Severe Thunderstorm Warning 179, NWS Jacksonville, FL

Area Forecast Discussion
National Weather Service Jacksonville FL
315 PM EDT Sat Jun 17 2017

.NEAR TERM...This afternoon through Sunday...

Showers and thunderstorms will continue to develop from west to
east with additional cells expected to pop along the east coast
sea breeze front by mid-afternoon. A vigorous eastward moving
outflow boundary was racing across south GA early this afternoon
as the parent upper level vortex rotated over southern AL. This
outflow boundary combined with diurnal heating and west coast sea
breeze convection is expected to converge across our SE GA zones
within the next few hours and will continue to trek eastward
toward the Atlantic through the early evening. Farther south
across NE FL west coast sea breeze convection will continue to
press inland toward the I-75 corridor through 2 pm while a few
cells begin to form along the late forming east coast sea breeze
front. NE FL precipitation is expected to converge between I-75
and the St. Johns River basin through 6 pm with SW steering flow
gradually shifting convection toward the Atlantic coast through 9
pm with gradual dissipation. Lingering showers and isolated
tstorms possible through midnight then mostly dry conditions less
some convection over the adjacent Atlantic waters. Although the
coverage of convection is not expected to be as great as recent
days a few stronger cells with gusty winds will be possible given
intrusion of dry mid/upper level air from the SW dry slot around
the Gulf Coast upper level low.

Mean layer 1000-500 mb steering flow 10 kts or less will
transition to more from the south tonight as the ridge axis across
south Florida begins to lift northward toward north Florida
tonight into Sunday. As this steering flow transition occurs, an
axis of very deep tropical moisture extending northward from the
low pressure system in the Caribbean will progressively overspread
the Florida peninsula from the south with precipitable water
values rising well above 2 inches. Although severe storm potential
will be lower Sunday due to increasing subsidence across the
local area, the increase in deep layer moisture combined with
diurnal instability will bring elevated rain chances during the
afternoon and evening especially across NE Florida where highest
moisture content will infiltrate. The more southerly steering flow
will enable both sea breezes to develop and press inland through
the day with a merger focused between the Highway 301 and
Interstate 75 corridors. Gusty wet downburst winds generally 30-50
mph will be possible due to precipitation loading as well as very
heavy, potentially locally flooding, rainfall. Temperatures will
range from the mid 80s coast to near 90 well inland.

.SHORT TERM...Sunday night through Tuesday night...Trough axis at
mid/upper levels will remain across AL/MS into the central Gulf of
Mexico while a surface low forms near the Yucatan peninsula. A deep
and moist southerly flow over ne Fl/se Ga will produce scattered to
numerous showers and storms...more likely in the afternoon/evening
hours. Temperatures will be at or just below average with pops above
average.

.LONG TERM...Wednesday through Saturday...Mid/upper level low
drifts south over the Gulf of Mexico next week with models differing
in the handling of ridging across ne Fl/se Ga. Latest GFS model
continues to be weaker with ridge than the ECMWF which builds ridge
stronger. This results in big differences with the forecast track of
surface low meandering near the Yucatan peninsula. GFS moves the low
north towards the central Gulf coast while the more preferred ECMWF
moves it towards the western Gulf coast Wedenesday-Thursday. GFS
solution would be much wetter for us as tropical moisture surges
north across Fl/Ga. ECMWF model solution would be drier as deep
tropical moisture would remain to our west and subsidence would be
stronger. Models in better agreement Friday and Saturday with deep
layer high pressure building across the area bringing lower rain
chances and higher temperatures.

&&

.AVIATION...Prevailing VFR conditions expected under SCT-BKN
ceilings generally 3-4 kft this afternoon under westerly winds.
Still expect the east coast sea breeze to develop and drift inland
which will shift winds to the SSE along the coast. Restrictions
expected in scattered afternoon and evening convection with VCTS
advertised in TAFs for now. Will add tempo groups based on radar
trends. Tonight MOS guidance not indicating a strong signal for
low stratus...but SREF suggested some potential for low visibility
and patchy restrictions to LIFR most likely near VQQ and GNV.
Drier upper level air expected to support better radiational
cooling conditions while low/mid clouds creep up from the south
through the night. For 18Z TAFs indicated marginal MVFR conditions
due to stratus at GNV/VQQ Sunday morning.

&&

.MARINE...Very long period easterly swells of 17-18 seconds
continued to be reported at all buoys with combined seas of 2.6 ft
or less. Prevailing SSW winds 10 mph or less will become SSE this
afternoon with a late forming east coast sea breeze with speeds
10-15 kts...nearing a solid 15 kts this evening. Prevailing SSE
winds develop Sunday through midweek as high pressure noses
northward from south Florida Sunday to over or just north of the
local waters Mon-Wed. Low pressure near the Yucatan peninsula will
drift northward into the central Gulf of Mexico this week.

Rip Currents: Moderate risk of rip currents for NE Florida coast
due to long period swells.

&&

.HYDROLOGY...Pottsburg Creek and the Black Creek at Penny Farms
remained at action stage this afternoon with a gradual fall. Any
locally heavy rainfall across these basins will raise water
levels.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  72  92  75  89 /  30  30  30  40
SSI  77  86  77  85 /  20  20  40  40
JAX  73  88  75  86 /  30  40  30  50
SGJ  75  86  74  84 /  20  30  20  40
GNV  72  90  73  85 /  30  60  40  60
OCF  73  90  74  86 /  30  60  30  60

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&

Enyedi/Zibura/McGinnis

Hazardous Weather Outlook
National Weather Service Jacksonville FL
243 AM EDT Sat Jun 17 2017

AMZ450-452-454-470-472-474-FLZ020>025-030>033-035>038-040-124-125-
GAZ132>136-149>154-162>166-180645-
Coastal waters from Altamaha Sound to Fernandina Beach FL out
20 NM-
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 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-
Hamilton-Suwannee-Columbia-Baker-Inland Nassau-Inland Duval-Union-
Bradford-Clay-St. Johns-Gilchrist-Alachua-Putnam-Flagler-Marion-
Coastal Nassau-Coastal Duval-Coffee-Jeff Davis-Bacon-Appling-
Wayne-Atkinson-Ware-Pierce-Brantley-Inland Glynn-Coastal Glynn-
Echols-Clinch-Charlton-Inland Camden-Coastal Camden-
243 AM EDT Sat Jun 17 2017

...MODERATE RISK OF RIP CURRENTS AT NORTHEAST FLORIDA BEACHES...

This Hazardous Weather Outlook is for Northeast Florida,
Southeast Georgia and the Adjacent Coastal Waters.

.DAY ONE...Today and Tonight...

Isolated to scattered thunderstorms are expected today and this
evening. Some storms may be strong and produce strong wind gusts,
in addition to frequent lightning and locally heavy rain.

There is a Moderate Risk of Rip Currents at the northeast
Florida beaches today.

.DAYS TWO THROUGH SEVEN...Sunday through Friday...

Scattered to numerous afternoon and evening thunderstorms are
expected through the period. The main thunderstorm hazards
continue to be locally heavy rainfall, frequent lightning, and
gusty winds.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

For additional information, visit the National Weather Service in
Jacksonville website on the internet at weather.gov/jax.

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>