NWS Miami, FL wrote its last area forecast discussion before the first event at May 17, 8:53 AM EST, 1 hour 7 minutes earlier.
Area forecast discussion, May 17, 8:53 AM EST, 1 hour 7 minutes before
Area Forecast Discussion
National Weather Service Miami FL
953 AM EDT TUE MAY 17 2016
.UPDATE...
12z MFL and model sounding data, along with global guidance are
suggesting a little more favorable atmospheric conditions for
small hail to develop with some of the stronger updrafts this
afternoon. Best area for this would probably be interior and
northern portions of the CWA. Thus, will include a quick update to
the hazard grids to mention small hail possible. Meanwhile, the
mid morning showers observed on radar have now either dissipated
or moved into the Atlantic coastal waters. A few more showers may
still happen during the rest of the morning hours, then becoming
more widespread in the afternoon. Any thunderstorm that forms will
bring periods of strong gusty winds, localized heavy rain and may
produce brief small hail.
&&
.PREV DISCUSSION... /issued 826 AM EDT TUE MAY 17 2016/
AVIATION...
A couple of thunderstorms moved near PBI and FXE earlier this
morning, while some VCSH are possible over the Atlantic terminals
through the rest of the morning hours. VCTS remains in the TAFS
this afternoon as increasing instability and low level moisture
will bring a more active day in terms of shower coverage and
potential for thunderstorms. Impacts on visibilities will likely
be adjusted during the next TAF package. Mainly southeasterly
winds will prevail today, except in the vicinity of thunderstorms
which may bring locally variable and gusty winds.
PREV DISCUSSION... /issued 541 AM EDT TUE MAY 17 2016/
UPDATE...
A quick update this morning to account for current conditions and
new hi-res model runs. The main change is a slight bump up in PoPs
this afternoon in value and in coverage. Models still indicating
showers and storms are still likely to develop starting around mid
day and persist into the evening hours.
PREV DISCUSSION... /issued 243 AM EDT TUE MAY 17 2016/
DISCUSSION...
Fairly messy forecast for the week ahead, with a much wetter
pattern in store...
Currently quiet weather across South Florida, with shower activity
just outside the area. Hi-res models now indicating it should be
fairly quiet into the mid morning, and possibly early afternoon
hours.
Moisture is increasing from last nights PWATs of 1.8 inches. The
GFS is showing this to increase to almost 2.25 inches in some
areas by this afternoon. 500mb temps were still a little warm last
night, at -7.5C. The should cool to near -9C by this afternoon.
These should help to create a more favorable environment for
convective activity this afternoon. Also, models are showing a
weak 500mb short wave moving across the area. This should be the
first of several over the next several days.
Looking at the actual soundings from yesterday, the NAM model
soundings did not do a great job at predicting various levels,
including the freezing level, which it was too low. Given this, a
freezing level of only 12.5k ft seems well too low, by possibly
around 1000ft, if it compares to the difference from last night,
which would put the level around 13k-14k ft this afternoon, which
makes sense, given the cooler temps forecast aloft. This will make
hail a better possibility than it has been. Also, the GFS is
showing some PVA at 500mb across the western Lake region at around
18z, which would help to enhance convection in the northern half
of the CWA. This is also supported by the ARW, which has most of
the activity from around I75, north. The HRRR is also beginning to
show the same scenario, although, it is towards the end of the
HRRR run. All in all, can not see any reason but to go with the
high PoPs for most of South Florida today, although, the activity
may begin along the coastal areas and push inland with any sea
breeze that may develop.
The models have changed some since last night, with a sfc low now
forming off the Carolina coast by Wednesday. They had shown this
later in the week in previous runs. This would bring a boundary
towards the region on Wednesday,although not into South Florida.
However, it may help to initiate convection on Wednesday. Some of
the storms may become strong with the added dynamics. Currently,
SPC does not have the area in anything but general thunderstorms.
A 500mb ridge begins to slowly build over the eastern Gulf. This
may allow Thursday to be a little less active than today and
Wednesday,although still have convective activity, but perhaps
more sea/lake breeze driven.
Models then have a strong 500mb low moving into the Mid-West
region by the weekend. This will push the 500mb ridge off to the
east by Saturday, as well as help build a sfc high well to the
northeast, putting South Florida into more of a southerly flow for
Saturday. By Sunday, a sfc low will form over the Eastern
Seaboard, bringing yet another boundary into the area. This low
will move to just offshore along the Mid-Atlantic coast through
the beginning of next week. This will keep PoPs in the forecast for
the weekend, and may help to bring in some drier air for the
beginning of next week, as some gets wrapped around into the low,
which models indicate will still be in place perhaps into the
middle of the week.
AVIATION...
A quiet morning will turn to more active weather by this
afternoon, with showers and thunderstorms developing across South
Florida today. Expected initiation is after 17z, and not only is
VCTS in the TAFs, but also a prob30 group, as there are high
chances of convection today. Some of the storms could be strong
with gusty wind, and perhaps small hail. The activity should
quiet down this evening, with the wind going light and variable
across the region.
MARINE...
A more active weather pattern this week, with showers and
thunderstorms possible each day through the weekend. Easterly flow
today will become more southeasterly tomorrow, then become more
variable across the region for the end of the week.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 86 76 88 73 / 90 60 70 30
Fort Lauderdale 86 76 87 74 / 80 60 60 30
Miami 88 75 87 74 / 70 50 60 30
Naples 86 75 89 74 / 60 30 50 10
&&
.MFL Watches/Warnings/Advisories...
FL...None.
AM...None.
GM...None.
&&
17/AR