several hours from now

The Weather Situation
Satellite imagery shows a more organized central dense overcast indicating that Isaias is getting a touch stronger before landfall. Radar indicates an eyewall forming. Heavy rainfall, storm surge and strong winds can be expected where landfall occurs and to the right of the path. Isolated tornadoes are possible in bands ahead of the eye. The eye is expect to move near Myrtle Beach, SC / Wilmington, NC to Greenville, NC overnight tonight then into SE Virginia by tomorrow morning.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 5:00 PM EDT Tropical Storm Isaias was centered at 32.0 N / 79.4 W or about 120 miles SSW of Myrtle Beach, South Carolina. It was moving NNE at 16 mph. Officially top sustained winds are estimated at 70 mph. Pressure was estimated at 993 hPa (mb).

Tropical Weather Forecast:
Isaias will move inland near the northern South Carolina / southern North Carolina coast by later this evening.... and inland up the east coast. The main effect will be heavy rainfall into the coastal Carolinas to Mid Atlantic. Additionally, strong winds of tropical storm force will be seen up to southern New England near and right of the pathway.

Interests on the U. S. east coast should continue to follow the progress of Isaias.

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Re: Isaias

Post by Caribbean Traveler » Tue Aug 04, 2020 9:56 am

Tuesday Morning Update

Isaias bringing heavy rainfall

The Weather Situation
IMO Isaias was not a hurricane at landfall. My reasoning is that no surface sustained winds of 74 mph were recorded. Gusts should have been to at least 90-100 mph. The highest gust noted was 80-85 near SE North Carolina in a very small area. Without going into a long discussion, I believe that the way winds are conveyed in advisories should be amended. Most wind gusts were in the 55-65 mph range inland over eastern North Carolina and 65-70 near the coast with a few higher gusts.

For more frequent updates: Twitter: https://twitter.com/richjohnsonwx

Current tropical weather
As of 11:00 AM EDT Tropical Storm Isaias was centered at 39.1 N / 76.1 W or about 20 miles SSW of Frederick, MD. It was moving NNE at 35 mph. Officially top sustained winds are estimated at 70 mph. Pressure was estimated at 993 hPa (mb).

Tropical Weather Forecast:
Isaias will continue into western New England through today. Heavy rainfall of several inches is likely and will cause flooding. Winds to tropical storm force will cause power outages and tree damage.

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Tropicast: GR Level III Radar 10:15 am edt
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NHC Location / Hazards / Outlook
https://www.nhc.noaa.gov/text/refresh/M ... 442.shtml?

NHC Track
https://www.nhc.noaa.gov/graphics_at4.s ... t#contents
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