581
FXUS64 KMOB 151602
AFDMOB

Area Forecast Discussion
National Weather Service Mobile AL
1102 AM CDT Sun Sep 15 2024

...New UPDATE...

.MESOSCALE UPDATE...
Issued at 1102 AM CDT Sun Sep 15 2024

15.12Z upper air analysis shows a west northwest flow pattern at
high levels over the central Gulf coast, southwest of a H20/H30
upper low over the central Appalachians. Within the westerlies
aloft, a series of jet streak maxima (ranging 70-90kts) was
analyzed within the southern stream. Working down into the
mid/lower levels, forecasters see a complex low pressure system
situated from the Mid-South to southwest MS, with a few trough
axis spokes extending out from the low which are providing a focus
for ascent within a moist and modestly unstable local environment
characterized by SB Capes ranging 1000-2000 J/KG. A look at
15.12Z pwat values along the central Gulf shows highest values =>
1.87" (LIX) being right near 1 standard deviation above the
climatological means for mid September. At the surface, a quasi-
stationary front was draped west to east across the central Gulf
coast. Along the boundary, a wave of frontal low pressure was
analyzed along the MS Sound. Radar shows returns lifting
northward over the interior in response to the more southerly
component in layer flow east of the low/mid level low pressure
system, while returns near and south of the coast are tracking
more eastward along and south of the surface front. Considering
the players mentioned to enhance forced ascent, environmental
instability and sufficient deep layer moisture, showers and storms
are forecast to trend higher in areal coverage through the
remainder of the day. The weakened state of bulk shear values at
this time, suggest that storms will remain sub-severe. The main
threats in storms today look to being efficient, locally heavy
rain rates and perhaps instances of flooding in those areas
subject to poor drainage where storms move over/or slowly across
the same areas. It is difficult to nail down just where the
heaviest rain axis develops as convection is just beginning. But
moving forward, forecasters anticipate a general area of excessive
rain/slight risk of localized flooding to be aligned along and
west of a line from Butler to Grove Hill to Atmore AL to Ft.
Walton Beach FL. Mobile and Baldwin Co`s may see an increased
threat of flooding rains. There is also the possibility of a few
waterspouts near shore. /10

&&

.PREV DISCUSSION... /issued 658 AM CDT Sun Sep 15 2024/

..New AVIATION...

AVIATION...
(12Z TAFS)
Issued at 658 AM CDT Sun Sep 15 2024

MVFR to IFR ceilings will impact much of interior south central
and southwest AL and portions of the western FL panhandle early
this morning. Ceilings should become predominantly MVFR over these
areas by around 15Z and generally linger through the afternoon.
Scattered to numerous showers and thunderstorms will develop,
especially by this afternoon. Convective activity will be
efficient rainfall producers and will have reduced visibility to
MVFR to IFR thresholds. MVFR to IFR ceilings will develop over
all of our region after 03-06Z this evening and linger into the
overnight hours. Potential also continues for scattered overnight
showers and storms, some with locally heavy rainfall and localized
visibility restrictions to IFR. /21

PREV DISCUSSION... /issued 507 AM CDT Sun Sep 15 2024/

.New NEAR TERM, SHORT TERM, LONG TERM, MARINE...

NEAR TERM...
(Now through Monday)
Issued at 507 AM CDT Sun Sep 15 2024

The remnant mid level circulation from Francine remains located in
the vicinity of northern MS early this morning. A weak surface
boundary has become draped from portions of MS and into coastal AL.
Most areas are starting off dry early this morning with the
exception of a few light rain showers that are drifting NW over
interior southwest and south central AL as of 430 AM.

A more unsettled weather pattern is expected to take shape across
our forecast area today and tonight. The mid level low pressure
system is forecast to slowly retrograde westward over northern and
northwestern MS through tonight. A weak surface low pressure system
is also expected to slowly meander/drift westward over southern MS
and southeastern LA through this evening. The surface boundary
should become oriented from interior parts of southeast MS and into
coastal portions of AL/the far southwestern FL panhandle today and
tonight. Deep layer moisture should pool along the boundary with
precipitable water values increasing to 1.9 to 2.2 inches per some
of the latest CAMs and short range forecast model guidance. Low
level convergence along the boundary along with weak shortwave
impulses along the base of the mid level trough will support the
development of numerous showers and thunderstorms later this morning
and especially during the afternoon/evening hours. A narrow band of
enhanced instability with MLCAPE values up to 1000-1500 J/KG also
looks to become oriented over the region today. Convection may have
a tendency to develop and train over southwest AL/southeast MS this
afternoon and evening, generally moving from S/SE to N/NW in the
relatively light deep layer south/southeasterly flow regime. There
will be increased concerns for heavy rainfall, especially with
convection that may tend to train over a few locations. Showers and
storms may also be efficient rainfall producers considering the
deeply moist airmass that will be in place. Some locations may pick
up in excess of 1-3" of rain with locally higher amounts in excess
of 4+" within a relatively short period of time. While the overall
confidence in exceeding FFG values remains low enough to preclude
the issuance of a Flood Watch, we will be messaging at least a
limited potential for flash flooding over southeast MS and portions
of southwest AL and the far western FL panhandle through this
evening. The 00Z WRF-ARW and 06Z HRRR, along with 00Z HREF ensemble
probability matched mean products have been showing potential
localized bullseye QPF values in excess of 4-5" over portions of
Mobile, Baldwin, and perhaps even into far southwest Escambia FL
counties through late tonight and we may have to monitor these
locations closely for an elevated flash flood potential through the
next 24 hours.

The unsettled weather pattern continues into Monday as broad
troughing remains in place over our region between Francine`s
retrograding mid level circulation and the next tropical or
subtropical system that will be pivoting into the Carolinas.
Precipitable water values will remain enhanced between 1.8 and 2
inches across our region along the residual surface boundary. We
will maintain high chances (50-70%) of showers and thunderstorms
across the forecast area again Monday and we may have to once again
watch for pockets of heavy rainfall and localized flooding concerns.
High temperatures will be cooler today and Monday, generally only
reaching around 80 to the lower 80s over interior areas, with a few
locations in the mid 80s. Lows tonight are forecast to range in the
upper 60s over interior communities and in the lower 70s along the
immediate coast. A LOW rip current risk continues along area
beaches for the next several days. /21

SHORT AND LONG TERM...
(Monday night through Saturday)
Issued at 507 AM CDT Sun Sep 15 2024

Rain chances will remain elevated through Tuesday as an upper low
meanders over the Carolinas and into the Tennessee Valley. This
places the base of the upper trough over the local area. At the
same time, a lingering surface boundary will be positioned along
coastal portions of the area with a general west to east
orientation. Deterministic guidance indicates this front may try
to lift slightly northward on Tuesday with a subtle surface low
lingering along the front. The combination of this surface
boundary, lower heights aloft, and PWATs around 1.8-2 inches will
aid in the development of showers and storms on Tuesday and into
Tuesday evening. Given the placement of the surface front, the
higher rain chances are expected to be focused along the southern
two thirds of the area and especially closer to the coast where
the current forecast has scattered to numerous showers and storms.
Similar to the last few days, these storms will be capable of
producing heavy rainfall which could lead to some localized
flooding concerns on Tuesday.

The good news is that the pattern will trend drier on Wednesday
and especially into the latter part of the week. The upper low
over the Tennessee Valley will amplify and slide southeastward
through Saturday as upper ridging over the Mississippi Valley
builds further overhead. The aforementioned surface boundary will
also become diffuse over the Gulf waters during this time. This
will place the local area within deep layer northwesterly to
northerly flow through Saturday. While there may be an isolated
shower or storm over eastern portions of the area on Wednesday,
the presence of much drier air will keep rain free conditions in
place through the remainder of the week. High temperatures will
trend higher as ridging builds east with values rising into the
upper 80s and to around 90 degrees by Thursday and Friday. /14

MARINE...
Issued at 507 AM CDT Sun Sep 15 2024

Winds/waves will be locally higher near scattered to numerous marine
storms that will develop today and into the early part of the week.
Light and variable flow this morning will become light southerly to
southeasterly this afternoon. A generally light to occasionally
moderate easterly flow will return Sunday night into the early part
of the week. Winds become light and variable in direction again by
midweek. /21

&&

.PRELIMINARY POINT TEMPS/POPS...
Mobile      70  84  68  84  68  87  70  89 /  50  70  40  50  10  10   0  10
Pensacola   72  83  72  83  72  86  72  89 /  60  70  50  60  10  20   0  10
Destin      72  82  73  84  73  86  73  89 /  60  60  50  50  20  20   0  10
Evergreen   67  83  65  86  66  89  65  91 /  60  60  30  40  10  10   0  10
Waynesboro  68  80  65  84  64  86  63  89 /  60  70  20  30   0  10   0   0
Camden      67  79  65  83  64  85  63  87 /  60  50  30  20   0  10   0   0
Crestview   69  84  68  85  67  88  67  91 /  50  60  40  50  10  20   0  10

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...None.
FL...None.
MS...None.
GM...None.
&&

$$

This product is also available on the web at:
www.weather.gov/mob