Special Weather Statement, NWS Birmingham, AL

Area Forecast Discussion
National Weather Service Birmingham AL
1234 PM CDT Mon Aug 6 2018

.UPDATE...
For 18Z Aviation.

&&

.SHORT TERM...
Today and Tonight.

Low level ridging remains in place across the area as the center
of a high pressure system is over Central AL. This will lead to
synoptic scale subsidence that should limit overall convective
coverage this afternoon. A weakening upper level low slowly
retrogrades southwestward through the ArkLaMiss and into the
Western Gulf of Mexico. This weak upper level low could have some
lift associated to it, which could at the very least increase
cloud cover for today, but I'm not sure it will provide enough
lift to overcome the subsidence of the low level high. Models do
pick up on some scattered showers/storms briefly this afternoon,
but this mainly looks to remain across our southern areas and
remain scattered to isolated in coverage. I have maintained 25%
PoPs for the south, but showers/storms will be hit or miss for
most locations. Otherwise, expect a mostly hot and humid day
across Central AL with highs in the low to mid 90s. Several areas
could approach or hit triple digit heat indices, but I don't
expect us to 105, so will not add any mention of heat impacts to
the HWO for today.

25/Owen

.LONG TERM...
Tuesday through next Monday.

Tuesday through Thursday:

Mid to upper level ridging will gradually decrease its influence
over the area through midweek as a positive tilted longwave trough
dives southeast into the High Plains with increasing amplitude by
Wednesday as it extends from Wisconsin southwest into Arkansas.

With relatively higher heights persisting over the southeast, the
trough swings east through the Ohio River Valley by Thursday
morning with a general zonal flow over the deep south.

Tuesday will feature isolated showers and thunderstorms with most
activity in the afternoon with greatest coverage southeast.
Expect convection to decrease in coverage overnight with few to
isolated showers with best chances northwest and southeast. Rain
chances will increase further Wednesday as the upper trough
approaches the region from the northwest. Convection will decrease
to an extent Wednesday night with isolated coverage over the
northern third of the forecast area while a few showers will
remain possible elsewhere. Scattered convection is likely again
Thursday encompassing the northwestern half of our forecast area
with isolated activity southeast. Expect isolated convection
persisting into Thursday night across much of the area.

Tuesday looks to be the warmest day in the extended with highs in
the low 90's followed by readings ranging from the upper 80's to
around 90 through Wednesday. Overnight conditions will remain
humid and mild with readings in the low to mid 70's through
Thursday.

Friday through Monday:

Through the late week time frame a shortwave trough develops over
the central plains and digs southeast into the Mid South region
by Friday and slides east across the Tennessee Valley in a
positive to neutral tilt on Saturday before losing definition as
it swings northeast into the southern Mid Atlantic region.

Scattered showers and thunderstorms again are expected across
much of the area Friday with an isolated coverage Friday night.
Scattered convection is forecast to be more confined to our
southern and southwest counties Saturday with convection more
isolated in nature north and northeast.

Broad positive-tilt troughing is left in its wake as most global
models have come into better agreement with regard to a deeper
trough moves out of Canada and further develops over the Great
Lakes region late Saturday then cuts off into an upper low near
the Chicago area.

Isolated convection is expected across all but our far southeast
on Sunday where scattered showers and storms are expected.
Isolated convection is forecast Sunday night areawide and
continuing into Monday northwest while activity will become
scattered in nature southeast.

Later this week highs are expected to range from the mid 80's to
near 90 with the additional convective activity. Slightly cooler
low temperatures are forecast for the latter portion of the long
term period with readings ranging from the upper 60's to the lower
70's from Friday through Monday morning.

05

&&

.AVIATION...
18Z TAF Discussion.

VFR conditions continue for all terminals with showers and
thunderstorms already beginning to develop primarily to the west.
Included TEMPO -TSRA for KTCL until 21Z and VCSH for KBHM and KEET
for now. Will amend if needed. Generally calm winds overnight. As
previously mentioned in the last discussion, some guidance shows
some MVFR fog development at KEET, KANB, and KASN tomorrow
morning however confidence is still low. Have not included any
mention of fog or low cloud development at this time for any
terminals.

Will continue adding AMD NOT SKED to KANB due to comms issues
impacting our obs. FAA is aware of the issue, but we do not have
an estimated time for repairs.

07

&&

.FIRE WEATHER...

Slightly lower rain chances expected through Tuesday. Min RH values
will remain high across the area with good moisture content
available in the lower levels after recent periods of heavy
rainfall. Localized light fog and low clouds will be possible
near bodies of water each morning. There are no fire weather
concerns at this time.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     71  92  72  89  71 /   0  30  20  50  50
Anniston    72  93  74  90  72 /   0  30  20  40  40
Birmingham  75  93  76  90  73 /   0  30  20  50  50
Tuscaloosa  75  95  75  92  73 /   0  20  20  50  40
Calera      73  92  74  89  73 /   0  30  20  40  40
Auburn      75  91  74  88  72 /  10  30  30  40  20
Montgomery  74  94  76  91  74 /  10  30  30  40  20
Troy        74  93  74  91  73 /  20  30  30  40  20

&&

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

&&

Hazardous Weather Outlook
National Weather Service Birmingham AL
503 AM CDT Mon Aug 6 2018

ALZ011>015-017>050-071315-
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-
503 AM CDT Mon Aug 6 2018

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...Tuesday through Sunday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

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

Special Weather Statement
National Weather Service Birmingham AL
117 PM CDT MON AUG 6 2018

ALZ014-061845-
Winston AL-
117 PM CDT MON AUG 6 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN WINSTON COUNTY UNTIL
145 PM CDT...

At 117 PM CDT, Doppler radar was tracking a strong thunderstorm near
Haleyville, moving east at 5 mph.

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

Locations impacted include...
Haleyville, Ashridge, Needmore, Delmar and Weiss.

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.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3424 8743 3408 8749 3414 8764 3424 8763
      3425 8763
TIME...MOT...LOC 1817Z 285DEG 5KT 3419 8759

56

Special Weather Statement
National Weather Service Birmingham AL
118 PM CDT MON AUG 6 2018

ALZ022-061845-
Pickens AL-
118 PM CDT MON AUG 6 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN PICKENS COUNTY UNTIL
145 PM CDT...

At 118 PM CDT, Doppler radar was tracking a strong thunderstorm near
Reform. This storm was nearly stationary.

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

Locations impacted include...
Gordo, Reform, Lubbub and North Pickens Airport.

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.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3353 8806 3353 8805 3352 8784 3331 8784
      3331 8802
TIME...MOT...LOC 1818Z 265DEG 1KT 3341 8795

56