textproduct: Jacksonville

KEY MESSAGES

For the latest NE FL and SE GA Daily Key Messages please visit: https:/www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf

- Wet Pattern Through Tuesday with daily showers and thunderstorms. Main Concerns: Localized Flooding, Gusty Winds up to 40-50 mph, and frequent lightning. Heaviest rainfall will be from the I-10 corridor northward today and into this evening.

- Moderate to high rip current risk Late Tuesday through Thursday

- Small Craft Advisory is likely Tuesday night through Wednesday

NEAR TERM /THROUGH TONIGHT/

Main Highlights This Period:

- Rainfall flooding risk mainly from the I-10 corridor northward and along the northeast FL coast

With PWATs around 2.0" and rising later today, as well as a relatively weak westerly flow, there remains a threat for flooding today. Along and north of I-10 has received the most activity this morning into the early afternoon, with several waves of showers and storms continuing through tonight closer to where the front is sitting. The Weather Prediction Center has this area highlighted for a 'Slight' Risk of excessive rainfall today, forecast rainfall totals today there are generally 0.5-1.5" however locally higher amounts up to 4" are possible.

The second area of concern will be closer to I-95 and the Atlantic coast later today, where the Gulf sea breeze will push far inland and interact with the Atlantic sea breeze. A few strong storms will be possible with gusty winds, and heavy downpours.

Convection will linger after sunset, especially near the front in southeast GA. Closer to midnight onward, activity should mainly be stratiform showers. Low temperatures will be mild in the 70s.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/

Main Highlights This Period:

- Scattered to Numerous Showers and Thunderstorms South of Waycross on Monday Afternoon and Evening

- Strong to Isolated Severe Storms Possible on Tuesday Afternoon and Evening

- Breezy Onshore Winds Develop at Coastal Locations on Tuesday Evening, with Small Craft Advisory Conditions Overspreading Our Local Waters

Deep and unstable west-northwesterly flow will prevail across our region on Monday between stout ridging over the northwestern Caribbean Sea and a digging trough over New England and the Mid- Atlantic states. Meanwhile, a wave of low pressure developing along a decelerating frontal boundary this evening near the FL/GA border will progress offshore after midnight, with this frontal low pressure center organizing on Monday afternoon well offshore. This subtle change in the weather pattern will advect a slightly drier air mass into southeast GA during the late morning and early afternoon, dropping PWATs to around 1.5 inches. Otherwise, deeper moisture will persist south of the stalling boundary from the Interstate 10 corridor southward, where scattered to numerous mainly afternoon and evening showers and thunderstorms are expected to develop and push southeastward. The drier and more subsident air mass filtering into southeast GA on Monday afternoon will limit convective coverage to scattered, except isolated for locations north of Waycross. The drier air filtering into our area may enhance the threat for a few stronger downdrafts as storms potentially pulse during the afternoon hours across northeast and north central FL.

Low stratus clouds developing overnight and early on Monday morning across southeast GA near the stalled front may be slow to erode, and some slight cool air advection may keep highs in the mid to upper 80s for locations north of Waycross. Highs elsewhere should climb to the lower 90s, with a delayed development of the Atlantic sea breeze boundary due to a northwesterly breeze bringing 90 degree temperatures to coastal locations, with heat index values peaking near 100 before convective coverage increases later in the afternoon.

A potent shortwave trough diving southward from the eastern Great Lakes on Monday night will drive a stronger cold front into the southeastern states by the predawn hours on Tuesday. A squall line of strong to severe thunderstorms may precede this frontal boundary along a pre-frontal trough that will be pushing southward across southern AL, GA, and the FL panhandle per latest short-term, high resolution guidance. Although this convective line should remain just west of our area, convection may linger into the evening hours across north central FL, and enough convergence may develop ahead of the approaching front to develop widely scattered showers and perhaps a few thunderstorms during the overnight and predawn hours on Tuesday across inland portions of southeast GA. Lows will generally fall to the 70-75 degree range across our region.

Deepening troughing over the eastern third of the nation will drive the stronger cold front across southeast GA on Tuesday afternoon and evening and then through northeast and north central FL on Tuesday night. This deep trough will develop a 110-knot jet streak based at 250 millibars (around 35,000 feet) off the Carolina coast by Tuesday evening, placing our region within the ascending region of this feature. Breaks in the morning cloud cover will help to destabilize our atmosphere ahead of this cold front, and strengthening high pressure over the Great Lakes in the wake of this front will begin to wedge down the southeastern seaboard during the afternoon hours, creating additional convergence over our area. The Storm Prediction Center has preliminarily placed most of northeast and north central FL within a "Marginal" risk (level 1 of 5) for severe thunderstorm development on Tuesday afternoon and evening. Downburst winds of 40- 60 mph, torrential downpours, frequent lighting strikes, and possibly some potential for hail will exist within any strong to isolated severe storms that develop and push southward. A potentially earlier afternoon onset of convective activity should again keep highs in the mid to upper 80s for locations north of Waycross on Tuesday afternoon, with lower 90s elsewhere. Heat indices may rise to the 100-105 degree range for locations south of I-10 on Tuesday afternoon before convection arrives later in the afternoon.

Strong to isolated severe storms will remain possible ahead of the southward moving cold front on Tuesday evening across northeast and north central FL, while a cooler and drier air mass advects into southeast GA after midnight, allowing skies to clear from north to south. High pressure will build into the southeastern states towards sunrise, tightening our local pressure gradient and creating breezy northeasterly winds across coastal southeast GA on Tuesday evening, with these breezy conditions spreading to coastal northeast FL towards midnight. Despite a northeast breeze at inland locations, cool air advection will drive lows down to near 60 degrees for locations north of Waycross, with mid to upper 60s arriving elsewhere inland towards sunrise as the front pushes to near the Interstate 4 corridor in central FL. Breezy onshore winds will keep coastal lows closer to 70.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Main Highlights This Period:

- Gusty Northeasterly Winds at Coastal Locations on Wednesday, with a High Risk for Rip Currents Anticipated at Coastal Locations on Wednesday and Thursday.

- Small Craft Advisory Conditions Likely Across Our Local Waters through Early Thursday Morning.

- Cooler and Drier Air Mass Arrives Area-Wide on Wednesday and Wednesday Night.

- Gradual Warm-Up Forecast Late this Week Next Weekend with Dry Weather Likely to Continue.

Deep troughing along the U.S. eastern seaboard will push a cold front into south FL on Wednesday. A few showers could linger in the immediate wake of this frontal passage across north central FL around sunrise on Wednesday, followed by seasonably cool high pressure building into the southeastern states, providing our area with one last gasp of Spring weather that should persist through Friday. A tight local pressure gradient on Wednesday will only gradually loosen, keeping breezy onshore winds in place along the I- 95 corridor from Wednesday through Friday. Despite plenty of sunshine, strong cool air advection will result in highs of only around 80 degrees on Wednesday afternoon for locations along and north of I-10, with lower 80s elsewhere. High pressure will then gradually weaken as it builds into the southeastern states on Wednesday night, dropping lows to the mid and upper 50s for inland locations north of I-10, with low to mid 60s elsewhere inland. Breezy onshore winds will continue to keep coastal lows closer to 70.

Weakening high pressure will push offshore of the southeast GA coast by Thursday evening, with ridging aloft then building over the lower Mississippi Valley and sliding slowly eastward from Friday through next weekend. This evolution of the weather pattern will allow for gradually warming temperatures, but a very dry air mass may persist all the way through next weekend, keeping rain chances far below normal for our region. Highs will warm to the low and mid 80s inland on Thursday afternoon and then the upper 80s by Friday, followed by afternoon highs approaching 90 next weekend. Breezy onshore winds through Friday should keep coastal highs in the low to mid 80s, with mid to upper 80s possible by next weekend. The unusually dry air mass will keep inland lows in the upper 50s and lower 60s on Thursday night, with a gradual warm-up through the 60s towards next weekend. A light onshore breeze will keep coastal lows around 70 late in the upcoming week, warming to the low to mid 70s next weekend.

AVIATION /18Z SUNDAY THROUGH 18Z MONDAY/

Difficult TAF forecast, with several waves of showers and isolated thunderstorms expected at the sites today into tonight. TEMPOs are in place for best timing of thunderstorm impacts this afternoon and evening, although rain may briefly reduce visibilities outside those windows. Westerly winds remain below 10 knots outside of convection through this evening, with northwesterly winds increasing towards sunrise Monday. A period of MVFR ceilings is likely Monday morning at all locations, with SSI having potential for a brief period of IFR.

MARINE

Additional rounds of showers and thunderstorms are forecast from Sunday through Tuesday evening as a front stalls over our area before a stronger cold front pushes southward across our local waters on Tuesday night. Northeasterly winds will surge in the wake of this frontal passage on Tuesday night as high pressure building over the Ohio and Tennessee Valleys wedges down the southeastern seaboard, creating Small Craft Advisory conditions from late Tuesday night through at least Wednesday night throughout our local waters. Breezy onshore winds and elevated seas are expected through Thursday night as high pressure gradually weakens over the southeastern states.

Rip Currents: Generally low-end moderate risk much of today. Rip current risk may begin to rise a little further by Monday. Probably looking at increased risk to moderate and high from Tuesday and into Wednesday and possibly Thursday.

FIRE WEATHER

- Low Daytime Dispersion Values This Afternoon For Southeast Ga - Areas Of High Daytime Dispersion Values Monday Through Friday

Widespread showers and thunderstorms are expected across our area this afternoon and evening, with strong storms and localized flooding possible, especially for locations along and north of Interstate 10. Breezy westerly surface and transport winds for locations south of I-10 will create good daytime dispersion values, with fair values for coastal northeast FL and poor to low values across southeast Georgia. Scattered to numerous mainly afternoon and evening showers and thunderstorms are forecast on Monday and Tuesday. Breezy west-northwesterly surface and transport winds will overspread our region on Monday, creating good daytime dispersion values, with areas of high daytime dispersion values at inland locations. Northwesterly transport winds on Tuesday will shift to northeasterly late in the afternoon, with breezy surface speeds developing at coastal locations. Scattered mainly morning showers and thunderstorms are forecast for north central Florida on Wednesday, with a cooler and much drier air mass then filtering into our region from north to south on Wednesday afternoon and Thursday. Breezy northeasterly surface and transport winds will prevail on Wednesday, followed by surface and transport winds shifting to east-northeasterly on Thursday.

FOG POTENTIAL AND OTHER REMARKS: Patchy fog will be possible early on Tuesday morning for inland portions of northeast and north central Florida. Strong to isolated severe thunderstorms will be possible on Tuesday afternoon and evening, mainly across northeast and north central Florida.

PRELIMINARY POINT TEMPS/POPS

AMG 70 86 69 86 / 50 30 20 80 SSI 74 88 75 86 / 70 40 20 80 JAX 73 90 73 90 / 50 40 10 80 SGJ 74 91 74 90 / 60 50 10 80 GNV 74 90 73 92 / 20 60 20 70 OCF 76 89 75 90 / 10 60 20 70

JAX WATCHES/WARNINGS/ADVISORIES

FL...None. GA...None. MARINE...None.