Area Forecast Discussion
Issued by NWS Miami, FL

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000
FXUS62 KMFL 141814
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
214 PM EDT Mon Jun 14 2021

...Localized/Urban Flooding Remains Possible...
...A Few Strong Thunderstorms Remain Possible Today...

.SHORT TERM...

Through Tuesday

An active weather pattern is in store today for South Florida, as
numerous thunderstorms encompass much of the region thus far today.
This is due to favorable synoptic scale dynamics, as a few impulses
embedded within a larger, positively tilted short-wave trough
progress through the mid/upper level flow. Upper level mass
divergence, a deepening moist layer, and enhanced low-level moisture
convergence are all contributing to the widespread convection across
the region. Furthermore, a few strong wind gusts and small hail will
be possible, as 500 hPa temperatures around -8C and effective bulk
shear of 15-25 kt may allow for taller and more organized convection
through this evening. The primary threat for today however will be
localized/urban flooding. The 12Z MFL sounding indicated a very
moist tropospheric column of 2.06 in, which is in the upper 10th
percentile in terms of climatology for the region. This will allow
for efficient warm-rain processes whereby rain rates may be very
intense at times. Metro localities that experience repeated storm
activity will need to be monitored closely, as significant rainfall
amounts may fall in a short period of time and present flooding
hazards.

The wet pattern looks to remain intact for Tuesday as well, albeit a
bit less overall coverage anticipated compared to today. Efficient
low-level moisture flux via southwesterly flow of 15-20 kt in the
SFC-850 hPa range should continue to support deep tropical moisture
over the region. Again with the upper trough not becoming reoriented
much by tomorrow, this should allow for the continuation of modest
effective bulk shear values and somewhat cooler temperatures aloft.
This may support scattered to numerous convection again, with
possibly a slightly more northerly shift in areal coverage compared
to today. Again localized/urban flooding will be the primary threat,
especially given rainfall that may have fallen from previous days.

Temperatures will remain much cooler than normal today due to
widespread cloud cover, storms outflows, and evaporative cooling from
rainfall. Maximum temperatures may only reach the mid/upper 80s
across the region for today. Tomorrow should warm up a bit more due
to a lesser spatial extent of expected thunderstorm coverage, as
maximum temperatures may reach warmer and more seasonable values in
the lower 90s across the region.

.LONG TERM...

Tuesday Night through Monday...

A middle to upper level trough will remain over South Florida
through the middle portion of this week, allowing for southwesterly
flow to prevail across South Florida. This will allow for the
continued advection of a moist and saturated airmass into South
Florida with precipitable water values between 1.8 and 2.0 inches
through Thursday. With the prevailing southwesterly flow, the
greatest coverage of showers and thunderstorms should continue to
focus over the interior and east coast metro areas during the
afternoon and evening hours. As soils across South Florida remain
saturated due to previous rounds of rainfall during the early
portion of the week, localized flooding concerns will continue to
remain an issue through midweek. In addition, flow in the vertical
column continues to remain light with a very moist boundary layer
and overall a slow storm motion. The potential exists for an
isolated strong thunderstorm or two with the strongest convective
activity. Small hail, strong wind gusts, and frequent lightning is
possible with the strongest convective columns.

Towards the end of the week, model guidance continues to suggest
that the Bermuda High will strengthen and rebuild back into the
region. During this time frame, model guidance also depicts a plume
of Saharan Dust approaching the region. Increased subsidence due to
the ridge of high pressure as well as the addition of the Saharan
Air Layer (S.A.L.) may act to reduce shower and thunderstorm chances
late this week into next weekend. As mentioned in previous
discussions, forecast uncertainty in this portion of the long term
forecast is high. The National Hurricane Center continues to monitor
an area of disturbed weather over the Bay of Campeche. This area of
disturbed weather looks to slowly move over the Gulf of Mexico well
to the west of the region as a mid level ridge of high pressure
builds back into the Bahamas and then over the Florida Straits by
the end of the week. The uncertainty is due to model disagreement on
how far to the west of our area the disturbance in the Gulf moves.
Depending on the placement of this feature relative to South
Florida, the larger expansive moisture envelope surrounding the
feature itself could allow for higher rain chances across the area
than if the airmass is dominated by the Saharan Air Layer. Be sure
to monitor future changes with the forecast as we progress through
next week.

&&

.AVIATION(18Z TAFS)...

More widespread convection expected today due to an upper level
disturbance. SCT/NMRS SHRA and TSRA have affected most terminals
thus far and will likely continue to do so until around 00-02Z.
IFR/LIFR conditions are possible due to intense tropical rain
rates as well as strong wind gusts. Winds generally SW around 8-12
kt. Convective coverage should return to the terminals tomorrow
morning around 13-15Z, and have accounted for this uncertainty
with PROB30s for now.

&&

.MARINE...

An upper level disturbance will allow for scattered to numerous
showers/thunderstorms to develop across the local waters of South
Florida. Outflows from any developing storms may produce locally
enhanced wind gusts and elevated seas, as well as frequent lightning
and small hail. Waterspouts will be possible across all local waters
as well, especially within any stronger thunderstorms that develop.
These hazards will linger through the early week, though presently
it does appear that drier conditions could be possible by mid/late
week.

&&

.PRELIMINARY POINT TEMPS/POPS...
Miami            77  91  79  88 /  30  70  20  70
West Kendall     75  91  77  89 /  40  70  30  70
Opa-Locka        75  91  77  89 /  30  70  20  70
Homestead        75  90  76  88 /  40  60  30  70
Fort Lauderdale  77  90  78  88 /  30  70  20  70
N Ft Lauderdale  76  90  78  88 /  30  70  20  70
Pembroke Pines   75  90  77  88 /  30  70  20  70
West Palm Beach  75  90  76  88 /  40  70  20  70
Boca Raton       75  91  78  89 /  30  70  20  70
Naples           77  89  78  88 /  60  70  30  70

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
GM...None.
&&

$$

Tonight/Tuesday and Aviation/Marine...Bhatti
Tuesday Night through Monday...Hadi

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