Area Forecast Discussion
Issued by NWS Jacksonville, FL
Issued by NWS Jacksonville, FL
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
052 FXUS62 KJAX 250834 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 434 AM EDT Tue Jun 25 2024 ...HEAT ADVISORY IN EFFECT FOR LOCATIONS FROM WAYCROSS AND JESUP SOUTHWARD THIS AFTERNOON... ...LATE AFTERNOON AND EVENING THUNDERSTORMS FOCUS ALONG U.S. HIGHWAY 301 TODAY... ...SOUTHWESTERLY FLOW CONTINUES THROUGH FRIDAY WITH INCREASING CHANCES FOR AFTERNOON AND EVENING THUNDERSTORMS... For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf .SYNOPSIS... Issued at 435 AM EDT Tue Jun 25 2024 Early morning surface analysis depicts a frontal boundary located just north of the Altamaha and Ocmulgee Rivers in southeast GA, with the axis of Atlantic high pressure suppressed across south FL. Aloft..."Heat Wave" ridging remains centered across the Desert Southwest and the southern Plains states, while troughing was progressing eastward along the New England and Mid-Atlantic coasts, producing northwesterly flow across our region. Latest GOES-East derived Total Precipitable Water imagery indicates that an unseasonably dry air mass prevails across inland southeast GA, especially for locations northwest of Waycross, where PWATS near the Ocmulgee and upper portions of the Altamaha Rivers have fallen to the 1.2 - 1.4 inch range, while values closer to late June climatology of 1.8 - 2 inches prevail for locations along and south of Interstate 10. A lingering area of mid-level cloudiness and sprinkles continues along upper portions of the Santa Fe River basin in north central FL early this morning, with fair skies in place elsewhere across our area. Temperatures were generally in the mid to upper 70s as of 08Z, with dewpoints in the low to mid 70s. && .NEAR TERM... (Today and Tonight) Issued at 435 AM EDT Tue Jun 25 2024 Troughing will push off the Mid-Atlantic and New England coasts by this afternoon, leaving little in the way of support aloft for the frontal boundary that has progressed into the Deep South. This boundary will stall across southeast GA this afternoon and will begin to dissipate tonight. Northwesterly flow aloft will continue to advect an unseasonably dry air mass across inland portions of southeast GA today, where dewpoints will crash through the 60s this afternoon and only isolated to widely scattered late afternoon or early evening convection is expected to develop. High temperatures will soar to near record levels across inland southeast GA and northern portions of the Suwannee Valley, where maximums will reach or exceed 100 degrees. The dry air mass should keep maximum heat index values around 105 degrees for locations to the northwest of Waycross, while values from Waycross and Jesup and points south and eastward climb to the 108-112 degree range, which has prompted a Heat Advisory from Noon through 7 PM. Northwesterly flow aloft will push weak shortwave energy across northeast and north central FL late this afternoon and this evening. A slightly looser local pressure gradient today should allow both the Atlantic and Gulf coast sea breezes to develop and move inland early this afternoon, with convective temperatures in the mid 90s per model soundings being realized early this afternoon, likely resulting in widely scattered convection developing along the inland moving Gulf and Atlantic sea breeze boundaries, in addition to the St. Johns River breeze. Mesoscale boundary collisions should focus around the U.S. Highway 301 corridor in northeast and north central FL late this afternoon and this evening, where likely to numerous POPs were placed in the forecast grids. Downdraft CAPE values in these areas will peak around 1,000 j/kg this afternoon, allowing a few storms to pulse and potentially become briefly strong, with downburst winds of 40-50 mph possible. Continued mild mid-level temperatures and potential slow storm motion will also result in locally heavy downpours across inland portions of northeast and north central FL, and localized flooding could again become a concern, especially at urban and more normally flood prone locations. Highs inland northeast and north central FL will soar to the mid and upper 90s, with low to mid 90s forecast for coastal northeast FL and southeast GA. Heat Index values will peak in the 108-112 degree range, with Heat Advisories covering all counties in these areas from Noon through 7 PM. Convection will again be slow to wind down this evening for locations between U.S. Highway 301 and I-75 in north central and northeast FL, with convective outflows potentially igniting scattered convection across inland southeast GA during the evening hours, especially over the Okefenokee Swamp. Convection should conclude by midnight, with debris cloudiness thinning out by the predawn hours on Wednesday. Lows tonight will generally fall to the low and mid 70s, except mid to upper 70s at coastal locations. && .SHORT TERM... (Wednesday and Thursday) Issued at 435 AM EDT Tue Jun 25 2024 Drier air will linger over SE GA, with PWATs around 1.5-1.75" limiting precipitation coverage to scattered, whereas NE FL will have ample moisture (PWATs 2.0"+) moving in with the help of southwest flow. Numerous showers and embedded thunderstorms will develop Wednesday afternoon/evening as the Gulf sea breeze pushes far inland. The east coast sea breeze will not make it far inland, however it will provide slight relief to the heat along the coast. Highs Wednesday will again be above normal, reaching near 10 degrees for portions of inland SE GA, with highs in the lower to upper 90s elsewhere. Temperatures will trend downward a tad on Thursday, but still remain above normal as southwest flow and an approaching front from the north helps numerous showers and thunderstorms develop area-wide. && .LONG TERM... (Friday through Monday) Issued at 435 AM EDT Tue Jun 25 2024 Temperatures will remain above normal during this period, with daily highs in the lower to upper 90s. Similar setup expected each day Saturday onward as winds shift from SW to S/SE, allowing both sea breezes push inland and interact, higher precipitation chances will remain over NE FL, with more scattered coverage daily in SE GA. && .AVIATION... (06Z TAFS) Issued at 225 AM EDT Tue Jun 25 2024 MVFR visibilities are expected to develop during the predawn hours at VQQ. A brief period of MVFR visibilities will also be possible around or just after sunrise at GNV, but confidence was too low to include in the overnight TAFs. Otherwise, VFR conditions are expected to prevail at the regional terminals through at least 18Z. Showers and thunderstorms will develop near the regional terminals along sea breeze boundaries during the afternoon hours, with activity possibly lingering past 00Z at the inland terminals. PROB30 groups were maintained at all of the regional terminals for brief wind gusts up to 30 knots and MVFR visibilities, mainly after 19Z. VFR conditions are then expected to prevail again by 03Z Wednesday. Southwesterly surface winds sustained at 5 knots or less overnight will become west- southwesterly after sunrise, with speeds increasing to 5-10 knots after 14Z. The Atlantic sea breeze boundary will begin moving inland a little earlier on Tuesday afternoon, resulting in surface winds shifting to east- southeasterly and increasing to 10-15 knots before 18Z at the SGJ and SSI coastal terminals. The Gulf coast sea breeze should cross the GNV terminal before 21Z, with winds shifting to southwest and increasing to around 10 knots outside of any developing convection. Surface winds will shift to southeasterly before 21Z at the Duval County terminals. Light southwesterly winds sustained at 5 knots or less are then expected after 02Z Wednesday. && .MARINE... Issued at 435 AM EDT Tue Jun 25 2024 A frontal boundary will stall over the southeastern states today, with prevailing offshore winds this morning becoming onshore towards noon over the near shore waters as the Atlantic sea breeze pushes inland. Scattered showers and thunderstorms will possibly develop over our local waters late this afternoon and early this evening. Outside of thunderstorm activity, southerly winds will briefly surge this evening before shifting to southwesterly while diminishing overnight. Speeds should remain below Caution levels during afternoon and evening wind surges, and seas of 2-4 feet will prevail throughout our local waters during the next several days. Southwesterly winds will prevail on Wednesday and Thursday ahead of another weakening frontal boundary that will stall and dissipate to the northwest of our local waters by Friday, with increasing chances for showers and thunderstorms, mainly during the afternoon and evening hours. Prevailing winds will become southeasterly by the weekend as the axis of Atlantic high pressure briefly lifts northward, with another frontal boundary then expected to enter the southeastern states early next week, which will shift prevailing winds back to southwesterly. Rip Currents: Breezy onshore winds developing early this afternoon will combine with a lingering east-southeasterly ocean swell to create a lower end moderate risk at the northeast FL beaches. Low wave heights at the southeast GA beaches should keep the risk low through Thursday, with a low risk also anticipated at the northeast FL beaches on Wednesday and Thursday. && .CLIMATE... Issued at 435 AM EDT Tue Jun 25 2024 Record high temperatures through Wednesday at our designated climate sites: June 25 June 26 ---------------------- Jacksonville 99/2016 101/1952 Gainesville 102/1950 103/1950 Alma, GA 100/1998 100/1954 Craig Airport 101/1998 95/2014 && .PRELIMINARY POINT TEMPS/POPS... AMG 101 74 99 74 / 20 10 40 20 SSI 95 78 90 77 / 20 10 30 20 JAX 98 73 95 75 / 50 40 60 20 SGJ 93 76 92 76 / 60 40 60 20 GNV 96 74 94 74 / 70 70 70 20 OCF 95 75 93 75 / 60 50 60 30 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...Heat Advisory from noon today to 7 PM EDT this evening for FLZ021-023-024-030-031-033-035-038-120-124-125-132-133- 136>138-140-220-225-232-236-237-240-322-325-340-422-425-522. GA...Heat Advisory from noon today to 7 PM EDT this evening for GAZ136-151>154-162-163-165-166-250-264-350-364. AM...None. && $$