Area Forecast Discussion
Issued by NWS Miami, FL

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403
FXUS62 KMFL 270726
AFDMFL

Area Forecast Discussion
National Weather Service Miami FL
326 AM EDT Sun May 27 2018

.DISCUSSION...

SHORT TERM (Today through Wednesday)
As of 2 AM NHC Advisory on Subtropical Storm Alberto, the center
is roughly 100 miles to the W of the Dry Tortugas. Its moving
north-northeast and should spend today moving north at around 10
to 15 mph, paralleling to the west of our outer Gulf waters,
which remain in Tropical Storm Warning. Maximum sustained winds
are 40 mph, and some strengthening is possible today, which will
likely bring TS force winds near our western waters (20-60 nm
offshore Collier County). For nearshore Gulf waters, gusts to
tropical storm force are possible through the day. To the east of
Alberto, very strong SSE LLVL jet should allow for any heavier
convective showers to mix down 30 to 40 mph winds, and there is a
marginal risk according to SPC of some severe-threshold wind gusts
across South Florida. Of greater risk (slight) is tornado
potential, as several storms have had marked rotation so far early
this morning. Despite the void in instability, 0-1 km shear
values are exceptional, 200-300 m2/s2, thus any cell should be
able to rotate and is capable of producing at least a quick spinup
tornado. Will have to monitor later this morning to see if any
dry slot moves in from the southwest, which could enhance
instability and tornado risk. If any dry slot arrives, as is
suggested by late morning, according to most CAMs, would lead to a
scattered out from the near steady rainfall that has occurred
overnight.

Perhaps the most significant hazard of the day is flood risk, as
watch remains out through the day for all areas. Some mesoscale
guidance is hinting at very intense band of rainfall along the
east coast, which would be of utmost concern later this morning
and will need to be closely monitored. Heaviest rainfall potential
through afternoon does appear to be east coast, but next 24 to 36
hours, WPC continues to depict a slight risk for excessive
rainfall due to widespread 3 to 5 inch totals.

In addition to the above hazards, synoptic/gradient wind may
approach wind advisory criteria over South Florida today,
particularly over the east coast, where winds may nearly sustain
at 30 mph at times.

Beyond today, rain chances only slowly diminish as does the risk
for tornadoes. It appears at least a marginal risk that Monday of
both tornadoes and flooding, as it appears the "tail" of Alberto
may reside over the region through the holiday weekend and perhaps
toward midweek.

LONG TERM (Wednesday night through Saturday)

Weather will gradually transition to traditional rainy season with
more scattered, diurnally driven convection. Still, PWATs look
abnormally high and overall coverage may be greater than usual for
the start of June. With increased sunshine, expect temperatures to
rebound to near normal for the start of meteorological summer.

&&

.MARINE...
Tropical Storm Warning in effect for Gulf Waters 20 to 60 nm
offshore Collier County, with Small Craft Advisory in effect for
the rest of South Florida waters. Expected Gale force gusts to
potential impact all waters at times today, with hazardous winds
likely with any of the heavier showers. Subtropical Storm Alberto
will move northward to the west of South Florida`s Gulf waters
through today, then begin to depart the region tonight. Hazardous
seas will likely persist through the holiday weekend.

&&

.AVIATION...
SE winds becoming breezy with gusts to 35 kt at times over the
Atlantic terminals through early this afternoon. Models show the
peak of the winds between 15-18Z today, but 30-35 kt winds could
occur at any time with passing squalls. Expect frequent periods
of MVFR or IFR conditions through the TAF period as extensive
cloud cover associated with the outer circulation of Alberto moves
across the state. A few thunderstorms are also possible this
afternoon.

&&

.BEACH FORECAST...
High risk of rip currents on all South Florida beaches through the
holiday weekend due to the effects from Subtropical Storm Alberto.
Conditions will only slowly improve through midweek.

A Coastal Flood Statement is in effect along the Gulf coast for
minor tidal inundation of up to a foot around high tide, which
will occur at roughly midday today.

&&

.HYDROLOGY...
Widespread 3 to 5 inches of rainfall is expected across South
Florida for the first part of this week, with localized much
higher amounts possible. A Flood Watch is in effect today. Of
greatest concern today is along the east coast where several
computer models indicate a N-S oriented band of intense rainfall
may set up this morning. This region will be closely monitored.
After today, locally heavy rainfall is again likely Monday and may
continue into Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach  83  75  85  75 / 100  60  70  50
Fort Lauderdale  84  76  84  75 / 100  70  70  60
Miami            83  75  84  75 / 100  70  70  60
Naples           84  75  85  74 /  80  50  70  50

&&

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

     High Rip Current Risk from 8 AM EDT this morning through Monday
     afternoon for FLZ069-075.

     High Rip Current Risk through Monday afternoon for FLZ168-172-
     173.

AM...Small Craft Advisory until 8 AM EDT Monday for AMZ610-630-650-
     651-670-671.

GM...Tropical Storm Warning for GMZ676.

     Small Craft Advisory until 8 AM EDT Monday for GMZ656-657.

&&

DISCUSSION...23/SK
MARINE...23/SK
AVIATION...17/AR
BEACH FORECAST...23/SK
HYDROLOGY...23/SK




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