Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/14/20
Area Forecast Discussion
National Weather Service Miami FL
647 PM EST Fri Nov 13 2020
Primarily VFR conditions through the period, with another round
of lower cigs possible before sunrise. At this time, confidence is
too low to include in the tafs and will handle with amendments.
Isolated SHRA will be possible through the taf cycle, but coverage
should remain sparse enough to maintain with VCSH.
Radar reveals dissipating showers over land this evening, with a
few lingering over the southern Atlantic in the vicinity of an
analyzed surface trough. With that said, much quieter than last
night. As drier air continues to trickle into the area, forecast
looks to be on track with a few isolated showers possible tomorrow
given ample lower tropospheric moisture sticks around. However,
given lack of coverage, the Flood Watch will be allowed to expire
The next concern for the weekend will be the highly advertised
King Tides. At this time, have foregone issuing a coastal flood
statement for the east coast as the upcoming high tide cycle
should stay below minor flood stage, but will likely be needed
with the next forecast package ahead of the morning high tide
.Prev Discussion... /issued 321 PM EST Fri Nov 13 2020/
Short Term...(This Afternoon through Saturday)...
Rest of This Afternoon:
Enhanced boundary layer moisture remains in place across the
southern portions of South Florida -- in association with the
departure of Post-Tropical Cyclone Eta and a surface trough
extending from Grand Bahama Island to the Atlantic waters off the
Upper Keys. The shallow (yet rich) low-level moisture continues to
support lingering cloud coverage and isolated rain showers across
the above mentioned area.
As daytime heating continues today, marginal destabilization of the
inland boundary layer will support isolated to scattered shower
development, with a focus across the southern/eastern portions of
South Florida and the adjacent Atlantic waters. This is where a
region of enhanced confluent flow is evident via the latest RAP
analysis and GOES-16 visible loops.
The 12Z MFL RAOB shows very dry air aloft, which is also evident via
the three GOES-16 water vapor imagery bands. This enhanced dry air
aloft will entrain into any updrafts that initiate this afternoon,
leading to shallow/weak convective structures and generally lower
rain rates. Very weak deep-layer lapse rates will also support
weak vertical accelerations within the updrafts. This is good news
for portions of metro Miami-Dade and Broward Counties, where we
continue to receive reports of standing water and highly saturated
soil conditions. That being said, the lingering boundary layer
moisture combined with confluent flow associated with the surface
trough will support isolated to scatters showers into the evening
hours, and any additional accumulations across the above mentioned
areas could lead to localized flooding.
Tonight through Saturday:
With the lingering moisture in place, isolated to scattered showers
remain in the forecast, especially along the east coast. These
showers should spread westward across southern Florida through the
day on Saturday along and near the surface trough which will
probably extend somewhere across the area. Dry mid/upper level air
associated with a strong 500 mb high pressure extending across
Florida from the Gulf of Mexico will limit the amount of available
atmospheric instability. Thus, most of these showers should
remain light, however with just a little surface heating a few of
the showers could be locally heavy. Therefore, we`ll just have to
continue watching for any localized flooding potential, but this
is a lower probability than previous days. For this reason, we
will probably let the Flood Watch expire at 7 PM this evening and
handle any additional flooding concerns with localized advisories
While highly uncertain, patchy fog will be possible again during the
morning hours -- especially across inland portions of southern
Florida. The low confidence precludes mention in the official
forecast at this time.
Long Term (Saturday Night through Friday)...
The strong 500 mb high pressure area is expected to gradually
move east over the western Atlantic through early next week as the
southern extent of a broad longwave trough over the eastern half
of North America moves into the Gulf coast and Florida region.
Some slight enhancement of shower activity is possible Sunday and
Monday around Lake Okechobee and the Palm Beaches as a small mid-
level impulse rotates northward around the west side of the high
and interacts with the surface trough which will stubbornly remain
over South Florida.
A cold front will move down the peninsula Monday night and
Tuesday, and is expected to move through and clear the southern
peninsula Tuesday night. Scattered showers and perhaps a
thunderstorm or two will accompany the front, but right now we`re
not expecting any significant potential for accumulating
precipitation or strong convection as the front moves through.
Winds behind the front will be fairly strong and gusty out of the NE,
so while this means we`re not expecting a shot of much colder air
to make it to South Florida due to the modifying effects of the
Gulf Stream, temperatures will be noticeably cooler for the middle
to latter part of next week. Temperatures look to run near to
even a few degrees below normal, which means low temperatures in
the 60s with a few upper 50s over inland SW Florida and highs in
the upper 70s. With a post-frontal NE wind flow, patches of
shallow stratocumulus clouds and a few sprinkles can be expected
from time to time, but nothing like what we`ve seen for the past
Realizing that by stating this I might jinx it, but it appears
that the South Florida dry season should finally start with the
passage of next week`s front. At least we can hope so.
A trough of low pressure and lingering moisture in the wake of Post-
Tropical Cyclone Eta will continue to support a few showers and
storms across the local waters though Saturday, primarily across the
Atlantic waters off South Florida. Waterspouts will be possible with
any updrafts that develop atop localized surface boundaries across
the Atlantic waters today. A ridge of high pressure begins to build
over the region this weekend from the east, generally leading to
benign marine conditions and lower precipitation chances. On Tuesday
and continuing for most of next week, marine conditions will deteoriate
behind the passage of a cold front as northeast winds increase to
20 knots or higher and seas build to greater than 6 feet.
The currently elevated rip current risk along the Atlantic beaches
of South Florida will continue to trend downward as swells and
onshore winds subside/weaken. However, there will still be at
least a moderate risk of rip current this weekend, particularly at
the beaches of Palm Beach County. Minor coastal flooding is
possible this weekend and into next week due to higher than normal
tides (King tides). On Tuesday, beach and surf conditions will
begin to deteoriate behind the passage of a cold front --
primarily across the Atlantic beaches of South Florida. Rough surf
and minor beach erosion could become a concern as well, in
addition to continued effects from the king tides.
.Preliminary Point Temps/PoPs...
West Palm Beach 74 82 75 85 / 20 40 30 30
Fort Lauderdale 75 84 76 85 / 30 30 20 20
Miami 74 84 75 85 / 20 30 10 10
Naples 71 86 72 86 / 0 20 20 20
FL...Flood Watch until 7 PM EST this evening for FLZ072-074-172-173.
High Rip Current Risk until 7 PM EST this evening for FLZ168.