re: Tropical Storm Debby - Flooding Threat Slowly Shifting NE

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390
FXUS64 KLIX 010827
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
327 AM CDT Thu Aug 1 2024

...New SHORT TERM, LONG TERM, AVIATION, MARINE...

.SHORT TERM...
(Today through Friday)
Issued at 310 AM CDT Thu Aug 1 2024

Low precip numbers will remain as the stacked SW high continues to
ridge in from the west. The heat will also remain and we will agin
be very close to heat warning criteria but most of the area should
remain just below. The heat advisory will remain but thoughts of
issuing a warning is getting more attention as heat accumulation
grows. This should continue into Friday but may get broken for the
weekend.

&&

.LONG TERM...
(Friday night through Wednesday)
Issued at 310 AM CDT Thu Aug 1 2024

The long term has its problems and we will give some attention to
the 10 ton elephant in the room after writing about conditons
expected, with the elephant being the tropical issues expected
around the SE CONUS by the weekend into the new work week.

The heat may get broken as we head into the weekend with some higher
rain chances possible as a front moves south to near the gulf coast
by Sat into Sun. As we move into the new work week, rain chances
will depend on the large amount of tropical moisture expected over
the SE and the large stacked high to our west.

Now for the elephant. At the moment, global suites are showing the
very large open tropical wave oriented meridionally over Puerto Rico
this morning possibly cutting off a circulation from its northern
end as it reaches central to western Cuba by Sunday or Monday.
This is common in the summer months and its one of the many
things we look for when something is trying to develop. The
steering is fairly straight forward "no pun intended" at first.
This is because the draw will come from the short wave digging
through the midwest this morning. These two features will be
closest when they are meridonal from each other along the 84th
longitude line by late Sat or early Sun with less than 10 degrees
of seperation. This will be the time of greatest draw northward
toward this trough. And whether this develops into a tropical
system or not, the draw of this mass will still be northward
during this time frame. From model perspective, this tropical
feature gets left behind as the short wave quickly swings through
and the tropical cyclone is just not moving fast enough to engage
the trough. This leaves a frontal boundary over or near the coast
and allows the SW CONUS high to then ridge back into the gulf
south blocking this tropical cyclones movement north by late
Monday. This is where models start to have their strongest
disagreement as they differ on how long the keep this ridging
active over the area and timing of the next short wave digging
into the midwest. Nothing to say after Monday at the moment. But a
simimlar solution is found in each model up to that time frame.
Basically, a circulation develops over the eastern
gulf/Florida/Western Atlantic moves northward Sun into Mon before
stalling somewhere near the lat30 line. Now for the biggest
problem with the extended fcast. Every model is bogusing if, when,
how and where they develop this circulation. And this is where
the problem is with fcasting any tropical system; something needs
to actually form first before it can be further assessed as to
what, where and when things will occur. It is always best to keep
up with the latest fcast and make sure you are always prepared,
especially during this time of year.

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Meridional

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Meridional

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