FXUS64 KBMX 230520

Area Forecast Discussion
National Weather Service Birmingham AL
1220 AM CDT Tue Apr 23 2019

For 06Z Aviation.



Updated the hourly trend this evening. We are experiencing various
local effects with some places warmer and some places cooler. A
batch of cirrus will move across the skies overnight, around the
top of an upper ridge centered in the western gulf. Therefore,
some of the Lyrids Meteor Shower may be visible across Central

The surface dew point depressions should remain a few degrees in
most locations to inhibit fog, but lower valley areas and
waterways may experience some light fog.


Previous short-term discussion:Through Tonight.

Surface high pressure continues to influence conditions across the
area, with clear skies and light winds today. With another hour or
so of warming, temperatures will top out in the low 80s. This
evening, winds will diminish to calm for most locations. Cirrus
might spill over the approaching upper level ridge axis.
Otherwise, skies will be clear. Lows tonight will be in the low to
mid 50s.

Taking a look at the extended and increased rain chances for the
second half of the week...only change made was to slow down the
arrival of rain slightly, by removing rain chances prior to 12Z
Thursday. Otherwise, the forecast is on track.


Tuesday and Wednesday.

The long-term forecast still looks on track as previously advertised.
High pressure across the Southeast will eventually begin positioning
more along the Carolina Coast Tuesday morning with mid/upper-level
shortwave ridging developing along the Appalachians. Thus, Tuesday &
Wednesday are expected to be our warmer days of the upcoming work
week with upper 70s in the far northwest, and more widespread low to
mid 80s elsewhere. Given considerations of higher heights and better
sunshine chances Tuesday, still believe it will be the warmer day of
the two but there shouldn`t be much difference overall and will
depend on the extent of cloud cover Wednesday. No rain chances are
in the forecast these two days, though upstream our next weather
maker will begin a period of severe weather across Texas this
afternoon and into Wednesday.

Thursday and Friday.

The upcoming disturbance continues to show trends consistent with an
easterly track as it fully detaches from Polar Jet and ejects into
the Southern Plains Thursday morning. After a third round of
possible severe weather in Texas, the upper-level and surface lows
are expected to become more vertically stacked and resultantly
weaken as it heads towards the lower Mississippi River Valley.
Nonetheless, downstream theta-e advection and synoptic forcing will
result in increasing PoPs from the west Thursday morning, but best
area-wide coverage of showers and thunderstorms is expected Thursday
night into early Friday as better quality low-level moisture is
available. Severe weather will not be mentioned in the forecast/HWO
again tonight as many considerations have yet to appear likely which
include sufficient buoyancy (broad coverage of 250-500 MLCAPE) and
shear profiles (20-25 kts 0-6 bulk shear), among other variables. It
also appears likely that better/stronger convection will remain
along the Gulf Coast & offshore where better dynamics from the sub-
tropical jet and instability are available. This will be watched in
the next couple of days as we get a better handle of the evolution
of upstream convection and resultant mesoscale areas more favorable
for stronger storms. A similar system affected Central Alabama
recently with a few isolated severe thunderstorms, though nothing
widespread or above a "Marginal Risk" unfolded. We`re still a day or
two too early to reliably predict a weaker signal such as that.
Either way, no significant or impactful weather is expected at
this time. Up to one inch of rainfall is possible with locally
higher amounts for those receiving any stronger convection. Have
maintained `slight chance" for thunderstorms in forecast.

Saturday and Sunday.

Weekend weather conditions are expected to improve with the system
exiting to our east and Central Alabama becoming more stable. It
appears that the Polar Jet will stay across the Northern CONUS
during this period, so heights will respond quickly after the
shortwave approaches the Florida Panhandle. 70s & 80s will stay in
the forecast for afternoon highs with no mentionable rain chances at
this time, other than a few lingering showers possible across the
southeast early Saturday morning.



06Z TAF Discussion.

A VFR forecast is expected for the next 24 hours. Surface high
pressure is in place over the Southeast U.S. with fair skies. We
have only some thin cirrus noted on satellite that is transversing
through zonal flow around an upper Gulf of Mexico ridge.
Overnight winds are light to near calm across Central Alabama.
With daytime mixing, southwest winds of 5-10 kts are expected
around the surface ridge.




A dry airmass remains across the area through mid-week. Clear
skies and calm winds tonight will allow patchy river and valley
fog to develop early Tuesday morning. Moisture slowly increases
through mid week, with relative humidity values in the mid 30 to
lower 40 percent range Tuesday and Wednesday afternoons. The next
chance of rain arrives early Thursday.


Gadsden     82  55  82  57  79 /   0   0   0  10  30
Anniston    83  56  83  57  80 /   0   0   0  10  20
Birmingham  83  58  83  60  79 /   0   0   0  10  30
Tuscaloosa  83  56  83  60  78 /   0   0   0  10  40
Calera      82  57  82  59  78 /   0   0   0  10  30
Auburn      82  58  82  58  79 /   0   0   0  10  20
Montgomery  84  57  84  59  81 /   0   0   0  10  20
Troy        84  57  84  58  81 /   0   0   0   0  20






NWS BMX Office Area Forecast Discussion