Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 270905

Area Forecast Discussion
National Weather Service Birmingham AL
405 AM CDT Tue Jul 27 2021

/Updated at 0347 AM CDT Tue Jul 27 2021/

Today through Wednesday.

A broad ridge remains centered over the Rockies today, extending
eastward toward the Deep South. A stalled front stretches across
Tennessee this morning. A weak shortwave, rotating through a trough
over the Midwest and Northwest, will aid pushing that front
southward today. It should lose definition with time, but provide a
focus for shower and storm development today. Through mid day, rain
coverage will be isolated to scattered, and outside of this
activity, temperatures will warm into the low 90s. This will send
heat indices toward 105-106F. A Heat Advisory will be issued for
most of the area for today. Will hold off on the northeastern
counties for now, and see how convection trends around mid day. If
activity does not develop, might need to expand the advisory to
include all counties.

Activity today will diminish this evening, and will need to watch
for fog development again tonight. Upper level flow will become more
northerly Wednesday as the ridge extends further eastward into the
Great Plains. Drier mid level air will help curb rain chances,
confining most activity to southern counties. However, low level
moisture remains elevated and with highs reaching into the low to
mid 90s, another Heat Advisory will be needed Wednesday.


/Updated at 0347 AM CDT Tue Jul 27 2021/

Thursday through Monday.

The center of a 597 decameter mid-level anticyclone will drift
southward from Kansas to Oklahoma Thursday and Friday. The
associated mid-level ridge axis and anti-cyclonic flow will extend
southeastward into Central Alabama. This combined with lower 1000-
500mb mean RH values will greatly limit diurnal convection potential
Thursday and Friday and PoPs have been reduced. The ridge should
result in the warmest temperatures of the summer so far. Low-level
thicknesses support temperatures in the mid to upper 90s though wet
ground conditions could be a small limiting factor. Global models
indicate some lower dew points will mix down though the wet ground
conditions could also limit this potential. Whether the mixing or
wet ground conditions win out, either should result in heat indices
in the 105 to 108 range in most areas except the far east-central
counties. Ridging over the area will be fairly short-lived, as
another amplifying western CONUS ridge begins to cause downstream
trough amplification over the eastern CONUS on Saturday with
northwest flow aloft developing over Central Alabama. Models may be
trending hotter and drier for Saturday and will have to monitor
trends. But by Sunday and Monday moisture will increase ahead of an
approaching cold front, with showers and storms becoming numerous.
This is also a pattern where we would have to watch for any MCSs
that develop. Some relief from the higher heat indices will arrive
by Monday.



06Z TAF Discussion.

A few lingering showers or storms are possible overnight, mainly
across the far south. Will need to watch boundary collisions
overnight for development that could impact terminals, but
generally coverage should be 20% or less.

Patchy fog is expected at all terminals, with MVFR vis. Could see
lower visibilities of around 2 miles, across the far north.
Conditions improve after sunrise. Rain chances increase Tuesday by
late morning, with scattered to numerous coverage by afternoon.
Will need to refine rain chances at each site with future updates
with prevailing TSRA rather than PROB30s. Winds will be light
overnight and west to west northwest 7kts or less.




A warm and moist airmass will persist across Central Alabama
through the upcoming week. Minimum relative humidity values will
remain elevated with scattered to numerous diurnal thunderstorms
through mid week. Rain chances decrease some as we head into the
latter half of the week, but minimum relative humidity values
remain elevated.


Gadsden     92  73  94  74  97 /  60  20  20   0  10
Anniston    91  73  93  74  97 /  60  30  30   0  10
Birmingham  92  75  94  75  97 /  60  30  30   0  10
Tuscaloosa  92  75  95  76  97 /  60  30  40   0  10
Calera      91  74  93  76  95 /  60  30  40  10  10
Auburn      92  73  91  74  95 /  70  40  50  10  10
Montgomery  95  76  94  76  97 /  70  40  60  20  20
Troy        94  74  92  75  96 /  80  60  60  20  30


Heat Advisory from 11 AM this morning to 7 PM CDT this evening
for the following counties: Autauga...Barbour...Bibb...Bullock...


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