Gale Watch 3, NWS Mobile, AL

Area Forecast Discussion
National Weather Service Mobile AL
201 PM CST Sun Jan 7 2024

...New AVIATION, NEAR TERM...

.AVIATION...
(18Z TAFS)
Issued at 201 PM CST Sun Jan 7 2024

VFR conditions will continue with a light easterly wind through
the forecast. A highly impactful system will move across the area
just outside the forecast period Monday night into Tuesday with
high low level wind shear, severe thunderstorms and reduced
ceilings and visbys. BB/03

&&

.NEAR TERM...
(Now through Monday)
Issued at 201 PM CST Sun Jan 7 2024

Dry and cool conditions persist today as a surface high pressure
drifts eastward across the area and weak shortwave ridging moves
overhead. Temperatures will top out in the upper 50s and lower 60s
later this afternoon with some passing upper level clouds expected
through the day. Northerly winds gradually shift to the east
overnight as the high pressure moves into the Tennessee Valley with
lows falling into the middle 30s to middle 40s.

Our next impactful system moves in to the area early this week and
will bring the potential for severe weather, strong gradient winds,
coastal hazards, and flash flooding. A very potent upper level low
will swing across the South Central US on Monday, before ejecting
into the Ohio River valley Monday into Tuesday. The associated
surface low pressure will follow a similar path with it's central
pressure dropping below 990 mb as it lifts out of the Mississippi
Valley Tuesday morning. The overall setup will support very strong
jet dynamics and synoptic forcing with guidance indicating a 120 to
130 knots upper level jet rounding the base of the upper low Monday
night and Tuesday morning. A low level jet of 70 to 80 knots is also
expected to develop over the area during this time frame so needless
to say there will be plenty of deep layer shear to support organized
convection.

Showers and a few elevated thunderstorms will begin to develop
across the area by Monday afternoon as the warm front lifts
northward across the Gulf. Coverage will become more widespread
Monday night along with the potential for severe weather. As the low
level jet strengthens overnight and the warm front lifts, there will
be a period after midnight Monday through Tuesday morning where rich
Gulf moisture advects northward and better instability will attempt
to work onshore. Given the kinematics in place and the presence of a
marine boundary layer things could get interesting with a higher end
severe environment possible. If this were to occur, storms would be
capable of rather intense damaging winds gusts and tornadoes given
the dynamic setup of this system. The question is does the
instability arrive and is it coupled with the intense dynamics
overhead to overcome the intense shear values or will the convection
early in the day limit that instability. If the instability does
make it onshore and the forcing can help maintain storms then the
environment will be primed for a very active morning in terms of
severe storms. Two focuses for severe would likely occur with the
potential for supercells along the advancing marine boundary along
the I-10 corridor and then the main punch with a powerful QLCS along
the front sweeping west to east. Both threats would have the
potential to bring damaging winds and tornadoes. The cold front will
move through the area Tuesday morning with rain chances tapering off
through the day.

In addition to the severe threat, this system will also bring a
multitude of other hazards..

1) Strong Winds...The anomalously strong surface low will produce a
very tight pressure gradient across the area which will result in
winds gusts of 40-50 mph developing outside of thunderstorms. These
kinds of winds will make trees and power lines more susceptible to
being blown over outside of any thunderstorms so it will be very
important to have multiple ways to receive warnings Monday night and
Tuesday morning. A Wind Advisory will likely be issued later today.

2) Heavy Rainfall and Flash Flood Threat...Confidence in the flash
flood potential is beginning to increase. Deep layer moisture will
spread across the area as a strong low level jet develops with PWAT
values (generally 1.5 to 1.75 inches) near the climatological max
for this time of year. This moisture and strong low level
convergence will likely result in high rainfall rates which could
lead to flooding concerns especially in areas where storms
repeatedly move over the same areas. The current forecast has
widespread 2-4 inches of rainfall accumulations with local totals up
to 6 inches possible. WPC has introduced a Moderate risk for flash
flooding and a Flash Flood Watch may become necessary future updates.

3) Beach/Coastal Hazards...A very strong onshore flow will develop
on Monday given the anomalously low pressure and tight gradient
winds. This will result in solid Gale Conditions and possible Storm
Force conditions over the offshore Gulf waters. Given the incredibly
long fetch of strong winds, seas will quickly climb to high surf
warning criteria. Surf heights along the coast Monday night through
Tuesday will likely approach 11 feet leading to beach erosion, life
threatening surf and rip currents. On top of the intense wave
action, strong low level winds will also push water leading to
coastal flooding. Current PETSS guidance supports at least solid
coastal flooding advisory conditions with higher end potentials
reaching coastal flood warning criteria Monday evening. A coastal
flood advisory will likely be issued on the day shift today and we
will need to monitor closely for a coastal flood warning.
Nonetheless, the usual flood prone areas should expect at least
minor coastal flooding and overwashing. /03/14

&&

.PRELIMINARY POINT TEMPS/POPS...
Mobile      41  65  51  63  34  53  38  64 /   0  90 100  60   0   0   0  10
Pensacola   45  64  53  68  39  53  42  64 /   0  80 100  90   0   0   0  10
Destin      46  64  55  69  42  56  45  65 /   0  80 100  90   0   0   0  10
Evergreen   34  59  46  65  32  54  32  64 /   0  70 100  90   0   0   0  10
Waynesboro  35  62  46  59  31  53  33  64 /   0  90 100  40   0   0   0  10
Camden      33  57  45  60  31  51  31  61 /   0  70 100  80   0   0   0  10
Crestview   36  61  50  67  34  54  35  65 /   0  80 100  90   0   0   0  10

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...High Rip Current Risk from Monday morning through late Wednesday
     night for ALZ265-266.

FL...High Rip Current Risk from Monday morning through late Wednesday
     night for FLZ202-204-206.

MS...None.
GM...Small Craft Advisory from 6 AM to 6 PM CST Monday for GMZ630>636.

     Gale Watch from Monday evening through Tuesday morning for
     GMZ630>636.

     Small Craft Advisory from 2 AM to 9 AM CST Monday for GMZ650-655-
     670-675.

     Gale Watch from Monday morning through Tuesday morning for
     GMZ650-655.

     Gale Watch from Monday morning through Monday afternoon for
     GMZ670-675.

     Storm Watch from Monday evening through Tuesday morning for
     GMZ670-675.

&&

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