Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Birmingham Alabama
359 PM CST Thu Nov 14 2019
/updated at 0322 PM CST Thu Nov 14 2019/
An upper level trough is dropping southeastward this afternoon,
approaching the lower Mississippi River valley, while a southern
stream system is moving into the northwestern Gulf. These two
features will merge this evening over the deep south, as the
trough amplifies and becomes a closed low by tomorrow morning.
Despite widespread radar returns across the area, not much
rainfall is making it to the ground. Current laps soundings
continue to show a significant dry layer below 10kft, although precipitable water
values have increased from around 0.40 inches this morning to near
0.80 inches north and 1.0 inch south. Locations that have reported
rainfall have not reported any accumulation, and will keep low
rain chances in the forecast through early evening. With such a
strong dry later above the surface, evaporative cooling is
allowing for a few sleet pellets to mix with the light rain.
Coverage is not enough to include a mention of sleet in the
forecast, and no impacts are anticipated.
The column will continue to moisten through the evening, with the
best rain chances in the southeast overnight. Rainfall totals
around a quarter inch are expected. By sunrise Friday,
temperatures will be in the low to mid 30s for most of the area,
with low 40s near and south of I-85. Coldest locations with
temperatures around freezing will be in the northwest, where
rainfall is not expected.
/updated at 0342 am CST Thu Nov 14 2019/
Saturday through Thursday.
The center of a 500 mb closed low is expected to track across
southeast Alabama on Friday. Clouds and light rain may continue to
plague the southeastern quadrant of our area due to enhanced lift
associated with strong vorticity near the center of the upper low.
Temperatures in this area are likely to hold in the mid to upper
40s during the afternoon. Other areas to the north and west should
see 50s for afternoon highs. The upper low will finally move out
of our forecast area on Friday night, leaving behind dry
conditions and temperatures ranging from the mid 50s to mid 60s
for afternoon highs on Saturday and Sunday.
A series of shortwaves will dig across the deep south and Carolinas
on Monday and Tuesday with strong height falls extending well into
the Gulf of Mexico. Models currently suggest the strongest lift
with this system will be aimed too far south to include rain
chances at this time. A transient ridge will move across the
region on Wednesday with dry conditions.
18z taf discussion.
The atmosphere has increasing moisture with rainfall expected to
reach the ground by the afternoon. Only included vcsh at each taf
site for now due to uncertainty in coverage and timing of showers
through the afternoon. This evening...most rainfall will be
limited to kmgm and ktoi...where enough low level moisture will
allow MVFR visibilities tonight through Friday morning. With
continued cloud cover and light winds...not anticipating fog
development in the early morning...but will amend if needed.
Widespread light rain is expected overnight for much of central
Alabama, but the best chances across the southeast. Some of this
rain could linger into Friday across our eastern counties. Dry
conditions will return for the weekend with afternoon relative
humidity values remaining above critical levels.
Preliminary point temps/pops...
Gadsden 36 53 32 58 32 / 20 10 0 0 0
Anniston 37 52 34 60 35 / 40 20 10 0 0
Birmingham 38 53 33 59 37 / 20 10 0 0 0
Tuscaloosa 37 54 31 59 35 / 20 0 0 0 0
Calera 38 52 33 59 35 / 30 10 10 0 0
Auburn 41 49 38 59 37 / 80 50 20 0 0
Montgomery 42 52 36 62 38 / 60 30 10 0 0
Troy 42 51 37 61 38 / 80 40 20 0 0