674 FXUS62 KMFL 061321 AAA AFDMFL Area Forecast Discussion...UPDATED National Weather Service Miami FL 921 AM EDT Mon Sep 6 2021 .UPDATE... Another stormy day with light wind that will allow sea breezes to develop and advance inland. Cannot rule out some strong convection around boundary collisions this afternoon. 12z MFL sounding sampled a drier atmosphere compared to previous days but one still capable of allowing convection to develop. The slightly drier air (1.67 inches of precipitable water) does allow for some potential for strong downburst winds this afternoon and early evening with the strongest storms. No major changes to the forecast this morning as it is on track. No additional updates are anticipated through midday. Have a wonderful Labor Day! && .PREV DISCUSSION... (Issued 734 AM EDT Mon Sep 6 2021) AVIATION(12Z TAFS)... Generally VFR through the period with light southwesterly to southerly flow becoming more southerly to southeasterly. Sea breezes will develop and push inland with convection increasing from west to east through the morning. Sub-VFR possible around convection with brief bouts of sub-MVFR possible at directly impacted terminals. Convection should diminish in the evening. PREV DISCUSSION... (Issued 242 AM EDT Mon Sep 6 2021) SHORT TERM (Today through Tuesday)... Models and satellite data show the decaying frontal boundary over central Florida finally breaking down and pushing into the west Atlantic. Over the SE CONUS, the high pressure is giving way to a mid level trough and accompanying sfc front, while mid level troughiness can being observed over the central portions of the peninsula. Weak high pressure remains over most of the GOMEX, with NHC showing a disturbance departing the Yucatan and moving into the southern Gulf waters. The overall synoptic scenario will keep SoFlo under very relaxed pressure gradients, with winds remaining relatively light. Wind direction gets more complicated through the short term as the weak sfc flow will be overwhelmed by afternoon sea breezes and outflow boundaries. Thus, mainly a light and variable at times wind regime should prevail, turning rather chaotic in the afternoon with sea breezes and outflow boundaries becoming focal points for convection. The scenario described above will again result in slow storm motion, which will enhance chances for localized flooding at times. Therefore, expect another round of showers starting over the Gulf coast and pushing into the eastern half of SoFlo early in the afternoon. Main hazards with any thunderstorm will be lightning, funnel clouds, strong wind gusts, and heavy rainfall. A similar forecast scenario is expected on Tuesday, but with models suggesting a gradual strengthening of ridging over the west Atlantic. This should mark the onset of returning SE flow over the eastern half of SoFlo and displace best POPs into the interior and west coast areas. A little drier air aloft may bring POPs down a little, but still in the 45-55 percent range in the afternoon for much of the CWA. Overall moisture content for thunderstorm activity should remain sufficient, but a close eye will be kept on the progress of the aforementioned disturbance over the GOMEX and its potential influence in the region air mass. The hot temperatures continue through the short term with afternoon highs in the lower 90s across much of SoFlo, along with heat index values reaching triple digits. LONG TERM (Tuesday Night through Sunday)... During the middle and end of the week, models continue to show the mid level ridge over the Bahamas continuing to strengthen. This will help to keep the very weak southwesterly steering flow in place during this time frame. At the surface, a weak area of high pressure will slowly try to move into the area from the western Atlantic. Farther to the west, guidance shows a tropical wave in the central Gulf of Mexico moving towards the northeast. The ridge of high pressure will help to keep that feature away from South Florida. There will still be plenty of lower level moisture in place to support shower and thunderstorm development. Convection will continue to be sea breeze driven and slow moving as well due to the very weak wind flow. Shower and thunderstorm development will start along the sea breezes as they push towards the interior and interact with each other. After that, thunderstorm activity will likely drift back towards the metro areas during the afternoon and evening hours. With the slow motion of thunderstorms and heavy downpours, the potential for localized flooding will remain in place especially across the east coast metro areas during the afternoon and evening hours. High temperatures through the end of the week will generally range from the upper 80s across the immediate east coast to the lower 90s across the interior sections. For the upcoming weekend, the latest model guidance shows the mid level ridge trying to gradually build westward into the eastern Gulf of Mexico. This would help to somewhat shift the winds around to more of an east to southeasterly direction. Shower and thunderstorm chances will remain in place during this time frame and will be sea breeze driven. The difference may be that the highest chances of showers and thunderstorms could be focused over the interior and west coast with a slightly stronger east to southeasterly flow developing. This of course remains highly uncertain at this time as it is towards the end of the current forecast period. The current forecast represents a blend of the models keeping pops at 40 to 50 percent across the region through the weekend. MARINE... The light to moderate WSW flow continues over the Gulf coastal waters, while a more southerly weak wind should begin returning across the Atlantic coastal waters today. Generally benign marine conditions continue through the beginning of the work week, outside of shower and thunderstorm activity. A minor east swell from Hurricane Larry remains in model solutions, which seems to reach the Palm Beach and Broward coastal waters by late tomorrow with increasing hazardous conditions over the offshore waters. && .PRELIMINARY POINT TEMPS/POPS... Miami 76 91 77 91 / 30 50 10 50 West Kendall 75 92 75 92 / 20 40 10 50 Opa-Locka 75 92 77 92 / 30 50 10 50 Homestead 75 90 75 90 / 20 40 10 40 Fort Lauderdale 76 90 77 90 / 30 40 10 50 N Ft Lauderdale 76 90 77 90 / 30 40 10 50 Pembroke Pines 75 90 76 91 / 30 50 10 50 West Palm Beach 75 91 76 92 / 30 40 10 50 Boca Raton 75 90 77 90 / 20 40 10 50 Naples 77 89 77 90 / 10 40 10 50 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. GM...None. && $$ Update/Aviation...RAG Visit us at weather.gov/miami Follow us on Facebook and Twitter at: www.facebook.com/nwsmiami www.twitter.com/nwsmiami