Area Forecast Discussion
Issued by NWS Mobile, AL
FXUS64 KMOB 311117 AAA
Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
617 AM CDT TUE MAY 31 2016
.DISCUSSION...Updated for latest aviation discussion below.
12Z issuance...General VFR cigs/visbys expected through the forecast.
Isolated shra/tsra forming south of the coast this morning along a
land breeze will transition to Gulf breeze created shra/tsra this
.PREV DISCUSSION... /issued 511 AM CDT TUE MAY 31 2016/
NEAR TERM /Now Through Tuesday night/...
An upper trough over the SE Conus Atlantic seaboard fills a bit, as
Bonnie weakens over the Carolinas. With a seasonably hot day
expected over the Southeast, a surface trough forms over the
Southeastern states, again allowing the formation of Gulf breeze and
its movement inland this afternoon.
With a weak surface ridge forming over the north-central Gulf today,
replacing the surface ridge over the Mississippi River Valley the
last few days, a general southwesterly synoptic flow works with the
Gulf breeze, allowing a better inland penetration of the Gulf breeze
along with any resulting TSRA outflows, as apposed to a more limited
concentration of storms over the I10 corridor Monday, so have went
with a more general scattered coverage over the fa today. Also, with
a greater coverage of TSRA possible today, any activity lasting into
the evening is more likely than the previous days, so have included
evening TSRA. With a surface ridge building north from Latin America
over the Gulf of Mexico, temps above seasonal expected, especially
when combined with precip h20 values (around 1.6") above seasonal
As with any storm this time of the year, there is a small chance of
a storm or two becoming strong to severe, with localized damaging
downburst winds possible.
SHORT TERM /Wednesday Through Thursday night/...
Weak ridging, both at the surface and aloft, will continue across
the forecast area as we head into the start of meteorological
summer. As such, an isolated to scattered coverage of convection is
expected to develop along the sea breeze just onshore from the
coast. The convection will likely move inland during the afternoon,
with additional shower and thunderstorm development possible along
outflow boundaries as they interact with the mesoscale environment.
Any showers/thunderstorms should dissipate by mid-evening.
Forecast soundings continue to indicate sufficient instability for
convective development, with ML-CAPE values hovering around 1000
J/kg (give-or-take). With forcing expected to remain confined to
the mesoscale (or as the result of boundary interaction) and deep
layer shear practically non-existent, we`re not expecting a
significant threat of severe thunderstorms. However, given the
"inverted-V" nature noted in some of the forecast soundings, we
cannot rule out strong wind gusts with the stronger thunderstorms.
LONG TERM /Friday Through Monday/...
Changes will start to be noted in the overall weather pattern Friday
as an upper-level low over Central Texas moves east. This feature
will attempt to phase with a system in the northern tier of states
Friday, and push a weak cold front into the Mid-South and Lower
Mississippi Valley. Moisture is expected to deepen across the
northern Gulf Coast, as a south to southwesterly flow through (at
least) the mid-levels develops in response. Given all this, there
should be a west-to-east gradient in convective coverage Friday,
with the greatest coverage expected across Southeast Mississippi.
Evolutionary details of the storm system are bit murky thereafter.
It looks like the upper low may make a little more movement eastward
before filling and becoming more of an open wave. The surface
boundary should park itself somewhere near the the IH-65 corridor by
Saturday morning. A deep south to southwesterly flow is expected to
remain in place, allowing precipitable water values to approach 2
inches. The increased synoptic scale forcing in a moist airmass will
likely result in scattered to numerous showers and thunderstorms for
much of the upcoming weekend. Elevated odds of seeing showers and
thunderstorms will likely continue through Monday.
Right now, it looks like drier air should start to work its way into
the forecast area from the north/west by Monday night as the front
Overall, I have increased shower and thunderstorm probabilities with
this morning`s forecast. Some additional adjustment will likely be
needed heading toward the weekend. /02/
A weak surface ridge forming over the northern Gulf of Mexico will
create a light, general onshore flow through the forecast. Afternoon
formation of a Gulf breeze will create a temporary increase in the
onshore flow during the afternoon/early evening hours through the
week, with winds becoming moderate at times.
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