552 FXUS62 KMLB 220917 AFDMLB Area Forecast Discussion National Weather Service Melbourne FL 417 AM EST Sun Nov 22 2020 .DISCUSSION... Today-tonight...A ridge that has been extending towards the mid-Atlantic states and southeast U.S. in the last few days, it will finally lift northeast today. This as a low pressure develops over the Ohio Valley. Locally, the pressure gradient will weaken even more, providing for a light wind flow generally from the east. Forecast soundings indicate that PWAT will increase to an inch and a half today as a bulk of moisture moves over our local forecast area. Coastal counties have observed on/off rainfall earlier this morning, remaining mostly over the coastal counties as moderate-heavy rain and dissipating quickly as these move to the west of I-95. A few lightning strikes were spotted over the waters. As the day progresses, the activity will focus towards Brevard/Osceola northward and with the mid levels flow from the south, activity will move towards Orange/Seminole. Mention of thunder was included as limited instability will be present as the cap between 850-700 mb erodes this morning. As showers/lightning storms start to decrease in coverage around sunset, interior areas should dry out this evening follow by coastal areas after late evening. With a focus of showers north from Indian River northward, I don't expect minor flooding concerns for St Lucie and Martin counties. High temperatures will reach near 80 this afternoon, followed by a drop to the mid-upper 60s tonight. Due to a persistent swell still reaching the local waters, a high risk for rip currents continues today for the local beaches. Monday-Wednesday...A mid-level trough pushing from the Ohio Valley into the Northeast states will drag a weak, dry surface cool front through east central Florida on Monday. Winds becoming northerly by sunrise on Monday, with breezy conditions returning mainly to the coast and the Atlantic waters. The front will pass through the local area through the afternoon, ushering in much drier air. Models suggest PWATs falling to as low as 0.6" Monday into Tuesday, with a slight rebound through mid week, but remaining well below 1". Forecast soundings also include a strong, very dry subsidence inversion above 850mb (though extending even lower at times, especially initially after the frontal passage). Thus, have no mentionable PoPs in the forecast through Wednesday, with the exception of a small area ~20% over the Atlantic waters as the front sags southward Monday. High pressure over the eastern US will not linger long before pushing eastward into the Atlantic ahead of the next low pressure system. Winds veering back to onshore Tuesday into Wednesday. Winds will remain breezy along the coast and offshore into Tuesday night, as the pressure gradient remains tight with the building high pressure. But, winds will decrease along with the gradient on Wednesday. Afternoon high temperatures remaining in the upper 70s to low 80s each day. Low temperatures will cool behind the front Tuesday morning, dropping into the upper 50s north of I-4, with mid to upper 60s along the immediate Treasure and southern Space Coasts. Dew points will be a bit more pleasant to start the week, in the upper 50s to low 60s. Thursday onward...Later in the week, models develop a slightly stronger area of low pressure over the central plains before pushing this feature through the Ohio Valley. A cold front dropping through the Deep South looks to stall over north Florida before dissipating. Winds will take on a more southerly component as the front approaches the area, becoming SE Wednesday night into the day on Thursday. However, winds will return to easterly late Thursday as the front diffuses. Have no mentionable PoPs through the end of the week at this time. However, some light PoPs could return to the forecast if the subsidence inversion breaks down sufficiently, which is low confidence at this time. Temperatures warming slightly into the lower 80s, with morning lows in the low to mid 60s. Isolated PoPs return late next weekend, ahead of yet another approaching frontal boundary. && .AVIATION... SHRA will continue this morning and early afternoon reaching the coastal terminals, reducing visibilities to 1-3SM and cigs to 1-3kft. Less coverage of SHRA after mid-afternoon for coastal terminals from KMLB to KSUA. Area of low stratus will continue streaming southwest and keep cigs at 5 kft over KLEE and at times for KDAB, KSFB, KMCO, and KISM. For interior terminals, SHRA reaching them this morning are in light intensity and dissipating as they continue to move westward, leaving KLEE rain-less. However, by late morning, coverage of SHRA will increase inland, with some small probabilities for TSRA. Impacts from these will be an occasional lightning strike and heavy rain, reducing visibilities. Winds will prevail from the east at 8-15 kt with brief gusts to 20-25 kt in the heavier storms. && .MARINE... Today-tonight...Winds will continue to decrease today as seas due the same thing. However, 7 feet seas were still being observed at buoy 41009 and 8 ft at 41010, the Small Craft Advisory was extended for the nearshore waters of Brevard and Treasure Coast through 10 am. Outer waters advisory remains through this evening. These could be adjusted as new observations come in today. So even for areas without an advisory, caution will need to be exercise as seas will be up to 6 ft. Showers and isolated lightning are expected today, producing localized higher seas and winds. Monday-Tuesday...A trough passing eastward through the Ohio Valley into the Northeast will drag a weak, dry cool front through ECFL on Monday. Hazardous boating conditions returning as winds veer N and increase to 15-20kts again. These wind speeds will persist through Tuesday; However, winds will veer back onshore by Tuesday afternoon. Seas 5-6ft, building up to 7ft offshore by Monday afternoon. A slight chance of showers possible offshore during the frontal passage on Monday, otherwise dry conditions expected. Wednesday-Thursday...Winds diminish Wednesday, as the high pressure over the eastern US pushes into the western Atlantic and the pressure gradient eases. Speeds becoming 10-15kts Wednesday, then 10kts or less on Thursday. Onshore flow will veer SE Wednesday then nearly S Wednesday night as another front approaches ECFL, but stalls across northern FL before dissipating. Seas diminishing along with the winds, becoming 5-6ft Wednesday afternoon, then 3-5ft Thursday. Dry conditions are expected to continue. && .HYDROLOGY... The Saint Johns River at Astor is forecast to remain in Minor Flood Stage through at least middle of next week. Forecast details are available on the daily River Flood Statement issued by NWS Melbourne until further notice. && .PRELIMINARY POINT TEMPS/POPS... DAB 79 65 76 60 / 40 20 0 0 MCO 81 65 80 60 / 40 20 0 0 MLB 80 68 79 64 / 40 20 10 0 VRB 81 68 80 66 / 40 20 10 0 LEE 81 64 79 58 / 40 20 0 0 SFB 81 65 79 59 / 40 20 0 0 ORL 81 67 80 61 / 40 20 0 0 FPR 80 67 79 65 / 40 20 10 10 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...Small Craft Advisory until 10 AM EST this morning for Sebastian Inlet to Jupiter Inlet 0-20 nm-Volusia-Brevard County Line to Sebastian Inlet 0-20 nm. Small Craft Advisory until 4 PM EST this afternoon for Flagler Beach to Volusia-Brevard County Line 20-60 nm-Sebastian Inlet to Jupiter Inlet 20-60 nm-Volusia-Brevard County Line to Sebastian Inlet 20-60 nm. && $$ Negron/Leahy