Area Forecast Discussion
Issued by NWS Birmingham, AL
FXUS64 KBMX 261733
Area Forecast Discussion
National Weather Service Birmingham AL
1233 PM CDT Sun Mar 26 2017
For 18Z Aviation.
With the overall coverage of activity on Saturday, today`s
activity will not be as widespread. We do remain in a southerly
flow during the day and this will allow the area to see scattered
showers and a few isolated storms during the day. Was thinking
that the morning would see the best coverage, but now it appears
that the afternoon will see the best in overall coverage with
scattered activity across the region. Almost summer-like this
afternoon with the shower activity. Another mild night in store as
we await the vorticity max to approach the area on Monday. More
on that below.
Monday through Saturday.
A broad-based shortwave over the ArkLaTex at 12Z Monday is expected
to bring our next chance for severe storms Monday afternoon and
evening. It is a bit unusual to see the cold front lagging to the
west of the upper-level trough axis, but that appears to be the case
for this event. This will allow colder air aloft (-16C at 500 mb)to
overlap with a wide warm sector. SBCAPE up to 2000 J/kg with mid-
level lapse rates of 7-7.5 C/km, and 0-6 km shear of 40-50 kt should
spread eastward across MS into West AL through the afternoon. This
will support bowing segments and supercells. Although not explicitly
shown in the model QPF, convection seems likely to develop well
ahead of the surface cold front in association with the approach of a
500 mb vort max and nose of a 300 mb jet streak. The synoptic
signals are suggestive of an event that could exceed expectations.
Our forecast will reflect a threat east of that indicated by SPC,
for hail up to ping pong ball size and damaging winds particularly
near and west of I-59. There may also be a small threat for a brief
tornado or two depending on how mesoscale features play out. I would
not be shocked to see the threat area expanded eastward and/or
upgraded in subsequent forecasts. With the cold front still to our
west and a modest low-level jet in place, additional showers/storms
could continue Monday night into Tuesday. However, the severe threat
will decrease as the best shear moves east after 9 PM Monday.
Wednesday is looking warm and drier as a 500 mb ridge amplifies over
the region ahead of yet another upper trough which will affect our
area on Thursday into Thursday night. This system has trended toward
more of an open wave with a better chance for severe storms. SBCAPE
of 1500-2000 J/kg and relatively strong low-level and deep-layer
shear may support all modes of severe weather including tornadoes.
Drier weather should return for Friday afternoon into Saturday.
18Z TAF Discussion.
MVFR stratus is finally beginning to mix out early this
afternoon, and all sites should become VFR by 20z at the latest.
Surface winds will continue to prevail from the south to
southwest around 10 knots, with a few gusts possibly up to 15
knots. The planning period of the forecast continues to highlight
fog development and low clouds once again overnight tonight. IFR
conditions are expected once again for most terminals, with
highest confidence for the southern terminals of KMGM and KTOI.
Central Alabama will remain in a moist southerly flow through the
middle of next week with rain chances through next Tuesday, with the
highest rain chances on Monday and Thursday. Critical fire weather
conditions are not expected through the next 7 days.
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 60 78 60 77 54 / 20 60 60 30 10
Anniston 60 78 61 77 57 / 20 50 50 40 10
Birmingham 62 79 62 78 57 / 20 60 60 30 10
Tuscaloosa 62 80 63 80 60 / 20 60 60 30 10
Calera 62 79 63 78 59 / 20 60 50 30 10
Auburn 60 79 61 79 60 / 10 30 20 40 10
Montgomery 63 82 63 82 61 / 10 40 30 30 10
Troy 62 83 61 83 61 / 10 30 20 30 10