Wildfire in Florida, May 13 to 23, 2020

Area Forecast Discussion
National Weather Service Miami FL
126 PM EDT Wed May 13 2020

.Aviation...
VFR conditions and gusty easterly flow is expected through the
period. Rain chances begin to increase from the south at the tail
end of the taf period.

&&

.Prev Discussion... /issued 945 AM EDT Wed May 13 2020/

Update...
Warm, dry, and breezy conditions are expected today. Temperatures
were raised a touch above guidance given current trends and the
observed highs yesterday. This will bring afternoon relative
humidities into the 35-45% range for some of the interior and west
coast areas. Given the breezy conditions, this will create an
elevated fire weather risk this afternoon. Otherwise, the
previous forecast appears to be on track.

Prev Discussion... /issued 231 AM EDT Wed May 13 2020/

WINDY AND RAINY CONDITIONS POSSIBLE BY THE END OF THE WEEK...

Short Term (Today and Tonight)...
The primary story today will be gusty east winds across south
Florida. Pressure gradient will continue to tighten as a 1029mb
high parks off the Carolina coast today and surface pressure
begins to gradually fall across the northern Caribbean.
Considered a wind advisory for today, however, gusts appear to be
just below the criteria, so will likely go with a SPS instead.
That said, if winds begin to outperform, a wind advisory will be
needed along the east coast.

Winds don't subside overnight tonight because 1) pressure gradient
reluctant to relax and 2) the atmosphere, especially along the
coast doesn't seem to decouple per the latest mesoscale forecast
soundings. Additionally, rain chances will begin to creep up as
the highly advertised surface trough upstream begins to amplify.
That said, the best rain chances will remain over the extreme
southern part of the region. Forecast soundings are still a bit
dry tonight in the mid levels. This will change as the air mass
quickly moistens as deeper moisture begins to stream into the
region by the end of the period and beyond.

Long Term...

Thursday through Sunday...

Elongated subtropical ridging will extend from the western Atlantic
into the South Atlantic states early in the period, as low-level
troughing locates from the southern Bahamas towards the northern
coast of Cuba. On Friday into Saturday a low pressure system is
forecast to develop, with a consensus of the available deterministic
and ensemble guidance suggesting this should take place over the
central and/or western Bahamas. Thereafter the low pressure system
may acquire subtropical characteristics as it tracks northeast away
from our area by Sunday. This is being monitored by the National
Hurricane Center, which places a 70 percent probability of
development over the next 5 days for areas north of the Bahamas.
Regardless of development, the key messages for South Florida at
this time are:

1. Increasing rain chances late Thursday night into Friday. This is
especially true along the Atlantic coast, where periods of heavy
rain are possible. The heavy rain potential may continue into
Saturday.

2. Strong and breezy winds are anticipated through Saturday. This is
especially true for the Atlantic waters and east coast metro areas.
Hazardous marine and beach conditions are expected, with gale force
gusts possible for the Atlantic waters.

Regarding rain chances, it appears that precipitation onset may be a
bit delayed on Thursday as the deeper moisture doesn't really arrive
until the late evening hours. Precipitable water values do climb
above 2 inches for all areas after midnight on Friday and remain
so through Friday evening. This should be the most likely time for
widespread rainfall, with current forecasts suggesting a rather
tight rainfall gradient along the east coast. This scenario is
plausible owing to frictional convergence along the coastal
interface potentially boosting totals for these areas. A very
preliminary estimate for rainfall amounts would suggest that 1-3
inches are possible along the Atlantic coast (with some potential
for locally higher amounts), tapering off to 0.5 inches or less
for inland areas. Please note that these totals may adjust up or
down with forecast updates as they are highly dependent upon the
ultimate strength and location of the developing low pressure
system.

Increasingly breezy conditions are likely owing to the tightening
pressure gradient associated with the developing low pressure area.
Forecast model soundings and layer averaged 1000-850 mb winds
suggest gust potential of 30-35 kt, especially late Thursday
night into Friday morning. This will bring hazardous marine
conditions to the local waters with fresh to strong breezes (along
with possible gale-force gusts). There is some potential for
reaching Wind Advisory criteria as well, especially for areas
along the Atlantic coastal interface. This will depend on the
overall boundary layer evolution and mixing depth during this
time, and this will be monitored with future forecast updates.

Given the onshore wind component below normal high temperatures are
expected for the eastern portions of South Florida throughout this
period.

Monday and Tuesday...

The low pressure system should migrate poleward along the
southwest periphery of the Atlantic subtropical ridge as weak
troughing progresses through the Atlantic Seaboard. Precipitation
chances may decrease somewhat during this time, but this is
dependent on the exact location and strength of the low pressure
system and the potential for a cold front to approach the area by
early to mid week. Forecast changes in this period are possible
owing to the current low predictability of the overall pattern
evolution.

Marine...
A very active period expected. First, strong easterly flow will
increase winds and wind wave heights through the weekend. SCA
conditions expected for most waters except Lake Okeechobee,
however, even the lake may need an upgrade from cautionary
headlines later on this week. Outside of the uptick in winds and
seas, rain and T'storm chances increase a a surface trough
develops and moves through our Atlantic waters later this week.
We'll need to watch this feature as models have it developing into
a closed subtropical low this weekend. Where the low develops will
have implications on winds, seas, and rainfall potential.

Beach Forecast...
Rip current risk will remain high along the Atlantic coast as
moderate to strong easterly winds continue. Rain chances begin to
increase later tonight and during the day Thursday. Thunderstorms
will be possible with some cloud-to-ground lightning not out of
the question.
&&

.Preliminary Point Temps/PoPs...
West Palm Beach  73  81  72  80 /   0  10  70  90
Fort Lauderdale  75  81  74  80 /   0  10  70  90
Miami            74  82  73  80 /  10  20  70  90
Naples           69  87  70  84 /   0  10  50  70

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Friday morning for FLZ168-172-173.

AM...Small Craft Advisory until 8 PM EDT Thursday for AMZ630-650-651-
     670-671.

GM...Small Craft Advisory until 8 PM EDT Thursday for GMZ656-657-676.

&&

Aviation...32/MM

Hazardous Weather Outlook for South Florida
National Weather Service Miami FL
1024 AM EDT Wed May 13 2020

AMZ610-630-650-651-670-671-FLZ063-066>075-168-172>174-GMZ656-657-676-
140230-
Lake Okeechobee-Biscayne Bay-
Coastal waters from Jupiter Inlet to Deerfield Beach FL out 20 NM-
Coastal waters from Deerfield Beach to Ocean Reef FL out 20 NM-
Waters from Jupiter Inlet to Deerfield Beach FL from 20 to 60 NM-
Waters from Deerfield Beach to Ocean Reef FL from 20 to 60 NM
excluding the territorial waters of Bahamas-Glades-Hendry-
Inland Palm Beach-Metro Palm Beach-Coastal Collier-Inland Collier-
Inland Broward-Metro Broward-Inland Miami-Dade-Metro Miami-Dade-
Mainland Monroe-Coastal Palm Beach-Coastal Broward-Coastal Miami-
Dade-Far South Miami-Dade-
Coastal waters from Chokoloskee to Bonita Beach FL out 20 NM-
Coastal waters from East Cape Sable to Chokoloskee FL out 20 NM-
Waters from Chokoloskee to Bonita Beach FL from 20 to 60 NM-
1024 AM EDT Wed May 13 2020

...High Risk of Rip Currents for Atlantic Beaches...
...Elevated Fire Weather Risk across the Interior and West Coast...

This hazardous weather outlook is for South Florida.

.DAY ONE...TODAY AND TONIGHT

Rip Currents: There is a high risk of rip currents for the Atlantic
Beaches.

Fire Weather: There is an elevated fire weather risk today due to
breezy winds and low relative humidity.

Wind: ENE winds around 20 knots with higher gusts across both the
Gulf and Atlantic waters. A Small Craft Advisory is in effect for
all coastal waters except Lake Okeechobee. A few gale force wind
gusts may be possible across the Atlantic waters late tonight.

Waves: Waves of 4 to 7 feet will be possible across the Atlantic
waters with the highest in the Gulf Stream.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

Hazardous marine and beach conditions will continue through much of
the week. Gusty easterly winds are expected to continue into Friday.

Rain and thunderstorm chances will begin to increase across the
region Thursday into Friday. Gusty winds, locally heavy rainfall,
lightning, and waterspouts will be possible with these showers and
storms, with the greatest chances across the East Coast metro areas
and Atlantic waters. Along with these showers and thunderstorms, an
area of low pressure may form near the Bahamas late this week before
moving northeastward across the Atlantic waters.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today.

For more information...visit the National Weather Service in
Miami website at www.weather.gov/miami.