Flash Flood Warning 20, NWS Birmingham, AL

Area Forecast Discussion
National Weather Service Birmingham AL
110 PM CDT Wed May 30 2018

.UPDATE...
For 18Z Aviation.

&&

.SHORT TERM...
Today through Thursday Night.

This AM, shortwaves rotating around the upper low situated over
KY/TN and what is left of Alberto have generated copious amounts of
rainfall with a large swath of showers and thunderstorms across
Central Alabama. We have decent southerly low level flow still
feeding in moisture off of the Gulf of Mexico along with dew points
generally in the lower 70s. What is left of the upper feature
associated with Alberto is expected to be pulled to the north
tonight and be absorbed into the main upper trough over the Northern
Plains into the Great Lakes. So, we should see less rain coverage
for tonight, but some scattered shower and thunderstorm activity is
still possible, generally across the north.

For Thursday, more upper shortwaves, with activity peaking during
the heat of the afternoon will allow for more thunderstorms. Also, a
front will move eastward out of the Upper Mississippi River Valley
and the Central Plains toward KY/TN. The front itself will likely
get hung up across there with an unfavorable upper flow to push it
through Alabama. However, with daytime heating, decent CAPE, still
elevated dew points, upper shortwaves, and outflow boundaries
possible from storms closer to the front, we could see a few strong
storms on Thursday afternoon across some of our northern counties.
The main energy decreases significantly after sunset, so would
suspect a decrease in coverage Thursday evening as a result.

08

.LONG TERM...
Friday through Thursday.

Overall the pattern has not changed much for the weekend and the
first of next week. A northwest upper flow pattern will develop east
of the Mississippi River Friday and remain through the weekend. This
pattern this time of year favors MCS development and the threat of
damaging straight-line winds. Warm and moist air on the eastern side
of the upper ridge will advect into Central Alabama Friday and
Saturday. A more significant short wave will slide through on Sunday
and shows a pretty good amount of storms developing along the
boundary. The GFS and ECMWF models are showing surface based CAPE
values Friday through Sunday afternoons between 3000 and 4000
J/kg. Will add a low confidence severe for Sunday and continue the
threat for Friday and Saturday as well. One caveat to all of this
will be to what extent does the previous days convection, or any
convection that develops overnight, impact the rain chances during
the day. This all depends on the exact timing of each minor
shortwave and other mesoscale features that will be determined as
we get closer to the days of concern. The upper ridge will likely
expand farther eastward by early next week and result in less
convective activity across central Alabama.

16

&&

.AVIATION...
18Z TAF Discussion.

Scattered showers and thunderstorms are possible around KMGM and
KTOI...though the chances are greater at KTOI for MVFR
visibilitiesand ceilings from convection. The rest of central AL
is seeing ceilings start to mix out behind a band of showers. VFR
conditions are expected to develop through the afternoon and
early evening. Confidence is low on forecast overnight. Models
show another band of showers and thunderstorms moving into east
AL...though instability is weak...so included VCSH for now with a
PROB 30 for the isolated thunder possibility. If showers develop
and move SE...sites could experience MVFR conditions through the
morning. Otherwise...enough moisture will cause fog development
and possibility for at least IFR ceilings.

24

&&

.FIRE WEATHER...

A moist pattern is expected through at least midweek, with a drier
and warmer trend for Thursday through the weekend. A northwest
flow for the end of period may result in scattered showers during
the evening and morning hours. Patchy fog and low clouds will be
possible tomorrow morning and again Thursday morning. No fire
weather concerns at this time.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     69  85  70  88  68 /  50  60  20  60  50
Anniston    70  86  71  89  70 /  40  60  20  60  50
Birmingham  71  88  73  90  72 /  40  40  20  60  40
Tuscaloosa  72  90  73  93  72 /  30  30  10  40  20
Calera      70  87  72  90  71 /  40  40  20  60  30
Auburn      70  85  71  88  71 /  30  50  20  40  40
Montgomery  71  89  72  91  72 /  20  40  10  30  20
Troy        70  88  71  90  72 /  20  40  10  30  20

&&

.BMX WATCHES/WARNINGS/ADVISORIES/...
Flash Flood Watch until 7 PM CDT this evening for the following
counties: Autauga...Bibb...Blount...Bullock...Calhoun...
Chambers...Cherokee...Chilton...Clay...Cleburne...Coosa...
Dallas...Elmore...Etowah...Greene...Hale...Jefferson...Lee...
Lowndes...Macon...Marengo...Montgomery...Perry...Randolph...
Russell...Shelby...St. Clair...Talladega...Tallapoosa...
Tuscaloosa.

&&

Hazardous Weather Outlook
National Weather Service Birmingham AL
446 AM CDT Wed May 30 2018

ALZ011>015-017>050-311300-
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-
446 AM CDT Wed May 30 2018

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

.DAY ONE...Today and Tonight.

Areas of showers and thunderstorms are expected again today. Due to
recent heavy rains, isolated locations may experience some flooding,
especially where the grounds are already saturated or are prone to
flooding.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

A pattern favorable for organized convective systems will develop
across Alabama. There is a low confidence for damaging straight line
winds on Thursday afternoon across the north. Damaging winds are
also possible across Central Alabama on Friday, Saturday, and Sunday.
Heavy rain will continue to be possible with this activity which
could cause localized flooding due to saturated grounds and flood
prone areas.

.SPOTTER INFORMATION STATEMENT...

Activation of storm spotters and emergency management may be
necessary Thursday through Sunday.

08

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1121 AM CDT WED MAY 30 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1030 AM     FLASH FLOOD      1 E MARION              32.63N 87.31W
05/30/2018                   PERRY              AL   BROADCAST MEDIA

            SIGNIFICANT FLOODING ON EAST LAFAYETTE
            STREET NEAR RICE CREEK. WATER RESCUE WAS
            NEEDED.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1123 AM CDT WED MAY 30 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1030 AM     FLASH FLOOD      CLANTON                 32.84N 86.62W
05/30/2018                   CHILTON            AL   BROADCAST MEDIA

            CLANTON HOMES OFF OF I-65 FLOODED.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1139 AM CDT WED MAY 30 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1120 AM     FLASH FLOOD      2 NE SAWYERVILLE        32.77N 87.70W
05/30/2018                   HALE               AL   COUNTY OFFICIAL

            WATER COVERING ROAD ON CR 30 AND RABEN RD.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1144 AM CDT WED MAY 30 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0600 AM     FLASH FLOOD      SELMA                   32.41N 87.02W
05/30/2018                   DALLAS             AL   EMERGENCY MNGR

            COUNTY ROAD 508 AND COUNTY RD 510 CLOSED DUE
            TO HIGH WATER.

&&

Special Weather Statement
National Weather Service Birmingham AL
1247 PM CDT WED MAY 30 2018

ALZ044-049-301845-
Pike AL-Montgomery AL-
1247 PM CDT WED MAY 30 2018

...SIGNIFICANT WEATHER ADVISORY FOR WESTERN PIKE AND SOUTHEASTERN
MONTGOMERY COUNTIES UNTIL 145 PM CDT...

At 1247 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Dublin to 6 miles northwest of Gantt.
Movement was east at 15 mph.

Pea size hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
Troy, Goshen, Ansley, Grady, Dublin, Troy Municipal Airport, China
Grove, Currys and Orion.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 3166 8615 3179 8615 3179 8620 3183 8618
      3193 8618 3196 8619 3197 8626 3206 8619
      3206 8600 3204 8598 3204 8597 3206 8595
      3205 8589 3197 8588 3162 8613 3162 8618
TIME...MOT...LOC 1747Z 275DEG 12KT 3200 8616 3149 8653

05

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
141 PM CDT WED MAY 30 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1230 PM     FLASH FLOOD      3 S OAKMULGEE           32.75N 87.04W
05/30/2018                   PERRY              AL   EMERGENCY MNGR

            APPROACH ROAD TO BRIDGE ON MEDLINE ROAD
            WASHED OUT. WATER STILL RISING ON AREA LAKES
            AND STREAMS.

&&