Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Jacksonville Florida
922 PM EDT sun Aug 2 2015
Update...fairly well defined surface low continues over the NE Gulf of
Mexico near 30n84w...drifting east-northeast past 12 hours. Weak trough
extends northeastward into southeast Georgia with low level convergence resulting in
scattered convection in that area during the afternoon peak daytime
heating. Now...only isolated to scattered shallow convection exists with
the more persistent low level forcing located east of the surface low
center over the NE Gulf and extending eastward to near I-75. Models are
not doing a good job with the surface low and preferred a slower
motion...similar to the GFS ensemble...moving the system slowly
eastward 5-10 knots. Current radar shows weak convection between
Gainesville and Trenton and while a narrow rain band may
setup...anticipate only localized heavy rainfall is possible
through 12z Monday owing to weaker forcing and nocturnal cooling.
Using hrrr and radar trends...will continue to lower probability of precipitation all
areas but keep elevated rain chances around the 50 to 70 percent
range west of I-75 south of Lake City. Elsewhere...rain chances are
at or below 40 percent with thunderstorms chances waning quickly as well.
Due to expected low track east-northeast to NE on Monday...elevated rain
chances in the 50-70 percent range expected southeast of a line from
Brunswick to Live Oak. Chances showers and storms northwest of that
line. Somewhat lower maximum temperatures in NE Florida due to precipitation and clouds
compared to southeast Georgia which are forecast in the lower 90s.
ceilings may briefly lower to MVFR from time to time overnight but
mainly VFR ceilings are expected at most taf sites. Gnv stands the
best chance of seeing a more persistent period of MVFR ceilings later
tonight as the threat for rain showers increases off the Gulf of
Mexico. Prevailing MVFR conditions expected at all terminals during
the day on Monday as a weak low slowly tracks across the region with
rain spreading across the area during the day. IFR conditions and gusty
winds can be expected with the heaviest showers/storms on Monday.
Marine...combination of surface low and high pressure ridge over the Atlantic
continues to lead to enhanced pressure gradient and result in
increased wind speeds through Monday. Therefore...Small Craft
Advisory conditions are expected for outer waters.
Rip currents: low to moderate rip current threat through Monday.
Preliminary point temps/pops...
amg 73 92 75 97 / 40 30 10 20
ssi 77 90 76 89 / 40 60 30 30
jax 74 91 75 93 / 30 60 30 40
sgj 75 88 75 89 / 50 70 30 40
gnv 75 88 74 89 / 70 70 30 40
ocf 74 87 74 88 / 80 80 40 50
Am...Small Craft Advisory until 4 PM EDT Monday for waters from
Altamaha Sound Georgia to Fernandina Beach Florida from 20 to 60 nm-
waters from Fernandina Beach to St. Augustine Florida from 20 to
60 nm-waters from St. Augustine to Flagler Beach Florida from 20
to 60 nm.