496 FXUS62 KMLB 060742 CCA AFDMLB Area Forecast Discussion...CORRECTED National Weather Service Melbourne FL 342 AM EDT Tue Aug 6 2024 ...New DISCUSSION, MARINE... .DISCUSSION... Issued at 326 AM EDT Tue Aug 6 2024 KEY MESSAGES: - Windy at times today with 60-70% coverage of showers and storms. There is a Marginal Risk of excessive rainfall leading to localized flooding in areas with repeated storms. - Turning hotter, with a Major HeatRisk beginning tomorrow. Highs soaring toward the mid 90s, even at the coast, from Wednesday through at least Friday. - Hazardous boating conditions persist today as winds remain strong offshore. Slow improvements are expected later this week. ----------Synoptic Overview---------- Tropical Storm Debby, located over SE Georgia, is slowly moving northeast this morning. Over the next 72 hours, it is forecast to meander to our north, giving us a broad southwest-to-west flow in the boundary layer. Later in the week, Debby is expected to get picked up by a trough over the Great Lakes, allowing heights to build over the Southeast U.S. The near-surface ridge axis will slowly lift toward South Florida by the weekend. Slightly drier total moisture values (PW's 80-90% of normal) should arrive from MS/AL toward Central Florida, beneath Debby, by the middle of the week. Late in the week and toward the weekend, moisture values will return to near normal. Meanwhile, boundary layer temperatures are forecast to remain above normal. The influence of Debby will give us breezy to windy conditions the next couple of days. Hot temperatures will become a concern again as storm chances return to near (and at times below) normal. -------Sensible Weather & Impacts------- Today - Tonight... A tail of deep tropical moisture streaking across Florida and up toward Debby will slowly shift southward today. This will serve as a focus for scattered to, at times, numerous showers and lightning storms. Locally heavy rain appears to be the primary threat, with a Marginal Risk of excessive rainfall leading to flooding of urbanized and poorly drained areas. 06/00Z HREF max- member QPF indicates isolated instances of 2-4" rainfall, with overall areal coverage of these values around 5% or less. CAMs would indicate that areas south of Orlando-Cocoa Beach have a relatively higher chance of seeing these tallies. With Debby still just north of our area, expect a gusty day with SW breezes reaching 15-20 mph and gusting to 25-35 mph. While this falls just below Wind Advisory criteria, it will be noticeable. However, there is a 20-30% chance that the strongest storms produce brief gusts of 40-45 mph. With some breaks of sun returning and offshore flow, we will turn hotter. Highs should reach the low 90s over much of the area, even at the coast. Heat indices should range from 100-107F. Wednesday - Friday... We'll still be watching Debby as some track uncertainty still exists among the grand ensemble. Thus, the forecast is of low to medium confidence. Working with consensus and official guidance, the storm is forecast to remain far enough north that some modestly drier air should get advected southeastward across Central Florida during the mid-week timeframe. Even the higher-biased NBM has cut rain chances down below 50% on Wed/Thu, and with the continued breezy west flow, it will be difficult to get a sea breeze to form until Thu (and especially Fri). Bottom line, expect 30-50% storm chances each day, perhaps closing in on 60% by late Friday as moisture deepens and the sea breezes begin to develop in earnest. Our source air mass during this period is quite a bit warmer than normal, evidenced by a reservoir of mid/upper 90s over the Deep South (to the west of Debby) yesterday. So... temperatures will turn even hotter, with widespread mid 90s forecast. These temperatures will extend to the coast due to the offshore mean flow. With modest mixing continuing into the night, lows in the upper 70s to near 80 will bring little relief. In all, this constitutes at least a Major HeatRisk, perhaps locally Extreme along the I-95 corridor. Peak heat indices from 102-107F on Wednesday look to increase to 105-110F Thu-Fri. A Heat Advisory may eventually be required for portions of the area if these trends hold. Next Weekend & Beyond... All-to-familiar flat H5 ridging regains control across the Gulf and W Atlantic. With a fairly impressive trough pushing over the Great Lakes, the surface ridge axis will likely be slow to lift northward, perhaps reaching Central Florida by early next week. However, background winds become light, so a fairly typical scenario of daily sea breeze-driven showers/storms appears in order, with 50-60% chances for now. There is some indication of a weakness in the ridge by Sunday, which could enhance storm coverage at that time. Total moisture returns to seasonable values and above-normal temperatures aren't going anywhere. So, a continuation of hot/humid weather is predicted with daily highs in the low/mid 90s and peak heat indices 102-107F each afternoon. && .MARINE... Issued at 326 AM EDT Tue Aug 6 2024 Today & Tonight... A Small Craft Advisory remains in effect for all of the waters through 4 PM today, continuing into tonight for all offshore waters beyond 20 NM as well as nearshore Volusia County. Debby remains close enough for strong offshore winds, SW 18-25 KT, through the day today, perhaps decreasing tonight nearshore south of Cape Canaveral to 15-20 KT. Occasional gusts to near gale force through much of today, particularly northeast of Cape Canaveral. Seas range from 2-5 FT nearshore and up to 7 FT well offshore of Volusia Co. Continued scattered showers and storms, some offshore- moving with briefly increasing wind gusts. Wednesday - Saturday... Advisory-level (SW ~ 20-25 KT) winds persist through at least a portion of Wednesday in the offshore waters as Debby only slowly moves northeastward. For nearshore boaters, moderate breezes (SW 10-17 KT) persist Wed/Thu. By Friday and Saturday, winds turn more southerly and lessen to 10-17 KT over much of the marine area. As the sea breeze begins forming again, winds will turn SE along the coast in the afternoon beginning Friday. Daily shower chances will range from 40-60% with a few embedded storms. Seas 2-5 FT on Wednesday, 2-4 FT Thu/Fri, then 2-3 FT next weekend. All told, improving boating conditions especially nearshore and on the Intracoastal. && .AVIATION... (06Z TAFs) Issued at 211 AM EDT Tue Aug 6 2024 Breezy/windy and gusty through Tuesday. Southwest to west winds will persist through the TAF period. Winds will be around 15 KT with gusts up to 20 KT early this morning before increasing to 15-20 KT with gust 20-30 KT later in the morning and persisting through the day on Tuesday. Winds will then begin to decrease Tuesday night, with guidance indicating 10-15KT, with gusts dropping off. Have maintained prevailing VCSH at all the terminals through the morning. Guidance continues to show the potential for lightning storms starting by mid to late morning. So have maintained VCTS through 21Z across the interior terminals and through 00Z along the coastal terminals. VFR conditions are expected to prevail, though brief MVFR VIS/CIG reductions will be possible as showers and storms move across the terminal. May need TEMPOs for the afternoon, but confidence was not high enough to add them in this package. Will reevaluate and amend as needed && .PRELIMINARY POINT TEMPS/POPS... DAB 91 77 94 77 / 60 30 50 30 MCO 91 81 94 79 / 60 20 40 10 MLB 92 79 95 78 / 60 20 40 20 VRB 93 77 96 76 / 60 10 40 20 LEE 89 79 92 79 / 60 20 30 20 SFB 90 79 94 79 / 60 20 40 20 ORL 91 81 94 80 / 60 20 40 20 FPR 92 77 95 77 / 60 10 40 20 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...Small Craft Advisory until 6 AM EDT Wednesday for AMZ550-570-572- 575. Small Craft Advisory until 4 PM EDT this afternoon for AMZ552- 555. && $$ DISCUSSION...Heil AVIATION...Watson