Area Forecast Discussion
Issued by NWS Jacksonville, FL

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FXUS62 KJAX 210821

Area Forecast Discussion
National Weather Service Jacksonville FL
420 AM EDT Sat Jul 21 2018


.NEAR TERM (Through tonight)...

Surface low along the Carolina coast and lifts northeast bringing
slightly drier air and lower rain chances to start out the day
across much of the area with the exception of the extreme southern
counties where there will still be enough deep moisture in place
with a continued chance of storms there. Continued consistency
between the MAV...ECS...and most of the high-res models on pops
increasing from late afternoon and possibly continuing into a
portion of the overnite hours as a possible MCS tracks Se across the
area as another surface low develops across the Carolinas. Model
soundings indicate deep layer shear increasing and combined with
heating could produce severe storms with damaging winds and hail and
a low chance of tornadoes. SPC has most of the area (except the far
south) under a marginal risk of severe wx and a slight risk for Se
Ga generally from a north of Homerville to Jesup line. Given more
heating for today...high temps will reach the lower 90s across much
of the area and combined with the humidity will produce heat indices
of 100 to 105 degrees.


Models show broad cyclonic flow in our area south of a broad low
pressure area over the Carolinas. Low level flow is mainly west to
southwest over the region with deep layer moisture somewhat limited
at least initially. GFS shows PWAT values of 1.6 inches or less
north of I-10 and up to 1.9 inches over the srn most areas.
Moisture may increase through the day south of a sfc trough that
will extend from SC west-southwest to srn AL. Additional shortwave
energy will drop in over southeast GA aiding convective vigor. Some
uncertainty of how convection evolves as early day convection is
possible which would disrupt daytime heating. Convection will be
moving relatively quickly at about 25 mph, given uniform westerly
wind profiles and main threat will be strong to potentially damaging
wind gusts. Anticipate high end sct to numerous storms with beaches
and coastal waters under the gun for thunderstorms as well. SPC has
highlighted most of the area in a slight risk of severe storms.

Hotter temps than prior days may be realized with highs of 90-
95...with coastal areas not seeing any sea breeze relief to keep
them cooler. Heat indices top out at about 107.

Sunday night...sfc low over the Carolinas will move southwest to
south central GA and trough will push through the wrn FL panhandle,
which may help move convection further southward with time.
Scattered evening convection will fade slowly with loss of heating
and skies become partly cloudy overnight with lows in the mid 70s.

Monday...Mid and upper level low will cut-off from the ern U.S.
trough over central GA/ern AL. Temps aloft at 500 mb around -8C and
sufficiently moist air-mass will lead to a good chance of showers
and storms. Steep low level lapse rates will result in gusty winds
with any stronger storms but can`t rule a storm or two with
marginally severe hail given cooler temps aloft. Highs will persist
in the lower 90s again. Mon night...sfc low over GA and the upper
level support will slowly retrograde backing low level winds to more
southerly component. Chance of showers and storms in the evening
will slowly fade after midnight.

The mid-upper level low and sfc low across the southeast states will
slowly lift out to the northeast and weaken, which will allow sfc-
mid level ridge to build back over most of central and south FL
during the week... closer to climatology norm. Overall deep layer
flow remains south-southwest 15-25 kt until Friday when is weakens
to 10-15 kt. The flow will favor moisture levels to remain at least
near or above normal...and as a result scattered to numerous showers
and storms...with highest chances especially over northeast FL.
Temperatures are expected to be near normal this period.


.AVIATION...Low clouds have developed across much of the area and
will persist this morning until around 14Z. Lower coverage of storms
expected today and have VCSH at all terminals.
A complex of storms (MCS) may track across the area sometime from
late this afternoon into the evening. Amendments may be needed
especially at SSI...JAX... VQQ...and CRG in the 20Z-06Z time frame.


.MARINE...Southwest winds decrease some today as the surface low
across  the Carolinas lifts northeast ..but increase again to
cautionary levels Sunday into early next week as another surface low
develops across the Carolinas and drops south which will tighten the
gradient. Fast moving showers and storms will be moving offshore
with bulk of activity in the afternoon and evening. Some storms may
be strong or severe.

Rip Currents: Low risk through Sunday due to offshore flow.


AMG  92  75  92  73 /  40  40  40  30
SSI  90  78  93  77 /  30  40  50  40
JAX  92  75  94  74 /  30  30  50  40
SGJ  92  77  94  75 /  20  20  40  40
GNV  92  76  92  75 /  30  30  40  40
OCF  90  76  91  75 /  40  30  30  30





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