Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 172120

Area Forecast Discussion
National Weather Service Mobile AL
420 PM CDT Sat Mar 17 2018

.NEAR TERM /Now Through Sunday/...A cold front will move into the
Tennessee Valley this evening then slowly sink southward and stall
across south central Mississippi and Alabama on Sunday. South of the
this front, a very moist airmass will remain in the place with
dewpoints in the mid 60s. This afternoon daytime heating is
generating scattered showers and isolated thunderstorms across
portions of the area. These will continue through early evening
before dissipating tonight as the boundary layer cools. Although an
isolated shower is possible overnight, most areas will remain dry.
The increased moisture and light winds will allow for at least
patchy dense fog to develop late tonight into Sunday morning. Lows
tonight fall into the low 60s inland to mid 60s along the coast.

A shortwave is expected to generate showers and storms across
eastern Texas this evening which may congeal into an MCS and move
eastward along the stalled front overnight. Depending on how well
developed the convection becomes, it could act to enhance
thunderstorm development on Sunday. Meanwhile, the airmass along and
south of the stalled front is expected to become moderately unstable
by tomorrow afternoon with MLCAPE values around 1000 J/Kg. In
addition strong deep layer shear of 50 to 60 knots is expected. As a
result, any cells that develop near or just south of the boundary
will be capable of becoming severe with damaging winds and large
hail. An isolated tornado is also possible due to the enhanced shear
near the front. This is where the Storm Prediction Center has
outlined a slight risk of severe storms, roughly north and west of a
line from Leakesville to Evergreen to Greenville. /13

.SHORT TERM /Sunday night Through Tuesday night/...An upper level
shortwave over the Great Plains pushes east into the Mississippi
River Valley Sunday night into Monday morning. Ahead of this
system, onshore flow will continue to pump Gulf moisture into
local area and convection will likely be ongoing along and south
of a quasi-stationary front draped across the Mid South. Despite
the loss of diabatic heating after sunset, an EML overspreading
the region from the west will maintain at least a modest amount of
elevated instability throughout the night, with MUCAPE remaining
around 1500 J/kg per latest guidance. Thus, expect storms to
continue during the overnight hours Sunday night into Monday.
Effective bulk shear around 50 knots and mid-level lapse rates
increasing to around 7.0 C/km (courtesy the aforementioned EML)
will support the chance for some strong to possibly severe
thunderstorms capable of producing large hail and gusty straight-
line winds.

The ingredients for strong to severe storms linger throughout the
day Monday as the upper trough and attendant surface low continue
to push east into the Tennessee Valley. The return of daytime
heating results in further destabilization of the warm sector,
with guidance continuing to suggest upwards of 2500 J/kg SBCAPE
developing during afternoon hours. Strengthening 850 mb flow
supports effective bulk shear values around 50 knots, meaning
storms that are able to form will have the chance to organize and
become strong to severe. However, there is some uncertainty
regarding convective initiation Monday afternoon, as some high-
res guidance suggests warm 850 mb temperatures maintaining a
capping inversion over our area through much of the day, and the
best forcing to overcome this cap would stay primarily to our
north in closer proximity to the surface low and upper shortwave.
Due to this uncertainty, have kept the best chances for strong to
severe thunderstorms on Monday over the northeastern portion of
the local area, where the best forcing will likely be realized
before the cold front eventually sweeps through. There is a
marginal risk across the remainder of the area, as any storms that
are able to form will be capable of organizing and becoming
strong to severe as well. The primary threats will be large hail
and damaging straight-line winds. Please see the Storm Prediction
Center website ( or our homepage
( for the latest information regarding severe
weather potential Sunday night and Monday.

The cold front passes through Tuesday morning, effectively ending
rain chances and ushering in cool and dry air to finish off the
short term period. Tuesday night lows will be much cooler as a
result, dipping into the low 40s across the area. /49

.LONG TERM /Wednesday Through Saturday/...A deepening upper
longwave trough over the eastern CONUS pushes east over the
Atlantic Ocean through the long term, with dry deep-layer
northwest flow setting up over the local area as an upper ridge
builds to our west. Will see cool and dry conditions beneath
mostly clear skies Wednesday through the remainder of the week as
a result. Highs reach the mid and upper 60s each day and lows dip
into the upper 30s to low 40s each night. /49


.MARINE...A predominantly light to occasionally moderate south to
southwest flow is expected to continue over the coastal waters
through Monday as Atlantic high pressure continues to ridge west
across the eastern Gulf and a frontal boundary remains nearly
stationary well to the north of the marine area. A stronger cold
front approaches the marine area Monday night and is expected to
move east across the coastal waters Tuesday with winds shifting to
the northwest and increasing, along with building seas. /13


Mobile      63  77  64  81  58  70  44  67 /  20  50  60  50  10  10   0   0
Pensacola   65  76  67  79  63  72  47  66 /  20  50  60  70  20  10  10   0
Destin      65  73  67  76  66  72  50  65 /  20  50  60  70  30  10  10   0
Evergreen   63  77  64  83  59  72  42  66 /  20  70  60  60  30  10  10   0
Waynesboro  61  75  63  82  54  65  41  65 /  30  70  60  30  30  10  10   0
Camden      62  74  63  81  57  68  42  63 /  20  70  70  50  30  20  10   0
Crestview   63  77  66  81  62  74  44  67 /  20  60  60  70  30  10  10   0




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