Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 200531

Area Forecast Discussion
National Weather Service Mobile AL
1231 AM CDT Sat Oct 20 2018

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


20/06Z issuance...Mostly VFR conditions through 20.08z at TAF
sites, but a few lingering showers over interior portions of
southwest Alabama to the north and south out over the Gulf waters
as well. Mainly MVFR cigs and visibilities through 20.08z through
20.15z with intermittent IFR fog. Scattered showers and
thunderstorms developing with a frontal passage from late Saturday
morning through much of the afternoon, with ocnl MVFR to perhaps brief
IFR conditions possible. Winds becoming mostly light and variable
overnight, followed by light southwest to westerly flow of 6 to 8
knots Saturday late morning and becoming more northerly during the
afternoon and overnight. 12/DS


.PREV DISCUSSION... /issued 732 PM CDT Fri Oct 19 2018/

DISCUSSION...Updated for latest aviation discussion below.

20/00z issuance...Mostly VFR conditions through 20.06z at TAF
sites, but a few lingering showers and storms over interior
portions of southwest Alabama to the north and south out over the
Gulf waters as well. Mainly MVFR cigs and visibilities through
20.13z with intermittent IFR fog around sunrise Saturday.
Scattered showers and thunderstorms Saturday afternoon, with ocnl
MVFR to IFR conditions. Winds becoming mostly light and variable
overnight, followed by light southwest to westerly flow of 6 to 8
kts Saturday late morning through afternoon. 12/DS

PREV DISCUSSION... /issued 350 PM CDT Fri Oct 19 2018/

NEAR TERM /Now Through Saturday/...A broad upper ridge of high
pressure stretching west from the western Atlantic to the TX coast
will continue to shift slowly east and south through Sat
afternoon in response to a deepening upper trof digging south over
the Great Lakes and northeast conus shifting east, combined with
strong surface ridge of high pressure on the back side of the
upper trof to the north diving southeast across MS river valley
and se conus late Sat night into early Sun. A strong cold front is
associated with this pattern a will approach the forecast area
from the north by late Sat afternoon. Ahead and along the front
expect better rain chances, mostly scattered in coverage, to occur
mostly during the late morning and afternoon hours on Sat. Model
soundings depict limited instability and moisture with this
pattern on Sat suggesting mostly moderate rainshowers with
isolated embedded thunderstorms through Sat afternoon. Limited
vertical shear is also noted through Sat afternoon suggesting
mostly general thunderstorms if they do occur. With antecedent
conditions on the dry side now and lack of heavy rainfall through
Sat the threat for flooding or nuisance flooding remains low to
nil. For tonight we will mention areas of fog for all locations in
the forecast area and monitor closely for dense fog this evening
and overnight.

Temperatures will continue to be above seasonal norms through Sat
afternoon with lows tonight ranging from the low to middle 60s for
most inland areas and the lower to middle 70s along the immediate
coast. Highs Sat will range from the middle 70s to near 80 over
the northern half of the forecast area and the lower to middle 80s
further south, stretching to the immediate coast. 32/ee

SHORT TERM /Saturday night Through Monday night/...The large
upper trough over the eastern conus moves off into the western
Atlantic through Sunday as a dome of cool high pressure builds
from the Plains into the eastern states. Clearing skies and cool
temperatures will return through the remainder of the weekend in
the wake of the cold front. Increasing clouds and rain will return
to the region late Monday night as the surface high pressure
system pulls eastward, allowing moisture to return to the area on
southerly winds. Low temperatures Saturday night will dip to
between 45 and 50 degrees inland to the mid 50s near the coast,
and Sunday night will be even cooler with lows around 40 degrees
inland to the upper 40s at the coast. Highs on Sunday will be in
the mid 60s to lower 70s, and slightly warmer on Monday.

LONG TERM /Tuesday Through Friday/...Another series of shortwaves
(ejected from an upper trof over the southwestern states) which
move across Texas and then across the northern Gulf coast Tuesday
and Wednesday. In response to the series of shortwaves, an
inverted surface trof developing near the Texas coast/western Gulf
is expected to evolve into a surface low which advances eastward
across the northern Gulf or into the north central Gulf coastal
states later in the period. While the timing and placement of this
surface low is highly uncertain, the overall pattern at least
supports a return of rain chances to the forecast. For now, will
have dry conditions for most of the area on Monday then slight
chance to chance pops follow for Tuesday and Wednesday and have
gone with good chance pops for Thursday. Temperatures during the
period will generally be near seasonable values. /22

MARINE...A light southerly flow is expected through late tonight
followed by a light to moderate west to northwest wind flow
through Sat afternoon. A strong northerly wind flow is expected by
early Sat night and will continue through Sun morning in the wake
of a strong cold front, then become northeast and gradually
diminish through Sun evening. A moderate easterly flow is expected
by early next week then gradually diminish through midweek. Small
craft advisories will likely be required in the wake of front by
early Sat night and continue through early Sun afternoon, followed
by exercise caution conditions through early Mon. 32/ee




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