FXUS64 KMOB 170055 AAB

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
655 PM CST Sat Feb 16 2019

.DISCUSSION...See updated information for land areas below.


.UPDATE...Bouy 42012 data 14 miles south of Orange Beach Alabama
are showing swell heights have come down to 2 feet, with a period
of 5 seconds. Wind observations along the Alabama and western
Florida panhandle beaches have decreased to less than 10 knots.
Tidal ranges remain at or just below 2 feet, but we are currently
going into high tide. This equates to a moderate risk of rip
currents, therefore allowed the high risk to expire at 6 pm. A
moderate risk will likley remain through early next week. Updated
products have been sent. /22


.PREV DISCUSSION... /issued 540 PM CST Sat Feb 16 2019/

DISCUSSION...Updated for latest aviation discussion below.

00Z issuance...VFR conditions will remain through midnight, with
the exception of ongoing MVFR and IFR ceilings along the immediate
gulf coast. These MVFR and IFR ceilings, along with some fog
developing, will very slowly move northward over the TAF sites
after 08z through much of the day Sunday. Any fog that develops
will dissipate by mid Sunday morning along with ceilings improving
to MVFR. A light southerly wind will remain through the next 24
hours. /22

PREV DISCUSSION... /issued 400 PM CST Sat Feb 16 2019/

NEAR TERM /Now Through Sunday/...An upper trof over the western
states evolves into an expansive, positively tilted trof extending
from the southwest states to the Great Lakes region. An
associated surface low advances along the Red River valley into
Arkansas tonight while a weak frontal boundary over the forecast
area moves well north of the area tonight. As the weak boundary
returns northward, a light southerly flow initially over the
coastal counties develops over the remainder of the area
overnight. Surface dewpoints will be mainly in the lower 60s
tonight then climb into the mid to upper 60s on Sunday. Patchy to
areas of fog are expected to develop overnight, with the better
coverage over the southern portion of the area where the longest
duration of the light southerly flow will exist. The potential for
dense fog development is less certain as for one thing, water
temperatures in the bay and near shore waters are mainly in the
lower 60s which are close to the surface dewpoint values at least
through tonight. The surface low moves off into the northeast
states on Sunday and brings a trailing cold front across the lower
Mississippi river valley to near the I- 65 corridor by late
Sunday afternoon. Dry conditions prevail tonight, followed by pops
increasing to chance to likely roughly along/west of I-65 as the
front moves into the area, with the highest over part of interior
southeast Mississippi and interior southwest Alabama. Slight
chance to chance pops are generally expected east of I-65. A high
risk of rip currents continues until 6 pm, after which a moderate
risk of rip currents is expected through Sunday. /29

SHORT TERM /Sunday night Through Tuesday night/...A moist
southwesterly flow pattern aloft will prevail across the region
through early next week well in advance of a deepening upper level
trough over the western CONUS. A cold front will push
southeastward across our region Sunday evening into late Sunday
night, and will remain well offshore through the day Monday.
Increased deep layer moisture and ascent along the frontal zone
will bring a good chance of rain showers to the forecast area
Sunday evening into late Sunday night, especially over interior
portions of the region. Patchy to areas of fog may re-develop near
the coast Sunday evening prior to frontal passage. The axis of
deeper moisture will become oriented over our central and southern
zones during the day Monday, where we will keep a low chance of
rain showers in place through the daytime hours. Cooler
temperatures are expected Sunday night and Monday behind the
front. Overnight lows Sunday night are forecast to range in the
upper 40s to mid 50s across locations roughly to the northwest of
I-65, and in the mid 50s to around 60 degrees over the
southeastern part of the area. Highs on Monday should mostly range
in the lower to mid 60s.

Deep layer moisture will continue to increase across the forecast
area Tuesday and Tuesday night as embedded shortwave impulses move
across the region within the southwest flow pattern aloft. Surface
flow is also expected to become southeasterly to southerly Tuesday
into Tuesday night as the boundary over the northern Gulf retreats
as a warm front across our region. Scattered to numerous rain
showers and a few thunderstorms are expected to develop over the
area Tuesday into Tuesday night. Highs Tuesday warm into the mid
to upper 60s, with increased low level moisture also bringing
milder lows in the upper 50s to mid 60s Tuesday night. /21

LONG TERM /Wednesday Through Saturday/...The moist southwesterly
flow pattern aloft will persist into the middle to latter half of
the week in advance of the persistent upper level trough over the
western U.S. Embedded shortwave impulses in the flow pattern along
with an approaching surface boundary that may tend to stall over
our forecast area will result in a continued good chance of
showers and a few thunderstorms each day Wednesday through the end
of the week. The latest medium range guidance continues to place
the heaviest rainfall totals to the north and west of our area mid
to late in the week underneath the region of strongest forcing.
However, there is potential for locally heavy rainfall amounts of
1 to 3 inches across our region through Friday, with the higher
amounts focused over southeast Mississippi and interior southwest
Alabama. We still may have to monitor for a few strong to
marginally severe storms Wednesday and Thursday where deep layer
shear and elevated instability will be in place near the stalled
surface boundary. A chance of showers and a few storms may linger
into Saturday before a stronger cold front potentially pushes
through our area late Saturday into Sunday (just beyond this
forecast period). Temperatures will remain above normal through
Saturday. /21

MARINE...Light southerly winds continue through Sunday while a
cold front approaches from the west. A moderate to strong
northerly flow develops late Sunday night into Monday morning as
the front moves through, then transitions to a strong easterly
flow by Monday night. A southeast flow follows on Tuesday then
subsides to a light to moderate southerly flow Wednesday into
Thursday. A Small Craft Advisory may be required Monday afternoon
through Tuesday evening. /29




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