000 FXUS62 KMFL 200020 AAA AFDMFL Area Forecast Discussion...UPDATED National Weather Service Miami FL 820 PM EDT Mon Apr 19 2021 ...A Few Strong Storms Possible Late Tonight Western Areas... .UPDATE... The showers and thunderstorms that been occurring over the northern areas of South Florida this afternoon should continue to slowly dissipate this evening as the heating of the day is lost. However, the steering flow will remain in a south to southwest direction over South Florida tonight, as a frontal boundary over South Central Florida remains nearly stationary. This will allow for tropical moisture to remain over the region tonight leading to some showers over the east coast metro areas this evening before shifting to the west coast metro areas after midnight tonight. POPS for the east coast metro areas will be in the chance range this evening tapering down to isolated for late tonight. There is a short wave in the mid to upper levels of the atmosphere over the Gulf of Mexico that will be moving eastward into and should be near the west coast of Florida by Tuesday morning. This short wave will help to increase the coverage of the showers and thunderstorms for the western areas around sunrise Tuesday. Therefore, the POPs for the west coast metro areas have been raised to numerous to widespread for early Monday morning. A few of the storms could even become strong with gusty winds, small hail, and frequent lighting strikes due to the closeness of the short wave bringing in colder air aloft. Rest of the forecast looks good at this time and no other changes are planned. && .AVIATION... The winds will remain light from the south southwest tonight over all of the TAF sites. VCSH will continue for all of the TAF sites tonight. However, KAPF taf site will have VCTS after 10Z due to storms possible. The ceiling and vis will remain in VFR condition but should fall down into MVFR or evening IFR conditions with any shower or thunderstorm passage. The TAF sites will be admin for the ceiling and vis with tempo's when showers and storms move over the TAF sites tonight. && .PREV DISCUSSION... (Issued 246 PM EDT Mon Apr 19 2021) ..Strong to Severe Thunderstorms Possible This Afternoon... ..Unsettled pattern remains over the next few days... MESOSCALE UPDATE (This Afternoon and Evening)... A stout 500 hPa short-wave impulse is allowing for a low-level mass response resulting in enhanced low-level convergence along and ahead of a stalled stationary boundary across South-Central Florida. Efficient transport of moisture via S/SW 1000-850 hPa flow of 15-25 kt will allow for an air mass characterized by high theta-e values to be transported along areas of enhanced localized convergence ahead of the aforementioned frontal boundary. This will allow for ML CAPE values of 2000-2500 J/kg to be realized across most of the CWA. An expansive cloud canopy associated with a complex of organized thunderstorms will limit the extent of instability where cooler outflow and cloud debris exist, however areas near Lake Okeechobee, particularly Glades, Hendry, and Palm Beach Counties appear to be within the greatest risk area for isolated strong to severe thunderstorms. Furthermore, the orientation of horizontal convective rolls and modest 0-6 km deep-layer shear of roughly 35-40 kt may allow for discrete supercells to form ahead of the primary convective complex associated with the larger synoptic forcing. Given the aforementioned setup and unfolding scenario, strong/severe storms capable of producing isolated damaging wind gusts, occasional/frequent lightning, and small hail are all possible with any storms that are able to take advantage of a favorable environment. An isolated brief tornado also cannot be ruled out. SHORT TERM (Tonight through Tuesday)... With the surface frontal boundary lingering, passing mid-level shortwave troughs and diurnal heating cycles will lead to surges and eventual erosion in convective activity. A lull late this evening into the early overnight is possible but another flare up in convection cannot be ruled out, particularly if a southerly boundary from Cuba survives a transit across the straits of Florida. The moisture profile will continue to increase, particularly around Lake Okeechobee closer to the boundary where today's repeated rainfall could end up being the start of a heavy rainfall event that could last through at least Tuesday. Precipitable water values could reach close to 1.75 to 2 inches in these areas, which would high for this time of year. The additional convection and the proximity of the front will enable increased cloud cover which will help keep temperatures a few degrees cooler with mid to upper 80s across the area. Showers and storms remain in the forecast with cool temperatures aloft (-8 to -9 deg C at 500 mb) remaining through Tuesday. With that, the concern for strong to severe thunderstorms continues with the primary concerns being damaging winds, hail, excessive rainfall, and tornadic activity. LONG TERM (Tuesday Night through Monday)... An exiting mid-level shortwave on Tuesday evening will allow for another lull in convection to start the long term but the presence of the surface frontal boundary will continue into Thursday when guidance suggests that a slot of drier air will attempt to push in behind the front as it sags southward over the southern part of the peninsula. This may allow some northern portions of the area, such as the Lake Okeechobee region, to have the potential of a respite from the moisture but the relative lack of available forcing around this time may also help clamp down on convection compared to earlier days. On Friday, the next system of interest to our region emerges into the central United States. With this system, a mid-level trough will push eastward with an associated surface frontal boundary pushing eastward across the Gulf towards Florida for the weekend. There is still some uncertainty with the extended period, the wet and unsettled trend appears to be the main story for the next 7 days. AVIATION(18Z TAFS)... A band of convection has set up just north of PBI this afternoon. Additional convection will be possible across the area through the afternoon before a brief break this evening. More showers and storms may develop later this evening across far southern portions of FL. Kept tempos up north closer to the afternoon convection and continued VCs overnight generally for APF and TMB. Southwesterly winds will decrease shortly after sunset but ramp back up during the daylight hours on Tuesday. MARINE... A cold front moving into south central Florida will bring showers and thunderstorms to the local waters through the middle of the week. Winds may reach cautionary levels at times, mainly over the Atlantic waters. Strong to severe thunderstorms may develop over the coastal waters during the next couple of days, bringing brief periods of gusty winds and rough seas. The front will linger around the region through much of the week. BEACHES... A moderate rip current risk continues today for the Palm Beaches. This enhanced risk might continue on Tuesday as a small residual ENE swell lingers over the northern Atlantic marine zones off Palm Beach County. && .PRELIMINARY POINT TEMPS/POPS... Miami 74 88 75 87 / 40 40 40 70 West Kendall 73 89 73 89 / 40 30 40 60 Opa-Locka 74 89 73 87 / 40 40 40 70 Homestead 74 87 73 87 / 40 20 40 50 Fort Lauderdale 73 88 74 86 / 40 40 40 70 N Ft Lauderdale 73 88 74 85 / 50 40 50 70 Pembroke Pines 74 88 73 87 / 40 40 40 70 West Palm Beach 71 87 70 83 / 50 60 60 80 Boca Raton 72 87 73 85 / 50 40 50 80 Naples 73 83 72 82 / 80 80 70 70 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. GM...None. && $$ Update/Aviation...BNB Tonight/Tuesday and Marine...RAG Tuesday Night through Monday...RAG Visit us at weather.gov/miami Follow us on Facebook and Twitter at: www.facebook.com/nwsmiami www.twitter.com/nwsmiami