Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Birmingham Alabama
956 PM CDT Wednesday Oct 1 2014

Discussion...

An upper level trough is currently moving across the Rocky
Mountains into the Central Plains. A surface low is deepening
across the Southern Plains in response to this upper level trough
and this will be the main feature we are watching for the weather
late Thursday into Friday. For tonight...the weather is pretty
tranquil as low level flow becomes southerly in response to the
surface low to the west. Low level moisture is plentiful across
the east and expect patchy fog will be possible once again late
tonight. Made minor changes to the hourly temperature and dewpoint
grids to account for current trends with the rest of the forecast
on track.

05/Massachusetts

&&

Aviation...
00z taf discussion.

Have continued the trend of mentioning IFR visible at mgm/toi early
Thursday morning and introduced MVFR ceilings at tcl also in the morning.

Surface high pressure weakens and shifts northeast while a strong
cold front take shape over the plains. This will allow winds
above the surface to increase out of the south overnight. These
winds should remain below any low level wind shear criteria but moisture transport
will begin. Some of the hi-res models are indicating more
widespread cloudiness developing toward daybreak and will monitor
this development for the 06z issuance.

The moisture increases enough that showers and thunderstorms are
possible across west central Alabama by Thursday afternoon. At
this time...confidence of occurrence at any terminal was too low
for mention.

Note...the National Weather Service will begin issuing seasonal
terminal forecasts for the Talladega Municipal Airport (kasn) in
Talladega...Alabama. The forecast will begin October 5th at 00z
and last through at least the 23rd of October.

75



&&

Previous discussion...
/issued 405 PM CDT Wednesday Oct 1 2014/

This afternoon...we have south to southeast flow in the lower
levels around a ridge extending southward across the northeast
U.S. From eastern Canada. A Bland zonal flow was present across
the southeast U.S. Visible satellite showed only fair weather
cumulus this afternoon and a clear radar. One more rain free night
is expected ahead of our next system with only some patchy fog
possible...mainly across the southeast counties with increasing
boundary layer moisture.

On Thursday...we will transition ahead of our first decent front
with dew points increasing as gradients tighten/onshore flow
increases. Rain chances will begin across the west Thursday
daytime ahead of the system but the better activity will be during
the overnight and morning hours on Friday. An upper shortwave is
expected to dig as it moves across the plain states Thursday with
the upper flow across Alabama becoming less zonal and more
southwest. Perturbations in this flow will allow for some
afternoon and evening thunderstorms. On Thursday night...the upper low
itself digs deep across the central U.S. And will aide in
intensifying a surface low as it moves to the northeast from
Oklahoma to the Great Lakes and dragging a front across Alabama on
Friday. Dynamics remain favorable for a marginal severe weather
wind event across the northern portions of the area in the predawn
and morning hours Friday ahead of the front. There will be
moderate cape and lift for decent updrafts...along with sufficient
bulk shear of around 30-4o kts...with fairly good middle level
winds. See no reason to make any changes to the severe weather potential statement and current
area looks good. Main instability moves out during the
afternoon...and rain comes to an end by early evening across the
far southeast.

Good cold air advection with tight gradients will allow for
temperatures to drop noticeably for the weekend. In the extended
the flow turns back for the first part of next week and
temperatures rebound with low probability of precipitation returning as weak disturbances
move across the state with a broad upper trough moving across the
eastern U.S.

08/mk

&&

Bmx watches/warnings/advisories...
none.

&&

$$

National Weather Service Glossary of Abbreviations