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Area forecast discussion...updated
National Weather Service Mobile Alabama
910 PM CDT Fri Jun 23 2017

Discussion...see updated information for land areas below.


Update...have updated to extend/expand the Flash Flood Watch
until late Saturday night for nearly the entire area. Have been
monitoring a confluent zone which resulted in gradually weakening
showers and storms, which have become isolated/scattered roughly
from near Wiggins, MS to Luverne, Alabama. This convection has probably
left a weak boundary in this general orientation. In addition, a
weakening convective complex advancing from Arkansas/northern
Louisiana/northwestern Mississippi will continue advancing
southeastward and bring convection (and likely an outflow
boundary) into the forecast area overnight. Meanwhile, a cold
front has been advancing from the north and will move into the
forecast area Saturday afternoon, then slowly into the southern
portion of the forecast area later Saturday night. Very high
precipitable water values will be in place over the area during
the period, with values near 2.25 inches, and the steering flow
for convection weakens considerably, resulting in slow moving
storms. Model soundings are open for convective development, and
expect convection developing on the boundaries and also the cold
front, with locally heavy rainfall possible due to anticipated slow
movement of the storms. After examining the rainfall for the past
24 hours, the portion of the area generally west of I-65 likely
has completely saturated soil conditions. While the portion east
of I-65 has not received much (if any) rainfall in the past 24
hours, this portion has received significantly excessive rainfall
(at least in some locations) over the past 2 to 3 days. The
antecedent soil conditions, high deep layer moisture, boundaries
and anticipated slow storm movement are the basis for the Flash
Flood Watch. Made other minor adjustments. /29


Previous discussion... /issued 723 PM CDT Fri Jun 23 2017/

Discussion...updated for latest aviation discussion below.

00z issuance...MVFR to IFR cigs and visibilities through 24.12z
followed by mostly MVFR cigs and visibilities through 24.00z.
Lower cigs and visibilities mostly in and around scattered to
numerous showers and thunderstorms moving eastward across the
forecast area through Sat afternoon. The best coverage of showers
and thunderstorms will occur through about 24.07z tonight,
reforming mostly after 24.15z Sat. Winds will be south to
southwest at 10 to 15 knots this evening diminishing to 3 to 8
knots late tonight through Sat afternoon. Higher gusts up to 25
knots will also be possible with a few of the stronger
thunderstorms through the forecast period. 32/ee

Previous discussion... /issued 653 PM CDT Fri Jun 23 2017/

Discussion...see updated information for land areas below. Note:
the climate info in the third paragraph of the previous
discussion has been corrected.

Update...have updated to increase pops along the line of showers
and storms advancing slowly from the western portion into the
central portion of the area this evening. Have also updated for
the expiration of the coastal Flood Warning for Alabama and the
coastal flood advisory for the western Florida Panhandle as
astronomical tidal values decrease along with gradually decreasing
onshore winds. A Flash Flood Watch remains in effect for
southeast Mississippi and part of southwest Alabama until 10 PM,
but adjustments to the watch are possible. No other major changes
at this time. /29

Previous discussion... /issued 350 PM CDT Fri Jun 23 2017/

Near term /now through Saturday/...remnant circulation of Cindy
over Kentucky and Tennessee was shearing out to the northeast. South and west
of the circulation, a resurgence in cold cloud tops =>
showers/storms were developing in a northeast to southwest band
from northwest Alabama to southwest MS. This convection was occurring
within a zone of high deep layer tropical moisture where total
pwat was in excess of 2.00 inches. To the east, a well defined
deep layer ridge was positioned from the southwest Atlantic into
the eastern Gulf causing a net lowering in deep layer moisture
along and east of the I-65 corridor. Considering the placement of
the deep layer moisture and afternoon instability with MUCAPE
values around 3000 j/kg, the higher precipitation chances remain
advertised over the northwest zones and will be carried over into
tonight. Lower chances southeast of the Interstate. Due to soil
moisture levels being at capacity, there remains concerns that
developing showers and storms, repeatedly moving over the same
areas, will likely result in runoff and flooding. Flash flood
watches continue from Clarke co. Alabama to George co. MS and points
west thru late this evening. Many area rivers remain in, or will
soon go into, minor to moderate flood.

A frontal boundary sags southward Saturday, bringing enhanced
ascent while interacting with a deeply moist environment. Thus,
the unsettled weather pattern continues with scattered, to at
times numerous showers and thunderstorms. Unfortunately, storms
initiating in this type of environment will be efficient in
depositing heavy rains in a short amount of time over already
saturated soil conditions. This of course will likely lead to
runoff and flooding problems going forward into the day Saturday.
Have extended the high risk of rip currents and high surf advisory into
the mid morning hours Saturday due to the potential of lingering
modest swell and breaker action up across the surf zone. Muggy
overnight lows in the mid to upper 70s. Daytime highs Saturday in
the mid to upper 80s.

Interesting climate fact...June has been wet even before rains
from tropical Cindy affected the area, and more rain is expected
this weekend due to a southward moving front. At Mobile regional,
the rain gauge has added up to 11.81" which is 7.30 inches above
normal, but still way less than the all time record 26.67 set in
1900. For Pensacola, the rain gauge has added up to an impressive
18.21" so far, and depending on how much rain we receive in the
coming days, it's possible that the monthly record for Pensacola
of 21.14" set in 1994 is within striking distance.

Short term /Saturday night through Monday night/...scattered to
at times numerous showers and storms Saturday night into Sunday as
frontal boundary settles south to the coast. Some of the rains
locally heavy. With the boundary slipping off the coast, a
reduction in rainfall probabilities is expected Sunday night thru
Monday night. Following the frontal passage, latest forecast for
overnight lows show potential of mid 60s over the interior Sunday
and Monday nights. Daytime highs Sunday and Monday 83 to 87. /10

Long term /Tuesday through Friday/...chances of rain will be
minimal as somewhat drier northwest to zonal flow aloft prevails
across interior portions of the forecast area Tuesday as our
region remains at the base of a longwave high level trough that
extends across much of the eastern Continental U.S.. an axis of deeper
moisture may still remain in the vicinity of coastal portions of
the region per the 23.12z European model (ecmwf) which favors a slight chance of
showers and storms. Medium range models remain in generally good
agreement with building an upper level ridge across the eastern
Seaboard and adjacent western Atlantic by the middle to later part
of next week, allowing an axis of deeper moisture to advect back
northward over the central Gulf Coast. This pattern should result
in a return to better rain chances as we close out this very wet
month of June.

Early morning lows begin to moderate back into the lower to mid
70s by Friday morning. Highs each day range in the mid 80s. /10

Marine...onshore flow decreases and seas subside in the short term.
Rain chances will increase over the weekend into early next week as
a frontal boundary sinks southward to the coast and eases offshore.
Winds, waves and seas will be locally higher in and near storms.


Mob watches/warnings/advisories...
Alabama...Flash Flood Watch through late Saturday night for alz051>057-059-

High rip current risk through Saturday morning for alz265-266.

High surf advisory until 10 am CDT Saturday for alz265-266.

Florida...Flash Flood Watch through late Saturday night for flz201>204.

High rip current risk through Saturday morning for flz202-204-

High surf advisory until 10 am CDT Saturday for flz202-204-206.

MS...Flash Flood Watch through late Saturday night for msz067-075-076-


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