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fxus64 kmob 060549 

Area forecast discussion
National Weather Service Mobile Alabama
1149 PM CST Thu Dec 5 2019

Discussion...updated for latest aviation discussion below.


06z issuance...VFR conditions will continue across the region
through Friday morning. Scattered to broken mid to high level
cloud decks will stream across the region through Friday morning,
with ceilings expected to lower to 4-5 kft above ground level by around 18z. MVFR
ceilings should develop Friday afternoon into early Friday
evening as scattered to numerous rain showers develop across the
region. Winds will remain light and out of the south to southeast.


Previous discussion... /issued 949 PM CST Thu Dec 5 2019/

Discussion...see updated information for land areas below.

Update...current forecast overall in good shape, with minor
downward adjustments to temperatures to reflect current
observations and increases in sky cover, with mid/high level
cloud cover continuing to move east over the forecast area. With
the cloud cover increasing after midnight, am expecting overnight
lows to bottom out after midnight, then level off or begin a slow
increase as radiational cooling over the forecast area decreases.
Updated package has been sent. /16

Previous discussion... /issued 530 PM CST Thu Dec 5 2019/

Discussion...updated for latest aviation discussion below.

00z issuance...VFR conditions prevail tonight with a broken to
overcast cloud deck remaining above 10kft. Mid-level cloud cover
increases Friday morning, eventually lowering to MVFR levels by
the afternoon as scattered showers develop across the area. Winds
remain light and out of the south to southeast. /49

Previous discussion... /issued 404 PM CST Thu Dec 5 2019/

Near term /now through Friday/...high pressure will continue to
move eastward tonight as a shortwave approaches from the west.
Ahead of this system, clouds will increase late tonight into
Friday. As the shortwave moves east on Friday, showers will
increase to our west and move into the area during the late
morning and afternoon hours. Meanwhile, a weak sfc low will move
southeast into the northern Gulf and weaken as the upper support
weakens and moves away. The combination of weakening upper support
and the lack of significant moisture return will keep rain
amounts generally light. We have also removed thunder from the
forecast as the instability remains very weak and well offshore.
The highest rain chances will be across northern portions of the
area where the best upper dynamics will be. Lows tonight will fall
in the mid and upper 40s inland to mid 50s along the coast. Highs
on Friday will be in the upper 60s and low 70s. /13

Short term /Friday night through Sunday night/...the forecast
area will be situated between the surface low over the
northeastern Gulf of Mexico and an area of surface high pressure
moving from the from the Midwest states to the northeast states.
This will keep a cool, light northerly wind flow over the area
through Saturday evening. The winds will then shift to the east
and then southeast through Sunday as a strong surface ridge of
high pressure sets up along the eastern Seaboard. As a result, the
surface low pressure area will evolve into an inverted trough, and
get shoved westward and dissipate. Scattered light rain Friday
evening will taper off from northwest to southeast overnight into
Saturday as the surface low moves further away from the area. Only
a few light showers are expected to remain east of I-65 through
Saturday night. Isolated to scattered light rain showers will
return Sunday due to over-running between the backside of the
surface ridge and trough. Low temperatures through the weekend
will range from 49 to 56 degrees. High temperatures will range
from 60 to 68 degrees on Saturday, and from 63 to 70 degrees on
Sunday. /22

Long term /Monday through Thursday/...a positively tilted upper
trough over the western conus, with an embedded closed upper low
over Southern California will advance eastward over the central
states into midweek. An associated surface cold front will move
southeast across the forecast area late Monday night through
Tuesday evening. A line of showers and storms should develop ahead
of this front, and mid level dynamics appear to be a bit stronger
than the previous frontal passage, so will have to monitor this
frontal passage for possible strong/severe storms as well. Despite the more
favorable conditions, the nocturnal timing of the system (moving
into the area before daybreak on Tuesday morning) will contribute
to limited instability. Isentropic lift ahead of the approaching
system will support slight chance to chance pops on Monday then
good chance to likely pops follow for Monday night through Tuesday
as the front moves through, then drier conditions are expected
midweek in the wake of the front. Daytime highs in the 70s on
Monday as the front approaches, and then back down into the 60s on
Tuesday behind the front and even cooler on Wednesday, in the
50s. Lows Monday night in the 50s, then cooler Tuesday night in
the wake of the front, primarily in the mid 30s to mid 40s. /22

Marine...a light southerly flow will develop tonight in response
to an area of low pressure approaching from the west. This area of
low pressure will move over the marine area on Saturday then shift
north over the weekend. A moderate southerly flow will develop
Sunday and continue into early next week ahead of a cold front
approaching from the west. /13


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