Area Forecast Discussion
Issued by NWS Jacksonville, FL

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FXUS62 KJAX 290822
AFDJAX

Area Forecast Discussion
National Weather Service Jacksonville FL
422 AM EDT Mon May 29 2017

.NEAR TERM /Through tonight/...

Early this morning...

Surface obs indicate while there are patches of low clouds...but
very little fog being observed which is probably due from elevated
boundary layer winds. Have opted to remove fog from the early am
grids but may still have a few patches of it in a few spots. Will
have mainly patchy low clouds which will lift by mid morning.

Today/Tonight...A deep layer ridge across central Fl will shift
northeast into the western Atlantic by tonight. An MCS will pass
well to the north of the area late this afternoon/eve.
However...outflows from the feature will move into Se Ga late this
afternoon which may help produce a round of scattered storms from
late afternoon into mid evening. Given the moderate amounts of
bulk shear and instability...SPC has an area in southeast
Ga...generally along and north of U.S. hwy 82 under a marginal
risk of severe wx with damaging winds and hail the main concerns.
Otherwise expecting another hot and muggy afternoon with continued
dry conditions across Ne Fl. Max temps reach the mid 90s away
from the coast with heat indices around 100. With the synoptic
flow lighter this afternoon (unlike yesterday) a seabreeze will
probably manage to get going at the coast but temps there will
still manage to reach the lower 90s.

Any storms that manage to get going across Se Ga will end by
mid evening due to loss of heating and the MCS lifting to
the Ne. Boundary layer winds will be lighter than this
morning which favors better chances of fog (as indicated
by the SREF). Have opted to go with patchy late night and
early morning fog mainly between I-75 and U.S hwy 301 in
Ne Fl. Confidence low whether there will be fog in Se Ga
due to the possibility of extensive debris clouds from
earlier convection.

.SHORT TERM...

Tuesday...A fairly complex scenario developing Tuesday as the
region will become more influenced by mid to upper level troughing
over the ern U.S. Weak frontal zone may push gradually southward
to near the Altamaha River. A piece of shortwave energy will be
moving across the lower MS Valley to AL and GA in the afternoon
and evening. Early on, model guidance is suggesting possible MCS
developing overnight Mon night into Tue morning. How this evolves
remains to be seen but increased debris cloud cover is likely over
SE GA. We may see outflow boundaries push east to southeast into
the north zones from the MCS during the day which will help
initiate convection. Forecast instability of 2000-3000 J/kg
possible with bulk shear of about 25 kt over SE GA. NAM Fcst
sounding at 21z shows a SBCAPE of 3100 J/kg. Isolated severe
storms look possible over SE GA. SPC has most of our SE GA zones
in a marginal risk of severe storms. Would appear primary risk is
damaging wind gusts with DCAPE values near 1100 J/kg. Overall
weaker cap will also lead to isolated to possibly scattered
showers and storms along the east coast sea breeze in the aftn and
evening. Highs a little lower over SE GA around 90/Lower
90s...but lower to mid 90s in NE FL. Max heat indices near 100
expected. Tuesday evening...should see isolated to scattered
showers and storms, mostly likely focused over the ern zones and
the marine waters then pushing offshore and fading/weakening after
midnight. Weak frontal zone may remain nearly stationary over SE
GA.

Wednesday...Guidance shows weak low level trough/diffuse frontal
boundary from around Brunswick GA southwest to the northeast Gulf
of Mexico. This boundary may drift southward slightly during the
day. This feature along with residual boundaries from prior days
convection and PWATS near 1.6 inches should be enough to kick off
scattered convection in the aftn given the increasingly moist and
unstable airmass over the region. Highs will be lower overall than
prior days due to increased clouds and precip.

.LONG TERM.../Thursday-Sunday/...

Model 00Z output continues to suggest daily summertime conditions
with a warm and moist airmass and generally weak 0-6 km wind
fields at around 10 kt or less. Initial weak sfc trough will be
located across the GA and perhaps extreme NE FL becomes much more
diffuse Fri and Sat and lifts northeast. Deep layer flow will be
weak westerly...gradually becoming southwesterly and we will see
PWATs rise to above normal by Friday. This should provide for at
least scattered showers and storms each day...possibly numerous at
times. Temps will still be hot Thursday in the lower to possibly
mid 90s...but slowly lower a bit Friday through Sunday.

&&

.AVIATION...

Patchy low clouds will be across the area early this morning
producing IFR cigs MVFR Vsby at JAX...VQQ...CRG...and GNV
til around 14Z. May also need to amend SGJ for it. Otherwise
prevailing VFR today.

&&

.MARINE...

Surface ridge south of the area will produce a light sw
flow the next couple of days. Afternoon seabreezes will
produce onshore winds near shore. Slightly stronger winds
may occur over the waters during the evening but conditions
expected to remain below headline criteria. A frontal boundary
will weaken and wash out across the waters towards mid week
which may increase the shower/thunderstorm activity. Winds will
be variable with afternoon and evening seabreezes near the coast.

Rip Currents: Better chance of a seabreeze along the coast
this afternoon but swells continue to be low (less than a foot)
so have opted to go with a low risk through Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  94  70  91  70 /  20  20  40  20
SSI  91  74  89  75 /  10  10  30  30
JAX  95  71  93  71 /  10  10  30  40
SGJ  92  73  91  72 /   0   0  30  40
GNV  95  69  94  70 /  10   0  30  30
OCF  94  70  94  70 /   0   0  20  20

&&

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

$$

Peterson/Shashy


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