NWS Jacksonville, FL wrote its last area forecast discussion before the first event at Apr 9, 4:30 AM EST, 1 hour 30 minutes earlier.
Area forecast discussion, Apr 9, 4:30 AM EST, 1 hour 30 minutes before
Area Forecast Discussion
National Weather Service Jacksonville FL
530 AM EDT Sun Apr 9 2023
...COASTAL FLOOD WARNING TONIGHT THROUGH MONDAY NIGHT ALL ALONG
THE ATLANTIC COAST...
...WINDY CONDITIONS ALONG AND EAST OF I-95 THROUGH MONDAY NIGHT...
...DANGEROUS SURF CONDITIONS WITH SIGNIFICANT BEACH EROSION
POSSIBLE THROUGH MIDWEEK...
...LOCALLY HEAVY DOWNPOURS THIS EVENING THROUGH MONDAY EVENING
ALONG THE NORTHEAST FL COAST AND THE ST. JOHNS RIVER BASIN...
...MINOR FLOODING AROUND TIMES OF HIGH TIDE WITHIN THE ST. JOHNS
RIVER BASIN FROM THIS EVENING THROUGH MIDWEEK...
.SYNOPSIS...
Issued at 530 AM EDT Sun Apr 9 2023
Early morning surface analysis depicts low pressure (1014
millibars) centered over the Gulf Stream waters adjacent to the
northeast FL coast. A cold front extends west-southwestward from
this feature across the Interstate 4 corridor in central FL.
Meanwhile, strong high pressure (1034 millibars) centered over the
eastern Great Lakes and New England continues to wedge down the
southeastern seaboard. Aloft...troughing continues to dig down the
U.S. eastern seaboard as ridging builds over the Mississippi
Valley and the Upper Midwest, with a shortwave trough diving
south-southeastward from the northern Rockies. Our local
nor'easter has begun as our local pressure gradient continues to
tighten, with low stratus ceilings and breezy northerly winds
prevailing at most locations. Weak isentropic ascent over
southeast GA and western portions of the Suwannee Valley was
producing a few light showers that were migrating eastward, while
areas of drizzle were in place across much of northeast FL.
Temperatures and dewpoints at 09Z have fallen to the mid and upper
40s across inland southeast GA, with 50s prevailing for most of
inland northeast FL, ranging to the lower 60s across north central
and coastal northeast FL.
&&
.NEAR TERM...
(Today and Tonight)
Issued at 530 AM EDT Sun Apr 9 2023
Our local pressure gradient will continue to tighten as strong
high pressure wedges down the southeastern seaboard, creating
strong north-northeasterly winds at coastal locations today, with
breezy conditions prevailing inland. A Wind Advisory has been
issued for locations along and east of the I-95 corridor in
southeast GA and northeast FL, where sustained wind speeds will
increase to the 25-35 mph range by late this morning, with
frequent gusts of 40-45 mph expected to continue through tonight.
Otherwise, the area of weak isentropic ascent streaming across
southeast GA will tend to shift southward across northeast and
north central FL this afternoon as a drier air mass advects into
inland southeast GA from the north. This drier air mass should
create breaks in the thick stratus for locations north of Waycross
during the mid to late afternoon hours. Meanwhile, thick stratus
will remain socked in across coastal southeast GA and all of
northeast and north central FL through early this evening, with
areas of drizzle continuing and periods of light showers expected
this afternoon, especially for locations along and east of I-95.
Highs this afternoon will likely remain in the mid to upper 50s
for locations north of I-10, with low and mid 60s expected
elsewhere. These values are 15-20 degrees below climatology.
A coastal trough will take shape over the near shore Atlantic
waters adjacent to northeast FL tonight, which will keep a tight
pressure gradient in place locally as strong surface ridging
slowly builds southward over the Mid-Atlantic states, wedging down
the southeastern seaboard. Low level convergence will strengthen
as the coastal trough sharpens, with short-term, high resolution
guidance in good agreement on bands of low-topped convection
developing over the Gulf Stream waters adjacent to the northeast
FL coast this evening that will initially move towards the Flagler
and St. Johns County coastlines after midnight tonight. These
bands of heavy downpours will then begin to shift northward along
the northeast FL coast towards sunrise on Monday. Meanwhile, a
drier air mass advecting into southeast GA and the Suwannee Valley
will allow for breaks in the stratus to extend southward to the
I-75 corridor in northeast and north central FL overnight. Lows
tonight will range from the mid and upper 40s over inland
southeast GA to the 50s elsewhere inland, except lower 60s along
the northeast FL coast.
&&
.SHORT TERM...
(Monday through Tuesday night)
Issued at 402 AM EDT Sun Apr 9 2023
Strong high pressure initially centered over Virginia will
continue to slowly shift southward, gradually pushing a drier air
mass into northeast and north central FL by Tuesday afternoon and
evening. Until then, coastal troughing situated over the near
shore waters adjacent to northeast FL will continue to generate
bands of low- topped convection that will advect onshore,
especially on Monday and Monday night. 1-2 inches of rainfall will
be possible for locations along and east of I-95, with locally
heavier totals possible at coastal locations and also within
southern portions of the St. Johns River basin. These heavier
downpours may exacerbate ongoing coastal flooding around times of
high tide (see Hydrology and Coastal Flooding discussions below),
especially at urban locations such as Flagler Beach, St.
Augustine, Jacksonville Beach, Palatka, and Green Cove Springs.
Strong northeasterly winds will prevail at coastal locations,
where frequent wind gusts of 35-45 mph will persist through at
least Monday night. Breezy conditions will prevail at inland
locations through around sunset on Monday, where partly cloudy
skies will allow highs to rebound into the mid and upper 60s, with
lower 70s expected for inland north central FL on Monday
afternoon. Northeasterly winds will gradually diminish at inland
locations on Monday night, while windy conditions prevail at
coastal locations. Lows will range from the mid and upper 40s for
inland locations north of Waycross to the 50s elsewhere, with low
and mid 60s expected at coastal locations due to strong onshore
winds.
Shortwave troughing currently diving south-southeastward from the
northern Rockies will begin to cutoff from the main flow pattern
over the Ozarks on Monday night, with this cutoff trough then
sinking towards coastal Texas on Tuesday night. This feature will
result in cyclogenesis near coastal Louisiana by Wednesday.
Meanwhile, our local pressure gradient will begin to gradually
loosen as coastal troughing breaks down and shifts inland across
northeast FL on Tuesday. Breezy northeasterly winds will continue
to produce occasional showers on Tuesday, mainly along the
northeast FL coast. A drier air mass will continue to prevail over
southeast GA, with a drier west-northwesterly flow aloft allowing
for more sunshine at inland locations, where highs will rebound to
the low and mid 70s. Breezy onshore winds, marine stratocumulus,
and occasional showers will keep coastal highs in the mid to upper
60s. A few coastal showers may continue through Tuesday evening
along the northeast FL coast, with fair skies inland again
resulting in lows falling to to the upper 40s for locations north
of Waycross, with 50s elsewhere inland and low to mid 60s along
the immediate Atlantic coast.
&&
.LONG TERM...
(Wednesday through Saturday)
Issued at 530 AM EDT Sun Apr 9 2023
With high pressure sitting to the north of our area, a developing
upper low over the north central Gulf will lead to frontogenesis in
which a warm front will stretch eastward towards Florida. The
high pressure will begin to move eastward during the overnight
hours from Wednesday to Thursday, the warm front will lift across
the state on Thursday into Friday. Strong storms are a possibility
for Thursday and Friday. Rain chances will remain for Saturday as
a cold front moves into the area. The pattern for the upcoming
week will see temperatures trend to above normal from Wednesday
through Saturday.
&&
.AVIATION...
(06Z TAFS)
Issued at 205 AM EDT Sun Apr 9 2023
IFR ceilings will prevail at the regional terminals, with periods
of LIFR ceilings of 300-400 feet and drizzle expected through the
period. Ceilings may attempt to lift to around 1,000 feet towards
00Z Monday. Focused bands of moderate to heavy rainfall and
potential isolated thunderstorms will likely begin to impact SGJ
after 02Z, and this activity is then expected to shift northward
towards CRG after 06Z Monday. Northerly surface winds sustained at
10-15 knots will shift to north-northeasterly towards 12Z Sunday,
with sustained speeds increasing to 15-20 knots, with frequent
gusts of 30-35 knots possible at SGJ, CRG, JAX and SSI. Sustained
speeds will increase to 20-30 knots at SGJ after 14Z, with
frequent gusts of 35-40 knots forecast. Frequent surface gusts in
excess of 30 knots are expected to develop at SSI towards 00Z
Monday.
&&
.MARINE...
Issued at 530 AM EDT Sun Apr 9 2023
Low pressure situated off the northeast FL coast will accelerate
northeastward today, pushing a cold front southward through the
Florida peninsula. Meanwhile, strong high pressure centered over
New England and the Mid-Atlantic states will continue to wedge
down the southeastern seaboard, creating Gale Conditions today for
the waters north of St. Augustine, with Gale conditions then
overspreading the rest of our local waters by early this evening.
Frequent gusts up to 45 knots are expected throughout our local
waters. Seas will build to the 9-15 foot range both near shore and
offshore by this afternoon, peaking in the 12-17 foot range
tonight and Monday.
A coastal trough will then sharpen over our near shore waters
late tonight and Monday, resulting in increasing coverage of
showers and embedded thunderstorms, mainly over the northeast
Florida waters. This coastal trough will persist on Tuesday and
Wednesday as high pressure gradually weakens and settles over the
southeastern states, with elevated onshore winds and seas
persisting through midweek. Otherwise, weak low pressure will
develop near coastal Louisiana on Tuesday night and Wednesday,
lifting a warm front northward across our waters by Thursday night
and Friday. This feature will result in gradually increasing
chances for showers and thunderstorms on Thursday and Friday as
winds shift to southeasterly and then southerly.
Rip Currents and High Surf: Dangerous surf conditions will only
worsen through Monday as onshore winds strengthen and seas build.
A high risk of deadly rip currents will extend through much of
this week at all area beaches, as breakers build to 10-13 feet at
the northeast FL beaches and 6-8 feet at the southeast GA beaches
from this evening through Monday evening. High surf conditions
will likely persist at the northeast FL beaches through Tuesday.
&&
.HYDROLOGY...
Issued at 530 AM EDT Sun Apr 9 2023
Flooding has peaked along upper portions of the Altamaha River,
where minor flooding will continue through around midweek. Minor
flooding has begun along lower portions of the Altamaha River near
the Everett City gauge, and water levels are expected to crest at
moderate flood levels later tonight or on Monday through around
midweek before subsiding late this week.
Focused bands of low-topped convection are expected to develop
along the northeast FL coast tonight through early Tuesday.
Locally heavy downpours are expected, and these downpours may
exacerbate existing coastal flooding around times of high tide
along the northeast FL coast. 1-2 inch totals will be possible for
locations east of I-95 in coastal northeast FL during this event,
with locally higher amounts possible where these bands of focused
downpours train over the same location. Urban flooding will also
be possible at locations such as Flagler Beach, St. Augustine,
Jacksonville Beach, and possibly as far inland as Palatka and
Green Cove Springs.
&&
.COASTAL FLOODING AND BEACH EROSION...
Issued at 530 AM EDT Sun Apr 9 2023
Gale conditions over our coastal waters will result in gradually
increasing water levels along the Atlantic coast today, and
within the St. Johns River basin this evening. Minor to possibly
moderate coastal flooding is currently anticipated along the
Atlantic coast during the late morning and early afternoon high
tide cycle today, with water levels rising to the 1-2 foot range
above Mean Higher High Water (MHHW). Moderate to possibly major
coastal flooding is then expected during the late evening and
overnight high tide cycle tonight, with water levels peaking 2-4
feet above MHHW during this high tide cycle. We have thus issued a
Coastal Flood Warning all along the Atlantic coast beginning this
evening. Water levels will likely continue to rise to the 1.5 -
2.5 feet above MHHW range during high tides on Monday afternoon
and Tuesday night. Minor flooding is expected around times of
high tide beginning late this evening within the St. Johns River
basin, with water levels likely reaching 1-2 feet above MHHW
during each high tide cycle through midweek.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 58 47 66 48 / 10 10 0 0
SSI 60 56 65 59 / 40 20 20 20
JAX 60 56 67 56 / 40 30 50 30
SGJ 66 63 67 62 / 50 60 80 60
GNV 63 57 70 55 / 20 30 50 20
OCF 68 59 72 56 / 20 30 40 20
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Advisory from 10 PM this evening to 5 AM EDT
Wednesday for FLZ024-033-038-132-137-225-325-425.
High Rip Current Risk through late Wednesday night for FLZ124-
125-133-138.
Coastal Flood Advisory from 8 AM this morning to 8 PM EDT this
evening for FLZ124-125-133-138.
Wind Advisory from 10 AM this morning to 11 PM EDT Monday for
FLZ124-125-133-138.
High Surf Advisory from 5 PM this afternoon to 5 AM EDT
Wednesday for FLZ124-125-133-138.
Coastal Flood Warning from 8 PM this evening to 5 AM EDT Tuesday
for FLZ124-125-133-138.
GA...Coastal Flood Advisory from 10 PM this evening to 5 AM EDT
Wednesday for GAZ153-165.
High Rip Current Risk through late Wednesday night for GAZ154-
166.
Coastal Flood Advisory from 8 AM this morning to 8 PM EDT this
evening for GAZ154-166.
Wind Advisory from 10 AM this morning to 11 PM EDT Monday for
GAZ154-166.
Coastal Flood Warning from 8 PM this evening to 5 AM EDT Tuesday
for GAZ154-166.
High Surf Advisory from 8 PM this evening to 5 AM EDT Tuesday
for GAZ154-166.
AM...Gale Warning until 6 PM EDT Monday for AMZ450-452-470-472.
Small Craft Advisory until 5 PM EDT this afternoon for AMZ454-
474.
Gale Warning from 5 PM this afternoon to 11 AM EDT Monday for
AMZ454-474.
&&