Area Forecast Discussion
Issued by NWS Melbourne, FL
Issued by NWS Melbourne, FL
988 FXUS62 KMLB 121401 AFDMLB Area Forecast Discussion National Weather Service Melbourne FL 1001 AM EDT Sun May 12 2024 ...New UPDATE, AVIATION... .UPDATE... Issued at 1001 AM EDT Sun May 12 2024 Mid to high level cloud cover across west Florida will build eastward through late morning as a disturbance moves overhead. CAM guidance suggests the potential for light precip to accompany the high cloud cover. However, model soundings indicate a dry layer generally below 700mb, and there remains low confidence for any of this precip to reach the surface. The current forecast continues to mention ~10 percent PoP as cloud cover builds, and any precip which can make it to the surface in the afternoon would be expected in the form of sprinkles. Accumulating rainfall is not forecast. Along the coast, northeast surface winds have promoted onshore moving strato cu. The cu field is forecast to gradually lift with daytime heating, eroding as the east coast sea breeze develops and moves inland. There is little indication of any shower development along the sea breeze boundary today. Onshore flow will keep temperatures near seasonal values with highs in the mid 80s along the coast, increasing into the upper 80s/ lower 90s west of I-95. The current forecast remains on track. && .AVIATION... (12Z TAFs) Issued at 1001 AM EDT Sun May 12 2024 Light and variable winds this morning are gradually becoming established out of the northeast. Winds veer more eastward as the east coast sea breeze moves inland, increasing to around 10-12 kts. Mid to high cloud cover builds through late morning and into the afternoon. VFR low level clouds along the coast will gradually lift and diminish through the day. Mostly dry today with only a 10 percent mention of sprinkles across east central Florida. && .PREVIOUS DISCUSSION... Issued at 404 AM EDT Sun May 12 2024 -Mostly dry today, with some occasional sprinkles possible this afternoon. -A brief reprieve from above normal temps today, but turning unseasonably hot again this week as highs soar well into the 90s. -Scattered rain and storms remain in the forecast for the work week. A few of the storms could be strong to severe. Today-Tonight...Frontal boundary has stalled just south of central FL, but should shift a little farther south into today, with a broad area of high pressure across the area. Light N/NE flow will increase out of the E/NE behind the developing east coast sea breeze as it forms and moves inland through this afternoon. Satellite imagery shows band of mid to high level clouds that will expand eastward across the area today, with a passing mid-level disturbance. Hi-res guidance indicating this may allow for some light precip to occur from this higher cloud deck. However, this light rainfall will likely evaporate before reaching the surface, at least initially, due to drier air in the lower levels. Therefore expecting this to remain mostly virga, but some occasional sprinkles may be possible into the afternoon. Measurable rainfall, however, from this activity is not currently expected, so mentionable rain chances remain out of the forecast. Clouds, low level N/NE flow north of the front and inland moving sea breeze will keep temps closer to normal today, giving us a brief reprieve from the hotter temps that creep back into the forecast for the upcoming work week. It will still be warm though with highs in the mid 80s along the coast and upper 80s to low 90s across the interior. A light E/SE flow into tonight will keep temps mild across the area, with lows overnight in the upper 60s to low 70s across much of east central FL. Synoptic Overview For Monday Through Next Sunday... Florida will reside on the northern edge of deep-layer ridging, characterized by H5 height anomalies of +3 sigma over the northwest Caribbean Sea. An unseasonably strong subtropical jet, with H5 zonal winds occasionally exceeding the 95th percentile, will extend from Texas to N Florida through much of the week. This jet will be sandwiched between the ridge over the tropics and a couple of mid- latitude troughs. The first trough will pass through the Tennessee Valley on Tuesday and Wednesday. Its surface front will approach the area Wednesday before stalling and retreating as the second trough exits the Rockies. Anomalously warm and moist air will be found over Florida for much of the period. This pattern continues to support at least a few opportunities for showers and storms. Some of the storms could be strong to severe. Daily high temperatures will tend to run 5-10 degrees above normal, occasionally approaching daily records. Sensible Weather & Impacts: Monday... Surface high pressure will be pushing out to sea as shortwave ridging moves overhead. The southeast flow will quickly deliver an increase in moisture. Courtesy of the ridge axis, proximity soundings show poor mid-level lapse rates across the area and weak buoyancy. Still, the embedded sea breeze should be enough to spark 30-40% coverage of afternoon showers/storms. 0-3 and 0-6 km shear will be sufficient for a few strong, gusty storms. Low-level CAPE looks less than ideal for isolated tornadoes, but with the backed profile, it cannot be completely ruled out if a little more instability can be realized. On the flip side, there is still a chance we fall just short of convective temps and see very little convection. Highs on Monday will reach toward the mid/upper 80s along the coast and low 90s for the interior. Tuesday-Wednesday... There have been a few changes in the guidance for this timeframe, and confidence remains less than desired. WPC QPF clusters from the 11/12Z guidance are suggestive of a stronger ridge to our south, with forced ascent harder to come by as you travel south through the state. This has pushed the focus of showers/storms on Tuesday just to the north of Central Florida. Consequently, now about only half of the members skirt areas north of Orlando with organized showers/storms on Tuesday. There is some potential for a pinned sea breeze along the I-95 corridor, and this may be a focus for showers/storms to develop late in the day. We will continue to advect warm and unstable air into the area on steady south/southwest flow, and bulk shear will remain more than sufficient for pulsing storms to severe levels if they can get going. All told, this has necessitated a reduction in rain/storm chances to 35-50% across the area. Then on Wednesday, the trough begins to exit to our northeast, leaving behind a weak surface front that is forecast to approach Central Florida before stalling. An axis of deep moisture will likely be found in its vicinity. Scattered showers and storms should try to focus near the front, though coverage may again be hindered by a lack of large-scale forcing and convergence. Decided to undercut statistical guidance on rain/storm chances, barely reaching "likely" wording for much of the area with 55-65% coverage. Unsurprisingly, temperatures are responding upward on Tuesday with the lower rain potential. Widespread 90s are now forecast, with 50- 80% chances of reaching/exceeding 95F from roughly Orlando to Port St Lucie and points southwest. Peak heat indices from 100-105 can be anticipated. Temperatures on Wednesday may get cut down slightly across the Daytona/Orlando areas (around 90F), but mid 90s are still forecast for the Treasure Coast and Lake O region. Thursday Through Next Weekend... Most members agree that ridging to our south will again build northward across the Gulf as the leading disturbance pushes into the Atlantic. 11/12Z clusters show some subtle differences in the progression of the next (weaker) trough emanating from the Rockies toward next weekend. A residual ribbon of anomalous moisture, left behind by the first trough, will remain close enough to Central Florida to promote diurnally-driven showers and storms each day, with 30-40% coverage. A few storms could be strong. A reservoir of well above normal temperatures will continue to sit beneath the strong ridge near the Yucatan Peninsula. With the boundary-layer ridge axis just to our south, a consistent feed of uncomfortable air will be sent toward Florida. Thus, little relief from the heat is expected with low/mid 90s at the coast and north of Orlando, and mid/upper 90s over South-Central Florida. Lows will only fall to the upper 60s to mid 70s. If dew points are not able to effectively mix out, we could end up approaching heat advisory territory in a few southern spots. && .MARINE... Issued at 404 AM EDT Sun May 12 2024 Today-Tonight...Boating conditions will be generally favorable, with N/NE winds 5-10 knots becoming E/NE into the afternoon as sea breeze forms and moves inland. Winds then veer E/SE into tonight, with speeds remaining around 5-10 knots. Seas will range from 2-3 feet. Monday-Thursday...Bottom line, poor to hazardous boating conditions return to the waters, due to increasing winds, from Tuesday through early Wednesday. High pressure moves out to sea early in the week, and low pressure will move well to our north by Wednesday. A weak front will attempt to settle toward the waters on Wednesday before stalling or dissipating. Isolated/scattered storms are forecast through the period, with some potential for offshore-moving storms Tue/Wed with gusty winds. Initially, prevailing winds will freshen from the SE on Monday and Tuesday to 15-20 KT. By Tuesday night, winds will increase to 20-25 KT, veering S before becoming SW around 15 KT on Wednesday. Winds will continue to decrease into Thursday to around 10 KT as onshore flow attempts to redevelop. Seas 3-4 FT Monday through Wednesday, except up to 5-6 FT well offshore Tuesday night and early Wednesday. Seas subside to 2-3 FT on Thursday. It will be somewhat choppy out there as dominant periods will be short and driven by local winds, 5-7 sec. && .FIRE WEATHER... Issued at 404 AM EDT Sun May 12 2024 Today...Fire sensitive conditions continue today across the far interior, where min RH values are forecast to fall to the mid to upper 30s, mainly near to NW of the I-4 corridor. Inland moving east coast sea breeze this afternoon will keep min RH values in the 40s and 50s toward the coast and just west of I-95. Light N/NE winds this morning will veer and become E/NE up to around 10 mph as east coast sea breeze forms and moves inland. Onshore winds may be a little bit stronger along the coast into the afternoon, south of the Cape, with speeds around 15 mph and gusts up to 20 mph possible. Monday-Thursday...Southeast winds on Monday (12-17 MPH) will become southwesterly from Tuesday into Wednesday (15-20 MPH with higher gusts to around 25 MPH). This will deliver more moisture to the state. Thus, afternoon min RH values should be above critical thresholds, lowest in the 40-50% range over the interior each day. Isolated storm chances will slowly ramp up toward 50-60% coverage by Wednesday as a weakening front approaches. Wetting rain will not occur for all areas; the highest potential for significant rain will be along the coast and/or north of Orlando- Titusville through midweek. && .PRELIMINARY POINT TEMPS/POPS... DAB 84 68 85 72 / 10 10 40 30 MCO 89 70 91 73 / 10 10 40 20 MLB 85 71 86 74 / 10 10 30 20 VRB 86 70 87 72 / 10 10 30 20 LEE 88 70 92 73 / 10 10 40 20 SFB 88 69 90 72 / 10 10 40 20 ORL 89 71 91 73 / 10 10 40 20 FPR 86 69 87 72 / 10 10 30 20 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ UPDATE...Law LONG TERM...Tollefsen AVIATION...Law