MOB issues Area Forecast Discussion (AFD) at Jan 12, 9:13 PM CST ...New UPDATE...225
FXUS64 KMOB 130313
AFDMOB
Area Forecast Discussion
National Weather Service Mobile AL
913 PM CST Sun Jan 12 2025
...New UPDATE...
.UPDATE...
Issued at 913 PM CST Sun Jan 12 2025
No major changes are needed to the forecast for the rest of the
night as a cold rain gradually increases in coverage and intensity
over the area. Previous near term discussion below handles the
situation well. Only minor adjustments made to hourly
temp/dewpoint/rain chances to reflect current obs/trends.
The main forecast update was to adjust the start time for the
Small Craft Advisory to start now instead of midnight over the
Gulf waters as winds are quickly increasing, especially over the
20-60nm zones. Winds over the marine area will continue to
strengthen through the night as the surface low currently
organizing south of the south central LA coast moves east
overnight, staying just south of our coastal waters. 34/JFB
&&
.PREV DISCUSSION... /issued 545 PM CST Sun Jan 12 2025/
..New AVIATION...
AVIATION...
(00Z TAFS)
Issued at 540 PM CST Sun Jan 12 2025
Deteriorating conditions are expected as we go through the course
of the night with rain and IFR ceilings spreading in from west to
east. There will be a gradual lowering of ceilings this evening
from current VFR bases to MVFR by mid/late evening with IFR/LIFR
ceilings becoming predominate after midnight. Heaviest rain is
expected along the coastal counties after midnight through sunrise
with rain tapering off from west to east Monday morning. IFR
ceilings will hold for most the day with improvement expected
close to 00z Tue. East to northeast winds will gradually increase
tonight and will become gusty (around 20 kt) closer to the coast
by early Monday morning. 34/JFB
PREV DISCUSSION... /issued 420 PM CST Sun Jan 12 2025/
.New NEAR TERM, SHORT TERM, LONG TERM, MARINE...
NEAR TERM...
(Now through Monday night)
Issued at 420 PM CST Sun Jan 12 2025
Mid level cloud cover will continue to expand through this
evening and begin to lower as abundant moisture ahead of a
shortwave trough currently positioned along the upper Texas coast
overspreads the region from southwest to northeast. A layer of dry
air in the boundary layer will continue to moisten eventually
becoming saturated later tonight which will support the
development and expansion of rain later this evening and
continuing through the overnight hours. Southwesterly flow aloft
will strengthen as the shortwave trough moves over the area by
Monday morning. Latest global models intensify the 300mb
subtropical jet to in excess of 170 kts across the Tennessee
Valley by 12z Monday. Our region becomes positioned beneath the
right entrance region of this powerful jet streak by this time
with strong large scale ascent. There will also likely be strong
frontogenetic forcing within the 925-750mb layer, with strong
elevated convergence in this layer, as strong southerly low level
jet winds between 2-3km become enhanced with 45-55 kts nosing into
the elevated boundary near the I-10 corridor. This strong
frontogenesis combined with the strong large scale ascent with the
upper jet should support a period of moderate to occasionally
heavy rainfall from around dawn through mid morning Monday. At the
surface, low pressure develops in response to the upper level
forcing across the northern Gulf coast and moves east offshore
through the near term forecast period. Widespread rainfall amounts
between 1-2 inches with locally higher totals up to 3+ inches
possible. This is most likely in a corridor across our coastal
counties. These rainfall amounts could result in ponding of water
in flood prone locations and poor drainage urban areas. Widespread
flooding is not anticipated at this time as the system will remain
progressive and the period of heavy rain relatively brief.
The surface low will move east well offshore through Monday. The
pressure gradient will tighten significantly ahead and immediately
behind the passage of the low. This will result in strong
northeast to eventually northerly surface winds with gusts
increasing to 20-30 mph across the coastal counties and higher
gusts approaching 40 mph at times offshore from late tonight
through Monday.
The rip current threat will increase to high for
Monday and Monday night with surf heights getting close but likely
remaining just below the 5 foot high surf height threshold. This
will be reassessed by the evening shift in case surf heights look
higher, but it does appear that the offshore winds should help to
cap the surf below 5 feet through the event.
Rain should come to an end later Monday evening as the low
pressure and upper level support shift east of the area. Skies
should gradually clear for Monday night with northerly winds
diminishing and low level cold air advection supporting cold
overnight lows ranging from the middle 20s over the interior to
lower 30s along the I-10 corridor and middle 30s along the
immediate coast. Cold temperatures and cold apparent temperatures
near the coast will likely necessitate a cold weather advisory for
Monday night into early Tuesday morning. The overnight shift will
take a closer look at this potential. /JLH
EXTENDED TERM...
(Tuesday through Sunday)
Issued at 420 PM CST Sun Jan 12 2025
Surface high pressure will build into the Deep South as the upper
level flow temporarily becomes zonal. Temperatures will slowly
moderate back to near normal by the end of next week with dry
weather conditions expected.
Another positively tilted upper level trough will dig southeast
from the Central Plains and across the Deep South by Thursday.
This will help to push a weak reinforcing cold front across the
area. There will likely be little in the way of temperature change
and with limited moisture advection ahead of this feature, dry
conditions should continue through the end of this week.
Another stronger shortwave trough will approach the region next
weekend. Strong dynamics are expected with this system along with
a period of return flow and increasing moisture levels and
temperatures. There remain questions regarding the overall quality
of the airmass as it may be shortened due to the preceding end of
week shortwave and cold front. There may be too little airmass
recovery time in advance of the weekend system to support a
quality warm sector. This will be something to watch closely as if
the moisture return is of greater quality or the weekend system is
slower then there may be some severe weather potential that will
need to be monitored. At this time, it appears that the most
likely scenario appears to keep the higher quality moisture
offshore and thus would limit any severe weather potential over
land. This is something that will be closely monitored over the
next several days. /JLH
MARINE...
Issued at 420 PM CST Sun Jan 12 2025
Moderate to strong northeasterly winds will develop in advance of
an approaching surface low pressure that will move east and
tighten the pressure gradient as it passes south of our marine
areas. There may be enough elevated lift and instability aloft to
support a few thunderstorms in the 20-60 nmi zones later tonight
into Monday as the low level jet intensifies and draws modestly
unstable air northward on top of the low level stable cool sector.
Winds will gradually diminish by Tuesday with light to moderate
northeasterly winds persisting through much of next week with dry
conditions expected from Tuesday onward. /JLH
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...High Rip Current Risk from 6 AM CST Monday through late Monday
night for ALZ265-266.
FL...High Rip Current Risk from 6 AM CST Monday through late Monday
night for FLZ202-204-206.
MS...None.
GM...Small Craft Advisory from 3 AM to noon CST Monday for GMZ630>632-
634.
Small Craft Advisory until 9 AM CST Tuesday for GMZ650-655.
Small Craft Advisory until noon CST Tuesday for GMZ670-675.
&&
$$
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Source:
MOB issues Area Forecast Discussion (AFD) at Jan 12, 9:13 PM CST ...New UPDATE...---------------
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