Area Forecast Discussion
Issued by NWS Jacksonville, FL
FXUS62 KJAX 270854
Area Forecast Discussion
National Weather Service Jacksonville FL
454 AM EDT FRI MAY 27 2016
...Low Pressure approaching Southeastern Seaboard this Weekend
will create an Increasing Rip Current Threat at Local Beaches...
Overnight surface analysis depicts high pressure (1023 millibars)
centered in between the North Carolina Outer Banks and Bermuda.
Disorganized low pressure (1010 millibars) was located about 500
miles to the east of Cape Canaveral and was moving west-
northwestward around 10 mph. Aloft...ridging prevails along the
U.S. eastern seaboard, with an upper level low cutting off beneath
this feature near the Bahamas. Deepening and convergent onshore
flow brought a few showers onshore into Flagler and St. Johns
counties during the late evening hours, which moved westward past
the St. Johns River before dissipating over Putnam and eastern
Marion Counties, where some leftover stratocumulus clouds persist.
Otherwise, skies are fair, which has allowed for another night of
radiational cooling inland. Temperatures and dewpoints inland
generally ranged from 60-65 at 08Z, while temperatures at the
coast were generally in the lower 70s.
.Near Term /Today and Tonight/...
Low pressure well east of our coastline is expected to gradually
organize and move northwestward today, possibly becoming a
subtropical or tropical depression or storm tonight or Saturday.
Our local pressure gradient will tighten today as the low pressure
center organizes, with breezy northeast/easterly winds expected by
late morning for locations along and east of Interstate 95. Our
region will remain on the dry and subsident side of the upper
level low over the Bahamas, which will limit rain chances area-
wide to less than 10 percent. Plenty of sunshine will boost highs
to near late May climo inland, where upper 80s are forecast.
Onshore winds will keep highs in the lower 80s at the coast.
Low pressure well north of the Bahamas will continue moving
northwestward tonight, and should be centered about 275 miles
east of Jacksonville during the overnight hours. Showers
developing on the western periphery of this potential tropical
storm will advect onshore after midnight, with generally isolated
coverage expected due to a lack of deep layered moisture over our
region. Near breezy conditions will likely continue tonight at the
beaches, with inland winds once again decoupling. A few showers
may cross U.S. Highway 301 towards sunrise, with dry conditions
prevailing well inland. Lows will fall to the low/mid 60s well
inland, with coastal lows remaining in the lower 70s.
.Short Term /Saturday through Sunday night/...
Low pressure will make its closest approach to our southeast
Georgia coast by late Saturday, with the center of this potential
tropical storm likely within 150 miles of St. Simons Island by the
late afternoon hours. This system will continue moving
northwestward, with winds becoming northeast and then northerly
late in the day and remaining breezy for locations along and east
of Interstate 95. Bands of showers may approach the coast early in
the day, with an Atlantic sea breeze enhancement expected during
the afternoon hours at inland locations. A broken line of showers
and thunderstorms should develop along I-95 towards noon and will
progress westward during the afternoon, with only isolated showers
expected at the coast as a largely subsident atmosphere prevails
on the west and southwest side of the passing cyclone. Highs in
the Suwannee Valley should approach 90 before convection
approaches during the late afternoon, with breezy conditions
keeping highs in the lower 80s at the coast.
Sat Night...The Atlantic surface low will approach the SE Atlantic
seaboard states...likely remaining north of the local area. Local
low level winds will back from a breezy ENE flow to the NW Sat
night. Diurnally enhanced evening rainfall will fade along the
I-75 corridor with most rainfall activity overnight expected to
remain offshore and just north of the Altamaha River basin through
the night. Low temps will cool to near climo inland into the the
mid/upper 60s under partly cloudy skies.
Sun & Sun Night...Weak steering flow will enable the surface low
to linger along the SE Atlantic seaboard during the period. 00z
model consensus kept the surface low and thus widespread heavy
rainfall potential north of the Altamaha River basin. Increased
deep layer moisture of 1-1.5" combined with diurnal heating under
a dry and weak NNW steering flow will enable both sea breezes to
move inland as temperatures rise to near 90 deg...but a dry slot
between higher bands of PWAT is expected to rotate across NE Fl
Sunday afternoon per the GFS20. This dry slot could prevent
clouds/rain and support warmer temps in the lower 90s. At this
time advertised diurnally driven rainfall of 20-30% developing
along the coasts and increasing in coverage inland into the
afternoon. Sun night evening precip will fade inland as NW flow
prevails and keeps most precip offshore overnight as inland temps
cool into the mid/upper 60s once again.
.Long Term /Monday through Thursday/...
Mon-Tue...Low pressure lingers along the SE Atlantic sea board
states with a trough axis extending across the local area. Weak
NNW steering flow will continue and continued with 20-30%
rain/tstorm chances across inland areas due to trough and sea
breeze interactions. Temps will trend above climo with max temps
in the lower 90s inland and lows in the upper 60s/lower 70s.
Wed-Thu...The Atlantic coast low begins to lift northward trailing
a lingering high moisture plume across the local area. Low level
ESE flow returns as the Bermuda ridge axis positions north of the
area. Rain chances return to near climo values in the 30-40% range
with a diurnal trend. Above normal temps expected to continue.
VFR conditions will prevail at the regional terminals through 00Z.
Periods of MVFR ceilings will be possible at SGJ and SSI after
00z. Easterly surface winds will increase after 13Z, with speeds
approaching 15 knots after 15Z, with frequent gusts near 20 knots
possible at the coastal terminals through sunset. Isolated showers
could impact the coastal terminals after 00Z.
Disorganized low pressure located about 500 miles east of Cape
Canaveral will continue moving northwestward and is forecast to
possibly organize into a tropical depression or a tropical storm
by tonight or Saturday. This potential tropical cyclone is
expected to approach the South Carolina coastline by early Sunday.
Northeast to easterly winds will strengthen this morning and could
approach caution levels this afternoon and evening. Winds will
become northeasterly tonight and then northerly by late Saturday
as this low pressure center passes to the north of our region.
Seas will gradually build and should reach caution levels of 4-6
feet offshore late tonight or early Saturday. Low pressure will
decelerate and meander near the Carolina coast on Sunday and
Monday, with winds locally becoming offshore, with seabreezes
expected each afternoon through midweek in the near shore waters.
Seas will gradually decrease beginning Sunday night.
Rip Currents: Breezy easterly winds and a developing northeasterly
ocean swell will create a moderate risk of rip currents at area
beaches today, especially during the outgoing tide this afternoon.
A high risk of rip currents is possible on Saturday due to the
combination of breezy northeasterly winds and a longer period
easterly ocean swell.
.PRELIMINARY POINT TEMPS/POPS...
AMG 89 62 89 67 / 0 10 20 10
SSI 83 71 82 69 / 10 20 20 10
JAX 85 66 86 69 / 0 20 20 10
SGJ 83 71 83 69 / 10 20 20 10
GNV 88 64 89 67 / 10 10 30 20
OCF 88 66 89 68 / 10 10 30 20