Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/13/21
Area Forecast Discussion
National Weather Service Jacksonville FL
856 PM EDT Wed May 12 2021
Low level clouds are building in following the storm passage with
winds building in from out of the north overnight. Scattered
showers and drizzle can be expected to move through the forecast
area overnight with overnight low temperatures dropping down into
the mid to lower 50s in southeast Georgia and ranging between the
upper 50s and mid to upper 60s through northeast Florida.
.PREV DISCUSSION [758 PM EDT]...
.NEAR TERM [Through Tonight]...
A slow moving cold front stretches across Srn SC and central GA
this afternoon, a little south of an arc from near Charleston, SC
to near Warner Robins. South of this front, our area remains in a
warm, humid, moderately unstable airmass. RAP analysis data shows
ML CAPE values in NE FL and coastal SE GA to be around 1000-1500
J/kg with effective bulk shear around 35-40 knots. There`s a
Marginal Risk of severe storms, with the main hazards being gusty
winds and small hail. The greater risk area for more intense
storms is still along the I-95 corridor of NE FL where sea breeze
is pinned close to the coastline and easterly low level flow is
in place beneath westerly mid-level flow, leading to directional
vertical shear as well as slightly stronger speed shear (45 kts).
The cold front boundary will sink steadily south through our area
overnight tonight, but thick low level clouds and lingering rain
showers behind the front could last into Thursday morning,
resulting in moderated low temperatures tonight. Lows will be in
the low-mid 50s in SE GA, and in the 60s in NE FL.
.SHORT TERM [Thursday Through Friday Night]...
A bit of a tricky forecast for Thursday. The cold front is poised
to push just south of our forecast area by Thursday morning, but
with strong northeasterly onshore flow behind the front, we may
be stuck under a thick deck of low level clouds with light rain
showers or drizzle hanging in through much of the day. How long
we`re stuck in those breezy, cloudy, drizzly conditions will
determine how much we will actually warm up on Thursday. Model
guidance has been pretty consistent with highs in the low-mid 60s
in SE GA over the last several runs, but how far south those temps
in the 60s will dig has been more up in the air. Current forecast
roughly keeps those 60s along and north of I-10, with temperatures
warming into the 70s south of I-10.
Showers should exit offshore Thursday night, with drier conditions
anticipated for Friday. As a ridge of low level high pressure
moves eastward, a cooler, drier air mass will push in. Friday
should be nice day with clearing skies and highs in the mid-upper
70s over most of the area, around 80 near Ocala and Gainesville.
Lows will be mostly in the 50s both nights, with low 60s near the
.LONG TERM [Saturday Through Wednesday]...
Deep layer ridging forecast over the area for this weekend, with
the low level ridge centered over the TN Valley Saturday and the
upper level ridge axis over the north-central Gulf coast Saturday,
with both sliding eastward through the weekend. Under mostly sunny
skies, temperatures will gradually warm, with highs forecast to
return to the 80s across the area on Sunday afternoon and upper
80s to low 90s forecast Tuesday and Wednesday. Winds will become
more easterly next week as the ridge continues to roll eastward
and when combined with the increasing temperatures will likely
lead to the return of scattered seabreeze showers and
thunderstorms around mid-week.
[Through 00Z Friday]
Showers and thunderstorms have moved offshore for most of the
region, with lingering developments near SSI and south of SGJ.
Ceilings are expected to drop to IFR levels overnight with gusty
winds building from out of the north to about 10-15 knots with
gusts of 20 knots. Ceilings should lift to be above 1000 feet by
A cold front lies just north of our coastal waters this afternoon
and will continue to nudge south into Georgia waters this
evening and the northeast Florida waters overnight. Ahead of the
front, showers and thunderstorms will increase over the waters
and will continue to move south through tonight. Behind the front,
shower activity may continue to linger through Thursday
afternoon. Winds will shift to the northeast and increase in speed
behind the front, allowing seas to build as well. Small Craft
Advisory conditions will develop tonight and last into Friday
Rip Currents: Moderate risk of rip currents this afternoon, high
risk of rip currents tomorrow at all area beaches.
Rounds of showers and thunderstorms will continue through tonight
ahead of an approaching cold front, with lingering showers
possible behind the front tomorrow. Strong northeast winds are
forecast along the coastline from Thursday through much of the
weekend, but further inland winds will be lower, and when combined
with low mixing heights, will lead to low-end daytime dispersions
(around 20-30) across inland portions of the area Thursday.
.PRELIMINARY POINT TEMPS/POPS...
AMG 52 64 51 75 50 / 50 40 10 0 0
SSI 57 66 59 73 61 / 60 60 10 0 0
JAX 60 67 57 75 58 / 40 50 10 10 0
SGJ 66 71 62 74 63 / 50 50 20 10 0
GNV 63 74 56 79 55 / 30 40 10 0 0
OCF 67 79 60 81 57 / 30 40 10 0 0
AM...Small Craft Advisory until 8 AM EDT Saturday for Coastal waters
from Fernandina Beach to St. Augustine FL out 20 NM-Coastal
waters from St. Augustine to Flagler Beach FL out 20 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.
Small Craft Advisory until 8 AM EDT Saturday for Coastal waters
from Altamaha Sound to Fernandina Beach FL out 20 NM-Waters
from Altamaha Sound GA to Fernandina Beach FL from 20 to 60