Scientific Forecaster Discussion
fxus64 kbmx 141733
Area forecast discussion
National Weather Service Birmingham Alabama
1233 PM CDT Tue Aug 14 2018
for 18z aviation.
today and tonight.
The frontal boundary that was across the southern portions of the
area is slowly lifting northward now as a warm front. Showers and
storms will be mainly along and south of this boundary, with
generally scattered coverage through the evening. This will be a
little more north and west from yesterday since the boundary has
lifted some. There could be a few stronger storms during the peak
heating of the day with winds and small hail possible. Flow will
also be weak so any storms that develop will need to be monitored
for training and localized flooding, especially in the southeast,
where the best moisture will be in place. Most activity should
dissipate between 10 PM and 12 am tonight, with patchy fog once
Wednesday through Monday.
The upper-level pattern will become more progressive by Wednesday.
The upper lows currently over the northeastern Continental U.S. And Central
Plains will have opened up into open waves, and moved into the
Atlantic and Midwest, respectively. A shear axis will extend
southward from the latter deamplifying wave over the Midwest,
into the lower Mississippi Valley. Precipitation associated with
this should remain west of the forecast area Wednesday, with weak
height rises located over central Alabama. Very dry air at 700 mb
will partially mix down to the surface and should suppress diurnal
convection across the northern two thirds of the area, while
isolated to scattered activity will be possible in the far
southern counties near the old frontal boundary. The lack of
convection and lower dew points mixing down will allow highs to
reach the mid 90s in many locations.
The mid/upper-level shear axis will continue to weaken Thursday as
it moves towards the MS/Alabama border, as a pair of subtropical
ridges strengthen over Texas and the Atlantic. The atmospheric
column will be in the process of moistening, however there will
still be a southwest to northeast oriented wedge of dry mid-level
air over the area. This is where a relative minimum in diurnal
convection may be, between one favored area in the far northwest
near the shear axis, and another favored area in the far southeast
near an enhancement in low-level onshore flow. Future updates may
be able to lower pops a bit more between these two areas as they
become more defined.
A return to a wetter pattern is expected on Friday through the
weekend as a shortwave in northwest flow aloft digs into the mid-
Mississippi Valley Friday and pushes eastward through the Ohio
Valley on Saturday with an associated surface low.
Cyclonic/slightly enhanced flow aloft to the south of this feature
in a weakness in the subtropical ridge combined with pwats
increasing to 2 inches will result in above normal coverage of
convection. The unsettled pattern looks to continue into early
next week as another shortwave moves through the central Continental U.S..
18z taf discussion.
VFR will be the dominate category thru the period. Diurnal convection
will develop along the back side of an upper trof axis that is located
across east Alabama. Isolated to scattered thunderstorms and rain near and south of
the trof will likely impact kmgm and ktoi thru 00z. The activity
will quickly diminish in areal coverage and intensity after 00z.
Models indicate a surge of low level moisture across South Alabama
after 09z, and included low cigs at ktoi.
Daily scattered showers and storms are expected through the next
several days. Morning fog and low clouds will be possible in
locations that receive afternoon and evening rainfall. There are
no fire weather concerns at this time.
Preliminary point temps/pops...
Gadsden 67 94 70 92 71 / 10 10 10 30 30
Anniston 68 94 71 93 71 / 20 10 10 30 20
Birmingham 73 95 74 93 73 / 10 10 10 30 30
Tuscaloosa 73 96 73 94 73 / 10 10 10 30 20
Calera 71 93 71 91 71 / 10 10 10 30 20
Auburn 70 92 71 90 71 / 30 20 10 40 20
Montgomery 71 95 73 92 73 / 20 20 10 40 20
Troy 70 93 72 91 73 / 30 30 20 50 20