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
401 FXUS62 KJAX 301738 AFDJAX Area Forecast Discussion National Weather Service Jacksonville FL 138 PM EDT Tue Apr 30 2024 ...New AVIATION... .UPDATE... Issued at 1010 AM EDT Tue Apr 30 2024 For the latest NE FL and SE GA Daily Key Messages please visit: https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf The basic forecast looks on track. Analysis shows mid level shortwave trough just to our west and expected to track to the east through the day. The observed sounding shows a large subsidence inversion at about 7500 ft, but weaker than yesterday, and added low level moisture. Forecast soundings shows the inversion breaking down further this afternoon with sufficient cooling aloft associated with the shortwave and added moisture with the east coast sea breeze to produce isolated to scattered showers and potential storms. Estimated MLCAPE still remains on the low end at about 500-1000 J/kg, potentially a bit higher along the sea breeze where moisture is more maximized. The forecast POPs today look good with only slight adjustments with some initial development along the east coast over northeast FL this morning. While we don`t anticipate severe storms, the bulk shear of about 30-35 kt could support a strong storm in southeast GA, closer to some upper level forcing. The main threat would be some small hail and strong wind gusts late afternoon and early evening, with increasing probabilities from southeast GA northwestward. && .NEAR TERM... Issued at 315 AM EDT Tue Apr 30 2024 A shortwave aloft will pass through the region today driving a weakening frontal boundary through the SE US. Meanwhile, surface high pressure off the GA/SC coast will shift further into the Atlantic causing flow to shift to south-southwesterly. This will allow for both Atlantic and Gulf sea breezes to shift inland this afternoon and likely converge along US 17 in the evening. Southerly flow combined with the passing shortwave will provide enough moisture and instability for isolated showers and storms to develop along the sea breezes mainly along their collision. Scattered showers and storms will move across inland SE GA late this afternoon into evening as the frontal boundary swings through. Lingering low level moisture and calming winds will lead to patchy fog developing for inland areas early Wednesday morning. Highs today will be in the mid to upper 80s inland and low 80s along the coast. Overnight lows will be in the 60s. && .SHORT TERM... (Wednesday through Thursday night) Issued at 315 AM EDT Tue Apr 30 2024 A shortwave trough that will be traversing the Deep South on Tuesday night will reach the Carolina coast on Wednesday morning, resulting in deep-layer flow over our region shifting to northwesterly. A weak surface reflection of this shortwave will be left behind over our region, with slightly deeper moisture (PWATS around 1.4 inches) pooling ahead of this feature, helping to trigger mostly isolated convection along mesoscale boundaries such as the Atlantic sea breeze and the St. Johns River breeze during the late afternoon and early evening hours. Following the dissipation of fog during the early morning hours, plenty of sunshine from the mid-morning through mid-afternoon hours will boost highs on Wednesday to the upper 80s to around 90 at inland locations, while the afternoon sea breeze keeps coastal highs generally in the mid 80s. Beneath fair skies, lows will only fall to the 60s on both Wednesday night and Thursday night, with patchy to areas of radiation fog expected to develop during the predawn and early morning hours at inland locations. A weak surface pressure pattern will prevail again locally on Thursday, with ridging aloft building into our area in the wake of Wednesday`s departing shortwave trough. Low level flow will shift to easterly, with a drier and more subsident air mass advecting over our area. Just enough moisture may remain around for isolated convection to develop towards sunset where the Atlantic and Gulf coast sea breezes collide towards sunset, generally for locations in north central FL and the Suwannee Valley. The drier air mass and plenty of sunshine will allow highs to soar to near 90 degrees on Thursday, while highs top out in the low to mid 80s at coastal locations, where prevailing onshore winds will become breezy during the afternoon hours. && .LONG TERM... (Friday through Monday) Issued at 315 AM EDT Tue Apr 30 2024 Ridging aloft over our region early on Friday will flatten in response to a slowly evolving and digging trough that will encompass the Pacific Northwest, the northern Rockies, and the upper Midwest. The flattening of the ridge will allow for a more zonal flow pattern to develop, and shortwave troughs embedded within this zonal flow will traverse our area, mainly on Saturday and then again early next week. A dry air mass is expected to linger throughout much of Friday across our area, with model guidance generally keeping convection associated with the upstream shortwave trough just west of our region, although some isolated convection developing along mesoscale boundaries cannot be ruled out. Plenty of sunshine from Friday morning through the mid-afternoon hours and the lingering dry air mass will again boost highs to around 90 at most inland locations, with the afternoon Atlantic sea breeze keeping coastal highs in the low to mid 80s. Lows on Friday night will only fall to the 65-70 degree range at most locations as convective debris clouds from upstream convection filter overhead. The aforementioned initial shortwave trough that is currently expected to traverse our area on Saturday should bring at least widely scattered convection to our area, especially during the afternoon and evening hours. Weak flow aloft should preclude any severe weather threat, with longer term models also suggesting that higher CAPE values will remain west of our region. Forecast confidence then decreases late in the weekend and early next week, as the longwave trough situated over the northern tier of the nation potentially lifts into Canada, leaving behind a weak frontal boundary over the southeastern states. Some subsidence in the wake of the initial shortwave trough passage may result in less convective coverage along mesoscale boundaries on Sunday, and then the 00Z operational GFS/ECMWF guidance diverges on the timing of the next shortwave trough that could impact our area early next week. Slightly above average temperatures will continue overall this weekend and early next week, with active sea breezes moving well inland as Atlantic surface ridging extends its axis across north central FL. && .AVIATION... (18Z TAFS) Issued at 130 PM EDT Tue Apr 30 2024 VFR cigs at this time. Given the low level moisture, forcing aloft, and sea breeze boundaries we are seeing a few showers develop over northeast FL, and may not be out of the question a weak brief t-storm forms near the northeast FL TAF sites through 00z. Not enough confidence for a TEMPO group at this time for any MVFR or lower condition. If any t-storm forms, would be relatively weak. Isolated showers and t-storm chances should be diminishing fairly quickly after about 01z-03z with skies tending to clear more later tonight just in time for some patchy-areas fog to form. Have continued to advertise MVFR and possible IFR or less at JAX, GNV, CRG, and VQQ from about 06z-13z. The fog should dissipate by 13z-14z. && .MARINE... Issued at 315 AM EDT Tue Apr 30 2024 High pressure centered off the South Carolina coast will weaken and shift eastward today as a weakening frontal boundary enters the southeastern states. South-southeasterly winds prevail this morning with a coastal surge in the afternoon as the Atlantic sea breeze shifts inland. Isolated showers and thunderstorms may develop over our local waters today into Wednesday as the dissipating frontal boundary moves over our area. Another high pressure center will then build over coastal New England late this week, resulting in onshore winds redeveloping over our local waters. A cold front is then expected to enter the southeast states by Saturday night and Sunday, possibly bringing a chance of showers and thunderstorms to our region by late in the upcoming weekend. Rip Currents: Moderate risk of rip currents continue through Wednesday with the potential for a high risk of rip currents at NE FL beaches on Wednesday. && .PRELIMINARY POINT TEMPS/POPS... AMG 63 88 63 90 / 30 10 0 10 SSI 67 84 67 81 / 10 10 0 10 JAX 65 88 65 87 / 20 20 10 10 SGJ 67 86 67 85 / 10 20 10 10 GNV 64 89 63 90 / 10 20 0 20 OCF 64 89 64 90 / 10 20 0 20 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk through late tonight for FLZ124-125-133- 138. GA...None. AM...None. && $$