Scientific Forecaster Discussion
fxus64 kbmx 181137
Area forecast discussion
National Weather Service Birmingham Alabama
637 am CDT Wed Oct 18 2017
for 12z aviation.
today and tonight.
Subsidence aloft and surface high pressure anchored along the
southern Appalachians will dominate our weather through the short
term. Precipitable water values generally less than 1/2 will promote strong
radiational heating and cooling with large diurnal temperature
ranges. Afternoon highs today and morning lows on Thursday should
be a couple of degrees warmer due to slow airmass modification.
Thursday through Wednesday.
High pressure remains in place across the southeast US Thursday
and Friday as an upper level ridge slides eastward across the
area. This could result in a little more efficient daytime warming
across central Alabama by Friday afternoon allowing temperatures to
increase slightly above normal. By Friday night, a trough begins
to dig into the western US, shifting the previously mentioned high
pressure eastward. This will shift our winds more southeasterly
to southerly beginning Friday night into Saturday, increasing
moisture across central Alabama. The high amplitude trough continues to
deepen as it propagates eastward through the Central Plains and
into the Mississippi River valley Saturday into Saturday night.
It's at this point (saturday night into Sunday morning) that models
begin to diverge significantly on the evolution of the trough. The
European model (ecmwf) has remained somewhat consistent the past few runs in bringing
the the associated cold front through central Alabama as part of a phased
trough, increasing rain chances for Sunday and moving out by the
early part of next week. However, the 00z GFS has now returned to a
previous solution and is developing a cutoff low at the base of the
trough, which then hangs around the Gulf states for an extra day or
two, increasing rain chances through at least mid-week before it
gets picked up by the next trough. I have very little confidence in
the cutoff low solution, so have trended pops closer to the Euro at
this time. It should be noted, however, that models keep coming back
to this closed low development, so I don't want to ignore that
solution completely just yet. For now, have increased pops to around
55% as the front moves through. As we get a better handle on the
timing, I could see these rain chances increasing.
12z taf discussion.
VFR conditions are expected to continue for the next 24 hours with
a surface high pressure in place across east central conus and
easterly flow around the this ridge across the terminals in
Cool and drier air will continue through the rest of this week.
Relative humidity values will remain above critical thresholds.
There are no fire weather concerns.
Preliminary point temps/pops...
Gadsden 72 42 74 44 76 / 0 0 0 0 0
Anniston 73 44 75 47 77 / 0 0 0 0 0
Birmingham 74 49 77 50 79 / 0 0 0 0 0
Tuscaloosa 76 47 79 51 81 / 0 0 0 0 0
Calera 73 48 76 50 78 / 0 0 0 0 0
Auburn 72 49 76 52 78 / 0 0 0 0 0
Montgomery 77 51 79 52 81 / 0 0 0 0 0
Troy 76 48 79 53 80 / 0 0 0 0 0