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Area forecast discussion
National Weather Service Jacksonville Florida
329 am EDT Thu Jun 29 2017

..elevated rain chances inland today with locally heavy
rainfall...

Near term...today and tonight...

A coastal trough offshore will bring clusters of showers inland early
this morning with gradual dissipation as they press farther west
through sunrise. An broad upper level across the northern Gulf of
Mexico will lift north-northeast of the region today as mean layer 1000-500 mb
high pressure edges across South Florida from the Atlantic. Between
these features, a plume of deep layer moisture with precipitable
water values near 2 inches will pivot northward from north-central
Florida to across our southeast Georgia zones today and linger across NE Florida. The
increase in deep layer moisture, combined with passing upper level
energy from the low across the Gulf Coast will bring elevated rain
chances, focused inland west of the Highway 301 corridor in the
afternoon and evening as East Coast sea breeze convection develops
and presses inland. Expect more insulation today across the Gulf
Coast today compared to yesterday with a developed West Coast sea
breeze by mid afternoon pressing inland toward I-75. Sea breeze and
outflow boundary mergers will focus between Highway 301 and the I-75
in the late afternoon into the evening. Once again locally heavy
rainfall will be the main convective hazard today as moisture
increases as well as upper level dynamical support from the west-southwest with
the proximity of the upper low. There is also a chance of a few
stronger storms capable of gusty wet downbursts this afternoon and
evening. Showers will drift inland toward the west-northwest this morning, then
as convection grows deeper this afternoon with diurnal heating,
storm motion will transition to more to the north-northeast around 10 kts or
less.

Precipitation will fade inland this evening with mostly dry
conditions expected after midnight. A continuation of onshore flow
and a weak coastal trough will continue a chance of coastal showers
along the coast after midnight.

Temperatures will range in the 80s today across much of the area,
with near 90 where more isolation is expected across inland NE Florida
south of Interstate 10. Low temperatures tonight will continued
above normal in the 70s under mostly to partly cloudy skies.

Friday through Saturday night...deep ridge will build north into
central Florida as upper troughing to the N lifts off to the NE. A
Summer like pattern will prevail with daytime temperatures reaching
the lower 90s. Seabreezes will move inland with convection
increasing over the interior each afternoon and evening. A moist and
unstable airmass with 2 inch pwats and CAPES 2000 to 3000 j/kg will
result in strong storms producing locally heavy rainfall...wet
microbursts...and frequent lightning strikes.

Long term...Sunday through Wednesday...deep layered ridge will
remain from the western Atlantic across central FL into the Gulf of
Mexico next week. A moist and unstable airmass will remain over NE
FL/se GA resulting in scattered seabreeze storms each afternoon and
evening...becoming numerous over the interior. A light westerly
steering flow with precipitable waters around 2 inches will contribute to areas of
locally heavy rainfall. Isolated strong storms will also likely
occur. Temperatures and rain chances will be at or above average.

&&

Aviation...onshore flow will bring coastal showers onshore this
morning with periods of MVFR cigs and reduced visibility.
Advertised tempo groups at both ssi and sgj at this time. Rain
chances will increase inland through the afternoon with thunderstorms in the vicinity
advertised at all terminals with a gradual decrease in rainfall
from east to west less isolated to scattered coastal showers.

&&

Marine...east-southeast winds 10-15 kts today with combined seas 1-3 ft.
Waves of showers will move inland through the morning, with a
chance of afternoon tstorms closer toward the coast. Winds shift
more toward the south-southeast Friday as high pressure builds across South
Florida. This weekend south-southwest flow develops between the ridge to the
south and an approaching surface front northwest of the region.
Thunderstorm activity will increase this weekend into early next
week ahead of the front.

Rip currents: moderate risk of rip currents today due to continued
onshore flow and longer period swells of near 11-12 seconds. Low
risk of rip currents expected Friday.

&&

Hydrology...the South Fork of Black Creek near penny farms
dropped below flood stage this morning as is now in action stage.
Several other area rivers are within action stage, and with
locally heavy rainfall potential through the weekend, rises are
possible.

&&

Preliminary point temps/pops...
amg 87 73 89 73 / 60 40 70 30
ssi 83 76 86 76 / 40 30 40 30
jax 86 74 89 74 / 50 20 60 20
sgj 84 75 88 74 / 40 20 50 20
gnv 90 73 91 73 / 60 40 60 30
ocf 91 74 91 73 / 60 40 60 30

&&

Jax watches/warnings/advisories...
Florida...none.
Georgia...none.
Am...none.
&&

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