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OT: Hurricane Isaias: heavy rain, high winds, and flooding in SC/NC/VA/MD/DE/PA/NJ/NY/New England

️ In addition to heavy rain leading to flash flooding, strong winds, and coastal flooding, tornadoes are also possible, particularly along and south/east of I-95 with #Isaias on Tuesday. The SPC has introduced a slight risk of severe weather to highlight this threat.

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Maybe look at the local NWS forecast before leaving at 5-6 pm. The graphic is for Edison, which will take you an hour to get to in the conditions tomorrow. Do you really want to drive in 50 mph wind gusts and biblical rainfall? At least try to avoid the winds by leaving before about 10 am or after 7 pm.

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Biblical rainfall? The only time my basement got flooded was with hurricane Irene . Are we approaching that tomorrow ?
 
Biblical rainfall? The only time my basement got flooded was with hurricane Irene . Are we approaching that tomorrow ?

It's not forecast to be as much as Irene or Floyd, which had up to 10" (or more in spots), but 3-6" is a serious amount of rain and 7-8" is possible in spots, especially if that 6-10" swath in VA/MD moves further north towards us.
 
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️ In addition to heavy rain leading to flash flooding, strong winds, and coastal flooding, tornadoes are also possible, particularly along and south/east of I-95 with #Isaias on Tuesday. The SPC has introduced a slight risk of severe weather to highlight this threat.

117107203_3488974024469304_320204589620260512_o.jpg
That possible 1-2 inch hail doesn't sound pleasant at all
 
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Interesting set up. Outer banks forecast for 1" of rain, while Raleigh gets pounded.
Similar forecast for Manasquan area (1-1.5") vs. Allentown, Pa (3-5 inches).
 
Some changes in the NHC forecast and not for the better; see the NWS-Philly sections of the forecast discussion below, including the hydrology and coastal flooding discussions; the usual links and graphics are below, also.

The forecast is now for the storm to arrive several hours earlier in the NJ area, as the center is forecast to reach CNJ by around 2 pm instead of 8 pm and the track has moved inland about 20-30 miles for our area, i.e., it will be along the NJ TPK in SNJ and about 10-20 miles W of the TPK north of about Trenton. The earlier arrival is part of why the storm is expected to be stronger than originally forecast, i.e., instead of generally ~50 mph winds, the forecast is for ~60 mph winds, meaning sustained winds could easily be 40-45 mph with gusts to 60 mph near the coast and gusts to 50-55 mph inland (as per the NWS discussion). Also, isolated small tornadoes are possible, especially east of the storm track from SC to Maine.

In addition, the forecast is for 3-6" of rain for the area (starting late tonight through Tuesday), especially along and NW of the 95 corridor, as more rain typically falls NW of a storm track for a tropical system that is transitioning to an extratropical system, as has been mentioned before (unlike in FL, where most of the precip was east of the storm track); rainfall amounts are likely to be more like 2-4" SE of 95 to the coast. This means significant urban/stream flooding is likely and with saturated soils and increased winds, the likelihood of downed trees and power outages is greater. Coastal flooding in our area is forecast to be mostly minor (a fast moving storm helps with that) with some locations seeing moderate levels (this is nowhere near Sandy levels or even Irene levels, but still, any coastal flooding can be dangerous).

Further south, Isaias is now forecast to strengthen a bit over the next 12 hours to a 75 mph Cat 1 hurricane, right before landfall this evening, somewhere between Charleston and the SC/NC border (this is also a little bit NW of where landfall was being forecast yesterday). And even if there is no landfall in Charleston, the storm will likely be only 10-20 miles offshore, with the eyewall still likely to be on-shore with hurricane force gusts and coastal flooding likely, as well as 3-6" of rains. Similar conditions are expected for much of NE SC and eastern/central NC/VA, with the storm still packing 65-70 mph winds and bringing 3-6" of rain. The heaviest rains are now forecast to be from DC to Baltimore (6-10").

https://www.nhc.noaa.gov/text/refresh/MIATCDAT4+shtml/030243.shtml?
https://www.wunderground.com/articl...ing-tropical-storm-isaias-forecast-east-coast
https://www.americanwx.com/bb/topic/53557-tropical-storm-isaías/page/49/
https://www.weather.gov/phi/

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Area Forecast Discussion
National Weather Service Mount Holly NJ
1145 AM EDT Mon Aug 3 2020

Tuesday...Tropical Storm Isaias will be speeding quickly northward
by early Tuesday in response to the aforementioned jet streak. The
cyclone will likely be undergoing an extratropical transition as it
moves from the Carolinas on Monday toward the Mid-Atlantic on
Tuesday. Important to note though, this may not actually weaken the
storm and it may even gain strength from the baroclinic support as
indicated by the latest ECMWF model run. The strong divergence aloft
will promote an enhancement of convection associated with the system
and support at least a maintenance of its strength. As far as the
track and timing, there isn`t been a big change in the forecast
track with this update but the trend with guidance has been for a
slightly faster timing. As we are getting closer to the arrival of
this system, confidence is growing in a track that takes the system
NE across the CWA. However even at this time range it`s important to
not focus on the exact track but rather the potential impacts. It
appears the greatest impacts will occur during much of the day
Tuesday, particularly late morning and through the evening hours
before the storm lifts northeast out of the area.

Multiple hazards are becoming likely with Isaias including, but not
limited to, fresh water flooding, coastal flooding/storm surge,
strong winds and even isolated tornadoes. The greatest
precipitation amounts are forecast to fall right along and just
west of the urban and I-95 corridor with 3- 6" of rain with
locally higher amounts possible. This will lead to a flash
flooding threat, especially for the more urbanized areas and
portions of Berks County that saw an excessive amount of rain
Sunday morning. In fact the flooding has the potential to be
widespread and significant. We also have growing concerns that
widespread damaging winds may be an issue. Again, the system
will be starting to lose its tropical characteristics but
because of the strong baroclinic zone it will be moving into
this could actually strengthen it. Winds will initially be from
the E/SE then shift to NW behind the system. Sustained winds of
40+ mph will be possible along the coast with gusts potentially
reaching over 60 mph here. Farther N/W towards the I-95
corridor, widespread gusts of 45 to 55+ mph are becoming
increasingly likely. The upshot is that there could be fairly
extensive impacts potentially including widespread power
outages. These impacts may be exacerbated by the rainfall
loosening the ground soil. Coastal flooding and/or storm surge
will be directly dependent on the exact timing and track of the
system and this is further described in the section below.
Finally, with a favored track near the coast or just inland,
this will set up very strong low level shear just ahead of and
east of the storm and this could cause a spin up of a few
tornadoes Tuesday afternoon. The most favored areas for this are
near and S/E of the I-95 corridor.

.HYDROLOGY...
Hydro concerns will begin as early as this evening as shower/storms
develop across the area ahead of Isaias. Any of these will be
capable of producing very heavy rain with at least localized flash
flooding possible. The heaviest, steadiest rain with the storm will
arrive later tonight through Tuesday. More widespread flash flooding
will be an increasing threat by this time. Most susecptible
areas will be near and N/W of the I-95 corridor especially
since places such as in Berks County have received so much
rainfall recently. With Isaias, 3 to 6 inches of rain, with
locally higher amounts are expected. Therefore, the Flash Flood
Watch remains in effect as again, flooding could be widespread
and significant.

In addition to flash flooding, river flooding is also becoming an
increasing threat especially in portions of southeastern
Pennsylvania which have already been affected by the earlier rounds
of heavy rain.

.TIDES/COASTAL FLOODING...
A coastal flood watch remains in effect for the eastern shore of
Chesapeake Bay in northeast Maryland. There remains considerable
uncertainty regarding the timing and exact track of Isaias and
its ultimate impacts on Chesapeake Bay. Models remain fairly
modest with forecast water levels, but this is a common bias in
these regimes, with guidance often performing quite poorly (and
much too low). We suspect surge associated with Isaias will
likely lead to minor to potentially moderate flooding Tuesday
afternoon into Tuesday night, with potential for large
deviations from the timing of high astronomical tide. We decided
to leave a large buffer on either side of the time of high tide
for this reason.

Isaias will likely accelerate as it moves through the region on
Tuesday. This tends to limit coastal flooding impacts in our
area, as the duration of onshore flow will be limited. However,
models are trending a little stronger with the low (and the
associated onshore flow), which is worrisome. The stronger flow
may compensate for the short duration. Furthermore, though
current forecasts would suggest the strongest surge would occur
out of phase with astronomical high tide, uncertainty in the
timing suggests this is not guaranteed. For these reasons,
suspect minor coastal flooding will be possible along the
Atlantic coasts of New Jersey and Delaware, with isolated
moderate flooding possible, especially in northern New Jersey.

For Delaware Bay and the tidal Delaware River, a few factors
lead to more elevated concerns. First, a strong southeast fetch
will occur in advance of Isaias, which is favorable for coastal flooding
in these areas. Second, the timing of high tide more closely
aligns with the strongest forecast surge. Third, for the tidal
Delaware River, freshwater runoff from anticipated heavy
rainfall may exacerbate tidal flooding. Have increased forecast
water levels in these areas on Tuesday, with at least minor
flooding a possibility.

edit: changed title from: "OT: TS Isaias finally forms: Bahamas, FL, GOM and East Coast need to watch this" to current title.

Pretty much the same forecast track (maybe nudged 5-10 miles to the east, right up the 95 corridor from Philly to NYC) and intensity (70-75 mph at landfall in NE SC to ~60 mph in our area). Highlights below and some graphics/links.
  • The one change in this forecast is a steeper gradient of rainfall from SE to NW with 1-2" along the coast, 2-4" from the coast to 95, and 3-6" from 95 to points well NW of 95.
  • Expecting the worst winds from about 2-6 pm in CNJ (earlier to the south/later to the north), as the storm's center approaches our area.
    • Forecast calls for 50-55 mph sustained and gusts up to 70 mph along/near the coast and ~40 mph sustained with gusts to 55 mph inland (from just SE of 95 to all points NW of there).
  • Coastal flooding should be minor in most locations, but perhaps moderate in Delaware/Chesapeake Bays.
  • Still a low chance of isolated small tornadoes to the SE of the storm's track, i.e., along and SE of the 95 corridor.
https://www.weather.gov/phi/
https://www.facebook.com/NWSMountHolly/
https://www.wunderground.com/articl...-storm-isaias-forecast-mid-atlantic-northeast
https://www.nhc.noaa.gov/text/refresh/MIATCDAT4+shtml/030243.shtml?
https://www.americanwx.com/bb/topic/53557-tropical-storm-isaías/page/51/

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Interesting set up. Outer banks forecast for 1" of rain, while Raleigh gets pounded.
Similar forecast for Manasquan area (1-1.5") vs. Allentown, Pa (3-5 inches).

Yep, but not sure I buy the gradient being that steep, but most of the models do show it. Amazing how the heavy rain shifts from completely east of the storm near FL, to mostly east of the storm now to equally west/east of the storm track in SC/NC, to more to the west/less to the east in the Philly-NYC corridor and north of there. Most of this progression is due to the storm transitioning from pure tropical (now), to a mix in the mid-Atlantic to purely extratropical NE of about western MA.

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Yep, but not sure I buy the gradient being that steep, but most of the models do show it. Amazing how the heavy rain shifts from completely east of the storm near FL, to mostly east of the storm now to equally west/east of the storm track in SC/NC, to more to the west/less to the east in the Philly-NYC corridor and north of there. Most of this progression is due to the storm transitioning from pure tropical (now), to a mix in the mid-Atlantic to purely extratropical NE of about western MA.

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We're going to stick it out and leave later. Better to be around the house in case there are issues with trees down, etc.
 
while certainly lots of rain..3-4 inches forecast for most of NJ isn’t exactly biblical
Agree that 3-4" isn't quite biblical, but it's enough for a record most days. I was also referring to his drive to Rochester which will take him through areas forecast to get 4-6" (or more possible), which is very close to biblical - for example, NYC has only seen 5 days with 5" or more of rain in 151 years, so 4-6" is pretty serious. Biblical would probably be 8" or more (once in 151 years in NYC).
 
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We're going to stick it out and leave later. Better to be around the house in case there are issues with trees down, etc.

Very good point. If the storm had stayed off the coast, my son and I were going to take a ride down to Sea Bright/Sandy Hook to see the storm, but with serious rain and wind in Metuchen and some history of water getting into our basement (and losing a 2 full trees in our 27 years here), we're going to stay put.
 
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While it may seem hard to believe, as #Isaias merges with a vigorous jet stream NYC/ NJ & especially Long Island / CT should prepare for wicked wind gusts tomorrow(Tues) afternoon-early evening. Winds just above the ground will be 90 mph+, so 80 mph+ gusts are possible. Bring in all loose items by morning. Expect power outages. NJ needs to watch for tornadoes per latest risk area from Nws
--Jeff Berardelli

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Eeh3Y4hUEAAergl
 
Severe t-storm warning until 9:15 pm for much of CNJ (warning below just says Morris/Somerset, but the map shows through Middlesex and the radar is lit up all through northern Middlesex)...crazy out there right now here.

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
826 PM EDT Mon Aug 3 2020
The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
Morris County in northern New Jersey...
Northeastern Hunterdon County in northwestern New Jersey...
Somerset County in northern New Jersey...
North central Middlesex County in northern New Jersey...

* Until 915 PM EDT.

* At 826 PM EDT, a severe thunderstorm was located over Bridgewater,
or near Somerville, moving northeast at 30 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Damage to roofs, siding, trees, and power lines is
possible.

* Locations impacted include...
Morristown, Somerville, Somerset, Bridgewater, Dover, Madison,
Middlesex, Florham Park, East Hanover, Bound Brook, Manville,
Chatham, Boonton, Wharton, Rockaway, Morris Plains, Mount
Arlington, Mendham, Mountain Lakes and High Bridge.

This includes the following highways...
Interstate 78 in New Jersey between mile markers 15 and 42.
Interstate 80 in New Jersey between mile markers 27 and 48.
Interstate 287 in New Jersey between mile markers 7 and 45.
 
By the way, as of 8 pm, we have Hurricane Isaias again with 75 mph winds. The storm is about 60 miles east of Charleston and 60 miles south of Myrtle Beach and moving NNE, so landfall right around the SC/NC border looks very likely in a few hours (moving at 16 mph).

BULLETIN
Hurricane Isaias Intermediate Advisory Number 27A...Corrected
NWS National Hurricane Center Miami FL AL092020
800 PM EDT Mon Aug 03 2020

Corrected to add extent of hurricane-force winds and surface ob

...ISAIAS REGAINS HURRICANE STRENGTH AND IS EXPECTED TO MAKE
LANDFALL TONIGHT WITH DANGEROUS WINDS AND STORM SURGE...
...STRONG WINDS AND HEAVY RAINFALL LIKELY FROM THE EASTERN
CAROLINAS TO THE MID-ATLANTIC COAST TONIGHT AND TUESDAY...


SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...32.8N 79.0W
ABOUT 60 MI...100 KM E OF CHARLESTON SOUTH CAROLINA
ABOUT 60 MI...100 KM S OF MYRTLE BEACH SOUTH CAROLINA
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NNE OR 15 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...988 MB...29.18 INCHES
 
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The Phillies/Yankees game at Yankee Stadium is now in a rain delay after six innings. It's not a big deal whether they finish; the Yanks are up 6-1.

Cherry Hill had a thunderstorm at about 7. My wife and I are not looking forward to the rain and wind. We have a couple of trees that my predecessor planted too close to the house, and the last thing we'd need is for either or both to come down.
 
While it may seem hard to believe, as #Isaias merges with a vigorous jet stream NYC/ NJ & especially Long Island / CT should prepare for wicked wind gusts tomorrow(Tues) afternoon-early evening. Winds just above the ground will be 90 mph+, so 80 mph+ gusts are possible. Bring in all loose items by morning. Expect power outages. NJ needs to watch for tornadoes per latest risk area from Nws
--Jeff Berardelli

117116404_3298272096883020_1051102306601028917_o.png



Eeh3Y4hUEAAergl

Love Jeff, but I think he's overdoing it on this one. The HRRR beyond 12 hours is crap and the Euro is known to overdo wind gusts. Have a very hard time believing this storm, which is definitely less powerful than Sandy will have gusts greater than Sandy had. Sandy had plenty of 80-90 mph gusts and everyone gusted over 70 mph, including inland, which is why so many trees were lost in CNJ/NNJ, despite only having a few inches of rain (the huge rains of 6-12" were all in SNJ). The NWS in Philly has 70 mph max gusts on their map; same for the NWS NYC. Doesn't mean gusts to 80 mph aren't possible but 90-100 mph just seems way overdone. We'll see, obviously.
 
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Yeah it is an absolute SHIT SHOW in Hoboken/JC already...Yijes!!

I thought this was hitting at 8 AM?
 
By the way, as of 8 pm, we have Hurricane Isaias again with 75 mph winds. The storm is about 60 miles east of Charleston and 60 miles south of Myrtle Beach and moving NNE, so landfall right around the SC/NC border looks very likely in a few hours (moving at 16 mph).

BULLETIN
Hurricane Isaias Intermediate Advisory Number 27A...Corrected
NWS National Hurricane Center Miami FL AL092020
800 PM EDT Mon Aug 03 2020

Corrected to add extent of hurricane-force winds and surface ob

...ISAIAS REGAINS HURRICANE STRENGTH AND IS EXPECTED TO MAKE
LANDFALL TONIGHT WITH DANGEROUS WINDS AND STORM SURGE...
...STRONG WINDS AND HEAVY RAINFALL LIKELY FROM THE EASTERN
CAROLINAS TO THE MID-ATLANTIC COAST TONIGHT AND TUESDAY...


SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...32.8N 79.0W
ABOUT 60 MI...100 KM E OF CHARLESTON SOUTH CAROLINA
ABOUT 60 MI...100 KM S OF MYRTLE BEACH SOUTH CAROLINA
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NNE OR 15 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...988 MB...29.18 INCHES


And as of 9 pm with hurricane hunter info, we now have 85 mph winds with this hurricane. It's about to get real for SC/NC and it's not going to be any picnic here.

Hurricane Isaias Tropical Cyclone Update
NWS National Hurricane Center Miami FL AL092020
900 PM EDT Mon Aug 3 2020

Data from an Air Force Reserve Hurricane Hunter aircraft and NOAA
Doppler radars indicate that the maximum sustained winds associated
with Hurricane Isaias have increased to 85 mph (135 km/h) with
higher gusts. The minimum pressure measured by the plane was 988 mb
(29.18 inches).

NOAA buoy 41004 recent reported sustained wind of 67 mph (108 km/h)
and a gust to 78 mph (126 km/h) in the southwest eyewall of Isaias.


SUMMARY OF 900 PM EDT...0100 UTC...INFORMATION
-----------------------------------------------
LOCATION...33.1N 78.8W
ABOUT 55 MI...90 KM SSE OF MYRTLE BEACH SOUTH CAROLINA
MAXIMUM SUSTAINED WINDS...85 MPH...135 KM/H
PRESENT MOVEMENT...NNE OR 15 DEGREES AT 18 MPH...29 KM/H
MINIMUM CENTRAL PRESSURE...988 MB...29.18 INCHES
 
Apparently winds up to 85 mph now per weather channel per 9pm advisory. So storm intensified over warm Atlantic Ocean waters off Florida coast
 
Severe t-storm warning until 9:15 pm for much of CNJ (warning below just says Morris/Somerset, but the map shows through Middlesex and the radar is lit up all through northern Middlesex)...crazy out there right now here.

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
826 PM EDT Mon Aug 3 2020
The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
Morris County in northern New Jersey...
Northeastern Hunterdon County in northwestern New Jersey...
Somerset County in northern New Jersey...
North central Middlesex County in northern New Jersey...

* Until 915 PM EDT.

* At 826 PM EDT, a severe thunderstorm was located over Bridgewater,
or near Somerville, moving northeast at 30 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Damage to roofs, siding, trees, and power lines is
possible.

* Locations impacted include...
Morristown, Somerville, Somerset, Bridgewater, Dover, Madison,
Middlesex, Florham Park, East Hanover, Bound Brook, Manville,
Chatham, Boonton, Wharton, Rockaway, Morris Plains, Mount
Arlington, Mendham, Mountain Lakes and High Bridge.

This includes the following highways...
Interstate 78 in New Jersey between mile markers 15 and 42.
Interstate 80 in New Jersey between mile markers 27 and 48.
Interstate 287 in New Jersey between mile markers 7 and 45.


5 minutes of rain, big bust IMBY
 
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