Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 240001 AAA

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
701 PM CDT Tue Jul 23 2019

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


00Z issuance...Showers and thunderstorms will end this evening as
a front moves through the area. VFR conditions will develop and
prevail through the remainder of the period. /13


.PREV DISCUSSION... /issued 324 PM CDT Tue Jul 23 2019/

NEAR TERM /Now Through Wednesday/...Showers and thunderstorms are
ongoing this afternoon along a front pushing through the local area.
Fed by abundant instability (MLCAPE ~2000 J/kg per 19Z mesoanalysis)
and deep-layer moisture (PWAT of 2.34 inches on this morning`s LIX
sounding), some storms ahead of the front have become strong enough
to produce locally-damaging winds in addition to frequent lightning
and torrential downpours. These hazards will remain possible through
this evening as the front and associated thunderstorm activity
continues to push towards the coast and offshore.

Northerly winds begin ushering in drier air tonight as the front
itself pushes into the northern Gulf of Mexico and stalls. Some
locations could approach record lows tonight as temps dip into the
mid 60s inland and upper 60s to around 70 along the coast. With
convection focused offshore along the front, carried little to no
rain chances for the area into Wednesday. Highs reach the mid 80s
west of I-65 and upper 80s to around 90 along the coast and east of
I-65. With dewpoints in the low 60s inland and mid to upper 60s
along the coast, should be a pleasant afternoon for July along the
Gulf coast. /49

SHORT TERM /Wednesday night Through Friday night/...
Surface front continues to push well off shore into the Gulf before
stalling Wednesday night into Thursday. This will allow overnight
temperatures and dew points to dip into the mid 60s for a second
night in a row. Dry conditions during the day Thursday are expected
across most of the Southeast with mean 1000-500mb RH values less
than 30% and PWATs less an inch. As a result little to no rain
chances are forecast. In addition, a 1024mb high pressure system
centered over the Ohio river valley is expected to maintain a light
northeasterly wind. The breeze should help the day time max
temperatures feel cooler, but regardless temperatures will be in the
upper 80s.

Friday, a rapidly moving shortwave north of the Great Lakes shifts
the high east. Locally this brings more easterly component to the
winds. The first half of the day should remain dry, but the
aforementioned stalled front may begin to lift north late Friday
afternoon as a surface boundary delineating between the dry
airmass over land and Gulf moisture. It is this same boundary that
the National Hurricane Center has outlooked for 20% chance of
tropical development over the next few days. Gulf waters remain
quite warm, so this frontal feature will continue to be monitored
throughout the week. Nevertheless depending on how far north this
boundary lifts rain chances could be increasing along the coast
Friday night into Saturday. /DJ/17

LONG TERM /Saturday Through Tuesday/...
A mid-level ridge over the southern Gulf begins to build during the
weekend. This ridge pushes the surface boundary and associated Gulf
Moisture northward overland. Precipitable water values over the
northern Gulf coast then rise to near 2.00 inches early Saturday
morning through Saturday. Scattered showers and isolated
thunderstorms should have an early start. CAPE values range around
1700-2000 J/kg in the late morning. Then with the additional moisture,
the convection in the afternoon may produce heavy rain with
localized nuisance flooding possible in poor drainage areas.
Temperatures Saturday remain relatively unchanged in the upper 80s
and low 90s inland. Residual cloudiness will keep overnight lows
in the low 70s.

Sunday through Tuesday sees a return to typical summerlike
conditions. The ridge which was once over the southern portion of
the Gulf migrates to the northern Gulf of Mexico. This keeps surface
winds light and variable through the beginning of next week. PWATs
above 1.8 inches and CAPE values above 2000 J/kg will provide plenty
of fuel for the afternoons showers and isolated thunderstorms. Long
range guidance has a trough axis moving through the Mississippi
River Valley Tuesday. The trailing weak front could enhance
convection Tuesday afternoon. As such opted to keep chance PoPs
through the end of the forecast package. DJ/17

MARINE...A light to occasionally moderate offshore flow develops
over the marine area tonight and lasts through Wednesday as a front
pushes offshore and stalls over the northern Gulf. A generally light
east to southeast flow sets up Thursday through the weekend as high
pressure builds into the northeastern Gulf. A weak surface low might
form along the stalled front by Thursday and conditions thereafter
could become marginally conducive for some development as it moves
north or northeastward late this week. The National Hurricane Center
has highlighted the northern Gulf with a 20 percent chance of
tropical development over the next 5 days. Will continue to monitor
this potential and provide updates as needed. /49




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