Flooding and Rip Current in Florida, May 20, 2018

Area Forecast Discussion
National Weather Service Miami FL
348 AM EDT Sun May 20 2018

.DISCUSSION...

SHORT TERM (Today through Tuesday)
Several bands of N/S oriented showers have moved ashore overnight
from the Atlantic, with rainfall amounts averaging 0.75 to 1.5
inches. These bands are associated with the convergence area on
the periphery of the subtropical ridge, where the deepest tropical
moisture has pooled. Expect this axis of moisture to remain over
eastern parts of South Florida at least through this morning,
bringing bouts of locally heavy rain. Thus, Flood Watch will
persist through at least 11 AM for Miami-Dade, Broward, and Palm
Beach counties. See Hydrology section for more information.

Guidance suggests that the deep-layer ridge to our east will
strengthen some and retrograde slightly west in the short term.
This will gradually send somewhat drier air toward the region.
However, at least through today, most of the area will remain in
very high PWAT airmass, with only inhibitor of widespread
convection being abundant clouds which have thus far curbed
instability and have played role in the lack of flooding rainfall
in the past 24 hours. The corridor of deepest moisture is forecast
to gradually shift to interior or west coast of Florida today and
tonight, then along the Gulf coast Monday, before moving off the
peninsula and bringing a relatively dry - as in only isolated to
scattered showers/thunderstorms for Tuesday. At least some threat
for locally heavy rainfall will remain Monday however.
Temperatures today and Monday will be significantly impacted by
rainfall, with maxima struggling to reach 80 degrees both days.

LONG TERM (Tuesday night through Saturday)
It appears that any lull in precipitation Tuesday may be short-
lived, with deep tropical moisture returning for the latter parts
of the week. There is a great deal of uncertainty in the extended
forecast as global models continue to diverge in solutions. ECMWF
provides for a stronger/longer lasting subtropical ridge
influence, leading to drier conditions through about Thursday,
then greatly increasing rain chances as moisture-rich air pouring
back into the region as a tropical disturbance moves toward the
central Gulf. GFS, however, keeps moisture basically intact
through the week with disturbance moving faster and in a more
northeast direction, with perhaps drier air arriving in its wake
at the end of the period. For now, will simply hold onto increased
rain chances for the 2nd half of the week, but the potential for
a return to heavy rainfall will have to be watched. More details
on this potential can be found in the Hydrology section below).

Temperatures in the extended are based on the assumption there
will be many more breaks in the clouds than this weekend, allowing
maxima to return to mid to upper 80s, and minima remaining
generally in the 70s.

&&

.MARINE...
Winds will be slightly stronger today than Saturday, with
southeast wind approaching 20 knots in Atlantic waters. Seas will
also rise in the Atlantic to 3 to 5 feet. Conditions are forecast
to be very close to advisory level, but for now will keep
cautionary statement in place and continue to monitor for stronger
wind. Similar conditions will likely prevail until about Tuesday.
Widespread showers with some thunderstorms will persist through
Monday, with the focus gradually shifting from the Atlantic into
the Gulf (and continuing for Lake Okeechobee). The heavier
activity could produce hazardous winds, locally higher waves, and
dangerous lightning.

&&

.AVIATION...
Scattered SHRA moving onshore SE Florida coast through at least
14z, with periods of MVFR ceilings 015-020 and brief IFR possible
with the heavier SHRA at the east coast terminals. Any TSRA should
be limited and not included in this forecast package, but will
monitor and update as necessary. After 19z, improving conditions
as precipitation shifts west to over the interior. At KAPF,
included VCSH through 14z, then PROB30 for TSRA after 19z as
precipitation shifts from east coast to interior/Gulf coast.

&&

.BEACH FORECAST...
With southeast wind of 15 to 20 mph today, conditions are likely
to be near the threshold for a high risk of rip currents on
Atlantic beaches. For now will hold with moderate risk but will be
closely monitoring for higher wind speeds and/or rip current
reports.  Similar conditions are likely into mid-week.

&&

.HYDROLOGY...
Grounds continue to saturate as drought conditions are
ending/being alleviated across South Florida. Thus far, heaviest
rainfall has been over the Naples area as well has Palm Beach and
Broward counties. Today's highest totals (2 to 4 inches with
isolated higher) are likely to be along the east coast (where the
Flood watch is in effect). Watch may need to be extended if bands
of showers dont propagate more westward with time. Additional
heavy rain, averaging 1 to 2 inches, with locally higher amounts,
are possible Monday, before a relative lull is expected into the
middle of next week. Thereafter, will have to monitor for
additional heavy rain/flood potential as deep tropical moisture is
poised to return. Latest WPC 7-day forecast rainfall totals range
from 3 to 7 inches, with greatest amounts across southeast
Florida.

&&

.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach  79  72  80  74 /  70  60  70  40
Fort Lauderdale  80  74  82  74 /  80  60  70  40
Miami            81  73  82  74 /  90  60  70  40
Naples           81  71  83  72 /  80  40  60  40

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...Flood Watch until 11 AM EDT this morning for FLZ067-068-071>074-
     168-172>174.

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

DISCUSSION...23/SK
MARINE...23/SK
AVIATION...59/RM
BEACH FORECAST...23/SK
HYDROLOGY...23/SK

Hazardous Weather Outlook for South Florida
National Weather Service Miami FL
436 AM EDT Sun May 20 2018

AMZ610-630-650-651-670-671-FLZ063-066>075-168-172>174-GMZ656-657-676-
201500-
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-
436 AM EDT Sun May 20 2018

...Flood Watch Miami-Dade, Broward and Palm Beach Counties Until 11 AM...
...Gusty Winds with Showers and Isolated Thunderstorms...

This hazardous weather outlook is for South Florida.

.DAY ONE...TODAY AND TONIGHT

Flooding: Periods of heavy rainfall are expected today, mainly over
metro Southeast Florida this morning through midday and over
interior and Gulf coast areas this afternoon and early evening. These
downpours will likely cause many areas of minor flooding on roadways
and poor drainage areas. Where the heaviest rain occurs, more
significant flooding is possible with water intruding on vulnerable
structures and causing impassable travel lanes and roadways.

Rip currents: Southeast wind of 15 to 20 mph will lead to a moderate
risk of rip currents at the Atlantic beaches.

Thunderstorms: Isolated thunderstorms are expected over Southeast
Florida, as well as the Atlantic, Gulf of Mexico and Lake Okeechobee
waters this morning through midday, with a few thunderstorms also
spreading to the interior and Gulf coast this afternoon and early
evening as well as the adjacent Gulf waters.

Waterspouts: A few waterspouts are possible over all local waters
with the stronger showers and thunderstorms.

Wind: Gusty showers and thunderstorms may produce wind gusts of 40 to
45 mph, mainly over Atlantic waters and Southeast Florida through
midday, and interior and Gulf coast and the Gulf of Mexico waters
this afternoon and early evening.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

Numerous showers and isolated thunderstorms with the threat of
localized flooding will continue on Monday. After a brief decrease
in showers and thunderstorms on Tuesday and Wednesday, another period
of heavy rainfall, thunderstorms and potential flooding is likely
starting Thursday and lasting into next weekend as deep tropical
moisture associated with a developing low pressure area surges north
over the region.

The risk of rip currents will remain moderate to high at the Atlantic
beaches through at least Wednesday.

.SPOTTER INFORMATION STATEMENT...

Widespread spotter activation is not anticipated, however individual
spotters are encouraged to report flooding to the National Weather
Service forecast office in Miami.

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

Molleda

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MIAMI FL
537 AM EDT SUN MAY 20 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0446 AM     NON-TSTM WND GST 2 E CORAL GABLES        25.73N  80.23W
05/20/2018  M45 MPH          MIAMI-DADE         FL   MESONET

            WIND GUST OF 45 MPH/39 KNOTS, RECORDED AT THE
            WEATHERBUG SITE AT MIAMI CITY HALL.

&&

EVENT NUMBER MFL1800094

MOLLEDA

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MIAMI FL
540 AM EDT SUN MAY 20 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0444 AM     NON-TSTM WND GST 3 SW KEY BISCAYNE       25.66N  80.19W
05/20/2018  M42 MPH          AMZ630             FL   MESONET

            A WIND GUST OF 42 MPH/37 KNOTS WAS RECORDED AT WXFLOW
            SITE XKBS IN BISCAYNE BAY.

&&

EVENT NUMBER MFL1800095

MOLLEDA

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MIAMI FL
542 AM EDT SUN MAY 20 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0451 AM     NON-TSTM WND GST 3 WNW KEY BISCAYNE      25.71N  80.21W
05/20/2018  M39 MPH          AMZ630             FL   MESONET

            A WIND GUST OF 39 MPH/34 KNOTS WAS RECORDED AT WXFLOW
            SITE XDIN IN BISCAYNE BAY.

&&

EVENT NUMBER MFL1800096

MOLLEDA