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Area forecast discussion 
National Weather Service Jacksonville Florida 
449 am EDT Sat Jul 20 2019 


Near term /today-tonight/... 


Early this morning...clear skies and near calm winds over inland 
areas have allowed for fog and low stratus development across southeast 
Georgia and inland NE Florida with widespread visibilities in the 1-5 mile 
range with some vsbys below 1 mile at times. Some patchy dense fog 
will be possible across inland southeast Georgia at times through sunrise 
with vsbys near 1/4 mile, with lowest vsbys near areas that 
received rainfall yesterday. Conds will improve after sunrise with 
fog dissipated by the mid-morning hours. 


Today/tonight...Bermuda high pressure ridge axis at the surface 
remains in place across the region while early morning satellite 
imagery shows that some drier air aloft has pushed into southeast Georgia and 
NE Florida north of the I-10 corridor while deeper moisture with 
precipitable water amounts (pwats) still close to 2 inches lingers 
across inland NE Florida south of Gainesville to Palatka. This will 
support lower rainfall chances across most of the region with 
storm coverage of 20-40% for southeast Georgia 30-50% along the I-10 and I-95 
corridors of NE Florida and 40-60% for the rest of inland NE Florida closer 
to the deep moisture near ocf/gnv. Southerly steering flow will 
push storms towards the north around 10 mph today as both sea 
breeze fronts from the Gulf/Atlc will push inland and expect storm 
activity to kick off across NE Florida by the early/mid afternoon 
hours and push north and trigger activity across southeast Georgia by late 
afternoon and early evening hours before fading after sunset. A 
few strong/severe storms possible again this afternoon as mid 
level temps remain cool enough to support some local wet 
microburst potential with wind gusts 50-60 mph especially over 
inland areas as storm mergers and sea breezes push together. 
Slightly earlier start to convection across NE Florida should hold Max 
temps into the lower 90s, while middle 90s expected across southeast Georgia 
and near 90 along the Atlc coast prior to the East Coast sea 
breeze pushing inland. Evening convection should end by midnight 
across southeast Georgia in the southerly steering flow leaving fair skies 
overnight with a few high clouds and lows in the 70s. Some patchy 
fog possible in areas that receive rainfall today. 


Short term (sunday through Monday night)... 


Atlantic surface ridging will begin to weaken on Sunday as its 
axis remains positioned along the Interstate 10 corridor. The 
axis of this ridging will then sink southward on Monday as a 
potent shortwave trough progresses across the Great Lakes. 
Subsidence on the periphery of the Atlantic ridge will remain in 
place over our region on Sunday, with near climo pwats in the 
1.7-1.9 inch range expected at most locations. Only widely 
scattered mainly late afternoon and early evening convection is 
expected to develop along inland moving sea breeze boundaries, 
with activity focusing for locations west of U.S. Highway 301 and 
only isolated showers and thunderstorms expected earlier in the 
afternoon at coastal locations. Dry air in the mid levels will mix 
down to the surface during the afternoon hours, allowing 
dewpoints to fall to the upper 60s to around 70 for most inland 
locations. Less convection will allow inland highs to soar to the 
mid 90s, with coastal highs reaching the lower 90s before the sea 
breeze pushes inland. Crashing dewpoints will keep maximum heat 
index values in the 100-105 degree range. Evening convection may 
linger near the I-75 corridor in north central Florida, with 
debris cloudiness otherwise thinning overnight and lows ranging 
from the lower 70s inland to the upper 70s at the coast. 


The weather pattern will change little on Monday, although 
subsidence over our region will gradually weaken as ridging 
aloft strengthens over The Four Corners region and troughing 
gradually digs southward into the Ohio and Tennessee valleys. Low 
level flow will become southwesterly during the afternoon hours, 
which may support a slight uptick in convection, but coverage 
overall should remain scattered as precipitable waters  remain steady or decrease 
a little from sunday's near climo values. Temperatures will again 
reach the mid 90s inland and the lower 90s at coastal locations, 
with maximum heat index values remaining 100-105 as dewpoints 
again crash during the afternoon hours at inland locations. 


Long term (tuesday through friday)... 


A much stormier pattern develops locally as deep-layered troughing 
digs from the Ohio and Tennessee valleys into the lower 
Mississippi Valley by late Tuesday, reaching the western and 
central Gulf of Mexico during the mid to late week time frame, 
which will keep the Atlantic ridge axis suppressed across South 
Florida. Deep layered flow will become southwesterly on Tuesday, 
and this southwesterly flow will gradually deepen by late 
Wednesday and Thursday as a frontal boundary sinks to near the 
Altamaha river and then stalls. Moisture will pool along this 
boundary, and precipitable waters  will remain above 2 inches across southeast 
Georgia from midweek Onward, resulting in numerous afternoon and 
evening thunderstorms each day. Meanwhile, deepening southwesterly 
flow and gradually cooling temperatures aloft will ignite 
convection along the Gulf Coast sea breeze by the late morning and 
early afternoon hours along I-75 in northeast and north central 
Florida, with activity increasing in coverage by early afternoon 
and possibly becoming strong to severe as it intersects a pinned 
Atlantic sea breeze boundary from midweek Onward. Highs will climb 
to the lower 90s on Tuesday at most locations, and then 
convection will develop earlier in the day beginning on Wednesday, 
keeping highs in the upper 80s to near 90 for the rest of the 
work week. Lows will fall to the lower 70s inland and the upper 
70s at coastal locations. 


&& 


Aviation... 
low stratus and fog will impact inland taf sites with LIFR ceilings 
and IFR visibilities this morning at vqq/gnv, with MVFR visibilities possible at 
jax/crg and none expected at the coastal sites of ssi/sgj. Conds 
will improve after sunrise around 12z with VFR conds through the 
morning hours. Scattered storms possible at inland taf sites after 
18z and have kept thunderstorms in the vicinity at vqq/gnv/jax/crg while convection should 
remain inland of the sgj/ssi sites this afternoon. Storm chances 
end after 00z this evening with mainly VFR conds with high clouds 
expected overnight. 


&& 


Marine... 
Bermuda high pressure ridge axis remains across the waters through 
Monday with mainly south winds 10-15 knots and seas 1-3 ft, then 
potential increase to 15-20 knots Mon night into Tuesday as low 
pressure trof develops northwest of the local waters and tightens 
pressure gradient and small craft exercise caution (scec) 
headlines may be required with seas building to 2-5 ft. Winds 
become southwest and weaken slightly to 10-15 knots by Wednesday 
as low pressure trof and weakening frontal boundary pushes into 
the waters. 


Rip currents: marginal moderate risk for the NE Florida beaches as 
southeast flow this afternoon will push surf/breakers into the 2-3 
feet range, while low risk remains along the southeast Georgia coast north of 
the high pressure ridge axis where onshore flow is a bit weaker. 


&& 


Preliminary point temps/pops... 
amg 94 71 93 73 / 30 10 30 20 
ssi 89 78 91 80 / 20 0 20 10 
jax 94 74 95 74 / 40 10 20 20 
sgj 91 75 92 78 / 30 10 20 10 
gnv 93 72 94 73 / 60 20 40 30 
ocf 92 72 92 73 / 60 30 40 30 


&& 


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



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