527 
FXUS64 KBMX 041719
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
1219 PM CDT Sat May 4 2019

.UPDATE...
For 18Z Aviation.

&&

.SHORT TERM...
Today and Tonight.

There are two separate systems to our west this morning. The first 
is a mesoscale convective vortex (MCV) sliding through the 
ArkLaMiss. The second is another MCV pushing through Southeastern 
Texas, which at this time is the more robust system of the two. 
Across Central AL, we've got a remnant boundary stretched just south 
of the I-20 corridor, which will likely be the dividing line between 
the two MCV tracks as they slide eastward/northeastward today. 
Synoptically, an upper level trough is swinging through, which will 
help provide some larger-scale lift due to the height falls and 
weaker positive vorticity advection. Otherwise, there's not much 
forcing synoptic forcing associated with these MCVs. The first MCV 
will lift northeastward through Central MS and into North-Central 
AL, generally along and north of the I-20/59 corridor before 10am. 
This is on the north side of the remnant boundary, where the 
dewpoints are in the low to mid 60s and surface instability is 
generally below 500 J/Kg. Therefore, expect some thunderstorms with 
this morning round to produce some isolated gusty winds, but I do 
not expect there to be any severe storms with the first MCV. 

There will likely be a break in the late morning to around noon 
where there won't be much rain or thunderstorms in the area, but the 
second MCV is expected to move east-northeastward into South-Central 
AL in the early afternoon. This round will likely track south of the 
remnant boundary, generally south of the I-20/59 corridor. This is 
the area that is already seeing dewpoints in the upper 60s to near 
70. With daytime heating, instability will likely increase to 1000-
2000+ J/Kg in this area, leading to the more robust storms of the 
day, some of which could be severe. High resolution guidance has not 
handled the evolutions of these MCVs very well, giving drastically 
different data in each run, which isn't a surprise given the weak
forcing and mesoscale nature of the propagation. With that said, 
some guidance keeps hitting on the more robust line of 
thunderstorms moving through Southern AL during the mid-afternoon.
If this were to take place, it would have the better chance to 
produce damaging winds when compared to the more disorganized 
thunderstorms. Therefore, I'll increase the risk for severe storms
capable of producing damaging winds to a "slight" risk generally 
along and south of the Hwy 80 corridor in South-Central AL. 
Locations north of this could still see strong to severe 
thunderstorms, but confidence in the coverage is relatively lower.
At this time, the tornado potential is extremely low given the 
unfavorable low level wind profiles. By roughly 10pm, any 
thunderstorm activity should be east of our area, ending any 
severe threat for Central AL. 

25/Owen

.LONG TERM...
/Issued at 0300 AM CT/

Sunday through Saturday.

Low level ridging builds in across much of the Southeastern CONUS 
with zonal flow aloft Sunday through early Tuesday. This will keep 
the area mostly dry with a gradual warming trend. Afternoon highs on 
Tuesday could reach into the upper 80s to near 90 degrees. A 
persistent trough remains over the Western US through mid-week and 
into the second half of the week. Several impulses move through the 
base of the trough, each bringing increased chances of thunderstorms 
for at least the northern half of Central AL through Saturday. For 
now, will not add any mention of severe potential with these systems 
as timing of any individual impulse remains uncertain. 

25/Owen


&&

.AVIATION...
18Z TAF Discussion.

Active afternoon and evening in store across central Alabama with
the majority of the TAF sites impacted. Currently most locations 
are experiencing MVFR ceilings except the far south which have 
cleared and lifted to VFR conditions. 

Isolated TSRA was noted just east of KBHM at 17z with more 
organized convection across Mississippi. This convection will 
increase in coverage and overspread the TAF sites this 
afternoon/evening. Have included a period of TSRA at all areas 
roughly between 21z and 01z with more widespread light 
precipitation after that time period. Ceilings will lower to the 
IFR range overnight before slowly improving late Sunday morning. 

15

&&

.FIRE WEATHER...

Showers and thunderstorms expected today across Central AL. Gusty
winds may become erratic in proximity to the thunderstorms. There
are no fire weather concerns at this time. 

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     61  79  57  84  59 /  80  20  10   0   0 
Anniston    62  80  58  85  60 /  80  20  10   0   0 
Birmingham  63  80  60  87  63 /  80  20   0   0   0 
Tuscaloosa  62  82  59  88  63 /  70  20   0   0   0 
Calera      62  80  60  86  62 /  80  20   0   0   0 
Auburn      63  79  62  85  63 /  70  40  10   0   0 
Montgomery  65  83  62  88  64 /  80  30  10   0   0 
Troy        64  82  62  87  64 /  80  40  10   0   0 

&&

.BMX WATCHES/WARNINGS/ADVISORIES/...
None. 

&&

$$