National Weather Service Melbourne FL
1040am EDT Sat May 18 2024
...New UPDATE,
Marine
REVIOUS
Issued at 1040am EDT Sat May 18 2024
Current local radar imagery shows dry conditions across east central Florida. Analysis charts depict a cold front over the Southeastern US and the Florida panhandle and a mid/upper level ridge centered over the Carribean and western Atlantic with 500mb heigheights at 590dm+ over central Florida. This morning's 10Z XMR sounding shows substantial dry air in the mid to upper levels and a PWAT (Precipitable Water) value of 1.2" which results in high DCAPE at 989 J/kg. Guidance continues to indicate that moisture will increase along sea breeze boundary interactions this afternoon near the coast along I-95 before pushing offshore into the evening hours. Forecast soundings show instability and moisture increasing into the afternoon with SFC CAPE values in the 3,000-5,000 J/kg range and PWAT (Precipitable Water) values around 2-2.3" near the coast, in addition to, 30-40kts 0-6km shear. For this reason, the Storm Prediction Center has outlooked northeastern Lake, Volusia, Seminole, eastern Orange, Brevard, eastern Osceola, eastern Okeechobee, Indian River, St. Lucie, and Martin counties. The main hazards associated with isolated strong to marginally severe storms are wind gusts up to 50mph with locally damaging wind gusts up to 60mph (5% risk), coin-sized hail with a 5% risk of hail up to 1," occasional to frequent lightning strikes, and periods of heavy rainfall. A brief tornado also cannot be ruled out (2% risk).
Afternoon highs are forecast to reach above normal to near record values (across the Treasure Coast) with temperatures in the low to upper 90s. Heat index values are expected to reach the 102-110 range with the highest values across Osceola, southern Brevard, Indian River, St. Lucie, Martin, and Okeechobee counties. A Heat Advisory is in effect until 8PM this evening over the aforementioned counties.
Marine
Issued at 1040am EDT Sat May 18 2024
Currently - Tonight
Mostly favorable boating conditions are forecast. South to southwest winds at 8-14kts will back southeast into the afternoon before veering offshore late this evening and into the overnight hours at 10-16kts. Seas are forecast to build to 1-2ft with up to 3 ft offshore overnight. Scattered showers and lightning storms are forecast to develop this afternoon and push offshore into the evening hours which will be capable of wind gusts up to 50-60mph, coin sized hail, and occasional to frequent lightning strikes.
.PREVIOUS Issued at 457am EDT Sat May 18 2024
This Morning...Patchy fog has begun to develop across portions of the Treasure Coast early this morning with surface observations reporting localized visibility as low as a half mile. There continues to remain low confidence in additional fog development across portions of the northwest interior including Lake and western Orange counties. If encountering localized visibility reductions due to fog while driving, slow down, use low-beam headlights, and increase following distance. Any fog which develops is expected to lift shortly after sunrise.
Today...Early morning IR satellite imagery shows a band of ongoing convection stretching across Louisiana into Mississippi ahead of a frontal boundary. 00Z CAM guidance suggests increasing convection as the feature tracks eastward through the morning with a low developing along the boundary as it moves across the Florida panhandle. The band of convection then loses organization on its approach to towards the Florida peninsula. Guidance further suggests a moisture boundary ahead of the main convective boundary with modeled PWATs (Precipitable Waters) increasing to around 1.8-1.9" across portions of east central Florida. The moisture boundary is expected to interact with a pinned east coast sea breeze in the afternoon, sparking scattered to numerous showers and scattered lightning storms near the coast. Elsewhere, scattered showers and storms are still forecast, driven by diurnal heating and outflow boundary collisions. Steep low level lapse rates and CAPE values greater than 2,000 J/kg could support strong updraft growth, particularly in developing convection along the sea breeze. Dry air aloft could be supportive of strong downdrafts with localized wind gust up to 60 mph. Additional hazards include coin-sized hail and cloud-to-ground lightning strikes. A brief tornado cannot be ruled out along boundary collisions. Storm Prediction Center has included a day one Marginal Risk for all coastal counties and western portions of the interior counties for strong to severe storms which could develop this afternoon.
Before convection begins to bubble up, heat will be of concern. Anomalous ridging aloft will support above seasonal temperatures into the afternoon, generally ranging within two degrees of records at the local climate sites. Conditions become muggy with increasing moisture, and peak heat index values are forecast to widely range 104-110 degrees. As a result, a Heat Advisory has been issued for southern Brevard, Okeechobee, and the Treasure Coast counties today. If pursuing outdoor activities, take frequent breaks in shaded or air conditioned areas and ensure you stay hydrated.
Sunday...The aforementioned frontal boundary sinks southeastward on Sunday. Isolated to scattered showers and isolated lightning storms are forecast to approach the I-4 corridor ahead of sunrise. Coverage then becomes numerous into the afternoon with Probability of Precipitation increasing between 50-70 percent. Strong to marginally severe storms are in play again on Sunday. Areas across the south will have the most favorable environment for strong to severe storms as the line of convection approaches closer to peak day time heating. Here, modeled CAPE values range 2,000-2,500 J/kg while low level lapse rates remain steep with a minimal inversion in place above 850mb. A dry air layer persists aloft, but to a less extent than what was present the day prior. While the most favorable environment lies southward, Storm Prediction Center has included all of east central Florida in a Marginal Risk of severe storms. Greatest hazards with any developing storms ahead of the front include localized damaging wind gusts, cloud-to-ground lightning strikes and coin-sized hail.
Increasing cloud cover will help to regulate afternoon temperatures with a gradient in place from north to south. Earlier cloud cover keeps temperatures along and north of the I-4 corridor in the mid to upper 80s while upper 80s to low 90s build southward.
Monday - Friday
The cold front pushes south of the area into Monday. Mid level troughing then builds across the western Atlantic stretching across the state of Florida. Troughing is pushed further offshore into mid week as ridging slides eastward across the Gulf, extending into Florida by Wednesday. Showers and storms remain in the forecast Monday (50-60%), and Probability of Precipitation gradually dwindle each day through mid week. Temperatures generally ranging the mid 80s to lower 90s Monday and Tuesday warm through the remainder of the week. Highs are forecast to range the low to mid 90s by Friday.
Marine
Issued at 457am EDT Sat May 18 2024
Today - Tonight
West to southwest winds around 5-10 kts back southward as the east coast sea breeze develops in the afternoon. The sea breeze will remain pinned to the coast with scattered to numerous showers and scattered lightning storms developing along it. Isolated severe storms with wind gusts up to 34 kts will be possible. Coverage may linger into the late evening. Seas of 2-3 ft persist.
Sunday-Wednesday...Coverage of showers and storms return across the local waters on Sunday as a cold front approaches from the northwest. A few storms could become strong to marginally severe with localized wind gusts of 34 kts. West to southwest winds around 10 kts on Sunday veer north into Monday as the cold front moves southward across the waters. Light onshore flow then develops from Tuesday onward. Seas of 2-3 ft increase to 4-5 ft across the Gulf Stream Monday night, subsiding Tuesday night.
NOAA Melbourne FL Office: Watches - Warnings - Advisories
FL...
Heat Advisory until 8pm EDT this evening for FLZ053-058-154-159- 164-254-259-264-547-647-747.
AM...None.
