Area Forecast Discussion
Issued by NWS Birmingham, AL

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844
FXUS64 KBMX 232349
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
649 PM CDT Tue Apr 23 2019

.UPDATE...
For 00Z Aviation.

&&

.SHORT TERM...

Surface ridge holding strong and centered on top of Alabama at
this time. An upper ridge was positioned from the Western Gulf
into the Appalachians. Only some cirrus cloudiness was spilling
over the ridge. Otherwise, high temperatures will reach the 80s
today in most places. These temperatures are just slightly above
normal.

This pattern will hold into Wednesday. Therefore, overnight lows
will be very similar to last night in the mid 50s to low 60s.
Southerly winds rotate around the high on Wednesday as the slow
moisture increase starts. Therefore, a few more clouds can be
expected by late in the afternoon.

75

Previous short-term discussion:Today and Tonight.

Surface ridging is in control across Central Alabama this AM with
high pressure across the Southeast U.S. As a result, we have near
calm winds and generally clear skies except for a few cirrus clouds
noted on satellite that are going through the upper zonal flow
across the top of the Gulf of Mexico ridge. The surface ridge will
begin to slowly weaken tonight. Our airmass will moderate with
milder temperatures expected for today and tonight. However with
southwest low level flow, moisture will be slow to reenter the
picture. Our forecast will continue to be rain free today and
tonight.

08

.LONG TERM...
Wednesday through Friday.

A positively tilted trough/upper-level low with begin to eject from
the Southern Rockies into the Southern plains Wednesday. This will
be our next weather maker across Central Alabama in the Thu/Fri
timeframe. Not a lot of changes in expectations for weather across
the area with a warm Wednesday afternoon (upper 70s to mid 80s)
despite increasing cloud cover from upstream convection and
southwesterly flow aloft. Broad ridging across the Southeast will
help set the stage for increasing rain chances as theta-e advection
and southerly surface flow increase on the western periphery of a
surface high to our east-southeast. Though no rainfall is
anticipated Wednesday, increasing PoPs from the west have been
placed in the forecast on Thursday as better quality moisture and
deep-layer forcing approach the Lower Mississippi River Valley by
Thursday morning.

A look at the thunderstorm parameter space has continued to suggest
best coverage of convection will remain along the Gulf Coast &
offshore where the best jet dynamics & tropical moisture are
available, but have trended farther north with modest shear profiles
(30-40 kts 0-6 km bulk shear with indications of a stronger mid-
level jet). Synoptically speaking a strong/severe storm cannot be
ruled out at this point, especially across the south where the best
overlap of ingredients occur, but likely ongoing/re-intensifying
Gulf Coast convection would limit destabilization such that more
favorable shear profiles are not taken advantage of. Regardless,
trends will continue to be monitored closely as we get closer to
Thursday. Once antecedent rounds of strong/severe thunderstorms have
taken place across Texas today and tomorrow, we can get a better
picture of where mesoscale areas more favorable for stronger
convection may develop. Due to low forecast confidence in any
particular outcome that involves severe weather at this time, will
continue to forego inclusion in the HWO again tonight.

Saturday through Monday.

Despite uncertainties/specific details of how weather evolves
Thu/Fri, the synoptic scale trough will be out of the area and to
our east by Saturday. Have decreased PoPs such that only a lingering
shower may be possible across the east/southeast early Saturday
morning. Thereafter, a polar jet across the northern tier of the
CONUS and zonal split-flow will help stabilize weather across the
area with high pressure/drier air establishing across the Southeast.
Warm temperature trends appear likely as we head into the long-term
with upper 80s possible by early next week.

40/Sizemore


&&

.AVIATION...
00Z TAF Discussion.

VFR conditions will stay put the next 24 hours. West to southwest
winds around 6kts will diminish quickly the next hour or so with
light to calm winds overnight. Plenty of cirrus will remain in the
sky as it spills over the ridge.

On Wednesday, winds pick up to around 8kts from the southwest as
the general pattern remains the same. A ridge axis remains near to
just east of Central Alabama and a front to our west and north.

Some patchy low clouds or fog may develop closer to the coast and
will monitor is slow northward push. Additionally, most locations
will have surface dew point depressions that will inhibit fog
development, but some patchy valley/river fog is possible. This
should not affect any terminals at the moment.

75

&&

.FIRE WEATHER...

A dry airmass remains across the area through mid-week. Increasing
cloud cover is expected today but will generally remain mid to
high-level. With surface high pressure slowly working its way
eastward, winds will become more southwesterly today and increase
to 5-8 knots by this afternoon. Relative humidity values in the
mid 30-40% range are expected this afternoon as well. Next
forecast rain chances begin Thursday morning from the west and
will continue through Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     56  83  58  78  59 /   0   0  10  40  80
Anniston    58  84  58  78  59 /   0   0  10  30  70
Birmingham  60  84  60  78  61 /   0   0  10  40  80
Tuscaloosa  57  84  61  77  61 /   0   0  10  60  80
Calera      58  82  59  78  60 /   0   0  10  40  80
Auburn      59  82  58  79  61 /   0   0   0  20  70
Montgomery  58  84  59  80  62 /   0   0   0  30  80
Troy        57  83  57  79  62 /   0   0   0  20  70

&&

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

&&

$$



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