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Area Forecast Discussion

FXUS62 KJAX 300820

Area Forecast Discussion
National Weather Service Jacksonville FL
420 AM EDT TUE AUG 30 2016

...High risk of rip currents today...

...Increasing chances of TD #9 impacting the local area late Wed
through early Fri...

.Near term...Today through Wed...

Meandering mid/upper level low over the GA/SC coast enhanced
convection along a low level convergent zone over our FL coastal
waters and the coastal counties last night. Upper level energy
around this mid/upper level low since rotated ESE of the local
area with now a spoke of negative vorticity advection brining
mostly dry conditions early this morning less some showers well
offshore of the NE FL coastal waters and a few showers drifting
inland over Flagler county. These areas of precipitation were
forming along a low level trough axis that was slowly pivoting
northward from south FL. This trough extended out on the NE side
of Tropical Depression (TD) #9 that was still drifting WNW over
the southern Gulf of Mexico.

As this low level trough axis continues to slowly migrate northward
toward our southern FL zones through this afternoon...onshore
convergent flow will once again bring waves of showers and
isolated tstorms inland today...with diurnal enhancement into the
afternoon as precipitation pushes inland toward the I-75 corridor.
Strong wind gusts of 35 to 45 mph will be possible again today in
showers and isolated thunderstorms that move onshore.

Showers will fade inland this evening with a chance of showers
and isolated thunderstorms continuing over the adjacent coastal
waters and over coastal counties. There will also be increasing
rain chances from the south after midnight across Marion...Putnam
and FLagler counties as the surface trough lifts northward from
central FLorida.

WedNEsday the low level trough axis is expected to bisect the
forecast area with a continuation of NE flow over SE Ga with a
lighter and more varied southerly flow developing across our
southern FL zoNEs on the southside of the trough axis. By Wed
aftn...PWAT values of over 2 inches will blanket most of SE GA
and NE FL with values upwards NEar 2.5 inches possible across our
SuwanNEe River Valley zoNEs. Widespread rainfall is expected to
impact much of NE FL by Wed afternoon as the moisture rich
airmass overspreads the area.

Temperatures will trend NEar normal today with highs in the
mid/upper 80s to lower 90s across drier inland SE GA.
Temperatures Wed will be a cooler and range in the mid/upper 80s
for most areas south of the aforementioNEd trough axis due to
increased rainfall. Overnight conditions will be muggy with min
temps in the mid/upper 70s.

.Short term...Wed night through Fri...

Models were in very good agreement tracking TD #9 across the NE Gulf
of Mexico Wed night and then across the local forecast area
through late Thu and Thu night as the system gets picked up by a
digging 500 mb trough across the eastern CONUS.

Waves of moderate to heavy rainfall will overspread the local area
west to east late Wed through Thu with storm total rainfall
amounts of 4 to 8 inches advertised across NE FL with generally
less than 3 inches over inland SE GA. Locally higher amounts are
highly possible...especially across the Suwannee River Valley of
NE Florida. Although much of the forecast area will welcome this
rainfall...too much rainfall in a short period of time could cause
flooding problems.

The NE quadrant of TD #9 relative to the storm track is expected
to move over NE FL...coastal SE GA and over the adjacent coastal
waters Thu. This sector is the more favored area for tropical
rain band tornadoes and thus the Storm Prediction Center now has
these areas highlighted in a Marginal Risk for potential
tornadoes Thu and Thu night.

Based on the latest forecast...tropical storm force winds will be
possible in convective rain band squalls beginning late Wed night
then overspreading west to east across NE FLorida and coastal
areas and the adjacent coastal waters Thu and Thu night.

Models were in reasonable agreement lifting the storm NE of the
local waters by Fri afternoon...with a wake trough lingering over
NE FL continuing elevated rain chances while a drier NNE flow
over SE GA will bring lower rain chances.

.Long term...Sat through Tue...

A trailing trough axis from TD #9 will linger across NE FL Sat as
a wedge of high pressure noses southward over central from a ridge
center over New England. Breezy onshore flow combined with the
lingering surface trough across NE FL will continue elevated rain
chances across the area. Late Sat or early Sun the trough axis is
shunted farther south of the local area as a backdoor cool front
pattern develops. This regime would bring waves of coastal showers
inland under breezy NE flow Sun-Tue as a cooler northerly flow
prevails aloft due to a 500 mb ridge center building eastward
over MS/AL/TN.

Temperatures will trend near to below climo values early next
week with max temps only in the mid/upper 80s inland to low/mid
80s coast. Minimum temperatures will range in the lower 70s to
even some upper 60s across inland SE GA where drier air will


.Aviation...Prevailing VFR conditions through today with periods
of MVFR due to waves of showers and isolated tstorms moving
onshore and then inland into the afternoon toward VQQ/GNV. Breezy
east winds with gusts of 20-25 kts are expected by mid morning at
the terminals with decreasing magnitudes late this evening...except
at SSI where a stronger NE gradient will continue through the
night as a trough axis pivots northward over the FLorida
terminals and brings lower and more varied winds overnight


.MariNE...High pressure north of the area will maintain a
moderate onshore flow pattern over the waters today. Easterly
swell will result in some increase in seas. Continued to
advertise Small Craft Exercise Caution conditions for both the
near shore and outer waters today with east winds 15-20 kts and
seas of 4-6 ft. A decrease in winds is expected tonight as a
surface trough axis pivots northward over the waters.

Winds will become southerly over NE FL waters Wed as a trough
axis moves northward over the region ahead of TD #9. TD #9 is
expected to track across the northeast Gulf of Mexico Wed and then
across N FL and the adjacent coastal waters Thu and Thu night...then
exiting northeast of the local waters Fri. Tropical storm force
winds will be possible during this time period in squalls. A
trailing front will push south of the area late Fri or Sat with
high pressure building NE of the region this weekend.

Rip currents: High risk today and again Wed. Breakers in the 3-5
ft range possible along the NE FL coast today.


AMG  91  73  91  74 /  50  20  60  50
SSI  86  77  87  76 /  60  40  70  60
JAX  87  75  88  75 /  60  40  70  60
SGJ  85  76  87  76 /  60  50  80  60
GNV  89  74  86  75 /  60  30  80  60
OCF  89  75  86  75 /  60  40  80  70


.JAX Watches/Warnings/Advisories...
FL...High Rip Current Risk through this evening for Coastal Duval-
     Coastal Nassau-FLagler-St. Johns.

GA...High Rip Current Risk through this evening for Coastal Camden-
     Coastal Glynn.





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