Area Forecast Discussion
Issued by NWS Birmingham, AL
FXUS64 KBMX 071713
Area Forecast Discussion
National Weather Service Birmingham AL
1113 AM CST Wed Dec 7 2016
For 18Z Aviation.
Today and Tonight.
A weak cold front has passed through Central AL this morning,
providing slightly cooler northerly flow to start off the day. Even
though the mid and upper levels are dry, the lower levels are still
saturated. This has resulted in a low stratus deck across much of
area that will moderate our diurnal temperature pattern today even
with some slight warm air advection ahead of the approaching
shortwave trough. End result will be seasonable temperatures with
Highs in the mid to upper 50s and lows in the upper 30s to low 40s.
Models are in good agreement with a dry cold front reaching the area
early Thursday morning, but given the lack of moisture return in the
mid and upper levels, precipitation amounts will be limited. I have
lowered the PoPs and QPF to account for this drying out in the model
Thursday through Tuesday.
A strong cold front will push through central Alabama on Thursday.
The models have all backed off the rainfall potential with the
frontal passage, due to lack of return flow ahead of front and
weak upper level forcing. Reduced rain chances to 20 percent for
Thursday. After days of cloud cover, the good news is the clouds
should finally move out of the area Thursday afternoon as much
drier air advects southward behind the front. Surface winds will
increase on Thursday behind the front with speeds in the 10-15 mph
range. The coldest air mass of the season will invade Alabama
Thursday through Saturday. The coldest daytime temperatures will
be on Friday while the coldest nighttime temperatures will be
Saturday morning as the surface high settles over the area.
Temperatures will moderate Saturday afternoon and Sunday as
surface winds veer to the southeast and south. The next upstream
short wave trof will pass well to the north of Alabama on Sunday.
A trailing cold front will push southward into the area Sunday
night and Monday. Increased rain chances Sunday night and Monday
as the GFS and ECMWF models are indicating higher QPF values along
the front. Both models push the front through the area Monday
night with drier conditions on Tuesday.
18Z TAF Discussion.
Weak cool air advection will continue across much of the area
today and tonight before an arctic front arrives during the day on
Thursday. Expect low CIGS to prevail at most terminals today and
tonight followed by slow clearing with a gradual increase in cloud
bases during the day Thursday. Expect generally light west to
northwest winds this afternoon and evening followed by northwest
winds developing tomorrow with the frontal passage and becoming
breezy at most sites, especially in the afternoon. Wind speeds are
expected to remain high enough tonight to discourage fog
Despite rain free conditions today, humidity levels will remain
on the high side due to cloud cover. A strong cold front will push
through central Alabama on Thursday. The air mass will be too dry
for any appreciable rainfall with the frontal passage. Much
colder air will move into the area Thursday through Saturday.
Rain chances will return on Sunday and Monday.
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 55 36 46 23 41 / 0 20 20 10 0
Anniston 57 38 47 24 42 / 0 20 20 10 0
Birmingham 55 38 46 24 42 / 0 20 20 10 0
Tuscaloosa 56 39 48 25 43 / 10 20 20 10 0
Calera 57 39 48 26 43 / 10 20 20 10 0
Auburn 58 42 52 27 44 / 0 10 20 10 0
Montgomery 60 42 54 28 46 / 0 10 20 10 0
Troy 60 41 54 28 46 / 10 10 20 10 0