Scientific Forecaster Discussion
fxus62 kmfl 210526
Area forecast discussion
National Weather Service Miami Florida
126 am EDT Sat Jul 21 2018
VFR with light SW flow continues at all terminals through late
Saturday morning. Stronger SW/west flow establishes Saturday early
in the afternoon but remaining generally VFR. Kept vcsh over the
Atlantic terminals after 18z, but probability of precipitation may drop even more in
Previous discussion... /issued 853 PM EDT Fri Jul 20 2018/
Update...showers and storms have ended over land this evening
with sunset, with one or two lingering over the nearshore Atlantic
waters. Since there are still a few boundaries around, can't rule
out a brief shower or two along the East Coast through late
evening as remaining instability plays out. Overall however,
expect dry conditions over land through the remainder of the
overnight with a few storms over the Atlantic waters overnight. No
significant changes to the ongoing forecast.
Previous discussion... /issued 747 PM EDT Fri Jul 20 2018/
Aviation...showers have diminished for the evening and should
hold off until Saturday afternoon. Coverage Saturday looks less
than today so have only placed vcsh where pops > 30%, over Broward
and northern Dade terminals. Light SW flow today, increasing to
around 10 knots Saturday.
Previous discussion... /issued 403 PM EDT Fri Jul 20 2018/
This afternoon and tonight: as expected, dry air continues to limit
coverage of showers and storms this afternoon. The isolated activity
that has developed has been limited to the East Coast Metro where a
diffuse Gulf Breeze is interacting with the Atlantic seabreeze
pinned along the coast. The remainder of this afternoon should
evolve similar to yesterday, with boundary-seabreeze interactions
driving widely scattered activity across the East Coast Metro
through just after sunset.
Forecast looks mainly dry for land areas overnight with the
potential for a few Atlantic showers to brush the coast at times.
This weekend: upper level low moving through the Great Lakes region
this afternoon will give the shortwave and low level trough that's
been stalled across central Florida a southward push into this
The boundary's progress will be slow, perhaps just making it to the
Lake Okeechobee region for the latter half of Saturday, then more
firmly settled across South Florida for Sunday. We will remain under
the influence of the ridge on Saturday, without a significant
moistening of the atmosphere. Rain chances will trend a little
higher towards the lake, but coverage across the remainder of the
region will remain isolated to widely scattered at best, as with the
past few days.
Falling mid level heights, cooling temperatures aloft, and a
moistening atmosphere as the low level boundary makes it into South
Florida on Sunday will lead to widespread showers and storms into
Sunday afternoon. Most activity looks to initialize along the
boundary itself, so showers and storms look to get going relatively
early across the area.
Next week: upper level low at the southern end of the East Coast
trough will continue to sink south into the Gulf early next week. As
we've seen a few times this Summer, it looks to become a cut-off low
retrograding west along the northern Gulf Coast through the week.
Main impacts from this feature look to be during the early part of
the week as the low is progged to be closest to US across North
Florida/NE Gulf. However, moist west-southwest flow (with pwats
potentially well above 2"), along with cooler temperatures aloft and
smaller vort maxes rotating around the main low will bring
widespread showers and storms through much of the week. Current
model guidance suggests a pattern of more showers with embedded
storms, along with the potentially for locally heavy rainfall if
higher moisture levels materialize.
Marine...weak boundary across central Florida will gradually settle
southward over the next few days. Moderate west-southwesterly flow
is expected to prevail as a result, with little if any development
of the Atlantic seabreeze. Seas continue 2 feet or less in both the
Gulf and Atlantic through Saturday, with the increasing westerly
fetch bringing seas to 3 to 4 feet in the offshore Gulf by Monday.
Coverage of showers and storms remains isolated on Saturday, with
more widespread coverage across all local waters into the upcoming
Preliminary point temps/pops...
West Palm Beach 94 76 93 76 / 20 20 60 50
Fort Lauderdale 93 79 93 77 / 30 10 50 40
Miami 93 77 92 77 / 30 10 40 40
Naples 92 78 90 77 / 10 30 50 60