Area Forecast Discussion
Issued by NWS Key West, FL

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FXUS62 KKEY 221929

Area Forecast Discussion
National Weather Service Key West FL
329 PM EDT Thu Oct 22 2020

Shower coverage has greatly diminished from this morning, however
some showers still persist across mainly across the Upper Keys and
surrounding waters. Cloud cover has kept temperatures down and as
such, ASOS observations reveal temperatures in the lower 80s.
Meanwhile, C-MAN stations continue to show winds around 15 to 20
knots across all of our waters.

Expanding our scope, the area remains under a tightened gradient
between a weak surface low over and near the Yucatan Peninsula and
a continental high over the eastern U.S.. This is keeping winds
at the surface from the east and southeast. In addition, it is
allowing for moisture to continue to pool across the region. In
the mid levels the flow is becoming more zonal, which is leading
to less organized ascent aloft. This is n part why we have had
less lightning strikes today versus yesterday, when a weak trough
was present.

.SHORT TERM (Tonight through Saturday night)...
Similar to last night, areas that were previously worked over,
i.e. the Lower and Middle Keys, will fill back in with showers and
possibly an isolated thunderstorm for the overnight. Aloft, zonal
flow will continue and become more pronounced across the area.
While we will continue to lose organized ascent aloft, moisture
will continue to stream into the area due to a deep east and
southeasterly flow. As such will maintain 50 percent pops for
Friday and Friday night. Thereafter, we continue to monitor a
feature in the northwestern Caribbean. Currently a low level
trough resides in this area producing a disorganized area of
showers and thunderstorms across the Cayman Islands and Jamaica.
This trough will traverse northeast, reaching the Florida Straits
by Saturday and then the northern Bahamas on Sunday. As this
moves northeast, rain chances will increase for Saturday. There
is some uncertainty how this feature will evolve but regardless,
impacts to the Florida Keys at this time will be the potential
for heavy rains with localized flooding.

.LONG TERM (Sunday through next Thursday)...
Rain chances diminish beginning Sunday as the trough moves out of
the area and high pressure from the west builds back in. This high
will also bring with it, drier air and will severely limit rain
chances starting Monday. This dry period is expected to linger
into at least midweek and there are hints it could last into the
end of the week. Rain chances beyond Monday will be near normal
(20 percent)


Moderate to occasional fresh easterly breezes persist this
afternoon across all waters. Expecting moderate to occasionally
fresh breezes to continue tonight, however there is a chance that
our western waters could see a period of fresh breezes tonight.
For now, will keep Small Craft Exercise Caution headlines in
effect for all waters. Winds will slacken starting Saturday and
continue into early next week.


VFR conditions will prevail at the Key West and Marathon terminals
through tonight. Radar imagery has shown a decrease in the showers
and isolated thunderstorms affecting the Lower and Middle Keys
during the past few hours. Only isolated showers are likely in the
afternoon and evening hours, but the rain activity is expected to
increase again tonight into the overnight hours across the island
chain and nearby waters. Winds E near 10 knots with gusts to near 20


In 2008, the daily record rainfall of 7.30" was recorded in Key
West. Precipitation records date back to 1871.


FL...Coastal Flood Advisory for FLZ076.



Data Acquisition.....SDR

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