Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 08/28/23
Area Forecast Discussion
National Weather Service Miami FL
733 PM EDT Sun Aug 27 2023
...New UPDATE, AVIATION...
.UPDATE...
Issued at 723 PM EDT Sun Aug 27 2023
Showers and storms have started to diminish as the wave exists the
area, allowing for a quieter evening across much of South Florida.
&&
.SHORT TERM...
(Rest of today through Monday)
Issued at 536 PM EDT Sun Aug 27 2023
Spotty showers and thunderstorms will continue to move across the
area this evening as a subtle wave moves eastward across South
Florida. This morning`s sounding showed a moister atmospheric column
than previous days, with PWATs of 2.20 inches, and gentle low-level
easterly/northeasterly winds. Coverage could become more numerous as
convection is augmented by sea breeze dynamics along the East
Coast/Everglades interface, meaning that portions of interior and
southwest Florida could see more showers and storms this evening
and overnight.
Conditions begin to gradually deteriorate on Monday as Tropical
Storm Idalia crawls northward over the Gulf of Mexico. Locally,
winds will begin to veer from the south/southwest early on Monday
morning, becoming breezy during the afternoon. Moisture will begin
to filter in over the area with this wind shift, which combined with
sea breeze dynamics will allow for another late afternoon of
scattered to numerous showers and storms across southwest Florida
and parts of the interior of the region. Conditions across the local
Gulf waters could also deteriorate on Monday as Idalia approaches,
possibly resulting in higher seas and winds.
&&
.LONG TERM...
(Monday night through next Saturday)
Issued at 536 PM EDT Sun Aug 27 2023
Overview: As you would expect the main concern in the extended
period will be Tropical Storm Idalia. This feature will finally
begin to lift northward into the eastern GOM Monday into Tuesday as
a narrow ridge builds between it an Hurricane Franklin. Idalia
should then gain an eastward component to its motion later in the
day on Tuesday as it feels the influence of an unseasonably
amplified trough over the eastern CONUS. The latest forecast from
the National Hurricane Center would support Idalia making landfall
sometime on Wednesday between the Central Florida Panhandle and the
central Gulf Coast of Florida as a Category 1 hurricane. One thing
to note is that due to the geometry of the Florida coastline and the
forecast track the further south/east track the landfall would occur
earlier. Confidence in this general forecast is slowly beginning to
increase as more observational data (such as Reconnaissance aircraft
data, and supplemental upper air soundings) is assimilated into
numerical models. However, there is still naturally a bit of
uncertainty given the weak nature of the system (right now) and the
complexities of the synoptic setup (both the unseasonably amplified
trough and the ridge sandwiched between two tropical cyclones
present forecast challenges).
Impacts: At the present time, we have relatively high confidence for
hazardous marine conditions (see marine discussion), hazardous beach
conditions, and coastal flooding (see the beaches discussion)
particularly for the Gulf waters/coast given the track of the
system. Beyond those impacts, other potential impacts such as
overland winds, heavy rainfall (see the hydrology section for more
details on this aspect of the forecast), and the tornado risk remain
more uncertain and tied to the specific track and intensity of
Idalia.
The wind threat will be particularly tied to Idalia`s exact
track and intensity with at least breezy conditions likely over the
entire area, with windy conditions possible along and near the west
coast. Based on the latest wind speed probabilities from the NHC
a tropical storm watch has been issued for Collier county. Note a
further east track would increase the probabilities of these
winds being realized, and vice-versa. Elsewhere, wind advisory
conditions look possible (if not probable) for at least parts of
the area in the Tuesday/Wednesday timeframe as the pressure
gradient increases. The tornado risk will also need to be
monitored as the low-lvl wind fields increase Tuesday into early
Wednesday. If the system trends further east, the low-lvl flow
would be more backed (SErly) increasing low-lvl SRH and the
tornado risk, whereas a more westerly track keeps the winds more
southerly limiting low- lvl shear and focusing any tornado risk
north of the area.
Behind Idalia, we will see mid-lvl ridging build in from the east
late this week into this weekend. We will have to monitor Idalia`s
tropical moisture tail on Thursday which may linger near the area
and enhance rainfall chances, but otherwise a more typical wet
season regime with afternoon sea-breeze driven thunderstorms looks
probable late week into the weekend. There is some indication that
high pressure to the north may build in by the weekend shifting the
flow more easterly and actually passing a moisture boundary through
the area over the weekend but naturally this is far enough out in
the forecast that uncertainty remains high. One thing that will need
to be monitored as the ridge builds will be a return to excessive
heat headlines as daily max ApparentTs could approach or exceed 110
degrees in some locations Thursday into Friday.
&&
.AVIATION...
(00Z TAFS)
Issued at 723 PM EDT Sun Aug 27 2023
Generally VFR conditions for all sites through the period. Light
and variable winds overnight will become more SSW as TS Idalia
enters the Gulf of Mexico on Monday morning. Sea breezes could set
up around noontime tomorrow along both coasts (SE along East
Coast, W along Gulf Coast), with VCTS possible at all sites.
Short- fuse amendments due to reduced vis/cigs could be possible
with some of the stronger storms.
&&
.MARINE...
Issued at 536 PM EDT Sun Aug 27 2023
All eyes will remain on Tropical Storm Idalia for potential impacts.
Increasing wind and building seas will create hazardous marine
conditions, particularly in the Gulf of Mexico where Tropical
Storm conditions will be possible. The forecast will evolve
quickly over the coming days as the Atlantic, Biscayne Bay, and
Lake Okeechobee could all see winds rise above advisory criteria
with at least gusts near or exceeding gales. All boaters and
mariners should continue to monitor the latest conditions and
forecasts this week.
&&
.BEACHES...
Issued at 536 PM EDT Sun Aug 27 2023
Atlantic: A high risk for rip currents is in effect for the Palm
Beaches. Swell from the distant Hurricane Franklin over the open
Atlantic will also need to be monitored as it could keep the rip
current risk elevated for the Atlantic beaches, particularly the
Palm Beaches, to start the work week. The elevated risk will linger
and grow through mid week along all of the Atlantic beaches.
Gulf: The Gulf beaches will see their rip current risk build as
Idalia enters the southeastern Gulf of Mexico. The risk will grow by
Tuesday and linger through the end of the week.
Coastal Flooding: As Idalia approaches the coastal flooding risk
will increase over the Gulf coast particularly in the Tuesday-
Thursday time frame, moderate to even locally major coastal
flooding will be possible during periods of high tide as increased
onshore flow combines with the upcoming perigean spring tides
associated with the full moon. Additionally the spring tides will
create a concern for minor coastal flooding on the east coast in
the same period.
&&
.HYDROLOGY...
Issued at 536 PM EDT Sun Aug 27 2023
With our eyes on Tropical Storm Idalia comes the consideration for
excessive rainfall impacts to portions of southern Florida. The
majority of the rainfall associated with the system is forecast to
fall Monday afternoon through Wednesday. The greatest risk for flash
flooding will be near the Gulf coast. Storm total rain amounts of 2-
3" with localized higher amounts.
&&
.PRELIMINARY POINT TEMPS/POPS...
Miami 80 93 80 93 / 30 60 40 70
West Kendall 77 94 79 94 / 30 60 40 70
Opa-Locka 78 93 79 93 / 20 60 40 70
Homestead 77 91 78 90 / 30 50 40 70
Fort Lauderdale 79 92 79 91 / 20 50 40 70
N Ft Lauderdale 80 93 80 92 / 20 50 40 70
Pembroke Pines 78 93 79 92 / 20 50 40 70
West Palm Beach 78 92 77 93 / 20 50 40 70
Boca Raton 79 93 79 93 / 20 50 40 70
Naples 80 93 80 91 / 60 60 60 90
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...Storm Surge Watch for FLZ069.
Tropical Storm Watch for FLZ069-070.
High Rip Current Risk until 8 PM EDT this evening for FLZ168.
AM...None.
GM...Tropical Storm Watch for GMZ656-657-676.
&&
$$
SHORT TERM...ATV
LONG TERM....Carr
AVIATION...ATV