079 FXUS62 KMLB 141933 AFDMLB Area Forecast Discussion National Weather Service Melbourne FL 333 PM EDT Thu Mar 14 2019 .DISCUSSION... ...Above Normal Temperatures Friday... Tonight...Scattered fair weather cu field will diminish with loss of daytime heating this evening. There will continue to be some cirrus streaming overhead. Temperatures will fall into the low and mid 60s by daybreak Fri, except holding in the upper 60s along the immediate coast. Fri...Atlc ridge axis will settle across central FL. This will produce a more southerly flow and also relax the pressure gradient somewhat so winds will be lighter, esp over the interior. There will be a SE sea breeze 12-15 mph along the coast in the afternoon. Temps will warm a couple/few degrees higher than today, reaching 86-87 interior and 80-82 at the beaches. Will keep showers out of the forecast during the day though a few showers may reach Martin county off the Atlc or move up from Palm Beach county early in the morning in one or two convergent bands. Then later in the evening, a sea breeze collision over the interior may spark a few showers roughly along the I 4 corridor. Copious dry air in the mid levels will prevent any deep convection (thunder). Sat-Sun... An unsettled WX pattern setting up for the weekend as a cold front trailing from a powerful late winter season storm system sags its way thru central FL. The H100-H70 ridge currently overhead will flatten and break down thru the day on Sat as the storm system rides up its NW flank. This will allow a shallow but potent cold front to push thru central FL on Sat, then into the FL Straits by daybreak Sun. Moisture pooling within the frontal trof will bring PWat values up to 1.50"-1.75" by late aftn Sat, where they will hold for the remainder of the weekend...H100-H70 mean RH values increasing to 80- 90pct on Sat, nearly 100% on Sun. Increasing moisture and low lvl convergence with the Sat fropa will require introduction of slgt chc PoPs to the fcst Fri night, then chc PoPs on Sat. Mid and upper lvl flow will maintain a strong zonal component thru the weekend as a 100-120KT H30-H20 jet streak inches its way acrs the Lwr MS Valley/Deep South. This flow will pull the post frontal ridge acrs the Deep South quite rapidly, as well as a mid lvl vort max/upr lvl div max acrs the FL Peninsula Sat night into Sun. With a brisk N/NE post frontal flow dvlpg thru the H100- H85 lyr, a saturating airmass, and broad scale H50-H30 ascent, will go with sct-lkly PoPs Sat night and lkly areawide on Sun. SWODY3 conts to show the southern half of FL in general tsra, but agree with the midnight crew to hold off on introducing into the grids as any sig mid/upr lvl dynamic support does appear to move in until Sun. By then, N/NE flow will dominate the H100-H70 lyr, which statistically is the least likely flow regime to generate deep convection. Furthermore, the H70-H30 lyr will maintain a strong W/SW component which lends itself to isentropic lift instead of convective lift. Expect the precip to be stratiform, which tends to be high coverage/low QPF in nature. Wide temp spread on Sat as the front advances down the peninsula... aftn maxes will range from the L/M70s along and north of the I-4 Corridor to the L/M80s acrs the Treasure Coast/Lake-O region. Noticeably cooler Sat night thru Sun with the post-frontal N/NE flow. Sat night mins in the M/U50s along and north of I-4 and U50s/L60 s to the south. Sun maxes in the U60s/L70s acrs the I-4 region, and L/M70s to the south. Mon-Fri...(Prev Disc) Main feature of interest will be a developing rain event for southern-central Florida as a combination of southern and northern stream energy carves out a deep trough across the SE CONUS Tue-Wed, which will move offshore Thu. This will induce surface wave development along the stalled front, which the models are indicating will move ENE through the FL Keys/Straits through Tuesday night, and then the central-northern Bahamas Wednesday. Showers embedded in NE post-frontal flow will continue Monday as the frontal moisture band remains parked across the southern half of Florida. Significant increase in deep layer forcing atop lower level (frontal) moisture convergence (outlined in yesterday's AFD) will produce thickening clouds and increasing rain chances starting Mon night, and peaking through Tuesday night. POPS will trend from low- mid range chance/30-50 to likely/70 (for now) SE. While the axis of highest mean PWAT/QPF looks to be south of Lake O, areally averaged precip amounts of 2-3" are indicated over the Treasure Coast and even higher just offshore. Higher amounts may be possible near the coast (local maxes are often 2-3X avg), which means potential for nuisance type urban/poor drainage flooding. As has been mentioned the past few days, this event is still 5+ days out, and adjustments to the forecast will no doubt occur. Precip pulls away from the state during the day Wednesday, with a lingering shower threat along the coast Wed evening. Turning drier on Thu. Clouds/precip will hold max temps down below normal through the extended range, especially Tue-Wed, with cool advection behind this system keeping the cooler temps in place Thu. && .AVIATION...VFR through 00Z/16. SE wind this afternoon will decrease with sunset and become more southerly Friday. Wind speeds will be 5-10 knots Friday over interior terminals and 10-15 knots at coastal terminals with a SE sea breeze. A few showers may reach the vicinity of SUA around sunrise. && .MARINE... Tonight/Fri...Wind flow will gradually veer as Atlc ridge axis slowly slips southward across the waters ahead of a weak cool front. Winds will become S/SE 10 knots across the northern waters and remain SE 10-15 knots across the south. A 10-15 knots SE sea breeze will develop near the coast Fri afternoon. Sat-Sat Night...Wndshft thru the day as a late season cold front presses down the FL Peninsula. At daybreak, sfc/bndry lyr winds a light to gentle S/SW breeze from Jupiter Inlet to Cape Canaveral...W/NW from Cape Canaveral to Flagler Beach. By early aftn...a light to gentle S/SW breeze south of Sebastian Inlet, gentle to moderate N/NW breeze north of the Inlet. By late evng, gentle to moderate N/NE breeze areawide. Winds will be lgt/vrbl in the vcnty of the cold front. Seas at daybreak generally 2-3FT...up to 4FT in the Gulf Stream off Volusia Co...building to 3-4FT north of Sebastian Inlet by late afternoon, areawide aft sunset. Sun-Tue...Post-frontal boating conds bcmg poor to hazardous as a continental hi pres ridge builds off the Mid Atlc Coast and reinforces the Bermuda Ridge. Persistent NErly breeze thru the first half of the upcoming week...gentle to moderate on Sun, bcmg moderate to fresh on Mon, then fresh to strong on Tue. Seas 3-4FT nearshore and 4-5FT offshore Sun, building to 5-7FT areawide Mon, building to 6-8FT Tue, then 7-8FT over the shelf waters and 9-10FT in the Gulf Stream Tue night. Chc of shras Sun/Mon, then shras likely on Tue. && .PRELIMINARY POINT TEMPS/POPS... DAB 62 84 65 72 / 0 0 10 30 MCO 63 87 66 80 / 0 10 10 30 MLB 64 83 65 80 / 0 10 10 30 VRB 64 83 65 81 / 0 10 10 30 LEE 63 86 65 77 / 0 10 10 30 SFB 62 86 65 77 / 0 0 10 30 ORL 64 86 66 79 / 0 10 10 30 FPR 64 83 65 81 / 0 10 10 30 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ SHORT TERM...Kelly LONG TERM....Bragaw