Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Birmingham Alabama
652 PM CDT Mon may 21 2018
today and tonight.
The combination of a surface trough across the eastern Gulf of
Mexico along with surface high pressure centered just offshore of
the mid Atlantic states is producing a general easterly flow
through the low and mid levels with more of a southeast flow near
the surface. This pattern will continue to support a moist airmass
in the low to mid levels and will support higher rain chances
with some thunderstorm activity across our southeast and eastern
counties today. Expect the overall coverage to decrease overnight,
but then increase again southeast just before daybreak. Pops
Tuesday will generally be the same as today.
Through the short term period, low temperatures will remain in the
upper 60's to around 70 degrees while high temperatures will
depend heavily on the coverage of precipitation. Highs will
continue to range from lower readings around 80 across the eastern
counties while readings will range from the mid to upper 80's
across the western counties due to thinner cloud cover and a lower
coverage of shower and thunderstorm activity.
Tuesday through Sunday.
Enhanced rain chances will continue on Tuesday as a disturbance
drifts across southeast Alabama. Pops range from around 40 percent
in the northwest to 65 percent in our southeastern counties. The
disturbance may be hard to detect by Wednesday and Thursday, but a
similar range and distribution of pops seems reasonable as high
precipitable water values remain in place.
Models continue to indicate the development of a large trough
encompassing the southeast states and the Gulf of Mexico for
Friday through Sunday. This system has the potential to gain
subtropical characteristics with perhaps an area of surface low
pressure in the Gulf. Above normal rain chances are expected
during this period as the trough remains nearly stationary.
00z taf discussion.
Areas of rain and isolated thunderstorms will move to the north-northwest this
evening, impacting much of east central Alabama. Lightning has been
limited with this activity, and will use rain showers and only thunderstorms in the vicinity for
weather groups. Isolated convection has developed near tcl and will
also include thunderstorms in the vicinity there. A brief period of MVFR vis is possible with
heavier rainfall, but conditions with most of this activity have
been VFR due to light rainfall and cigs above 3kft.
This activity will gradually diminish thru 03z. Another round of
showers is possible across the southeast tonight, after 04z, and
spreading north-northwest through the pre-dawn hours. Between rounds of
rainfall, MVFR cigs are expected to develop given increased low
level moisture. Cannot rule out light fog as well. Cigs at times
could hover near IFR heights, and will have to monitor for updates.
Scattered showers and thunderstorms will be possible again Tuesday.
Have maintained thunderstorms in the vicinity at all terminals to account for uncertainty
with timing and coverage.
A moist pattern is expected over the next seven days and should
result in daily rain chances. Patchy fog/low clouds will be
possible each morning particularly where rainfall occurs during
the prior afternoon and evening.
Preliminary point temps/pops...
Gadsden 65 82 66 86 65 / 50 50 40 40 20
Anniston 65 81 66 85 66 / 50 60 40 50 20
Birmingham 67 84 68 88 68 / 50 50 40 40 20
Tuscaloosa 67 86 68 89 68 / 50 40 30 40 30
Calera 66 82 67 86 68 / 50 60 40 40 30
Auburn 66 78 66 82 67 / 70 70 50 60 30
Montgomery 67 83 69 87 69 / 60 60 40 60 30
Troy 67 82 68 85 68 / 70 70 50 60 30