FXUS62 KJAX 220806
Area Forecast Discussion
National Weather Service Jacksonville FL
405 AM EDT Sun Jul 22 2018
...POTENTIAL OF A FEW SEVERE THUNDERSTORMS TODAY...
.NEAR TERM (Through tonight)...
An amplified mid/upper trough will continue to dig into the deep
south which will push another frontal boundary towards the area
while short wave energy rounds the base of the trough.
The added lift from the short wave as well as outflows... daytime
heating...and moderate amounts of instability and deep layer shear
will result in another active day of strong to possibly severe
storms. SPC has most of the region under a slight risk of severe
storms with damaging winds the main concern. Exact timing of storms
in question but it appears storms could get going as early as late
morning across the Gulf coast and move inland during the afternoon
with best coverage of storms between U.S. HWY 301 and I-75 during
the late afternoon and evening. Models indicating slightly hotter
afternoon temps in the lower to mid 90s combined with the humidity
will produce heat indices near advisory thresholds of 108 degrees.
Models are in general agreement that anomalous mid/upper level
trough/low pressure area over ern TN valley southward into the ern
GOMEX will retrograde slightly and weaken with 500 mb heights
rising. At sfc...broad low pressure centered over central GA with
trough extending to the south roughly through the FL big bend area
into the ern GOMEX will shift west in tandem through late Tue.
Monday...Daytime heating...cooler than normal temps aloft at 500 mb
around -8C...and sufficiently moist air-mass will lead to a chance
of storms. Some dry air aloft will help limit convective coverage to
about 40-50 percent. Shortwave disturbances rotating about the base
of the trough and 0-6 km bulk shear near 30 kt may result in some
organized convection...capable of producing strong to severe wx.
Isolated damaging wind gusts are the primary hazard but can't rule
out some hail given steeper mid level lapse rates and shear in the
hail growth zone. Highs forecast in the lower 90s. Mon
night...Isolated to scattered showers and storms expected in the
evening...but could continue well past midnight given added synoptic
forcing from the aforementioned mid/upper trough.
Tuesday...deep layer flow will back as the mid/upper level trough
shifts to the west a bit. With deeper southwest flow, moisture may
increase and result in better coverage of showers and storms. Will
probably go with high end chance to likely POPs, around 50-70
percent. Once again...bulk shear upwards of about 20-35 kt and aftn
destabilization will lead to a chance of some strong to potentially
severe storms. High temps may a bit lower closer to 90 due to higher
moisture levels and precip. Tue night...generally sct showers and
storms will slowly fade overnight with skies becoming partly cloudy.
The mid-upper level low and surface low across the southeast and
generally just west of the forecast area will linger on
Wednesday...then upper level ridging returns to central and southern
Florida Thu-Sat as the trough lifts northward and weakens. Overall
deep layer flow remains southwest continuing the trend for a
stronger Gulf coast seabreezes. Highest convective potential this
period appears to be on Wed with numerous showers and storms...then
a gradual trend toward more typical scattered showers and storms for
most areas to finish the week. Temps near normal are expected.
.AVIATION...Low clouds have developed again across much of the area
which will persist until around 14Z. Scattered afternoon storms
expected for Sunday afternoon and have VCTS at all terminals aft 16Z-
17Z. Amendments may be needed after that time for storms with strong
wind gusts and possible brief MVR/IFR.
.MARINE...Southwest flow will continue as low pressure develops over
the Carolinas and drops southward early next week. Speeds generally
in the 10-15 knot range may increase to cautionary levels offshore
early next week. Offshore moving storms with wind gusts of 35-50
knots will be possible today and possibly on Monday and
mariners/boaters will need to be prepared for rapidly changing
Rip Currents: Low risk today due to offshore flow. Have gone with a
moderate risk Ne Fl beaches Monday as the flow increases and becomes
onshore in the afternoon.
.PRELIMINARY POINT TEMPS/POPS...
AMG 92 72 90 73 / 40 40 50 30
SSI 93 76 88 77 / 40 40 50 50
JAX 94 73 91 74 / 40 40 50 30
SGJ 94 76 90 75 / 60 40 40 20
GNV 92 74 90 73 / 60 40 40 20
OCF 90 75 89 74 / 60 50 40 30
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