Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 210005
AFDMOB

Area Forecast Discussion
National Weather Service Mobile AL
705 PM CDT Thu Jul 20 2017

.DISCUSSION...Updated for latest aviation discussion below.

&&

.AVIATION...
21/00Z issuance...A few lingering convective cells over the
coastal counties through around 21/00Z, but no more than VCTS in
TAFS.Otherwise, VFR conditions through most of the period, with
VCTS again expected late tonight and early Friday morning, especially
near the coast, then scattered storms anywhere across the area during
the afternoon Friday. Light and variable surface winds tonight,
especially over inland areas, becoming more south to southeast
during the day on Friday. 12/DS

&&

.PREV DISCUSSION... /issued 401 PM CDT Thu Jul 20 2017/

NEAR TERM /Now Through Friday/...Latest radar loops show isolated
to scattered showers beginning to form over the western FL panhandle
moving southward towards the coast and offshore. Other light showers
were near the immediate coast of AL and MS moving west, forming near
and along a developing seabreeze front advancing inland over the
coastal counties of AL and NWFL. Further development will continue
through about 5 or 6 pm this afternoon then diminish slowly later
this afternoon and this evening as daytime heating begins to cool.
To the east broad mid to upper cut off low near the GA/SC coast is
still progged to shift SW then W through Fri afternoon reaching the
NWFL/AL/MS coastal areas and adjacent gulf waters by 00z Sat. With
this pattern expect increased coverage of showers and thunderstorms
beginning early Fri morning generally to the east and along the
immediate coast and offshore shifting inland by afternoon. Model
soundings show drier aloft in the boundary layer this afternoon
through sat afternoon along with slightly better lapse rates in the
lower levels and high values of instability suggesting a few storms
could be stronger compared to the last few days, possibly leading to
gusty straight line winds and frequent cloud to ground lightning
with the stronger cells. Pwats increase to 1.8 to 2.0 inches this
afternoon and continue through Fri afternoon suggesting periods of
heavy rain can be expected with most of the convection through Fri
afternoon. Due to the good movement to the southwest and west the
threat of flooding looks to be minimal through the next 24 hours.

Temperatures will continue to be on the warm side through Fri
afternoon with lows tonight ranging from the lower to middle 70s
inland and the mid to upper 70s along the immediate coast. Highs Fri
will range from the mid 90s for most inland areas and the lower 90s
near the immediate coast. Heat indices for Fri are expected to range
from 101 to 105 degrees. 32/ee

SHORT TERM /Friday night Through Sunday night/...A strong surface
ridge extending from the western Atlantic across the Gulf of Mexico
will persist through the short term, resulting in a light south
to southwesterly wind flow. Meanwhile the upper closed low just
south of the forecast area will drift slowly westward along the
northern gulf coast through Saturday afternoon then stall over the
northwest Gulf of Mexico. The low will eventually evolve into a
weak upper trough extending from southeast Texas to the southeast
conus Saturday night. A diurnal precipitation pattern will
continue across the forecast area through the short term.
Decreasing stability each day will result in scattered showers and
storms developing, followed by evening convection inland areas
dissipating. Some of the storms could be capable of producing
torrential downpours and frequent lightning.

Low temperatures each night will range from 72 to 75 degrees
inland areas, and from 76 to 79 degrees along the immediate
coast. High temperatures over the weekend will range from 88 to
93 degrees. The heat index will range from 98 to 103 degrees.
/22

LONG TERM /Monday Through Thursday/...An upper level trough
extending south-southwest from a larger northeast trough will
persist through the long term, while embedded shortwaves move
from northwest to southeast in the base. A surface ridge extending
from the western Atlantic across the Gulf of Mexico will remain
intact, resulting in a light and variable or light northwest wind
flow each night, followed by a developing light southwesterly flow
each afternoon. A diurnal precipitation pattern will continue
across the forecast area through the long term, with a few
afternoon storms capable of producing gusty surface winds,
torrential downpours, and frequent lightning. Little change in
temperatures through the long term. /22

MARINE...Surface high pressure will continue over the northern and
central gulf through the weekend though weaken somewhat late Fri
into early next week as an upper low to the east retrogrades to the
west generally along the northern gulf coast. With this pattern a
light south to southwest wind flow will develop later this afternoon
and this evening, then become light and variable late tonight and
early Fri, followed by a light to moderate southwest to westerly
flow through early next week. Rain chances begin to increase late
today and continue through early next week as better moisture and
lift associated with the upper system approaches from the east
combined with the moderate instability in place across much of the
region. A few strong storms will be possible this weekend especially
during the afternoon hours due to daytime heating. Thunderstorms are
expected to the move to the south and southwest through early next
week. With the better flow from the southwest seas are expected to
build to around 2 feet over the weekend then 2 to 3 feet by early
next week. 32/ee

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...None.
FL...None.
MS...None.
GM...None.
&&

$$

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