Area Forecast Discussion
Issued by NWS Melbourne, FL
Issued by NWS Melbourne, FL
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133 FXUS62 KMLB 151439 AFDMLB Area Forecast Discussion National Weather Service Melbourne FL 1039 AM EDT Sat Jun 15 2024 ...New UPDATE, PREVIOUS DISCUSSION... .UPDATE... Issued at 1039 AM EDT Sat Jun 15 2024 Current local radar imagery shows dry conditions over east central Florida with scattered showers and isolated lightning storms along the southwest coast of Florida moving northeast. GOES-16 satellite imagery shows a weak boundary located across east central and southern Florida with higher moisture to the south of the boundary (PWATs ~ 2-2.4"). Current temperatures are in the low to upper 80s with dew points in the low to mid 70s. Scattered showers (PoPs ~ 30-60%) and lightning storms are forecast to develop into this afternoon as forcing increases with interactions between the sea breeze and outflow from storms to the west-southwest. Light and variable winds this morning are forecast to increase into the afternoon at 5-10mph generally from the southwest well inland and from the east-southeast near the coast. Weak wind fields will result in slow moving storms with a minor flooding potential mainly over areas that have received recent heavy rainfall. A Marginal Risk for Excessive Rainfall exists over east central Florida for this reason. Isolated lightning storms will also be capable of wind gusts to 30-40mph and occasional to frequent lightning strikes. Afternoon highs in the mid 80s to low 90s with heat index values in the mid 90s to low 100s are forecast under party to mostly cloudy skies. && .PREVIOUS DISCUSSION... Issued at 243 AM EDT Sat Jun 15 2024 Current...KMLB 88D shows mostly dry conditions over land across ECFL and ISOLD shower activity over the local coastal waters. The pressure gradient is relatively weak as winds range from L/V to calm. Humid conditions with temperatures/dewpoints in the 70s. For clouds, just a few low clouds speckled in observations, with satellite imagery showing a BKN/OVC layer of high cloudiness near Orlando southward. North of Orlando there are fewer overall clouds and will monitor for some early morning shallow, patchy fog here, but confidence is low. Today-Tonight...A weak pressure pattern continues across the area. The ECSB will develop again today and move inland, quicker across the north as winds veer onshore behind it. Ample moisture will exist along with daytime heating and boundary interactions to spark SCT, mainly afternoon-evening showers and lightning storms. Activity will diminish into mid-late evening. Steering flow aloft is light so expect slow-moving convection. Primary convective threats will be occasional to frequent lightning strikes, gusty winds 30-40 mph locally, and heavy downpours which could cause minor flooding, especially for areas that may have recently received heavy rainfall and/or from repeated rounds. Max temps in the M-U80s with near 90F to L90s in play across and north of I-4. Peak heat indices well into the 90s and L100s possible near/north of a central Osceola-Melbourne line. Overnight mins mainly in the 70s with conditions humid. Sun-Sun Night...Onshore flow becomes deeper across the area as weak high pressure slides southward across the Eastern Seaboard and southeast U.S. Light onshore flow areawide. ISOLD-SCT convection along the coast during the morning/early afternoon, with SCT showers/lightning storms favoring interior reaches in the mid-late afternoon and early evening. Mainly U80s for highs, except L90s for N/W of I-4. Overnight lows remaining in the 70s. Mon-Fri...Stout mid-level ridge across the mid Atlc/southeast U.S. extending into the FL peninsula will strengthen thru Tue night along the Eastern Seaboard, but is undercut Wed-Fri by some westward moving mid-level impulses. Temperatures warm aloft, as well, -4.0C to -5.5C. Plentiful PWAT values near 2 inches on Mon, then some overall drier air moves in through mid-week before a return to more moist conditions Thu-Fri. The deep onshore flow continues thru the period and along with the warm temperatures aloft may at best provide for ISOLD lightning chances, especially over land. Slightly cooler temperatures aloft Wed-Fri, along with an influx of moisture may be enough to promote SCT wording for thunder during this timeframe. Showers will remain in the SCT category with perhaps NMRS showers Thu-Fri. With the persistent onshore flow at least into Wed, we will likely see greatest precip chances along the coast overnight/morning-early afternoon hours, with higher afternoon- evening convective chances across the interior. By Wed night thru Fri, medium range models suggest higher PoPs areawide due to the previously mentioned energy/cooler temps aloft and increased moisture. The pressure gradient begins to tighten next week and we may see some breezy onshore conditions each day, perhaps remaining elevated along the coast during the evening/overnight periods. This will create additional convergence along the coast and the latter part of this period, we may have to watch for some pockets of heavy low-topped showery precip, especially along the coast, should this scenario play out. Have undercut the NBM`s high-PoP bias in the extended for now. Thanks in part to the onshore flow, temperatures will be seasonable through the period, with afternoon highs in the U80s to L90s (interior), and overnight lows remaining mild in the 70s. && .AVIATION... (12Z TAFs) Issued at 730 AM EDT Sat Jun 15 2024 VFR conditions outside of convection through the TAF period. Some models continue to show possible MVFR conditions developing this morning, especially along the coast, but confidence remains too low that this will occur. Thus, have kept this out of TAF for now, but will continue to monitor and amend if necessary. Light and variable winds will increase to 5-10 KT by late morning and become E/SE from ISM- MCO- SFB- LEE- DAB- TIX, and W/SW from MLB- VRB- FPR- SUA. SCT/NUM SHRA and ISM/SCT TSRA in the afternoon. Have included VCTS for all sites starting at 18/19Z. Have included TEMPOs for MCO-LEE-TIX-MLB (where the greatest potential for convection to occur this afternoon) for TSRA starting at 19/20Z. Timing and coverage remains too uncertain at the other sites to include TEMPOs at this time. Activity will dissipate or move away from the local area shortly after sunset. Winds will become light and variable once again overnight Saturday, with winds becoming onshore by mid morning on Sunday. && .MARINE... Issued at 243 AM EDT Sat Jun 15 2024 Today-Tonight...Weak pressure gradient over the area with L/V morning winds, remaining mostly light (under 10 kts) and variable over the open Atlc and transitioning onshore near the coast with sea breeze formation. An offshore wind component develops again this evening and overnight, mainly AOB 10 kts. Seas up to 2 ft near shore and 2-3 ft offshore. Sun-Wed...An onshore wind component will develop on Sun continuing into next week while getting deeper/stronger. Wind speeds increasing 8-13 kts on Sun, 11-16 kts Sun night, and we may be looking at 15-20 kts Mon-Wed as the pgrad tightens. Seas remain 2-3 ft into Sun evening, 3-4 ft Sun night, 4-5 ft Mon-early Tue, 4-6 ft Tue aftn-Wed night. ISOLD-SCT convection thru Sun with SCT showery precip into Wed, possibly ramping up to likely Wed night. && .PRELIMINARY POINT TEMPS/POPS... DAB 90 74 89 76 / 30 10 20 20 MCO 90 74 89 75 / 60 20 40 10 MLB 88 74 88 77 / 60 20 40 30 VRB 88 73 88 76 / 60 20 30 20 LEE 93 76 92 75 / 50 10 40 10 SFB 92 74 91 75 / 50 10 40 10 ORL 90 75 91 75 / 60 20 40 10 FPR 88 72 88 75 / 60 20 30 20 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ UPDATE...Fehling AVIATION...Watson