558
FXUS62 KKEY 191548
AFDKEY

Area Forecast Discussion
National Weather Service Key West FL
1148 AM EDT Sun Jul 19 2026

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

.KEY MESSAGES...

- Gentle to moderate southeast to south breezes are expected
  across Florida Keys coastal waters for the next few days peaking
  overnight and lulling during the day.

- Heat indices may approach 108 to 110 degrees each afternoon for
  some Florida Keys island communities.

- Saharan Air Layer plumes will transit the area over the next
  several days, limiting rain and thunder chances.

&&

.DISCUSSION...
Issued at 919 AM EDT Sun Jul 19 2026
An upper-level composite analysis this morning reveals newly
formed Tropical Depression Two over the northeastern Gulf of
America, with deep-layer mean anticyclones positioned to its east
and west. The Florida Keys lie within the deep southerly flow
between the deep-layer mean cyclonic circulation containing the
new depression and the anticyclone centered over the subtropical
Atlantic east of the Bahamas. Data from the Key West morning
radiosonde balloon indicated a very moist and unstable
thermodynamic stratification with near nil convective inhibition.
However, at the moment, Key West Doppler radar scans are nearly
void of precipitation echoes over the service area. The balloon-
derived data likely is more representative of the atmosphere over
the Gulf waters just north of the lower Keys as satellite-derived
total precipitable water measurements suggest much drier air
upstream over the Straits of Florida and Cuba. This factor
combined with a lack of mechanisms to initiate deep convection
would explain the dearth of cumulus convection observed this
morning.

Current air temperatures in most Keys island communities are in
the upper 80s, with dewpoint temperatures in the upper 70s
yielding heat indices of 100-105F. Steady southerly breezes
prevail in most areas.
&&

.PREV DISCUSSION...
Issued at 440 AM EDT Sun Jul 19 2026
CIMSS products shows the split ridge pattern remaining in place
once again early this morning. One ridge is centered over the
western North Atlantic with its western fringe sliding a little
further west influencing the breezes more across the Florida Keys
coastal waters. The other ridge remains across the western Gulf
and Texas. In between, there is Invest 91L which the National
Hurricane Center now gives a 60% chance of development through 48
hours and 7 days. The system has become slightly better organized
overnight, though, it still is producing disorganized showers and
thunderstorms. While we are watching Invest 91L, this system does
not pose a threat to the Keys. Marine observation platforms
surrounding the Island Chain are recording southeast to south
breezes near 15 knots. KBYX radar has remained active overnight
with isolated showers across the SE Gulf and across the Straits of
Florida. GOES 19 Nighttime Microphysics imagery shows partly
cloudy skies throughout the Keys with mainly cumulus and cumulus
congestus. Temperatures along the Island Chain are in the mid 80s
and dew points are in the mid to upper 70s.

.FORECAST...
The big elephant in the room will be Invest 91L for the next few
days. The National Hurricane Center (NHC) currently highlights
this system across the northern Gulf with a medium (60%) chance of
tropical development through 48 hours and 7 days. The system
poses no risk to the Florida Keys. Ridging will continue to be the
name of the game going forward for the next week or more for the
Keys. Moisture undulations will occasionally slide through the
Keys resulting in slight chances of showers and thunderstorms. The
timing on this appears to be one round this morning with another
round this evening. Model guidance seems to be more bullish on the
activity this evening, therefore, chances of showers with a
slight chance of thunderstorms is in the forecast for tonight.
Some guidance is pointing to convection forming either over or
just north of Cuba and then racing northward towards the Island
Chain, especially the Lower Keys. Any showers and storms this
evening will be capable of heavy downpours, gusty winds, and
occasional lightning strikes. Outside of that, continued
seasonably warm conditions will continue with highs near 90
degrees and overnight lows in the lower to mid 80s. There is the
potential for highs to reach the lower 90s this week which will
push the heat index values up to 105 to 110 degrees. However,
heat Advisories are not being considered at this time.

The Atlantic ridge will continue to dominate the pattern across
the Keys resulting in peaking and lulling breezes mainly out of
the southeast to south for at least the first half of the week
before becoming more east to southeast for mid to late week and
beyond.
&&

.MARINE...
Issued at 919 AM EDT Sun Jul 19 2026
No watches, warnings, or advisories are in effect across Florida
Keys coastal waters. At 11:00 a.m. EDT, newly formed Tropical
Depression Two was centered over the northeastern Gulf of America,
about 280 nautical miles northwest of Key West Harbor, moving
north- northwestward at 2 knots. Tropical Depression Two is
expected to move slowly northwestward or north-northwestward
during the next day or two, followed by a turn toward the west. On
the forecast track, the depression will move near or along the
northern Gulf coast during the next several days. An Atlantic
ridge of high pressure will extend to the Florida Peninsula for
the next several days. Gentle to moderate south to southeasterly
breezes are expected to prevail across Florida Keys coastal waters
from this afternoon through Thursday.
&&

.AVIATION...
(12Z TAFS)
Issued at 919 AM EDT Sun Jul 19 2026
Through 20/12Z, prevailing VFR conditions are expected at both EYW
and MTH. Although a sub-VFR episode from a transient rain shower
cannot be ruled out completely, the event probability is quite low
at both EYW and MTH.
&&

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

$$

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

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