Flood and Heavy Rain in Florida, December 14 to 15, 2018

Area Forecast Discussion
National Weather Service Jacksonville FL
944 AM EST Fri Dec 14 2018

.UPDATE...
Heavy rainfall was moving into the Suwanee Valley with rainfall
rates up to 1 inch per hour this morning, with lighter rain
elsewhere. Extended the Flood Watch to cover the rest of
northeast/north central Florida this morning due to models
shifting the heavier rainfall a bit further south across this
region. Storm totals of 2-5 inches across northeast Florida with
localized amounts of 6 to inches inches is possible as waves of
heavy rain move across the area through late tonight. Rainfall
amounts of 1-3 inches are expected across southeast Georgia, with
locally heavier amounts.

The 12Z sounding this morning showed 50 knots of 0-6km bulk shear,
but little to no instability. Thus far there have not been any
storms across the area, with lightning confined to the Gulf
waters. An MCV did move into the Suwanee Valley this morning, and
this is aiding in rainfall rates of around 1 inch per hour.
Another heavy band has developed near I-75 as well. This region
will continue to be monitored for localized flooding this morning,
with the heavy rain then spreading eastward through the
afternoon. The latest model guidance indicates that instability
will increase from a line south of Jax Beach to Gainesville in the
afternoon, and that an intense line of showers and storms will
develop around 2-3 PM. It is possible that there could also be
discrete cells for a short period of time in the mid to late
afternoon hours before it becomes all linear. The main threat will
be gusty winds of 40-60 mph, but an isolated tornado or two
cannot be ruled out as well. Heavy rainfall will then continue
through the night before becoming to diminish near sunrise on
Saturday.

&&

.AVIATION...
MVFR to IFR conditions will prevail through the period due to rain
and embedded storms. Some storms this afternoon could become
strong to severe for the northeast Florida TAF sites, especially
near KGNV and KSGJ.

&&

.MARINE...
Small Craft Advisory remains in effect for the offshore Atlantic
waters due to southerly winds of 20 to 25 knots and seas of 6 to 8
feet.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  68  57  68  47 / 100  90  20  10
SSI  67  59  68  49 / 100 100  30  10
JAX  71  61  70  50 / 100 100  30  10
SGJ  74  62  70  52 /  90 100  30  10
GNV  71  61  71  51 / 100 100  30  10
OCF  74  62  72  52 /  90 100  30  10

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Flood Watch through late tonight for Alachua-Baker-Bradford-Clay-
     Coastal Duval-Coastal Flagler-Coastal Nassau-Coastal St.
     Johns-Columbia-Gilchrist-Hamilton-Inland Duval-Inland
     Flagler-Inland Nassau-Inland St. Johns-Marion-Putnam-
     Suwannee-Union.

GA...Flood Watch through late tonight for Appling-Atkinson-Bacon-
     Brantley-Charlton-Clinch-Coastal Camden-Coastal Glynn-
     Coffee-Echols-Inland Camden-Inland Glynn-Jeff Davis-Pierce-
     Ware-Wayne.

AM...Small Craft Advisory until 10 AM EST Saturday for Waters from
     Altamaha Sound GA to Fernandina Beach FL from 20 to 60 NM-
     Waters from Fernandina Beach to St. Augustine FL from 20 to
     60 NM-Waters from St. Augustine to Flagler Beach FL from 20
     to 60 NM.

&&

Kennedy/Zibura/Cordero