709
FXUS62 KMFL 111106
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
706 AM EDT Tue Jun 11 2024

...New AVIATION...

.SHORT TERM...
(Today through Wednesday)
Issued at 152 AM EDT Tue Jun 11 2024

A cold front and associated weak surface low is currently
progressing into northern Florida this morning, with the front
projected to stall in that general area through the short-term
period. At the mid-lvls, longwave troughing will be in place over
the eastern CONUS with ridging pinned to our southeast (centered to
the SW of the Turks and Caicos). This configuration will result in
strengthening deep-layer SWrly flow overspreading our area, which
will in turn transport rich tropical moisture, characterized by
PWATs around 2.5 inches (approx 3 SD above climo) NEwrd into SFL
today. This anomalous moisture plume, which will largely remain
pooled over South and Central Florida over the next several days,
will set the stage for an active and wet pattern over our area.

In terms of forecast details, the overnight CAMs continue to
highlight the threat of heavy rainfall and locally very heavy
rainfall over portions of our area through Wednesday. In large the
highest totals look to be focused over SWFL where low-lvl
convergence will be maximized in the SWrly regime. However, the
anomalous moisture and deep warm-cloud layer will enable efficient
warm-rain processes, and any convective elements that can form (in
the limited instability tropical environment) will be capable of
high rain rates and localized flooding concerns... with the more
widespread flooding concern being dictated by which areas can
receive repeated rounds from these heavy rainers. Consequently the
flood watch remains in effect for the entire area through Wednesday
night, although as will be discussed in the long term, the hydro
threat will likely linger into the latter half of the workweek.

In terms of specific rainfall amounts, the HREF means yield
widespread totals of 2-4 inches across SEFL through Wednesday
afternoon, with 3-7 inch totals over SWFL. The Probability Matched
Mean (PMM), which is likely more representative of higher-end (but
not necessarily the absolute maximum values) in this regime, would
bump those ranges to 3-6 inches over the east coast and 6-10 inches
over portions of SWFL. Individual CAMS even depict some very
localized maxima of 10+ inches (in just the next 36-48 hours)
largely over SWFL. Our forecast QPF values are a blend of the more
conservative (but likely decent as an area-average) HREF mean, and
the more aggressive PMM values that may better capture the higher
end possibilities. However, it must be emphasized that large spatial
gradients in totals are very likely given that the tracks of
individual poorly-organized convective cells will likely drive
totals, and these tracks are nearly impossible to predict with much
lead-time.

Outside of the periods of heavy rain and associated flooding
concerns, a silver lining will be the somewhat cooler temperatures
as abundant cloud cover and periods of rainfall should keep highs
only in the low to mid 80s through Wednesday.

&&

.LONG TERM...
(Wednesday night through Monday)
Issued at 152 AM EDT Tue Jun 11 2024

The wet and active period will continue for the first half of the
extended period as the boundary to our north remains stalled and the
tropical moisture remains focused over south-Central Florida. A mid-
lvl shortwave trough will pivot southeastward and phase with the
longwave east-coast trough in the Wednesday night-Thursday time
frame, amplifying and elongating the trough from SW-NE. Ultimately
the building ridge to our north will cause the increasingly
enlongated trough to split Saturday, with the northern split lifting
northeast while the southern split looks to retrograde into the
Central GOM. This will hopefully result in the tropical moisture
plume being reoriented west of the area by Sunday-Monday with mid-
lvl ridging then building into the eastern CONUS in that time
period.

In terms of sensible weather, the main concern will remain the
flooding potential Thursday/Friday as the lingering tropical
moisture will interact with upper-lvl disturbances pivoting through
the base of the trough. Although raw totals don`t look quite as high
as the initial surge on Tuesday/Wednesday (although they could be
comparable over SEFL) it is possible the ground will be already
saturated from the earlier week rainfall, so any additional heavy
rainfall could exacerbate hydro issues. Consequently, assuming the
Tues/Wed rainfall more or less pans out as expected, the flood watch
will likely need to be extended into the Thursday/Friday timeframe.

Assuming the aforementioned synoptic evolution occurs, Saturday will
hopefully mark the end of the heavy rainfall threat, as the
retrograding trough and building ridge combination should direct the
deep tropical moisture to our west. Although lingering low-lvl
moisture will support at least scattered showers and storms through
the period, the strengthening easterly flow and building heights
should limit the chances for widespread heavy rainfall beyond Friday
night/early Saturday (although exact forecast details remain
uncertain).

&&

.AVIATION...
(12Z TAFS)
Issued at 704 AM EDT Tue Jun 11 2024

Poor flying conditions at times during the 12Z TAF period as deep
tropical moisture results in periods of heavy rain and
thunderstorms. Prevailing MVFR ceilings is expected with
occasional IFR/LIFR ceilings and visibilities during periods of
heavy rain. Southerly winds around 10 kts however winds will be
erratic in and near thunderstorms.

&&

.MARINE...
Issued at 152 AM EDT Tue Jun 11 2024

Periods of strong showers and thunderstorms are expected over the
area waters the next several days, which will result in locally
hazardous winds and seas. Outside of thunderstorms, cautionary-
level (at time near hazardous) south-southwesterly winds can be
expected through Wednesday with seas 3 ft or less.

&&

.PRELIMINARY POINT TEMPS/POPS...
Miami            86  77  86  77 /  90  90  90  90
West Kendall     87  75  87  75 /  90  90  90  90
Opa-Locka        87  76  88  77 /  90  90  90  90
Homestead        87  76  86  77 /  90  90  90  90
Fort Lauderdale  86  78  86  77 /  90  90 100  90
N Ft Lauderdale  86  77  86  77 /  90  90 100  90
Pembroke Pines   89  77  88  77 /  90  90  90  90
West Palm Beach  86  74  86  75 / 100  70 100  90
Boca Raton       87  75  88  76 /  90  90 100  90
Naples           86  77  87  77 / 100  70 100 100

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...Flood Watch through Wednesday evening for FLZ063-066>075-168-
     172>174.

AM...None.
GM...None.
&&

$$

SHORT TERM...Carr
LONG TERM....Carr
AVIATION...CMF