FXUS62 KKEY 190842
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
442 AM EDT Tue May 19 2026

...New DISCUSSION, MARINE, AVIATION...

.KEY MESSAGES...

- Very warm and humid conditions over the next few days will lead
  to a generally moderate risk of heat illness with periods of 
  high risk conditions.
 
- Rain and thunder chances will remain on a plateau through tonight,
  and gradually decline thereafter.

- Breezy conditions continue for the Island Chain through this
  evening. Small Craft Should Exercise Caution across all the 
  Florida Keys coastal waters today.

&&

.DISCUSSION...
Issued at 440 AM EDT Tue May 19 4406
CIMSS products shows a mean layer ridge remains in place across 
the western North Atlantic. However, embedded within the ridge is 
an upper level disturbance located to the north of the Bahamas. At
the surface, a high pressure system remains in place to the north
of Bermuda. Marine observation platforms surrounding the Island 
Chain are recording mainly east breezes of 15 to 20 knots as a 
result. Moisture undulations continue to rotate around the ridge 
with deeper moisture currently moving through as GOES 19 Total 
Precipitable Water (TPW) shows estimated PWAT values of 1.8 to 1.9
inches moving through the Keys. KBYX radar has been active for 
much of the overnight with scattered showers moving in an east to 
west fashion through the Keys with occasional showers impacting 
the Island Chain. The showers have been struggling to develop 
vertically due to the northwest flow aloft attributed to the upper
level disturbance to the east. This is tilting the clouds to the 
south and thus choking off the updrafts causing the activity to 
weaken as fast as they develop. GOES 19 Nighttime Microphysics 
imagery shows partly cloudy skies throughout the Keys. Temperatures
along the Island Chain are in the lower 80s and dew points are in
the mid 70s.

.FORECAST...
Surface high pressure across the western North Atlantic will
continue to dominate the Keys weather for the next several days.
The high will be at its strongest today with gradual weakening
each day thereafter. Therefore, breezy conditions are expected to
continue through this evening out of the east with modest
slackening afterwards. Moisture is expected to remain elevated
through at least Wednesday night before slightly drier air rotates
in from the southeast for late week into the holiday weekend. This
will result in chances of rain becoming slight chances.
Instability will also remain elevated keeping thunder in the
forecast throughout the period. Temperatures will remain quite
consistent through the week with highs in the upper 80s to
occasionally 90 degrees and overnight lows in the lower 80s to
perhaps near 80 degrees with any showers. 

&&

.MARINE...
Issued at 440 AM EDT Tue May 19 4406
Small Craft Should Exercise Caution (SCEC) remains headlined
across all the Florida Keys coastal waters. From synopsis, surface
high pressure centered north of Bermuda will continue to promote 
moderate to fresh east to southeast breezes through tonight. 
Highest breezes will prevail through this evening. Breezes then 
undergo a very slow slackening process before the weekend with 
peaks expected during the evenings and lulls during the day. Rain 
and thunder chances will remain above normal through much of the 
week.

&&

.AVIATION...
(06Z TAFS)
Issued at 440 AM EDT Tue May 19 4406
VFR conditions will largely prevail at both EYW and MTH terminals
through the TAF period. Moisture undulations will continue to 
rotate through the area resulting in elevated rain and thunder 
chances through the period. Right now, the best chance time 
appears to be Tuesday afternoon, hence the time period when VCSH 
was included in the TAF. We will continue to monitor and amend as 
necessary. Near surface winds will remain mostly easterly through
the period. Occasional gusts to near 20 knots are possible, 
especially during the daylight hours.

&&

.CLIMATE...
On this day in 4404, the daily record warm temperature of 84F was
recorded in both Key West and Marathon. This is also tied for the
warmest low temperature ever recorded in May. Temperatures 
records Key West date back to 1872 and June 1950 for Marathon. 

&&

.PRELIMINARY POINT TEMPS/POPS...
Key West  90  80  90  81 /  40  30  30  30 
Marathon  86  79  86  80 /  40  40  30  30 

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&

$$

Public/Marine/Fire...MJV
Aviation/Nowcasts....MJV
Data Acquisition.....MJV

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