Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 170022

Area Forecast Discussion
National Weather Service Birmingham AL
722 PM CDT Sun Jun 16 2019

For 00Z Aviation.



Showers and thunderstorms have begun to develop along a convergent
boundary (oriented northeast to southwest) generally along and east
of I59/I20. This activity is primarily driven by daytime instability
and an axis of PWAT values 1.25-1.5 inches. Isolated stronger storms
cannot be ruled out with this activity given SBCAPE values 3000-3500
J/kg along this boundary. Showers and thunderstorms will decrease in
coverage by this evening with the loss of daytime heating.
Overnight, the best chances for a shower or storm will be in our
northwest counties associated with the activity currently in


/Issued at 340 AM CDT/

Monday through Saturday.

Long-term weather conditions across Central Alabama will be
relatively warm & humid, with daily chances of showers &
thunderstorms primarily driven by diurnal heating. High temperatures
should fall within a few degrees of `normal` values for this time of
year with upper 80s to lower 90s the overall theme through next
weekend. Overnight lows in the upper 60s to lower 70s are expected
as temperatures cool to just above their respective dewpoints. A
couple days during the week will likely be wetter than others, with
current expectations that Tuesday & Thursday will be more active as
shortwave disturbances aid in forcing for ascent. As such, Central
Alabama can expect a variety of afternoon showers & thunderstorms as
tropical air encompasses the region.

By Monday, southerly surface flow and southwesterly weak mid-level
flow will be in place as a shortwave trough passes over the ArkLaTex
region. This is expected to continue east-northeastward amidst
relatively quasi-zonal flow overall, with enhancement to rain
chances expected primarily to our northwest by that afternoon.
Tropospheric PWs ~1.8" & modest instability suggests a decent
coverage of showers/thunderstorms across Central Alabama with PoPs
adjusted to 40-50%, with an increase to 50-70% for Tuesday afternoon
as better lift & moisture content (PWs ~2.0") is available just
downstream of the shortwave now generally over our area.

After somewhat of a lull in convective activity on Wednesday
afternoon (still have chances for diurnal convection), a more potent
shortwave is progged to enter from the northwest amidst a
strengthening Polar Jet by Thursday morning. This particular wave is
set to contain more substantial mid-level flow around its base (~40
kts at 500 mb), which yields a scenario such that a moist/buoyant
lower troposphere will have 30-40 kts of effective shear available.
This suggests a few storms could be strong/severe, though timing and
other unseen mesoscale considerations need to come together. Thus,
despite the synoptic signal, will need to get closer to Thursday for
enough confidence to mention in the HWO. A simple change in speed
and/or trajectory of this shortwave trough would result in a much
different scenario (ie. stronger/organized convection displaced out
of our forecast area). Regardless, rain chances remain in the
forecast through next weekend as the Gulf airmass remains situated
across the Southeast & diurnal convective remains possible.
Generally have kept `chance` PoPs in for Fri/Sat afternoons to
account for available moisture with expected decreases in
coverage/intensity into the overnight hours. Forecast rain chances
hopefully brings good news to those needing rainfall to improve any
localized short-term drought conditions.



00Z TAF Discussion.

A few scattered showers and thunderstorms persist this evening
across north Central Alabama. Initial development began along a
NE/SW boundary generally along I59/I20 with further development caused
by merging outflow boundaries. Added TEMPO TSRA for KBHM/KEET
until 02Z to account for continued activity. Beyond this point
showers and storms should dissipate by 04/05Z with high clouds
and light winds overnight. I did include the mention of fog in for
KANB/KASN to account for rain at these sites earlier this afternoon.
Tomorrow afternoon more showers and storms are expected. I have
included a PROB30 TSRA beginning at 18Z for all sites.




Scattered showers and thunderstorms are possible through this
evening, but it will be hit or miss. We will see a continued
recovery in minimum relative humidity values thanks to the
southerly flow. KBDI values remain high, but the increased low
level moisture will keep us from reaching critical fire weather
criteria. We will have elevated chances for wetting rains for much
of this week.


Gadsden     69  88  67  86  67 /  20  50  30  80  50
Anniston    69  89  69  87  68 /  20  50  30  70  50
Birmingham  72  90  71  87  71 /  30  50  30  80  50
Tuscaloosa  73  91  71  89  71 /  30  50  30  80  40
Calera      70  89  69  87  69 /  30  50  30  70  50
Auburn      71  89  70  87  70 /  10  40  20  70  40
Montgomery  71  92  71  91  71 /  20  40  20  60  40
Troy        68  91  69  90  70 /  20  40  20  60  40




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