TROPICAL STORM ROSE FORMS, JOINS PETER, TWO MORE BEING WATCHED

Florida hurricane News weather

National Hurricane Center Says 17th Storm Formed Sunday Afternoon East Of Florida…

Tropical Storm Activity Sunday Afternoon, September 19, 2021.

BY: WEATHER TEAM | BocaNewsNow.com

BOCA RATON, FL (BocaNewsNow.com) (Copyright © 2021 MetroDesk Media, LLC) — The National Hurricane Center just announced that Rose, the 17th storm of the season, formed.

Rose joins Peter — a tropical storm that formed in the early morning hours of Sunday.

Tropical Storm Rose as of Sunday afternoon, September 19, 2021.

Two additional systems, one off the coast of Africa, and another off the Northeastern United States, are being watched by forecasters for possible formation.

While paths and tracks can change, none of the systems — as of Sunday afternoon — appear to be a threat to the United States.

This is the official Rose forecast, filed by the NHC Sunday afternoon:

Satellite images show that deep convection has increased in 
coverage near the low-level center during the last 6 hours, while 
the overall structure of the tropical cyclone has also improved. 
Based on the improved organization and consensus T-2.5 numbers from 
TAFB and SAB, the initial intensity is set to 35 kt, making Rose 
the seventeenth named storm of the busy 2021 Atlantic hurricane 
season.  Only 2005 and 2020 have had the seventeenth named storm on 
an earlier date.

The 12-hour motion is north-northwest, or 330/14.  However, Rose 
appears to be moving more in a northwest direction during the past 
few hours.  This is probably the start of a northwest motion 
that should continue through day 4 as the system moves along the 
southwestern and western periphery of a subtropical ridge that 
extends from Africa across the Cabo Verde Islands.  A turn to the 
north is predicted in about 5 days, as Rose comes under the 
influence of a strong mid-level trough approaching from the 
northwest.  No significant changes were made to the previous track 
forecast.

Environmental conditions are conducive for strengthening during the
next day or so, with low wind shear, SSTs near 27C, and sufficient 
mid-level atmospheric moisture.  Therefore, a little more 
strengthening is shown compared to the previous NHC forecast.  The 
new NHC forecast is in agreement with the various consensus aids, 
but slightly below the SHIPS model, in deference to the global 
models which show a weaker cyclone.  Westerly wind shear will 
likely increase in about 36 hours as a strong upper-level trough 
approaches from the northwest.  Given that the cyclone is forecast
to remain rather small, it will likely be vulnerable to the higher 
shear so weakening is forecast in the 36-72 h time period.  Beyond 
day 3, a further increase in wind shear is expected to cause Rose to 
weaken to a tropical depression.  Although not explicitly forecast, 
it is possible that the cyclone could become a remnant low in 4-5 
days if the shear is too much for the system to handle.


FORECAST POSITIONS AND MAX WINDS

INIT  19/2100Z 14.3N  29.9W   35 KT  40 MPH
 12H  20/0600Z 15.9N  31.4W   40 KT  45 MPH
 24H  20/1800Z 17.9N  33.3W   45 KT  50 MPH
 36H  21/0600Z 20.0N  34.8W   45 KT  50 MPH
 48H  21/1800Z 22.0N  36.0W   40 KT  45 MPH
 60H  22/0600Z 23.5N  37.0W   40 KT  45 MPH
 72H  22/1800Z 24.7N  38.0W   35 KT  40 MPH
 96H  23/1800Z 26.7N  40.6W   30 KT  35 MPH
120H  24/1800Z 28.7N  41.2W   30 KT  35 MPH

This is the Peter Discussion:

Tropical Storm Peter path for Sunday, September 19th, 2021.
Over the past few hours deep convection with cloud tops as cold as
-85 degrees C have developed near and to the east of the center of
Peter. An Air Force Reserve Hurricane Hunter aircraft investigating
the system earlier provided data during several legs of the flight
that confirmed an intensity of 40 kt. A blend of the latest Dvorak
T- and CI- numbers from TAFB are consistent with that data, and
therefore the initial intensity remains 40 kt for this advisory.

The vertical wind shear that stripped Peter of its deep convection 
earlier today is forecast to increase further through tonight and 
persist for at least a few days. Global model simulated satellite 
imagery suggests this latest burst of convection will also become 
removed from the center within several hours, with the cyclone 
struggling to maintain persistent deep convection throughout much of 
the 5-day forecast period. Therefore, despite being over very warm 
waters, Peter is forecast to slowly weaken over the next several 
days. The intensity model guidance is in decent agreement on this 
scenario, and the NHC forecast remains near the various intensity 
consensus solutions. As mentioned in the previous discussion, there 
are some indications, particularly by the GFS, that Peter could open 
back into a wave within a few days which adds some additional 
uncertainty to the intensity forecast.

Peter's initial motion remains 290/15 kt. The storm is forecast to 
continue to move in this west-northwestward direction for the next 
couple of days as it is steered to the south of a subtropical ridge. 
This ridge is expected to weaken in a few days which should cause 
the cyclone to slow its forward motion and turn northwestward. Late 
in the forecast period a turn to the north and possibly northeast 
is expected to occur as Peter gets caught in the flow around a 
large trough to its north. The model guidance has shifted westward 
beyond day 2, in part due to a faster forward motion. While the 
timing of the cyclone's turn to the north remains the same, the NHC 
forecast was shifted to the left beyond 48 h, but still remains to 
the east of the consensus.

Based on the track, intensity, and wind radii forecast, no tropical
storm watches or warnings are required for the northern Leeward
Islands, Virgin Islands or Puerto Rico.  However, interests there
should monitor the progress of the system as locally heavy rain is
possible on Monday and Tuesday when it is expected to pass to the
north of the area.


Key Messages:

1. Rainfall around the southern periphery of Tropical Storm Peter
may lead to areas of urban and small stream flooding from late today
into Tuesday across Puerto Rico, the Virgin Islands, and the
Northern Leeward Islands.


FORECAST POSITIONS AND MAX WINDS

INIT  19/2100Z 18.4N  57.8W   40 KT  45 MPH
 12H  20/0600Z 19.1N  59.8W   40 KT  45 MPH
 24H  20/1800Z 19.9N  62.1W   35 KT  40 MPH
 36H  21/0600Z 20.8N  64.3W   35 KT  40 MPH
 48H  21/1800Z 21.9N  66.0W   35 KT  40 MPH
 60H  22/0600Z 22.9N  67.2W   35 KT  40 MPH
 72H  22/1800Z 24.1N  68.2W   30 KT  35 MPH
 96H  23/1800Z 26.1N  68.3W   30 KT  35 MPH
120H  24/1800Z 27.7N  67.5W   30 KT  35 MPH

And this is the outlook for additional systems:

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

The National Hurricane Center is issuing advisories on Tropical 
Storm Peter, located several hundred miles east of the northernmost 
Leeward Islands, and on Tropical Depression Seventeen, located a few 
hundred miles west-southwest of the southernmost Cabo Verde Islands.

1. A tropical wave located along the west coast of Africa is forecast 
to emerge offshore this evening.  Environmental conditions appear 
conducive for gradual development over the next several days, and a 
tropical depression could form late this week as it moves westward 
at 10 to 15 mph across the eastern and central tropical Atlantic 
Ocean.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...40 percent.

2. A gale force non-tropical low pressure system, the remnants of 
Odette, is located a few hundred miles south of Newfoundland.  This 
system could acquire some subtropical or tropical characteristics 
by the middle of this week as it moves slowly eastward and then 
southeastward over warmer waters across the north-central Atlantic 
Ocean.  Additional information on this system, including storm 
warnings, can be found in High Seas Forecasts issued by the 
National Weather Service.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...30 percent.

Public Advisories on Tropical Storm Peter are issued under WMO 
header WTNT31 KNHC and under AWIPS header MIATCPAT1.
Forecast/Advisories on Tropical Storm Peter are issued under WMO 
header WTNT21 KNHC and under AWIPS header MIATCMAT1.

Public Advisories on Tropical Depression Seventeen are issued under 
WMO header WTNT32 KNHC and under AWIPS header MIATCPAT2.
Forecast/Advisories on Tropical Depression Seventeen are issued 
under WMO header WTNT22 KNHC and under AWIPS header MIATCMAT2.

High Seas Forecasts issued by the National Weather Service can be 
found under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and 
online at ocean.weather.gov/shtml/NFDHSFAT1.php

 

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