Flash Flood Warning 10, NWS Birmingham, AL

Area Forecast Discussion
National Weather Service Birmingham AL
734 PM CDT Tue May 29 2018

.UPDATE...
Evening Update and 00Z Aviation.

&&

.SHORT TERM...

Alberto has now moved out of Alabama and was located in south
central Tennessee. The main rain mass associated with this
feature was also just north of central Alabama. But there were a
few convergent rain bands rotating around Alberto that will still
impact the area tonight. Will go ahead and let the Flash Flood
Watch expire because widespread heavy rains are not .
Precipitable Water values remain over 2 inches area wide and with
some breaks in the clouds, SBCAPES jumped to near 2000.
Therefore, some thunder and localized heavy rainfall is not out of
the question overnight. With the loss of daytime heating, the
intensity of the showers should go down. Made some adjustments on
pops per radar and expectations.

75

Previous short-term discussion:
High PoP's will remain in the forecast across our northwestern
counties through early afternoon then decrease to an extent. To
the south and east expect isolated to scattered showers and
thunderstorms to develop with some strong storms possible south
and southwest. Expect a reduced coverage of showers and a few
thunderstorms this evening with the loss of daytime heating.

05

Revised previous short-term discussion:
Today through Wednesday Night.

For tonight the main low will be north of the area, and our weather
will be based on on the outer bands that will slide through the
state. Do not plan on extending the watch at this time for that
activity as it will be difficult to pinpoint which counties will see
the heaviest rains. By Wednesday the low will be well north of the
area and the really only impact will be the southern edges of the
outer bands. will go with highest pops in the east during the
afternoon and then reducing chances with the loss of the heating
during the day.

16

.LONG TERM...
Thursday through Monday.

Thursday will be a transition day across Alabama as the remnants of
Alberto and its associated trof lift away from Alabama and the
upper ridge over Texas nudges east of the Mississippi River. Mainly
diurnal afternoon thunderstorms will develop on Thursday, with the
better chances east of I-65 due to higher 500mb heights west of
I-65. A northwest upper flow pattern will develop east of the
Mississippi River Friday through the weekend. This pattern this time
of year favors MCS development and the threat of damaging
straight-line winds. Warm and high low level theta-e air on the
eastern periphery of the upper ridge will advect into Central
Alabama Friday and Saturday. The GFS and ECMWF models are showing
surface based CAPE values Friday and Saturday afternoons between
3000 and 4000 J/kg. Will add a low confidence severe for Friday and
Saturday. A more significant short wave trof will rotate down the
eastern periphery of the upper ridge Saturday night or Sunday.
Given the uncertainty of the timing, will hold off mentioning severe
for Sunday at this time.  The upper ridge will likely expand farther
eastward by early next week and result in less convective activity
across central Alabama.

58/rose

&&

.AVIATION...
00Z TAF Discussion.

Alberto has exited Alabama with a few convergent bands still
across the area. Therefore, have mention of some VCSH/VCTS for
several hours and again on Wednesday. Will start off with a
mixture of VFR/MVFR ceilings. There have been some breaks in the
clouds but expect clouds to fill in overnight. Due to the
saturated grounds and very high precipitable water values, have
ceilings developing at MVFR by around 06z and dropping to IFR for
several locations around daybreak. The ceilings should rise to
MVFR/VFR rather quickly on Wednesday. We will need to watch the
potential development of some fog and will address next run.

Scattered to numerous showers and thunderstorms are expected again
Wednesday.

75

&&

.FIRE WEATHER...

A moist pattern is expected through at least midweek, with a drier
and warmer trend for Thursday through the weekend. Best rain chances
will be tonight through tomorrow, with heavy rainfall associated
with the tropical moisture across the area. 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  83  69  88  70 /  60  60  30  50  30
Anniston    70  83  70  88  71 /  70  60  30  50  30
Birmingham  71  85  71  90  73 /  60  60  30  40  30
Tuscaloosa  71  88  72  92  73 /  60  60  20  30  20
Calera      70  85  71  89  72 /  70  60  20  40  20
Auburn      71  82  69  86  71 /  50  70  30  50  20
Montgomery  72  87  71  91  72 /  60  70  30  40  10
Troy        72  86  70  90  71 /  50  70  30  50  10

&&

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

&&

Hazardous Weather Outlook
National Weather Service Birmingham AL
759 PM CDT Tue May 29 2018

ALZ011>015-017>050-310400-
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-
759 PM CDT Tue May 29 2018

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

.DAY ONE...Today and Tonight.

A few locations may experience heavy rainfall overnight. This
rainfall is not expected to be widespread, but some places could have
some minor flooding.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Tropical showers are anticipated again on Wednesday. Isolated
locations may experience some flooding, especially where the grounds
are already saturated or are prone to flooding.

A pattern favorable for organized convective systems to impact
Alabama will develop later this week. There is a low confidence for
damaging straight-line winds on Friday and Saturday, mainly along and
east of I-65.

.SPOTTER INFORMATION STATEMENT...

Activation of storm spotters and emergency management may be
necessary Friday and Saturday.