Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Birmingham Alabama
704 am CDT Friday Aug 28 2015
for 12z aviation.
Looking at the big picture...weak upper level troughing continues
across the eastern Continental U.S. With ridging centered over the Desert
Southwest. A shortwave is currently tracking eastward across the
northern plains along the northern periphery of the upper ridge.
At the surface...broad ridging is in place across the eastern half of
the U.S. With weak low pressure areas across Nebraska and also
just off the Carolina coast. Surface winds are now out of the east
here in central Alabama and this will allow moisture values to
slowly begin increasing today. Based on forecast soundings
vertical profiles will still be rather dry across much of the area
but a few showers/storms may develop in the east later today as
there will be some upper level lift in place. Temperatures will rise into
the middle 80s to low 90s this afternoon.
Rain chances increase on Saturday as a cutoff upper low moves
northward out of the Gulf and into Alabama. The highest probability of precipitation will
continue to be across east central Alabama which corresponds to
the eastern side of the upper low where the lift will be the
greatest. The rain and cloud cover will help keep temperatures several
degrees below normal. The upper low lifts northeast into the
Appalachians on Sunday with rain chances decreasing a bit.
The forecast for next week remains somewhat in limbo due to ts Erika.
The forecast track has shifted to the west with model concensus now
bringing Erika northward closer to the West Coast of Florida...
versus the East Coast...early in the week with some weak troughing
still in place across the deep south. Through Tuesday we would likely
see little if any impact from Erika here in central Alabama. From
Wednesday Onward model solutions diverge. The European model (ecmwf) pushes the
remnant energy eastward off the Atlantic coast while the GFS pulls
it westward into a cutoff upper low over the Texas/la coast.
Therefore will continue with low probability of precipitation in the extended.
12z taf discussion.
Easterly flow around the surface ridge helping to bring in some
cloudiness from Georgia this morning. For mgm/toi ~7-8kft.
Further to the north with the higher elevations we are seeing some
MVFR stratus moving in...but think the IFR will not make enough
progress from Georgia before we get sufficient mixing. Have
tempoed in MVFR ceilings for asn/anb. To the west of there for
bhm/eet/tcl...we should remain VFR but some higher stratocu is
possible. Low rain chances will be returning from the southeast.
Confidence is still low on timing of decent moisture return...so
for now will leave out of terminals but do have some bkn040
cumulus for the afternoon.
Moisture values will slowly begin to rise today. Some isolated/scattered
convection is possible in the east/southeast today and tonight
with rain chances increasing from east to west on Saturday. For
next week...look for generally isolated shower/storms each day. No
fire weather concerns are expected at this time.
Preliminary point temps/pops...
Gadsden 88 69 84 69 84 / 20 20 50 40 40
Anniston 88 70 83 69 85 / 20 20 60 40 40
Birmingham 89 71 84 70 86 / 20 20 40 30 30
Tuscaloosa 91 71 87 70 89 / 10 20 30 20 20
Calera 89 71 85 70 86 / 20 20 50 30 30
Auburn 88 71 83 70 85 / 30 30 60 40 40
Montgomery 92 71 87 71 90 / 30 30 60 30 30
Troy 91 70 84 69 89 / 30 30 60 30 30