Area Forecast Discussion
Issued by NWS Jacksonville, FL
FXUS62 KJAX 211957
Area Forecast Discussion
National Weather Service Jacksonville FL
255 PM EST Tue Feb 21 2017
...Numerous to widespread showers and a few storms Wednesday into
.SHORT TERM...Tonight and Wednesday...Mid level low and
associated weak surface low currently over La-Ar will move se
across the eastern Gulf tonight...and into s Fl late Wednesday.
Main band of precip ahead of the center will move into our western
zones after 00z Wed and into eastern zones by 12z Wed. Weak
instability expected to develop across ne Fl on Wed with GFS model
soundings showing MUCAPE reaching 400 J/kg. Expect widespread
rain...with isolated embedded thunder across ne Fl. Above normal
temperatures will continue with lows tonight in the lower 60s.
Highs on Wed will be slightly cooler than today due to clouds and
Wed night...nearly stacked low pressure system across the extreme ern
Gulf of Mexico just southwest of Tampa FL Wed evening will slowly
shift east to southeast with the NAM model a bit faster. Overall
prefer the GFS and ECMWF handling of this system. A plume of rich
moisture continues to be shown in models with PWATS of about 1.65
inches which would be about 175% of normal. Best lift expected to
stay south of the area as shown by mid to upper level Q-vector
convergence field but onshore flow and vorticity lobe rotating
cyclonically around the northern side of the low will force
numerous showers and a few thunderstorms over the coastal land and
marine zones. Periods of heavy rainfall possible mainly near
and south of JAX metro area...mainly St Johns and Flagler
counties. Further details on this will still need to be ironed
out but looks like some heavy rainfall is possible St Augustine
southward. Lower rain chances over the interior areas
where there`s less forcing and somewhat drier air. As system becomes
more removed from the forecast area overnight rain chances should
diminish somewhat...especially over inland areas.
Thursday...increased subsidence should eventually develop as the
cutoff low pressure near near Srn FL slowly moves east into the
Bahamas. Moist onshore convergent flow and daytime heating will
continue to result in a chance of showers and perhaps a few aftn
tstms given small instabilty...mainly in northeast FL. Highs will be
in the 70s to near 80 inland with breezy east to northeast winds.
Thursday night...the cutoff low over the Bahamas continue to push off
to the east and shortwave ridging aloft moves in and subsidence
strengthens subsidence inversion. Could see a round of late night
fog develop given these conditions but breezy conditions just above
the sfc may develop a mix of low stratus and only light fog in most
locations. Less overall cloudiness will dip lows into the upper 50s
in most locations.
Friday...mainly dry and a warmer day on tap with subsidence aloft
from shortwave ridge. Highs in the lower to mid 80s possible
inland...closer to mid 70s near the coast from onshore flow.
Short wave ridging pushes east of the area Friday night as broad mid
to upper level troughing moves in over the Eastern U.S. ...with srn
extent of trough fairly weak moving into our zones late on Saturday.
A sfc cold front pushes through on Saturday but moisture is limited
and only a few afternoon showers expected. Cooler and drier
conditions move in Sun-Mon as a cool area of high pressure builds
into the area. Temps will be above normal through Saturday then
cool to near normal Sunday. A warm up is expected again beginning
early next week.
.AVIATION...Cigs will gradually lower tonight but VFR conditions
still expected until around 12z. MVFR cigs expected with rain
becoming predominant Wednesday morning...continuing through the
day. Isolated thunder possible over ne Fl but will leave out of
TAFs due to low probability.
.MARINE...Low pressure system will move slowly from the Gulf into
the Atlantic...south of the waters Wednesday night through Thursday
night. East winds and seas will increase to Advisory levels for
mainly offshore zones Wednesday night through Friday. A cold front
will move across the waters late Saturday with Advisory conditions
possible again by Saturday night.
Rip Currents: Low risk today. Moderate risk on Wednesday as
onshore winds increase.
.PRELIMINARY POINT TEMPS/POPS...
AMG 61 75 61 78 / 30 50 20 20
SSI 62 69 63 73 / 30 50 40 20
JAX 61 74 63 77 / 30 70 50 40
SGJ 62 74 64 76 / 30 80 60 50
GNV 61 74 62 79 / 30 90 50 40
OCF 62 74 62 78 / 40 90 50 40