Killarney, Florida Weather Forecast Discussion

019
FXUS62 KMLB 161759
AFDMLB
Area Forecast Discussion
National Weather Service Melbourne FL
159 PM EDT Tue Sep 16 2025
...New DISCUSSION, MARINE...
.KEY MESSAGES...
Issued at 154 PM EDT Tue Sep 16 2025
- A high risk of life-threatening rip currents continues at all
  area beaches today, entering the water is discouraged
- Low rain chances through today, coverage gradually increases
  from south to north mid to late week; locally heavy rainfall
  possible across the Treasure Coast Thursday into Friday
- Temperatures remain near to slightly below normal this week and
  into early next week, especially across the south, where higher
  coverage of clouds and rain are forecast
&&
.DISCUSSION...
Issued at 154 PM EDT Tue Sep 16 2025
Rest of Today-Tonight...Isolated to scattered showers have developed
around the area, mainly along and inland from the Treasure Coast, as
of early this afternoon. This is in line with the current forecast,
as the highest moisture remains over southern portions of the area.
Lingering drier air, especially north and west of I-4, are expected
to continue to limit convective development there, with PoPs 15% or
less. CAMs suggest convection continuing across southern portions of
the area through the afternoon, with a sea breeze collision
occurring over the interior late this afternoon and into this
evening. Thus, have maintained PoPs 20-30% across portions of
Osceola and Okeechobee Counties through the evening hours. Some
drift back towards the Treasure Coast is possible into the nighttime
hours, as steering flow is light but westerly. Regardless, showers
and storms will remain possible over the Atlantic waters overnight
and could occasionally brush the Treasure Coast into the early
morning. PoPs 20-40% overnight. The slight increase in moisture
today will keep temperatures in the 70s for most areas, though
cooler locations north of I-4 could see the upper 60s again.
Wednesday...The cut off low over the NC/VA area early Wednesday will
begin to drift northeastward, as the upper level low opens up and
merges with a trough digging southward from Canada. Locally deeper
moisture begins to build northward, with PWATs from near Melbourne
southward rebounding to around 2". PoPs will increase in turn,
becoming up to 50-60% south of Orlando. To the north, lingering
drier air will help to continue to somewhat limit convective
development, with PoPs 20-40% there. While a few lightning strikes
cannot be ruled out, low CAPE (below 1000 J/kg) will limit coverage
across the area. Instead, the locally heavy rainfall threat will
begin to increase, with slow storm motions (10 kts or less) and
opposing low level and mid-level flow. Quick rainfall accumulations
of 1-2" will be helpful for continued drought conditions along the
Treasure Coast, but could set the stage for a greater flooding
rainfall threat late week, especially in areas that see multiple
rounds of heavy rainfall over several days. While the greatest
chance for showers and storms will be in the afternoon and evening
hours, chances (30-60%) will continue along the coast overnight.
Onshore flow will keep temperatures near-normal along and north of I-
4, in the upper 80s to near 90. Meanwhile, high coverage of clouds
and showers will keep areas to the south in the mid-80s.
Thursday-Tuesday (previous)... The mid-upper level trough axis
across the eastern US on Thursday will gradually shift eastward into
the Atlantic as a low pressure over Canada deepens and moves
eastwards towards Quebec and the far northeast US into the weekend
and early next week. The aforementioned surface low pressure will
move northeast off of the New England coast and open into a trough.
Deeper moisture will continue to build northward across the Florida
peninsula each day, with a surface boundary settling near to just
south of the local area late late week into early weekend. This
boundary will shift southward just off the Florida peninsula/across
the Florida Keys into early next week.
The greatest potential for locally heavy rain fall continues to be
Thursday into Friday as forecast PW values increase to 2"+ from
around Melbourne southward, with comparably drier air ( PW values of
1.5"-1.7") farther inland and northwest. The highest coverage of
showers and storms on Thursday looks to be along and inland from the
Treasure Coast. This may help put a dent in the drought conditions
across portions of the Treasure Coast. However, with training of
showers and locally heavy rainfall, minor flooding concerns remain
for Thursday across the Treasure Coast despite the dry antecedent
conditions.
Despite increasing moisture from south to north, models continue to
show a moisture gradient persisting over the area. Thus, even with
PW values increasing north and west of I-4 through early next week,
the PW values will remain below the values across the south. Because
of this, a gradient for rain chances will exist. A medium to high
chance (60-70 percent) chance of rain and lightning storms are
forecast south of Melbourne and towards Okeechobee each day, with 30-
50 percent chance to the north and west. Exactly where this gradient
develops, however, will be dependent on the location of the
boundary. Onshore flow will persist through the time period, with
speeds increasing to 10-15 mph behind the sea breeze each afternoon.
Temperatures will remain near to slightly below normal, especially
where added cloud cover prohibits more efficient daytime heating.
Afternoon highs will be in the mid to upper 80s to near 90
degrees.
&&
.MARINE...
Issued at 154 PM EDT Tue Sep 16 2025
Generally favorable boating conditions continue through Wednesday,
as northeast winds become increasingly easterly as a low pressure
system moves from near North Carolina/Virginia and into the
Northeast US. Wind speeds will remain around 10-12 kts or less
through this period, before increasing to 10-15 kts late week and
into the weekend, as a weak boundary reestablishes itself near to
just south of the local Atlantic waters. Seas 3-5 ft today
diminishing to 2-4 ft through the remainder of the week, before
building once again to up to 5-6 ft offshore. Coverage of showers
and storms will increase into Thursday from south to north, with
scattered to numerous convection then continuing into the weekend.
Rain chances will persist through the overnight hours across the
waters, especially near the Gulf Stream.
&&
.AVIATION...
(18Z TAFs)
Issued at 145 PM EDT Tue Sep 16 2025
Increasing coverage of showers through the remainder of this
afternoon across all terminals, with activity diminishing after
00Z. ENE winds 5 to 10 knots diminish overnight, becoming light
and variable. Winds pick up out of the east at 5 to 10 knots after
15Z, with VCSH possible at the coastal terminals. Shower and
storm chances increase tomorrow afternoon, with VCTS at the MCO
and interior terminals after 18Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB  72  86  73  85 /   0  20  20  40
MCO  72  88  73  87 /  10  50  30  50
MLB  75  86  74  85 /  20  60  50  60
VRB  74  86  73  86 /  30  60  60  70
LEE  71  88  72  87 /  10  30  20  30
SFB  72  88  73  87 /  10  40  20  50
ORL  72  88  73  87 /  10  50  30  50
FPR  73  86  73  85 /  30  60  60  70
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...None.
&&
$$
DISCUSSION...Leahy
AVIATION...Tollefsen/Alvarez

NWS MLB Office Area Forecast Discussion