Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Birmingham Alabama
647 PM CDT Wednesday Aug 20 2014
for 00z aviation.
Shower and thunderstorm development has remained somewhat limited
this afternoon...but will need to continue to monitor for isolated
severe microbursts with the stronger storms. This diurnally-driven
activity should diminish through the evening.
By tomorrow afternoon the much anticipated upper-level ridge will
have strengthened substantially with anticyclonic flow and
subsidence squelching convection. Have left a silent 10 pop in
across the eastern County Warning Area in case low-level moisture is sufficient
enough for very isolated shower or storm. Conditions are expected
to remain rain-free for Friday and Saturday.
The heat is the main concern for Thursday through Sunday as highs
climb into the middle to upper 90s. Decided to go with dewpoints on
the lower end of the guidance (mid to upper 60s) for the afternoon
hours on each day as boundary layer moisture may become more
limited due to northwesterly flow. This would result in heat index
values in the 100-104f range for most areas. If dewpoints end up
slightly higher than forecast...heat advisory criteria (105f or
greater) would be met over a large portion of the County Warning Area.
Models have become rather consistent in showing a back door front
moving westward from Georgia on Sunday as the upper-level ridge
amplifies and retreats to the northwest. Have increased rain
chances across the east for Sunday afternoon with activity
shifting westward across the forecast area on Monday. Temperatures
should drift back closer to normal for Monday and Tuesday in
association with deep easterly flow.
00z taf discussion.
Shower and thunderstorm coverage was limited across central
Alabama today...and that should remain the case overnight. We are
watching an outflow boundary heading south into northeast Alabama
from Tennessee. That boundary could help a few more showers or
storms develop north of anb...but my gut feeling is that the whole
thing should dissipate before it gets that far. Will watch it over
the next couple hours nonetheless.
Otherwise...will go with a persistence forecast for the overnight
hours. That means mostly clear skies...with just a bit of patchy
fog around tcl. Rain chances will be sufficiently low on Thursday
to leave out of the forecast for now.