Area Forecast Discussion
Issued by NWS Jacksonville, FL

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FXUS62 KJAX 161513

Area Forecast Discussion
National Weather Service Jacksonville FL
1113 AM EDT Wed Aug 16 2017

.UPDATE...Heat and humidity will be the main weather headline
today, as plenty of insolation and a prevailing westerly flow
boost highs into the mid 90s inland (perhaps a few upper 90s) and
lower 90s at the beaches. The intense heating should allow
dewpoint temps to mix to the low to mid 70s during the afternoon
hours, which should keep max heat index values in the 103-107
degree range, which is just below the precipice of the heat
advisory criteria.

Low level moisture will remain abundant today. This morning`s 12z
JAX sounding has 2.21" of precipitable water. The afternoon PWATs
are forecast to be in the 2.0-2.2 inch range. However, subsidence
associated with the ridge aloft will prevail and mid-level
temperatures will continue to be relatively mild (-5 to -7 Celsius
at 500 millibars). Anticipate limited convection (isolated to
perhaps widely scattered). The genesis of convection will be
mainly late this morning through early afternoon along the Gulf
coast sea breeze, with light nwly steering flow keeping activity
generally confined to areas along and west of Interstate 75
through mid afternoon. During the mid to late afternoon, the
Atlantic coast sea breeze, may move eastward, pushing further
inland mainly south of SR 16 leading to merging sea breezes along
the I-95 corridor across southern St. Johns, Flagler and Putnam
counties. A few storms can be strong with gusty winds of 35 to 50


.AVIATION...VFR conditions will prevail during the next 24 hours. Only
isolated thunderstorms are expected to develop during the mid to
late afternoon, with GNV the most likely terminal to be impacted
by sub-VFR conditions between 18z-20Z as activity along the Gulf
coast sea breeze pushes towards the Interstate 75 corridor.
Timing, coverage and intensity remain in question, and VCTS was
placed in the 06Z TAF for GNV. Isolated late afternoon or early
evening thunderstorms cannot be ruled out at the remainder of the
terminals, but confidence remains too low to include VCTS at this
time. The Atlantic sea breeze will develop and cross SGJ towards
18Z, SSI towards 19Z, CRG towards 20Z, and JAX by 21Z. Light
westerly surface winds will otherwise prevail.


.MARINE...An eastward extension of Atlantic ridging will expand into the
southeastern Gulf of Mexico and will lift northward through Friday.
This weather pattern will maintain a light offshore wind flow,
with our local pressure gradient loosening enough to allow the
Atlantic sea breeze to develop near the coast during the mid
afternoon hours through Friday. South-southwesterly evening wind
surges will bring wind speeds up to near 15 knots in the offshore
waters each evening through Friday. Atlantic ridging will build
northward this weekend, with prevailing southerly winds expected
on Saturday and then southeasterly winds by Sunday afternoon. The
Atlantic sea breeze will develop earlier in the afternoon at the
coast this weekend. A southerly wind surge on Saturday evening may
bring winds into the caution range of 15-20 knots, but speeds
will otherwise remain below caution through the weekend, with seas
remaining in the 2 to 4 foot range.

Rip Currents: A long period easterly ocean swell will linger at
area beaches today, but offshore winds, low wave heights of 1 to 2
feet, and the outgoing tide not occurring until late this
afternoon should equate to a low risk. A low risk will likely
continue through Saturday.


AMG  95  76  95  76 /  20  10  40  30
SSI  92  80  92  78 /  10  10  50  30
JAX  95  76  95  76 /  10  10  60  40
SGJ  93  78  92  76 /  20  20  50  40
GNV  94  75  94  75 /  30  10  50  30
OCF  93  75  93  74 /  40  10  60  30




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