Special Weather Statement, NWS Birmingham, AL

Area Forecast Discussion
National Weather Service Birmingham AL
314 PM CDT Sun Jul 25 2021

.SHORT TERM...
/Updated at 115 PM CDT Sun Jul 25 2021/
Through Monday.

Deep ridging remains the dominant feature across the Southeast.
Beneath the ridge, convection will be scattered and less organized
without a well-defined focusing mechanism. A remnant mesoscale
boundary has helped to initiate a line of scattered showers and
occasional thunder across the central portion of the forecast
area, but highest PoPs are still 50 percent. Activity will move
slowly today, and we will watch for more isolated instances of
flooding in the areas that have received consecutive days of
rainfall and remain saturated. Temperature profiles are hot and
humid and, similar to yesterday, we will be watching heat indices
with expected ranges of 100-104 degrees. Brief instances of 105
degree heat indices may be achieved in western portions of the
area, but should be short-lived and will not necessitate a Heat
Advisory at this time. However, trends will need to be monitored
heading into tomorrow where highs are forecast to be a degree or
two warmer and may push more portions of the area towards Advisory
criteria. Temperatures will drop into the lower to mid 70s
tonight, and more patchy fog is likely to develop.

A weak surface front will move into the Tennessee Valley and will
produce enhanced rain chances across our north tomorrow afternoon.
The increased coverage of rainfall and cloud cover should help to
cool temperatures during the warmest part of the day, but there may
still be a couple hours of lower to mid 90s during the early
afternoon.

86

.LONG TERM...
/Updated at 314 PM CDT Sun Jul 25 2021/
Monday night through Saturday.

Extended forecast remains a broken record with continued warm
conditions and high humidity through the forecast. I have added
Friday to our cautionary list of elevated heat index days in the
hazardous weather outlook (now mentioning M-F).

Tuesday is expected to be our day of highest rain chances and
greatest coverage. The flow aloft will consist of a large ridge
over the lee side of the Rockies, weak ridging spread across the
Deep South, and a low over E Canada with dull troughing into the
NE US. In the lower levels, with moisture and hot conditions well
in place, a low pressure/inverted trough will drift WWD into
Alabama from what is now the tropical moisture just E of the FL
Atlantic coast. This system will continue to affect Alabama on
Wednesday as it retrogrades WWD across the N Gulf Coast. However,
on Wednesday, the highest pops will be across the S half of the
state. In addition to this, there will be a degraded boundary
across the N that may scrape the area as well as it falls apart
for Tuesday into mid week.

By Thursday, rain chances go down to more typical summertime
levels as ridging builds over the Deep South in the mid and lower
levels. By Friday into Saturday, another front will be slowly
sagging down across the central part of E Conus. However, over
Alabama the upper flow indicates weak ridging and supportive of
helping progress it much into the state as we head into the
weekend.

08

Previous long-term discussion:
/Updated at 340 AM CDT Sun Jul 25 2021/
Monday night through Saturday.

Warm and humid weather pattern will persist through the upcoming
week.

A lingering frontal boundary will slowly push southward through
Central AL on Tuesday. Considering the moisture in place, I would
expect a higher coverage of afternoon thunderstorm activity with
boundary forcing in the area. The biggest impact, however, will be
the warm temperatures coupled with the high moisture content of this
airmass. Forecast highs are expected to be in the 90-95 degree range
on Tuesday with dewpoints in the mid to upper 70s. This will result
in heat index values exceeding 100 degrees for almost all of Central
AL. There will be several locations that could reach 105-107 degree
heat indices, so I'll be adding heat impacts to the hazardous
weather outlook for Tuesday. There's some uncertainty on just how
widespread the precip could be, which could impact the temperatures,
but it's likely that most of the area will reach into the triple
digit heat indices.

The frontal boundary is expected to push across the southern
portions of Central AL or just to our south Wednesday into Thursday.
The amplified ridge across the Mountain West begins to build in
across the northern half of Central AL around this same time. It's
important to note that while the frontal boundary will push through,
this really isn't a cold front - temperatures on the north side of
the boundary will likely still be in the mid 90s. The ridging
continues to build Thursday through Saturday as the boundary lingers
to our south. There could be some isolated to scattered
thunderstorms across the south, but the northern portions of Central
AL will probably see enough influence from the ridge to see a
significant decrease in convective activity compared to the last few
weeks. High temperatures Wednesday through Saturday are forecast to
be in the low to mid 90s with dewpoints remaining elevated. The
saturated grounds from recent rainfall will likely help keep
dewpoints elevated, which will result in afternoon heat indices
remaining in the triple digits for most of the week. While
confidence is low that we'll see widespread heat indices exceed 105
degrees (criteria for heat advisory), I think the prolonged nature
of the 100-105 heat indices that are currently forecast could lead
to impacts to vulnerable groups; therefore, I'll add a lower
confidence mention in the hazardous weather outlook for heat impacts
through at least Thursday.

25/Owen

&&

.AVIATION...
18Z TAF Discussion.

VCSH have developed around EET and BHM early this afternoon. This
activity is moving very slowly and trends will be watched for
development near the terminals as coverage expands over the next
several hours. Otherwise, expect VFR to continue into the
overnight hours with potential for patchy fog and MVFR
visibilities at the northern sites as early as 08Z before
returning to VFR around 13Z.

86

&&

.FIRE WEATHER...

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.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     73  92  73  92  73 /  30  60  40  80  20
Anniston    74  92  75  91  74 /  20  50  40  80  30
Birmingham  75  92  74  93  74 /  30  60  40  70  30
Tuscaloosa  75  93  75  93  74 /  30  50  40  70  30
Calera      75  92  75  91  74 /  30  50  40  80  30
Auburn      74  92  74  91  74 /  10  30  30  80  40
Montgomery  75  96  76  94  75 /  10  40  30  80  40
Troy        74  95  75  94  74 /  10  30  30  70  40

&&

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

&&

86/08/25

Hazardous Weather Outlook
National Weather Service Birmingham AL
213 PM CDT Sun Jul 25 2021

ALZ011>015-017>050-262215-
Marion-Lamar-Fayette-Winston-Walker-Blount-Etowah-Calhoun-Cherokee-
Cleburne-Pickens-Tuscaloosa-Jefferson-Shelby-St. Clair-Talladega-
Clay-Randolph-Sumter-Greene-Hale-Perry-Bibb-Chilton-Coosa-Tallapoosa-
Chambers-Marengo-Dallas-Autauga-Lowndes-Elmore-Montgomery-Macon-
Bullock-Lee-Russell-Pike-Barbour-
213 PM CDT Sun Jul 25 2021

This Hazardous Weather Outlook is for the counties served by the
National Weather Service office in Birmingham.

.DAY ONE...Outlook through Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Warm temperatures with high humidity values will lead to heat
indices approaching or exceeding 105 degrees for portions of Central
Alabama each afternoon Monday through Friday.

.SPOTTER INFORMATION STATEMENT...

Activation of storm spotters and emergency management is not
expected at this time.

08

Special Weather Statement
National Weather Service Birmingham AL
519 PM CDT Sun Jul 25 2021

ALZ015-252245-
Walker AL-
519 PM CDT Sun Jul 25 2021

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL WALKER COUNTY UNTIL 545
PM CDT...

At 519 PM CDT, Doppler radar was tracking a strong thunderstorm near
Parrish, or near Jasper, moving southwest at 10 mph.

Winds in excess of 40 mph will be possible with this storm.

Locations impacted include...
Jasper, Parrish and Oakman.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Birmingham.

&&

LAT...LON 3387 8733 3384 8723 3368 8726 3367 8739
      3375 8747
TIME...MOT...LOC 2219Z 023DEG 8KT 3380 8732

40/Sizemore

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