Area Forecast Discussion
Issued by NWS Melbourne, FL

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FXUS62 KMLB 181951

Area Forecast Discussion
National Weather Service Melbourne FL
351 PM EDT Sun Mar 18 2018

...Severe Storms with Damaging Winds Possible on Tuesday...

Current....Southwest flow on the backside of high pressure and
ahead of a stalled frontal boundary over Georgia produced another
abnormally warm afternoon with most locales making it into the
mid 80s. Temps are cooling a bit at the beaches behind a well-
defined sea breeze boundary that remains pinned close to the
coast. Meanwhile, low level convergence to the northeast of the
Big Bend region has managed to squeeze out a couple of showers
that are moving toward Lake County.

Rest of Today/Tonight...Guidance continues to indicate the best
prospects for rain will remain north of the area as the
aforementioned front acts as a focusing mechanism for convective
development. Energetic flow aloft will generate a weak surface
low along the front, along with widespread showers and
thunderstorms across north Florida. Hi-res guidance keeps nearly
all of this activity to our north, though recent runs of the HRRR
and ARW indicate an outflow boundary and some convective debris
could make it to our northern areas well after midnight. With that
in mind, have maintained a low chance for showers, no thunder,
north and west of Interstate 4. Otherwise, most areas should
remain dry with a chance for some stratus and fog across the far
interior (western Lake, Osceola, and Okeechobee counties).

Monday...The surface boundary remains to our north while offshore
flow keeps temperatures well above normal locally. Moisture
levels are forecast to build through the day with PWATs between
1.40 and 1.60" across central and northern areas by the
afternoon. Given the area remains far enough removed from the
front and more energetic flow aloft, PoPs will remain low,
generally 30% north of 528 and 20% south. Something to note,
however, is that the evolution of tonight`s convection across
north Florida could play a role in our precip coverage tomorrow,
especially if an outflow boundary manages to settle over the area
and act as a focusing mechanism for showers. Highs will be above
normal reaching the mid 80s over much of the region, even at the
coast as elevated offshore flow will keep the east coast sea
breeze from moving inland.

Monday Night...Strengthening WSW low level, mid level impulses aloft
and increasing moisture levels across the nrn peninsula will lead to
low convective chances across nrn portions of east central FL into
the evening. Short range models also hint at more substantial
prefrontal convection organizing across the ern FL Big Bend after
midnight with a low shower chance expected across Lake county
through the night. Lows will be in the mid to upper 60s.

Tuesday...Short range model guidance continues in good agreement in
advertising a strong mid/upper level trough across the Southeast
accompanied by favorable coupled jet streak induced upper divergence
across central FL through late morning into the afternoon. Low to
mid level wind fields will increase with H9 wind to 40-45 knots and
850 mb winds to near 50 knots. As the trough approaches, mid level
temps will cool at 500 mbs to -13 C by afternoon leading to steep
low to mid level lapse rates. Expect a line of strong to potentially
severe storms to move across nrn sections from morning to early
afternoon and then across southern sections through the remainder of
the mid to late afternoon and early evening. At this time the
primary hazards with storms will be strong straight line winds,
hail, locally heavy rain, frequent lightning. Deep layer shear,
strong mid layer wind fields combined with marginally sufficient low
level helicity should allow for a low tornado threat as well. Have
added possible severe storms from Osceola/Brevard northward. Breezy
to windy offshore flow in the morning will allow highs to reach the
lower 80s north to mid to upper 80s south before the convection
moves through.

Tue Night...Evening convection with some strong storms across
Okeechobee and the Treasure coast should move southeast into late
evening with much drier air moving in from the west through the
night. Pressure gradient will support breezy conditions at times
behind the front with lows in the 50s.

Wed-Sun (Previous)...Dry and cooler conditions expected behind the
front into mid to late week as ridge across the central U.S. shifts
gradually eastward and maintains a predominantly northerly flow
across the area. Highs will generally range from the upper 60s to
mid 70s, with lows again dropping into the 40s Wed and Thu nights.
High pressure then shifts offshore of the Southeast U.S. coast into
the weekend with flow veering to the south Saturday, which will warm
temperatures to more seasonable values.


.AVIATION...Continued VFR with an isolated shower in the vicinity
of KLEE through 21Z. Expect scattered to numerous showers and
storms to remain across north Florida tonight, though debris
cloudiness (remaining VFR) is expected to move across the north.
IFR cigs and some fog expected to redevelop over the west coast of
Florida and spread toward KLEE/KISM early Monday morning.


Tonight...Low level winds disturbed by the Atlantic sea breeze
will veer back to the southwest at about 8 to 12 knots overnight.
Seas 1 foot near the coast, 2 feet offshore.

Monday...Offshore flow increases a bit in the afternoon as a
surface front remains stalled over Georgia. Generally favorable
boating conditions expected to continue with seas 1-2 feet
nearshore and up to 3 feet well offshore. Small chance for
lightning storms to push offshore, mainly north of Sebastian

Tuesday/Tue Night...Boating conditions will become hazardous on
Tuesday with strong to possibly severe storms moving west to east
across the waters and southwest winds increasing to around 20 knots.
Winds will become westerly behind the front Tue Night and increase
to 20-25 knots near shore and 25-30 knots offshore. Expect building
seas across the offshore waters through the night with convection
exiting the southeast marine area past late evening.

Wed-Fri...NW winds to 15-20 knots offshore will keep seas elevated
beyond 20 nautical miles into mid week with poor to hazardous
conditions for small craft. Winds will become northerly Friday to 10-
15 knots offshore keep seas poor across the offshore gulf stream


Extended...Windy SW flow will develop with a line of
showers/storms expected to cross east central FL from late morning
into the afternoon. Dispersion values will be very high with
transport winds increasing to around 30 knots.

A dry airmass behind the front from mid to late week will allow
Min RHS to drop to critical levels across the interior each
afternoon. Breezy NW winds Wed will gradually decrease into late


DAB  61  83  66  81 /  30  40  30  70
MCO  63  85  69  83 /  10  30  20  70
MLB  62  85  69  86 /  10  30  10  60
VRB  61  84  69  86 /  10  20  10  50
LEE  64  83  70  82 /  20  40  30  70
SFB  63  84  69  83 /  20  40  20  70
ORL  64  84  68  82 /  10  30  20  70
FPR  60  84  67  87 /  10  10  10  40




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