Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 301134

Area Forecast Discussion
National Weather Service Birmingham AL
634 AM CDT Fri Jul 30 2021

For 12Z Aviation.


/Updated at 0314 AM CDT Fri Jul 30 2021/

Through Saturday.

Not expecting any major relief from the heat due to showers/storms
in the afternoon as high pressure remains to our west. There is a 20
to 30 percent chance in the northeast during the afternoon, but most
will remain dry versus seeing rain. Another hot day on Saturday, but
we could see more clouds in the afternoon along with widely
scattered showers/storms. Temperatures will be in the mid to upper
90s with a few near 100. Heat indices above 100. Several areas will
see heat indices as high as 107 to 109. Use caution and hydrate if
outdoor for extended periods.


/Updated at 0314 AM CDT Fri Jul 30 2021/

Saturday night through Thursday.

The highly amplified ridge is expected to persist across much of the
Mountain West as we go through next week. A deep trough digs through
the Ohio Valley and into the TN Valley Saturday night through
Sunday, pushing a frontal boundary southward through Central AL on
Sunday. This will lead to numerous showers and thunderstorms in the
afternoon and could continue through much of the overnight hours
into Monday morning. The question will be how quickly the boundary
pushes through on Sunday afternoon. It`s possible the the
rain/precip is slow enough to allow us to see peak heating before
the boundary pushes into the area. If this happens, we`ll once again
see numerous locations reach or exceed 105 degree heat indices. It`s
possible that the rain moves in quicker or at least the cloud cover
builds in quicker, limiting the heating. For now, I`ll continue
mentioning heat impacts through Sunday afternoon, especially
considering how many days we`ve seen heat stress impacts. Model
guidance picks up on a secondary shortwave swinging through the
larger scale trough on Monday, enhancing the lift along the boundary
as it moves through the southern half of Central AL Monday afternoon
and evening. This will likely lead to widespread rain and
thunderstorms as we begin the upcoming work-week, which will also
mark a decrease in the afternoon high temperatures.

The upper trough stalls out over the Eastern CONUS with the ridge
remaining persistent in the west. For now, model guidance hints at
much of the uplift associated with the trough and any
lingering/stalled boundary should remain just to our south through
mid-week. However, there`s enough uncertainty on where those
features set up that will warrant continued inclusion of
rain/thunderstorms chances across the southern and western
portions of Central AL each day through Thursday. I don`t believe
it will be continuous rainfall, as it will be enhanced spatially
by the passage of upper shortwaves that model guidance will
struggle to resolve this far in advance. Therefore, I would expect
the rain/thunderstorm chances to change both in timing and
location as model guidance comes into better agreement in the
coming days.



12Z TAF Discussion.

Becoming normal for morning fog at TAF sites. Already starting to
see the fog burn off and should be gone by 13z. Generally looking
for northerly winds less than 10 kts this afternoon. Could be a
shower or two in the northeast (ANB and ASN) but chances remain
just low enough to not mention. Will need to evaluate at the 18z
issuance. Went ahead and added in light fog for ANB, ASN, EET,
TCL, and TOI overnight tonight. While brief the plausibility is
there as the airmass really does not change.




A warm and moist airmass will persist across Central Alabama
through Sunday. A strong upper ridge will build over the area and
suppress rain chances. Better rain chances return Sunday and
Monday as our next system pushes in from the north. Highs Thursday
through Saturday will be in the middle to upper 90s with heat
indices at or above 105 degrees.


Gadsden     97  74  96  75  94 /  30  20  20  20  70
Anniston    97  75  96  75  93 /  20  20  20  10  70
Birmingham  99  76  97  77  95 /  20  10  20  10  70
Tuscaloosa  98  77  98  78  95 /  10  10  20  10  60
Calera      96  77  95  77  93 /  10  10  20  10  60
Auburn      96  77  96  76  93 /  10  10  30  10  60
Montgomery  98  77  99  77  96 /  10  10  30  10  60
Troy        97  77  98  78  95 /  10  10  40  20  70


Heat Advisory until 7 PM CDT Saturday for the following
counties: Autauga...Barbour...Bibb...Blount...Bullock...
Shelby...St. Clair...Sumter...Talladega...Tallapoosa...


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