Marine Weather and Tide Forecast for Lower Grand Lagoon, FL

NEAR TERM
(Today and tonight)
Issued at 323 AM EST Sat Dec 7 2024

Elongated surface high pressure through the TN/MS river valleys will slide southeast through the day. As it does, northerly winds currently will gradually clock to northeast today then to the east to southeast overnight tonight. Dry air remains in place featuring dewpoints in the low to mid 20s and upper teens just to our north.
Those upper teens dewpoints will make an appearance across our northern tier counties this morning ahead of winds becoming east to southeast allowing moisture levels to slowly increase later today and tonight. Looking upstream, high level clouds are streaming in from the southern Plains and anticipate that to continue, maybe becoming thicker later today and tonight. Highs today will be a few degrees warmer compared to Friday with readings in the upper 50s mainly north of the FL state line to low 60s approaching the coast.
Lows tonight may be a little more problematic and impacted by thicker cirrus. Overnight readings fall into the low/mid 30s which is close to MOS consensus and a little cooler than NBM. However, if thicker clouds transpire, as well as east to southeast winds set up a little sooner, lows may not be as cool as forecast and may need to be raised a few degrees by the next shift. Otherwise, the near term remains dry.

SHORT AND LONG TERM
(Sunday through Friday)
Issued at 323 AM EST Sat Dec 7 2024

We have quite the potpourri of weather through the short and long term forecast. First, we'll experience a warming trend that sees temperatures back above normal Sunday and into early next week. Next up are periodic bouts of rain, and potentially quite a bit of it for areas along and west of the Flint and Apalachicola Rivers, Monday through Wednesday. And to cap it off, a mid-week cold front that sends temperatures tumbling below normal again for the second half of next week.

Surface high pressure moseys east of the region Sunday into Monday, opening the door for southerly flow to return to the area. This should push temperatures back into the 70s for highs and overnight lows in the 50s to 60s. That southerly flow will also increase surface moisture quite a bit and lead to the potential for some sea fog along the coast of Apalachee Bay.

An incoming H5 shortwave riding the southern jet stream arrives Monday into Monday night with rain blossoming out ahead of it.
Precipitable water values (PWATs) are forecast to surge to between 1.5" to 1.7", or above the 90th percentile, across the Florida Panhandle northeastward into southwest Georgia. With large scale lift from the shortwave, the region being in the right entrance region of an upper-level jet and a surface cold front pushing southeast, there is an increasing likelihood of widespread rain for areas along and west of the Flint and Apalachicola Rivers.
Probabilities of those areas exceeding 2" in a 24 hour period between 6am CST Monday and 6am CST Tuesday are around 20%. With probabilities this low, the Weather Prediction Center (WPC) has taken the Slight Risk (level 2 of 4) for Excessive Rainfall out of area, but has maintained the Marginal Risk (level 1 of 4) for the areas along and west of the Flint and Apalachicola Rivers through 12Z, or 6am CST, Tuesday.

That's round number 1. Round number 2 is forecast to occur during the day on Tuesday as a corridor of moisture funnels northeastward over the region due to us being between a developing H5 trough to the northwest and a ridge over the Bahamas. PWATs are forecast to remain above the 90th percentile, so rain will remain in the forecast through Tuesday, but may be a bit more spotty due to upper- level support not being as favorable Tuesday morning and afternoon.

That changes Tuesday night into Wednesday as the aforementioned H5 trough dives towards the Gulf Coast, pushing a cold front through the southeast. Upper-level support will be more favorable with the right entrance region of the H25 nearby. Ample moisture available along with increasing instability will lead to more rain.
Probabilities of 2" or more of rain remain around 20% for the 24 hour period between 12Z Tuesday and 12Z Wednesday for areas along and west of the Flint and Apalachicola Rivers. As a result of that, WPC has maintained a Slight Risk (level 2 of 4) for Excessive Rainfall during that time period.

While a few rumbles of thunder cannot be ruled out at this time, especially Tuesday into Tuesday night, severe chances remain low at this time. Still, it is something we will continue to monitor through the weekend into early next week.

The cold front then barrels through as temperatures drop from the 70s Monday and Tuesday afternoons to the 50s and 60s Wednesday and stuck in the 50s for highs again Thursday. Overnight lows will follow a similar trajectory by going from the 50s and 60s to the 20s and 30s Wednesday and Thursday nights.

AVIATION
(18Z TAFS)
Issued at 1216 PM EST Sat Dec 7 2024

VFR conditions for all terminals with only cirrus clouds through the period. Winds north to northeast today around 5 knots.

MARINE
Issued at 323 AM EST Sat Dec 7 2024

Moderate northerly winds will subside through the morning as high pressure settles over the northeastern Gulf of Mexico. The high then scoots east of Florida Sunday into Monday, allowing winds to turn more southerly. These southerly winds may lead to the formation of some sea fog in Apalachee Bay early next week. Another cold front is forecast to sweep through Wednesday and turn winds out of the north and increase to advisory level conditions with very low, less than 10 percent, chances of gale conditions behind the front.

FIRE WEATHER
Issued at 323 AM EST Sat Dec 7 2024

Elevated fire weather conditions will exist today as afternoon RH values will be less than 28 percent in the SE FL Big Bend as well as Flint and Chattahoochee valley of SW GA into SE AL. Mixing heights will generally be around 2000 feet with low dispersions.
Afternoon RH values won't quite be as low Sunday as surface winds become southerly, however, the low mixing heights and dispersions will continue. Heading into next week, rain chances increase Monday through Wednesday with the entirety of the tri-state area expected to receive wetting rains.

HYDROLOGY
Issued at 323 AM EST Sat Dec 7 2024

Multiple rounds of rain, some locally heavy, are expected Monday through Wednesday. As of now, the highest rainfall amounts are anticipated between a Panama City to Albany line where 2" to 4" of rain is forecast. A closer inspection of the ensembles show the EURO ensembles are on the higher side with 1" to 5" of rain, whereas the GFS and Canadian ensembles are generally between 0.25" and 3". As there is some uncertainty, and the potential is there for higher rainfall amounts, the Weather Prediction Center (WPC) has a Marginal Risk (level 1 of 4) for Excessive Rainfall along and west of the Flint and Apalachicola Rivers for Monday and a Slight Risk (level 2 of 4) for Excessive Rainfall Tuesday into Tuesday night for the same areas. In the grand scheme of things, this rainfall is beneficial due to the ongoing drought for those areas, but a few occurrences of nuisance flooding, especially in more urban areas, cannot be ruled out.

SPOTTER INFORMATION STATEMENT

Spotter activation is not requested. However, spotters are always encouraged to safely report significant weather conditions when they occur by calling the office or tweeting us @NWSTallahassee.

PRELIMINARY POINT TEMPS/POPS
Tallahassee 60 38 68 50 / 0 0 0 0 Panama City 62 42 69 57 / 0 0 0 10 Dothan 58 36 66 51 / 0 0 10 10 Albany 58 34 66 48 / 0 0 0 10 Valdosta 59 36 69 49 / 0 0 0 0 Cross City 63 34 71 48 / 0 0 0 0 Apalachicola 60 45 66 58 / 0 0 0 0

TAE WATCHES/WARNINGS/ADVISORIES
FL...None.
GA...None.
AL...None.
GM...None.