Area Forecast Discussion
Issued by NWS Jacksonville, FL

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FXUS62 KJAX 241518

Area Forecast Discussion
National Weather Service Jacksonville FL
1118 AM EDT Mon Sep 24 2018


Late morning surface analysis depicts weak low pressure (1012
millibars) centered about 500 miles to the east of Jacksonville.
Meanwhile, a backdoor frontal boundary was stalled along the
Savannah River Valley, with strong high pressure (1039 millibars)
was centered over southern Quebec and Maine. Aloft...deep-layered
ridging centered near Bermuda is extending its axis westward
across the southeastern states, deflecting weak shortwave energy
northeastward through the Tennessee and Ohio Valleys. GOES-East
derived Total Precipitable Water imagery depicts a pocket of
enhanced PWAT values (1.7-1.9 inches) progressing westward across
our region this morning. Isolated showers that moved onshore along
the St. Johns and Flagler County coasts this morning are
increasing in coverage and intensity as they progress across the
St. Johns River basin, while isolated showers were developing
elsewhere along the Interstate 95 corridor. A healthy cumulus
field was developing per morning visible satellite imagery across
much of our region within this moist air mass, with temperatures
as of 15Z rising into the mid 80s, with dewpoint temperatures
generally in the mid 70s.

Scattered convection is expected to continue moving westward
across the U.S. Highway 301 corridor early this afternoon, with
activity congregating along the I-75 corridor by late afternoon.
Short-term, high resolution guidance indicates that additional
low-topped coastal showers will be possible late this afternoon
through around sunset over northeast Florida in advance of the
next pocket of drier air (PWATS of 1.1-1.3 inches) that will
move onshore overnight. Highs will again reach around or just
above 90 degrees at inland locations this afternoon before
convection develops, with breezy easterly winds keeping coastal
highs in the muggy mid to upper 80s. Coastal shower activity
should be limited overnight as the drier pocket of air gradually
spreads over our region from east to west, with some potential for
patchy fog formation at inland locations during the predawn and
early morning hours on Tuesday. Lows will range from the lower 70s
inland to the upper 70s at area beaches.



Periods of MVFR ceilings between 2000-2500 feet are expected through
around 18Z at the regional terminals. Scattered showers and
thunderstorms could impact the inland terminals through around
sunset, where confidence was high enough for a TEMPO group at VQQ
and GNV to account for brief periods of sub-VFR conditions from
around 18Z-24Z. Easterly surface winds will remain sustained at
10-15 knots with occasionally higher gusts at the coastal
terminals through sunset.



A weak low pressure center was positioned about 500 miles to the
east of Mayport late this morning. This feature will move
northwestward over the Gulf Stream waters adjacent to the Carolina
coast and then will turn northward while weakening near the Outer
Banks on Wednesday. An east-northeasterly long period ocean swell
will keep combined seas elevated in the 3-5 foot range throughout
our waters today, with near shore seas decreasing slightly
overnight. The axis of Atlantic ridging will then build to the
south of our waters by midweek, resulting in a southerly wind
surge up to around 15 knots on Wednesday evening. Our local
pressure gradient will loosen later this week as a frontal
boundary remains stalled well to the northwest of our region, with
a persistent swell keeping seas in the 3-5 foot range offshore.
Otherwise, light offshore winds will prevail for a brief period
later this week, followed by onshore winds resuming during the
upcoming weekend as high pressure builds over the Carolinas.

Rip Currents: Jacksonville Beach life guards report very choppy
conditions continuing this morning with numerous rip current
sightings despite fairly low surf heights. A long period ocean
swell of 11-12 seconds will keep a high risk in place at the
northeast Florida beaches today, with a moderate risk continuing
at the southeast Georgia beaches.


AMG  90  72  91  72 /  30  10  10  10
SSI  86  77  87  76 /  20  10  10  10
JAX  88  73  90  73 /  50  10  10  10
SGJ  87  77  88  75 /  50  10  10  10
GNV  90  72  92  73 /  50  10  30  10
OCF  90  73  92  73 /  50  20  40  20


FL...High Rip Current Risk until 8 PM EDT this evening for Coastal
     Duval-Coastal Flagler-Coastal Nassau-Coastal St. Johns.



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