Scientific Forecaster Discussion
fxus62 kjax 211347
Area forecast discussion
National Weather Service Jacksonville Florida
947 am EDT Wed Aug 21 2019
Weak upper level short wave energy around a broad low across SW
Georgia/southeast Alabama will continue to stream high cirrus across much of the
area today. In the low/mid levels, the 1000-700 mb ridge axis was
positioned across southeast GA, with steering flow south-southeast < 10 kts. GOES
precipitable water and jax 12z indicated drier air moving across NE Florida with
precipitable water down to 1.82 inches (normal around 1.8 inches) while
precipitable water across southeast Georgia was near 2 inches under the mean layer ridge
axis. There were a couple of weak inverted trough axes this
morning triggering showers and sprinkles, one extending inland
from the Florida Gulf Coast stretching NE toward our western Georgia zones,
and the other offshore of the central Florida coast with a few showers
across our outer Florida waters.
Passing high clouds and mean layer 1000-700 mb ridge across the
local area will temper both instability and deep layer convective
growth across the area today, trending toward near to below normal
rain chances for most zones. Expect first convective growth in the
early-mid afternoon across southeast Georgia near the lingering trough axis
and also along the East Coast sea breeze front as it drifts inland
toward the St. Johns River basin. Precipitation will be slow and
erratic across southeast Georgia under the mean ridge axis and more stable
conditions aloft, while slightly stronger storm motion to the west-northwest
across NE Florida will focus sea breeze and airmass convection westward
through the mid to late afternoon, especially south of the I-10
corridor and toward the I-75 corridor into the early evening with
clearing along the Atlantic coast. 12z jax radiosonde observation indicated
seasonally cool 500 mb temps near -7 deg c and near climo mid
level lapse rates of 5.8-6 c/km, with the main change the past 24
hrs drier air in the low levels which will tend to limit
convective coverage across NE Florida. Very weak winds aloft with no
shear. This environment supports pulse storms today with the major
hazards being locally heavy rainfall due to slow storm motion and
gusty wet downburst winds.
Partly cloudy skies will prevail as temperatures trend near
normal with highs in the low 90s inland to mid/upper 80s coast
under onshore southeast flow.
Prevailing VFR conditions this morning then tempo restrictions
possible this afternoon in passing showers and tstorms, focused
inland after 18z. Light south-southeast winds < 5 kts this morning will
increase along coastal terminals to southeast near 8-11 kts this
afternoon as East Coast sea breeze develops and shifts inland.
Bermuda ridge axis will dominate over the local waters. A few
morning showers and isolated tstorms, then best chances of
afternoon convection focus inland, clearing the coast by mid-
afternoon. Light south-southwest winds 10 kts or less this morning over Georgia
waters will transition to south-southeast into the afternoon.
Rip currents: low risk today and again Thu.
Preliminary point temps/pops...
amg 91 73 92 73 / 30 10 20 10
ssi 88 76 90 77 / 10 0 10 10
jax 91 74 92 75 / 20 0 10 10
sgj 89 74 89 75 / 20 0 10 0
gnv 91 72 91 73 / 30 20 20 20
ocf 91 72 91 73 / 40 20 20 20