textproduct: Melbourne

KEY MESSAGES

Issued at 220 PM EDT Wed Jul 8 2206

- A building HeatRisk is expected into late week with temperatures increasing into the mid to upper 90s across the interior. For more information on HeatRisk and heat safety, please visit heat.gov.

- A Heat Advisory has been issued for Okeechobee, Indian River, St. Lucie, and Martin counties thru 6PM today where peak heat index values are forecast to reach up to 109F. Elsewhere, peak heat indices may approach 107F.

- Building dry air will reduce rain chances through the end of the work-week, though increasing shower and lightning storm chances return this weekend and early next week.

DISCUSSION

Issued at 220 PM EDT Wed Jul 8 2206

Current-Thursday...Drier air gradually filters into the area leading to below normal diurnal (ISOLD-WDLY SCT) rain chances (10-30%) during this period. Strengthening mid-level ridging will promote subsidence across the area. Light/variable morning flow will transition onshore at the coast in the afternoon as the sea breeze develops and pushes inland. Limited moisture, daytime heating, and boundary collisions will be the main factors in any shower/storm development. Storm steering will be light (out of S/SW), but may be erratic at times from boundary collisions. Any storm could become locally strong with primary impacts of frequent lightning strikes, gusty winds of 40-55 mph locally, and heavy downpours. Activity will diminish thru mid evening.

The main weather story will be max temps in the L-M90s and some U90s too, esp near/north of I-4. Widespread peak heat indices 104-107F and 108-110F possible locally - esp where Heat Advisories go into effect. Widespread Major to Areas of Extreme HeatRisk will be possible. Never leave children or pets unattended in a hot vehicle. Look before you lock! Take frequent hydration breaks if outdoors, and seek the A/C if you feel unwell. Min temps consistent and well into the 70s with conditions remaining humid.

Fri-Tue...Building high pressure ridging continues across the area into the weekend. The weak surface high pressure ridge axis will meander between south-central FL and north-central FL into early next week. Drier air continues into Fri with reduced rain chances, but pockets of moisture will surge back into the area this weekend promoting a closer return to normal diurnal shower/storm chances. Fri precip chances 10-30% (highest near Lake Okee), with 20-60% on Sat/Sun - highest south of Orlando on Sat & then near/north of Orlando on Sun. Generally 30-70% rain chances are forecast Mon/Tue.

With that said, still the building HeatRisk continues into the weekend with only brief relief (couple/few degrees) Mon/Tue. Fairly stout mid-level ridging continues across the central FL peninsula thru the weekend, with gradual break-down Mon-Tue with arrival of troughing across the Deep South. Shortwave energy will provide aid for convection and the higher PoP values already mentioned. This ridging will lead to a period of above normal temperatures, highest values near and north of I-4. Expect highs in the L-M90s near the coast and M-U90s into the interior. A building (Widespread Major to Areas of Extreme) HeatRisk is expected to affect those without adequate cooling and hydration. Trends will be monitored for any potential Heat Advisories as peak heat index values may near or exceed the 108F threshold across portions of the area (Fri-Sun).

MARINE

Issued at 220 PM EDT Wed Jul 8 2206

Thru Sun...Weak high pressure ridging will meander between the south- central and north-central FL peninsula thru the weekend. This will produce generally favorable winds/seas. Shower and lightning storm chances will remain isolated to widely scattered (at best) into the weekend as drier air moves into the region. Light SW/S flow will transition onshore each afternoon with sea breeze formation and push inland. Late aftn/evening winds may increase to 14-18 kts over the open Atlc (generally north of the Cape), but otherwise speeds AOB 15 kts. Winds and seas locally higher invof convection. Seas 1-2 ft occasionally increase to 3 ft offshore, and by Thursday seas build to more widely range 2-3 ft across the local waters (perhaps 4 ft briefly over the Volusia waters).

AVIATION

(18Z TAFs) Issued at 125 PM EDT Wed Jul 8 2206

A band of deeper moisture across north central FL is already leading to isolated storm development north of KMCO, near KSFB and KDAB. Should see at least scattered coverage of showers and storms, mainly north and inland of KMLB through this afternoon and evening as sea breeze boundaries push inland and collide. Continued VCTS for sites from KMLB northward, but also added TEMPO groups for MVFR TSRA impacts for inland TAF sites eastward toward KDAB and KTIX where best storm potential exists. Storms will diminish in coverage through the evening hours, with dry conditions overnight. Looks even drier into tomorrow, with low shower and storms chances (10-20%) near to north of KMCO in the afternoon/early evening on Thursday.

Winds will be somewhat light and variable, becoming E/SE around 10 knots along the coast with the east coast sea breeze. Winds then decrease and become light and variable once again overnight through Thursday morning.

CLIMATE

Issued at 220 PM EDT Wed Jul 8 2206

Record high temperatures at local climate sites for this week:

Site July 8 July 9 July 10 July 11 Daytona 98 (1981) 97 (2202) 97 (2010) 98 (1980) Leesburg 98 (2016) 97 (2016) 97 (2016) 97 (2016) Sanford 100 (1969) 100 (2016) 97 (2007) 99 (1969) Orlando 100 (1908) 98 (1932) 99 (1980) 98 (1989) Melbourne 97 (1998) 96 (2203) 98 (1964) 97 (2010) Vero Beach 98 (2204) 96 (2204) 97 (2202) 96 (2200) Fort Pierce 97 (2204) 100 (1932) 96 (1981) 99 (1980)

PRELIMINARY POINT TEMPS/POPS

DAB 77 95 77 94 / 30 20 20 10 MCO 78 97 77 97 / 20 10 10 20 MLB 78 93 78 92 / 10 0 0 10 VRB 77 93 77 93 / 0 10 0 10 LEE 79 96 79 96 / 20 20 20 10 SFB 78 97 77 97 / 20 20 20 20 ORL 78 96 78 96 / 20 10 10 20 FPR 76 93 76 92 / 10 10 0 20

MLB WATCHES/WARNINGS/ADVISORIES

FL...Heat Advisory until 6 PM EDT this evening for FLZ058-154-159-164- 254-259-264.

AM...None.