Tropical depression 7

FLORIDA: Get Ready, Another Storm Is Set For Next Week

Florida hurricane News weather
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Still VERY Early In The Forecast Track, But South Florida Is In Cone…For Now.

BY: WEATHER TEAM | BocaNewsNow.com

BOCA RATON, FL (BocaNewsNow.com) (Copyright © 2021 MetroDesk Media, LLC) — Fred may turn out to be much of nothing for Broward and Palm Beach County, but Tropical Depression Seven may be a different story. While we stress it is much too early to know for sure, the current track brings it right over the region towards the middle or latter part of next week.

If the depression does become a tropical storm, it will be named “Grace.”

This is the Friday night update from the National Hurricane Center:

Tropical Depression Seven Discussion Number 3
NWS National Hurricane Center Miami FL AL072021
1100 PM AST Fri Aug 13 2021

While Tropical Depression Seven has maintained a irregularly shaped
cirrus canopy of deep cold cloud tops near its estimated center, the
convection does not appear well organized. Several SSMIS microwave
passes between 2011 UTC and 2205 UTC did not reveal much
organization under the cirrus, with just a few patches of deeper
convection contributing to the larger stratiform region. A helpful
ASCAT-B pass at 0030 UTC showed that the center was near the
southeastern end of this cirrus canopy, and found peak winds lower
than earlier today at only 27 kt. The 0000 UTC subjective Dvorak
estimates were T2.5/35 kt from SAB and T2.5/30 kt from TAFB and the
most recent objective ADT estimate was in between at T2.2/32 kt. A
blend of these data support keeping the initial intensity at 30-kt
for this advisory.

The small cyclone continues to move quickly off to the west at
280/18 kt. A large low- to mid-level ridge draped across the central
and western North Atlantic is expected to maintain the system on a
general west-northwest heading, though with gradual deceleration as
the ridge is eroded some by a mid- to upper-tropospheric trough. The
latest track guidance remains tightly clustered but a bit more
poleward through the first 72 hours. Afterwards, more track guidance
spread becomes apparent. A quick look at the latest ECMWF ensemble
guidance suggest that some of this spread is driven by the forecast
intensity of the system, with stronger members taking the cyclone on
a more poleward track. For now, the latest NHC track forecast is
fairly close to, but a little poleward of the previous track. This
track remains close to the HCCA and TVCN consensus aids, and roughly
splits the difference between the deterministic GFS and ECMWF model
solutions.

The intensity forecast is somewhat conflicting. Even though both the
GFS & ECMWF based SHIPS guidance depict low 200-850 hPa vertical
wind shear between 5-10 knots over the next 48 hours, the depression
is also embedded in very dry mid-level air, with 700-500 hPa layer
mean relative humidity as low as 44 percent currently in the
ECMWF-SHIPS. In addition, the system is moving rapidly westward,
and a continued fast motion in the short-term may result in higher
westerly mid-level shear which may have a larger than normal effect
to a small tropical cyclone in a very dry environment. After 48
hours, vertical wind shear out of the northwest is expected to
increase, ahead of a large upper-level trough digging southwestward,
upstream of the cyclone. Moreover, land interaction with both Puerto
Rico and Hispaniola remains a distinct possibility, especially if
the cyclone tracks left of the current forecast track. It is worth
noting the latest HWRF run continues to be a extreme outlier with a
much higher intensity than the remaining guidance. In fact, much of
global model guidance and COAMPS-TC regional hurricane model barely
maintains a closed circulation over the next 36-48 hours. I have
elected to maintain a very similar forecast to the previous
advisory, with peak winds of only 45 kt in 48-60 hours. This
forecast remains conservative and is still lower than the SHIPS and
HCCA intensity guidance.

Key Messages:

  1. Tropical storm conditions are expected in portions of the
    Leeward Islands late Saturday or early Sunday, and are possible over
    the Virgin Islands and Puerto Rico on Sunday. The risk of strong
    winds will then spread westward to the Dominican Republic Sunday
    night and Monday.
  2. Heavy rainfall could lead to flash and urban flooding over the
    Leeward and Virgin Islands. Across Puerto Rico, heavy rainfall may
    lead to flash, urban and small stream flooding, along with the
    potential for mudslides.
  3. There is a risk of wind and rainfall impacts across Haiti, the
    Turks and Caicos Islands, the southeastern Bahamas, and Cuba next
    week, and interests in those areas should monitor the progress of
    this system.

FORECAST POSITIONS AND MAX WINDS

INIT 14/0300Z 15.5N 53.8W 30 KT 35 MPH
12H 14/1200Z 16.0N 56.8W 35 KT 40 MPH
24H 15/0000Z 16.7N 60.3W 35 KT 40 MPH
36H 15/1200Z 17.5N 63.5W 40 KT 45 MPH
48H 16/0000Z 18.3N 66.2W 45 KT 50 MPH…INLAND
60H 16/1200Z 18.9N 68.2W 45 KT 50 MPH…OVER WATER
72H 17/0000Z 19.6N 70.4W 35 KT 40 MPH…INLAND
96H 18/0000Z 21.7N 74.3W 40 KT 45 MPH…OVER WATER
120H 19/0000Z 24.3N 78.6W 40 KT 45 MPH

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