Area Forecast Discussion
Issued by NWS Birmingham, AL

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000
FXUS64 KBMX 260018
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
718 PM CDT Fri May 25 2018

.UPDATE...
For 00Z Aviation.

&&

.SHORT TERM...
Today and Tonight.

With the presence of three identified low-level boundaries across
portions of our eastern counties, increased PoP`s for late this
morning through the afternoon and into the early evening hours
across our east-central and southeast counties.

Expect humid conditions to prevail today with scattered showers
and some thunderstorm activity developing later this morning and
into the early afternoon hours and persisting through the early
evening hours tonight. Convective initiation is most likely across
our eastern counties late this morning and into the early
afternoon. The combination of high PWAT values along with
relatively slow storm motions will support a risk of flash
flooding, especially in urbanized and poor drainage areas through
the short term period. High temperatures will be greatly
influenced by the coverage of convection with readings in the low
to mid 80`s east with readings in the mid to upper 80`s to the
west.

As convection wanes overnight look for temperatures to fall into
the mid 60`s across the north and eastern counties with readings
descending into the upper 60`s across the remainder of the
forecast area. Patchy fog formation will be possible as it was
this morning toward daybreak on Saturday morning.

05

.LONG TERM...
Saturday through Thursday.

Revised Information:
Newly-formed and named Subtropical Storm Alberto by the NHC is
being closely monitored and is expected to result locally in
increased rain chances in the early to middle portion of next week
time frame. The latest computer model track guidance envelope has
contracted more and is more centered across the Central Gulf
Coast. Of course, this far out there remains much uncertainty in
the forecast and all are advised to continue to check in for the
latest forecast information from your local NWS forecast office
and from the National Hurricane Center.

An aircraft reconnaissance flight is scheduled for this afternoon
and our office will initiate special 6-hour upper air flights
beginning at 18Z today to help support the computer modeling
efforts.

Depending on the track of the system, there may be a tornado risk
along with the risk for heavy rainfall and flooding. Continue to
monitor for updates to the forecast packages along with the
Hazardous Weather Outlook for more information on expected impacts
to our forecast area.

05

&&

.AVIATION...
00Z TAF Discussion.

Similar pattern to yesterday with decreasing convection as we head
toward sunset. This trend should continue. Only TAF with ongoing
convection still is TOI and that should be over soon. With rain
today, we have wet grounds. Also, our lower levels remains in a
moist flow. Will again have opportunity for low MVFR & IFR stratus
and patchy fog again tonight late into the early morning hours,
before we do this all over again with more afternoon showers and
thunderstorms as this wet pattern continues ahead of Alberto.

08

&&

.FIRE WEATHER...

A moist pattern is expected over the next seven days and should
result in daily rain chances. Patchy fog and low clouds will be
possible each morning particularly where rainfall occurs during
the prior afternoon and evening. No fire weather concerns at this
time.

&&

.HYDROLOGY...

Antecedent conditions across the forecast area are not excessively
wet despite the recent rainfall. Even though there has been
locally heavy rainfall at times during the past few days, it has
been scattered, falling in different areas each day. Current one-
hourly FFG values (county average) are generally in the vicinity
of 2.5 inches per hour, and 3-hourly values of 3-3.5 inches.
Streamflows as indicated by USGS river gauges are also mostly in
the normal range for this time of year, although a few, especially
in our southeastern counties, are currently somewhat above
normal.

Until more widespread heavy rainfall occurs late this weekend and
early next week, we should continue to have mostly localized
flooding issues. As Alberto draws closer late in the weekend and
into the first of next week, more widespread heavy rainfall could
lead to more widespread flash flooding concerns and eventually to
some significant rises on area rivers. This will be highly
dependent on the eventual track of Alberto. Based on current QPF
forecasts from WPC, we could see rises to caution stages or
possibly minor flood stage by early next week, if basin-wide
rainfall averages begin to reach or exceed three inches.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     67  85  67  81  66 /  50  60  40  70  60
Anniston    67  84  67  80  67 /  50  50  40  70  70
Birmingham  68  87  69  83  68 /  50  60  40  70  60
Tuscaloosa  69  87  69  85  69 /  50  60  40  60  60
Calera      67  85  67  81  68 /  40  60  40  70  60
Auburn      68  83  67  77  70 /  40  50  50  80  70
Montgomery  69  85  68  80  71 /  30  60  50  80  70
Troy        68  84  67  77  70 /  30  50  60  80  70

&&

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

&&

$$

05/08



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