Scientific Forecaster Discussion
fxus64 kbmx 210455
Area forecast discussion
National Weather Service Birmingham Alabama
1155 PM CDT sun Oct 20 2019
for 06z aviation.
/updated at 0223 PM CDT sun Oct 20 2019/
Low clouds were noted across central Alabama this morning with
patchy fog as well. It took awhile for the stratus to clear out
and thus for many to warm up this am. Some stratus and patchy fog
are again possible for tonight into Monday morning ahead of our
next frontal system. Low clouds should develop in the pre-dawn
hours ahead of the front from the south/southwest, while fog will
likely develop patchy but across a larger area from the south/
southeast. Temperatures should moderate some for tonight as dew
points rise ahead of the next system as well in addition to some
clouds developing. Most of the precipitation should hold off until
after 12z for central Alabama. I only have a slight chance of
light showers mentioned in the far northwest counties after 9z.
We continue with a marginal low chance for severe storms on Monday
from noon through midnight Tuesday across central Alabama. The
main threat continues to be straight-line winds, but a brief spin
up tornado cannot be ruled out.
The only changes I made to the extended part of the forecast
were to Thursday night into Friday to bump rain chances up with
better timing agreement on rain chances ahead of the next front.
/updated at 0339 am CDT sun Oct 20 2019/
Monday through Saturday.
Shower and storms will be ongoing near or just east of the
Mississippi River at 12z Monday as a large storm system moves
eastward from the plains. There is very poor model agreement
regarding the evolution of convection as it moves into Alabama.
This is likely due to the influence of a subtropical shortwave
ejecting northeastward from the western Gulf of Mexico into the
base of the larger-scale trough. Models cannot agree on exactly
how much focus will shift away from the synoptic-scale trough and
toward the increasingly influential southern stream disturbance.
This complicated scenario could result in a messy situation with a
negligible severe weather threat, but for now the marginal risk
will be maintained across the entire forecast area.
The northwestern counties appear to have the best chance of being
affected by a stronger low-level jet during the early afternoon,
which could yield some marginally severe wind gusts with the
strongest storms. A brief tornado cannot be completely ruled out.
The non-zero severe weather threat may continue across the
remainder of our area but will be dependent on mesoscale
influences and convective evolution. The timing of the threat has
been adjusted faster based on hi-res guidance, arriving around
noon in the northwest and ending around midnight in the southeast.
Dry and mostly sunny conditions will move into the region on
Tuesday behind a cold front, with high pressure remaining dominant
through Thursday afternoon. The next weather system is expected
to take shape Thursday night to our west, leading to the potential
for widespread rainfall for Thursday night through Saturday.
06z taf discussion.
A narrow band of high clouds is stretched through central al,
splitting mostly clear skies across the north and south. Fog has
started to develop early tonight across the southeast and the
northeastern portions of central Alabama. Anb and asn have been
bouncing between IFR and VFR, but I believe the IFR or LIFR visible
could set in almost at any time over the next few hours and
continue through much of the overnight. Similar conditions are
expected at toi and mgm, though mgm could remain VFR through
roughly 09z before the fog builds in.
Southerly flow picks up after roughly 12z tomorrow ahead of a cold
front that will move through the region. Along and ahead of the
front, expect rain and thunderstorms to persist through roughly
06z. If any stronger storms move over the terminals, visible will
likely be reduced, but confidence in any specific terminal seeing
these reduced visible is low at this time.
Showers and thunderstorms will be possible ahead of a cold front
Monday afternoon into Monday night. Cooler and drier conditions
will follow for mid week.
The Alabama forestry commission continues to have a fire alert in
effect that includes all of central Alabama. For more information
about restrictions, visit their web site at forestry.Alabama.Gov.
Preliminary point temps/pops...
Gadsden 55 78 53 68 41 / 10 80 90 10 0
Anniston 59 79 56 69 42 / 10 80 90 10 0
Birmingham 62 78 55 69 44 / 10 80 90 10 0
Tuscaloosa 64 79 53 70 44 / 10 90 90 10 0
Calera 61 78 55 69 43 / 10 80 90 10 0
Auburn 59 78 60 70 45 / 10 50 90 20 0
Montgomery 62 82 59 72 44 / 10 60 90 10 0
Troy 60 81 60 72 43 / 10 50 80 20 0