Tropical Discussion 2025

[tireman4]

000
FONT15 KNHC 181540
PWSAT5

HURRICANE ERIN WIND SPEED PROBABILITIES NUMBER 29
NWS NATIONAL HURRICANE CENTER MIAMI FL AL052025
1500 UTC MON AUG 18 2025

AT 1500Z THE CENTER OF HURRICANE ERIN WAS LOCATED NEAR LATITUDE 23.1
NORTH...LONGITUDE 70.8 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 120
KTS...140 MPH...220 KM/H.

Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH)
ATLANTIC STANDARD TIME (AST)...SUBTRACT 4 HOURS FROM Z TIME
EASTERN DAYLIGHT TIME (EDT)...SUBTRACT 4 HOURS FROM Z TIME
CENTRAL DAYLIGHT TIME (CDT)...SUBTRACT 5 HOURS FROM Z TIME

WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS

CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST
...34 KT (39 MPH... 63 KM/H)...
...50 KT (58 MPH... 93 KM/H)...
...64 KT (74 MPH...119 KM/H)...
FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS

PROBABILITIES FOR LOCATIONS ARE GIVEN AS OP(CP) WHERE
OP IS THE PROBABILITY OF THE EVENT BEGINNING DURING
AN INDIVIDUAL TIME PERIOD (ONSET PROBABILITY)
(CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN
12Z MON AND THE FORECAST HOUR (CUMULATIVE PROBABILITY)

PROBABILITIES ARE GIVEN IN PERCENT
X INDICATES PROBABILITIES LESS THAN 1 PERCENT
PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN
THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT.
PROBABILITIES FOR 34...50...64 KT SHOWN WHEN THE 5-DAY
64-KT CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT.


- - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - -

FROM FROM FROM FROM FROM FROM FROM
TIME 12Z MON 00Z TUE 12Z TUE 00Z WED 12Z WED 12Z THU 12Z FRI
PERIODS TO TO TO TO TO TO TO
00Z TUE 12Z TUE 00Z WED 12Z WED 12Z THU 12Z FRI 12Z SAT

FORECAST HOUR (12) (24) (36) (48) (72) (96) (120)
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
LOCATION KT

HIBERNIA OILFD 34 X X( X) X( X) X( X) X( X) X( X) 6( 6)

CAPE RACE NFLD 34 X X( X) X( X) X( X) X( X) X( X) 10(10)
CAPE RACE NFLD 50 X X( X) X( X) X( X) X( X) X( X) 4( 4)
CAPE RACE NFLD 64 X X( X) X( X) X( X) X( X) X( X) 1( 1)

ILE ST PIERRE 34 X X( X) X( X) X( X) X( X) X( X) 9( 9)
ILE ST PIERRE 50 X X( X) X( X) X( X) X( X) X( X) 3( 3)

BURGEO NFLD 34 X X( X) X( X) X( X) X( X) X( X) 4( 4)

PTX BASQUES 34 X X( X) X( X) X( X) X( X) X( X) 3( 3)

EDDY POINT NS 34 X X( X) X( X) X( X) X( X) X( X) 7( 7)

SYDNEY NS 34 X X( X) X( X) X( X) X( X) X( X) 6( 6)

SABLE ISLAND 34 X X( X) X( X) X( X) X( X) 1( 1) 19(20)
SABLE ISLAND 50 X X( X) X( X) X( X) X( X) X( X) 7( 7)
SABLE ISLAND 64 X X( X) X( X) X( X) X( X) X( X) 3( 3)

HALIFAX NS 34 X X( X) X( X) X( X) X( X) 1( 1) 3( 4)

YARMOUTH NS 34 X X( X) X( X) X( X) X( X) 3( 3) 4( 7)

ST JOHN NB 34 X X( X) X( X) X( X) X( X) 1( 1) 2( 3)

HYANNIS MA 34 X X( X) X( X) X( X) X( X) 3( 3) X( 3)

NANTUCKET MA 34 X X( X) X( X) X( X) X( X) 8( 8) 1( 9)

PROVIDENCE RI 34 X X( X) X( X) X( X) X( X) 4( 4) 1( 5)

MONTAUK POINT 34 X X( X) X( X) X( X) X( X) 6( 6) X( 6)

NYC JFK AIRPRT 34 X X( X) X( X) X( X) X( X) 3( 3) X( 3)

ATLANTIC CITY 34 X X( X) X( X) X( X) 1( 1) 2( 3) X( 3)

CAPE HENLOPEN 34 X X( X) X( X) X( X) 2( 2) 3( 5) X( 5)

OCEAN CITY MD 34 X X( X) X( X) X( X) 4( 4) 3( 7) X( 7)

WALLOPS CDA 34 X X( X) X( X) X( X) 4( 4) 3( 7) X( 7)

NORFOLK NAS 34 X X( X) X( X) X( X) 3( 3) X( 3) X( 3)

NORFOLK VA 34 X X( X) X( X) X( X) 3( 3) 1( 4) X( 4)

OCEANA NAS VA 34 X X( X) X( X) X( X) 8( 8) 3(11) X(11)

ELIZABETH CTY 34 X X( X) X( X) X( X) 5( 5) 1( 6) X( 6)

CAPE HATTERAS 34 X X( X) X( X) 1( 1) 22(23) 3(26) X(26)
CAPE HATTERAS 50 X X( X) X( X) X( X) 4( 4) 1( 5) X( 5)
CAPE HATTERAS 64 X X( X) X( X) X( X) 1( 1) 1( 2) X( 2)

CHERRY PT NC 34 X X( X) X( X) X( X) 6( 6) X( 6) X( 6)

NEW RIVER NC 34 X X( X) X( X) X( X) 4( 4) 1( 5) X( 5)

MOREHEAD CITY 34 X X( X) X( X) 1( 1) 14(15) 1(16) X(16)

SURF CITY NC 34 X X( X) X( X) X( X) 10(10) X(10) X(10)

WILMINGTON NC 34 X X( X) X( X) X( X) 4( 4) X( 4) X( 4)

BALD HEAD ISL 34 X X( X) X( X) 1( 1) 8( 9) X( 9) X( 9)

LITTLE RIVER 34 X X( X) X( X) X( X) 6( 6) X( 6) X( 6)

MYRTLE BEACH 34 X X( X) X( X) X( X) 4( 4) X( 4) X( 4)

BERMUDA 34 X X( X) X( X) X( X) 3( 3) 13(16) 1(17)

GRAND BAHAMA 34 X X( X) 4( 4) 1( 5) X( 5) X( 5) X( 5)

NEW PROVIDENCE 34 X 4( 4) 3( 7) 1( 8) X( 8) X( 8) X( 8)

ANDROS 34 X 3( 3) 2( 5) X( 5) X( 5) X( 5) X( 5)

GREAT EXUMA 34 3 4( 7) 3(10) X(10) X(10) X(10) X(10)

SAN SALVADOR 34 16 14(30) 4(34) 2(36) X(36) X(36) X(36)
SAN SALVADOR 50 2 2( 4) 1( 5) X( 5) X( 5) X( 5) X( 5)

MAYAGUANA 34 26 4(30) 2(32) X(32) X(32) X(32) X(32)
MAYAGUANA 50 3 X( 3) X( 3) X( 3) X( 3) X( 3) X( 3)

GRAND TURK 34 99 X(99) X(99) X(99) X(99) X(99) X(99)

PUERTO PLATA 34 3 X( 3) X( 3) X( 3) X( 3) X( 3) X( 3)

$$
FORECASTER PASCH

[tireman4]

Noah Bergren

[tireman4]

NHC

[tireman4]

Erin

[tireman4]

Erin on track to impact the U.S. East Coast with waves and erosion while we size up the disturbances behind it in the Atlantic
Next wave up may aim out to sea, while the one behind it stays weaker and sneaks west
The Eyewall and Matt Lanza
Aug 19






READ IN APP

In brief: Hurricane Erin is fighting off some dry air and shear this morning, which has caused it to lose intensity but maintain a large size. Forecast impacts to the U.S. East Coast are virtually unchanged today. Two tropical features in the Atlantic behind Erin are worth keeping tabs on, but none looks to be a serious land threat at this time.

Hurricane Erin

(NOAA/NHC)
Erin has finally hit a bit of a wall since last night in terms of intensity. Maximum sustained winds have dropped to 110 mph. Where Erin has not hit a wall is its size, which remains quite large. For the U.S. East Coast and Outer Banks in particular, this means little has changed since yesterday.


Erin continues to brush the Bahamas and hit the Turks and Caicos with persistent bands of thunderstorms, despite its disheveled appearance this morning. (Tropical Tidbits)
We'll get the easy part out of the way quickly this morning. Erin's track forecast remains pretty solid with very little model spread over the next 3 to 4 days as it turns north and eventually northeast. Track forecast confidence is probably a bit higher than usual at 4 days of lead time. There's a little more spread in the guidance once it gets south of Newfoundland, but all modeling currently keeps it well offshore.

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Erin's intensity forecast is a little trickier. Given the look this morning, with dry air wrapping into the storm and exposing the core, I have to think that Erin is embarking on a long road down. We could see some reintensification once Erin starts to pick up a little more speed. But I think the question is how much weaker it gets in the near term. Erin isn't in a hurry right now, and it may be churning up relatively cooler water underneath the ocean. Between that and dry air, it's just flat at this time. Whatever the case, Erin is likely to remain somewhat flat today, with some chance of reintensifying tomorrow and Thursday as it marches north. Erin will then slowly transition into a non-tropical (extratropical) storm by late in the weekend and it begins to accelerate out to sea.

Erin's impacts remain mostly unchanged. We've now got Storm Surge Watches and Tropical Storm Watches on the North Carolina Coast.


(NWS Morehead City)
Wind gusts of 50 mph will be possible on the Outer Banks and in Pamlico Sound. The wave action and higher tides will be what causes extensive damage, likely damaging vulnerable coastal buildings and perhaps even Highway 12. While the surge forecast itself is not eye-popping (2 to 4 feet), in this area, when combined with the waves, that's more than enough to cause damage. North winds will peak Soundside flooding on Thursday.


(NWS Morehead City)
As we've been hammering since the weekend, in addition to the storm impacts on the Outer Banks, waves, tidal flooding, and rip currents are going to impact much of the Eastern Seaboard, causing beach erosion and making swimming challenging, if not dangerous the next several days.


Rip current risk is high the next two days from about West Palm Beach through Block Island. This will continue farther north Thursday and Friday. (NOAA NHC)
Rip currents kill over 100 people each year. These are avoidable deaths. Please heed all flags and warnings this week.

Wave trailing Erin + Invest 99L
Looking at satellite this morning, it's kind of interesting that the wave we've been monitoring for the last few days looks far less impressive than the new one behind it. In fact, that wave near the Cabo Verde Islands is termed Invest 99L. For those curious, now that we're at Invest 99L, we will recycle the list of Invests. So whenever the next system comes around, it will be tagged 90L. It's entirely possible that the wave ahead of 99L gets tagged 90L at some point. Whatever the case, here they are.


The wave west of the Cabo Verde Islands is mostly unchanged today and has 60% development odds, while the wave closer to Africa looks very impressive. (Weathernerds.org)
Over the next 2 to 3 days, it is expected that Invest 99L will actually weaken, while the wave in front of it will actually strengthen. As the leading wave strengthens while moving west, it will probably begin to get drawn into the weakness in upper-level ridging left behind by Erin. You can see that by looking at the upper-level weather map on Thursday evening. The leading wave is approaching the islands. Between Erin's proximity to the north and the weakness in upper ridging left behind, this wave should turn northwest near the islands.


The upper pattern late Thursday shows the next tropical wave (not Invest 99L) in position to turn more northwesterly, following Erin just to the east. (Tropical Tidbits)
Both AI modeling and the Euro ensemble members today favor a sharper turn north, which would draw it on a track east of where Erin is going. I would say this is worth keeping an eye on for the islands and for Bermuda at this point. A long way to go still with this one.

So what about Invest 99L? Well, I'm always leery about waves like this one. As noted above, it should begin to fall apart in a day or two, so any development risk is short-lived in the near-term. But because it falls apart and stays relatively weak or undeveloped, it's likely to sneak under everything going on to its north and west. This means it will probably ultimately find the Caribbean. From there, it's anyone's guess, but interestingly, virtually all modeling (except the GFS operational of course) basically keeps the wave a suppressed, weak feature into Central America. Either way, it's at least 10 days from probably doing anything, so we have plenty of time to watch and it's nothing anyone needs to worry about right now.

[tireman4]

Erin

[tireman4]

Eastern Tropical Atlantic (AL99):
A tropical wave located a couple of hundred miles to the southeast
of the Cabo Verde Islands continues to produce a concentrated area
of showers and thunderstorms. Environmental conditions appear
generally favorable for additional development over the next couple
of days as the system moves westward at around 15 mph. Towards the
end of this week, this system could encounter a less favorable
environment, limiting its development chances after that time.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 7 days...low...30 percent.

[tireman4]

Borrowed from S2K

[tireman4]

Erin

[tireman4]

211
ABNT20 KNHC 191738
TWOAT

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Tue Aug 19 2025

For the North Atlantic...Caribbean Sea and the Gulf of America:

Active Systems:
The National Hurricane Center is issuing advisories on Hurricane
Erin, located a couple of hundred miles to the northeast of the
Southeast Bahamas.

Near the Leeward Islands in the Tropical Atlantic:
A tropical wave located over the central tropical Atlantic continues
to produce a broad area of disorganized showers and thunderstorms.
Environmental conditions appear conducive for gradual development of
this system, and a tropical depression could form toward the end of
the week or this weekend. This system should move westward to
west-northwestward at about 20 mph and approach the vicinity of the
northern Leeward Islands on Friday.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...medium...60 percent.

Eastern Tropical Atlantic (AL99):
A tropical wave located about a hundred miles to the south of the
Cabo Verde Islands continues to produce disorganized showers and
thunderstorms. Environmental conditions appear marginally favorable
for additional development over the next couple of days as the
system moves westward at around 15 mph. Towards the end of this
week, this system could encounter a less favorable environment,
limiting its development chances after that time.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 7 days...low...30 percent.

$$
Forecaster Bucci

[tireman4]

US Tropics

[Stratton20]