Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 221745
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
1245 PM CDT Fri Mar 22 2024

...New SHORT TERM, AVIATION...

.SHORT TERM...
(This afternoon through Saturday)
Issued at 1243 PM CDT FRI MAR 22 2024

Light rain is back on the radar this afternoon amidst increasing
isentropic ascent and rising low-level moisture ahead of an
approaching lower to mid-level shortwave over the Lower MS River
Valley. There is one factor that`s been somewhat throwing a wrench
into the forecast, and that is mid-level dry air intrusion
wrapping around the low as evident by water vapor satellite
imagery and diminishing cloud cover seen on visible satellite
imagery across portions of our southwest. There`s been much less
rain development across the southwest as a result, and most of the
light showers are focused across northern and eastern portions of
Central Alabama at this time. Made some adjustments to PoPs as
short term guidance has been slow to properly resolve the depth
and impact of the dry layer which has resulted in less coverage of
rain up to this point than previously expected. The breaks in the
cloud cover has also allowed temperatures to rise into the upper
60s to lower 70s in the southwest, so highs have been adjusted
accordingly.

The surface low is progged to track along the Gulf Coast tonight,
and some scattered to numerous showers are likely to continue
overnight as the low moves towards Georgia. Deep northerly flow
develops behind the trough which will result in decreasing moisture
throughout the morning tomorrow. Any lingering showers in the east
should end by midday with clouds gradually clearing west to east
during the afternoon. Highs will range from the lower 60s north to
upper 60s south.

86/Martin

&&

.LONG TERM...
(Saturday night through next Thursday)
Issued at 400 AM CDT FRI MAR 22 2024

Saturday night through Sunday night.

Broad longwave ridging will move east from over the Southern Plains
to over the Lower Mississippi River Valley Region Saturday night
into Sunday while deep mid-level troughing will be positioned over
the Carolinas. The longwave ridge axis will move east of the area
during the day Sunday as it increases further in amplitude due to
the broadening of the mid-level trough over the Desert Southwest
east to over the Plains. Strong and expansive surface high pressure
will be positioned across Southern Canada to over the Great Lakes
that will expand southward across the Lower Mississippi River Valley
Region. The surface cold front will stall along the Northern Gulf
Coast later in the day on Sunday.

Expect fair skies with dry conditions Saturday night through Sunday
morning areawide, followed by gradual increasing clouds from the
west during the afternoon into the evening hours. Lows Sunday
morning will range from the mid 30s far north to the mid 40s far
southeast followed by highs from the mid 60s in the higher
elevations east to he low 70s south and central.

Monday through Tuesday.

The forecast area will become positioned between amplified longwave
ridging to our east and broad, deep troughing over the Desert
Southwest on Monday while a potent shortwave will swing northeast
over the Central Plains toward the Great Lakes Region. Locally, a
southwest flow will develop aloft while a potent surface low
develops along the Front Range of the Rockies and deepens with time
as it quickly moves northeast toward the Great Lakes late in the day
on Monday. Surface high pressure will become centered across
Southeast Canada with residual wedging effects down the Appalachians
into East/Northeast Alabama through Monday morning while the diffuse
remnant surface front along the Central Gulf coast begins moving
inland in response to the advancing trough over the South-Central
Plains.

On Tuesday, the longwave trough will continue to move further east
over the Central Plains while most modeling depicts an embedded
shortwave that will pivot northeast around the base of the trough
early Tuesday over South Texas and will take on a more negative tilt
as it swings northeast over the Mid-South Region Tuesday afternoon
and Evening. The corresponding cold front will extent from near
Chicago southwest to near Memphis during the morning while surface
low pressure is progged to develop near New Orleans at the triple
point where the remnant coastal/marine front will push inland across
South Alabama and the Western Florida Panhandle through the day.

The forecast will call for continued increasing clouds late Sunday
through Monday with chances for scattered showers and a few
thunderstorms during the afternoon hours Monday across the northwest
and west-central Counties. Expect this activity to continue to
expand east with time, affecting more of the area into the day on
Tuesday with widespread showers and at least isolated thunderstorm
activity reaching a climax during the afternoon through the mid
evening hours before activity begins to taper off from the northwest
late Tuesday night. Temperatures will moderate during this time
frame with lows from the mid 40s east to the low 50s west Monday
morning and highs from the mid 60s north and northeast to the low
70s south to lows areawide in the 50s Tuesday morning and highs from
the mid to upper 60s north while highs will reach into the mid 70s
far southeast Tuesday afternoon.

Sufficient wind shear with decent low-level instability appear to be
present on Tuesday, especially from midday through early evening, to
support some strong to severe storms with better potential across
the southern, southeast and east-central counties that look to be
near and south of a developing surface low track that may
materialize from near New Orleans to near Atlanta through this time
frame that would permit the warm sector to advect northward with
time towards the Interstate 20 corridor, potentially allowing the
warm sector to move north into this area from midday Tuesday through
the early evening. There are, however, some limiting factors
including weak mid to upper level lapse rates and uncertainty
regarding how unstable the low levels can become given such high
rain chances through much of the day. This time frame will continue
to be closely monitored as additional modeling becomes available and
as we get a more detailed look at the environment once higher-
resolution modeling becomes available for this time frame.

Wednesday through Thursday.

Broad and expansive mid-level troughing will be over much of the
Country with a deep upper low over the far Northern Plains on
Wednesday. A southwest flow will persist over our area while
expansive surface high pressure will be centered across much of the
Plains while surface low pressure will be centered across South
carolina. A diffuse cold front will be positioned roughly parallel
to the Interstate 59 corridor on Wednesday morning as it continues
to decelerate with time.

Longwave ridging looks to build over the Four Corners States late
Wednesday into Thursday, resulting in the downstream trough over the
Plains to respond accordingly by deepening in amplitude. The more
progressive nature in the flow pattern aloft will help force the
trough further east over the Mid and Lower Mississippi River Valley
Regions by early Thursday morning and moving east over the forecast
area later in the day. Feature timing and placement issues are quite
notable between some global model solutions during this time frame,
resulting in a lower than usual confidence in this portion of the
forecast.

Clouds will gradually decrease from west to east while some shower
activity may linger across the east and southeast Counties through
midday Wednesday. Shower chances will continue to decrease through
the afternoon with dry conditions forecast areawide after sunset. A
potentially slower progression would maintain some shower activity
across at least the eastern third of the area into Thursday and
would also result in more cloud cover than currently forecast for
this issuance. Lows Wednesday morning will range from near 40 far
northwest to the mid 50s southeast followed by highs from the low
60s northwest to the low 70s far southeast. Low temperatures will be
cooler Thursday morning ranging from the upper 30s far northwest to
the mid 40s far southeast and highs from the low 60s far north to
the low 70s south.

05

&&

.AVIATION...
(18Z TAFS)
Issued at 1243 PM CDT FRI MAR 22 2024

A surface low will move across the Gulf Coast region resulting in
aviation impacts during this TAF period. Periods of -SHRA will be
possible at all terminals leading to lowered visibility in
addition to gradually falling ceilings. Ceilings will vary from
IFR to MVFR this afternoon then area-wide IFR after 00Z. Winds
will shift from easterly to north-northwesterly overnight as the
low moves towards Georgia, and speeds will increase to around 8 to
12kts with occasional gusts up to 25kts.

86/Martin

&&

.FIRE WEATHER...

Rain returns to the area this morning and will continue through
evening before exiting Saturday morning. 20 ft winds increase from
the east southeast today, at 10-15 mph. As a front moves through
the area on Saturday, winds become northerly at 12-18 mph. Minimum
RH values will remain above critical threshold through Saturday,
with values ranging from 30-40 percent Sunday afternoon. The next
wetting rains look to be Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     54  64  36  70 /  90  20   0   0
Anniston    54  65  37  70 /  80  20   0   0
Birmingham  55  63  39  70 /  80  10   0   0
Tuscaloosa  56  67  39  72 /  80  10   0   0
Calera      55  64  39  70 /  80  10   0   0
Auburn      57  67  41  69 /  60  30   0   0
Montgomery  58  68  41  71 /  50  20   0   0
Troy        58  69  44  72 /  50  20   0   0

&&

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

$$

SHORT TERM...86/Martin
LONG TERM....05
AVIATION...86/Martin


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