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Area forecast discussion...updated 
National Weather Service Mobile Alabama
946 PM CDT Sat Aug 29 2015

Update...ten years ago today it was rather rainy and windy...but for
tonight we will just have isolated showers and storms lingering
overnight. Have made adjustments to probability of precipitation along with other minor
adjustments. /29


Previous discussion... /issued 634 PM CDT Sat Aug 29 2015/

00z issuance...VFR conditions will prevail for the next 24 hours for
most of the area...except for occasional MVFR conditions in showers
and thunderstorms over a portion of south central Alabama this
evening. Surface dewpoints have risen several degrees compared to
this time yesterday...and this additional moisture looks sufficient
to include a period of MVFR conditions in light fog in patchy areas
late tonight. Light southeast winds will become northeast tonight
then return to a southerly direction on Sunday. /29

Previous discussion... /issued 420 PM CDT Sat Aug 29 2015/

Short term [tonight through Monday night]...for tonight through
Sunday...Tropical Storm Erika has degenerated into an open tropical
wave with remnant center located just north of eastern Cuba coast.
The trough axis associated with the remnants of Erika is expected to
move into the southeast Gulf of Mexico by late Sunday (and continue
drifting north across the eastern Gulf into the middle part of next
week). We will have to monitor the remnants for the potential of
redevelopment early next week...NHC gives a 40% chance of
redevelopment over the next 5 days.

Any possible affects (primarily heavy rain potential) from the
remnants of Erika will be beyond the short term period...and most
likely east of our forecast area. In the meantime...the upper low
situated along the Gulf Coast and clearly seen in water vapor
imagery this afternoon just south of the Mississippi coast is
expected to drift slightly east and north tonight...then weaken and
begin lifting more rapidly to the northeast on Sunday. The forecast area
is dissected by this upper feature...with a deep moisture flow
streaming north over the eastern part of the forecast area...with much
drier conditions over western portions of the forecast area. Current
radar imagery shows scattered showers and storms east of a
Camden...Brewton...Destin line with more isolated coverage of precipitation
to the west of that line. For this evening...expect this general
setup to continue...with a well defined east-west precipitation gradient over
the region. Best rain chances this evening over the northeastern
counties (50 to 60 percent)...30 to 40 percent over central portions
of the forecast area...and decreasing to 20 percent over the western
half of the forecast area. While rain chances will remain highest over
northeast and east counties overnight...expect gradually diminishing
chances from west to east late tonight as the upper low moves slowly
east and drier air to the west works into the area. Rain chances
then lower more dramatically on Sunday (20 percent or less) as the
upper low weakens and lifts more rapidly northeast away from the
forecast area.

At the surface...high pressure will continue to ridge into the forecast area
from the northeast through Sunday. The slightly cooler and drier low
level airmass associated with this ridge will drain down into the
forecast area tonight as diurnal flow switches to the northeast late
tonight. As a result...low temperatures tonight falling into the middle to
upper 60s inland and the lower 70s at the coast. High temperatures on
Sunday similar to those of the upper 80s and lower 90s.

Sunday the upper ridge off the SC/GA/FL coast builds west
over the northeastern shifts the upper trough over the
southeastern Continental U.S. over the Southern Plains. The
remnants of Erika move over the eastern Gulf of mex...and work with
a surface ridge over the middle Atlantic region to shift the general
east to southeast flow to northeast to east. This keeps the forecast area under
moist flow...but with the forecast area coming under influence of the upper
ridge...the chance of rain decreases for Sunday night.

Monday through Monday night...the remnants of Erika move north
across the eastern Gulf of Mexico...with guidance trying to develop
a surface low over the north-central Gulf. Helping to keep Erika
from re-developing into a tropical system will be unfavorable upper
level winds. Even it moves brings an increased
chance of rain... mainly to southeastern portion of the forecast area Monday
into Monday night.

Long term [tuesday on]...Tuesday through Tuesday night...the
remnants of Erika move over the southeastern Continental U.S....with the European model (ecmwf)
and GFS diverging. The European model (ecmwf) loops around a now upper high centered
off the Florida coast...with this system ending up over the Florida/GA/SC
coast. The GFS takes it inland...over al/GA. Needless to say...this
leads to a significant difference in the chance of rain. The GFS
solution is cooler/wetter than the European model (ecmwf) solution...especially over
eastern portions of the forecast area. Have went with an in-between solution for
the forecast. This means temperatures a bit above seasonal...with probability of precipitation

Wednesday through Thursday night...the GFS and European model (ecmwf) come into
agreement...with the remains of Erika either getting absorbed into an
upper low moving east from the Southern Plains to over the lower
miss River Valley or off the the Atlantic coast. The European model (ecmwf) is also
advertising this upper low moving over the lower miss River Valley by
Friday morning. Have continued to blend the two varying solutions until
this time. Temperatures a bit above seasonal with the chance of rain
remaining below.

Friday through Saturday...the agreement between the European model (ecmwf) and GFS is
only temporary...with the GFS advertising the upper low deepening over
the lower miss River Valley...whilst the European model (ecmwf) opens it up and moves
it east as an upper near the Atlantic coast. The chance
of rain rises to around seasonal in both...with temperatures a scooch above

Marine...a ridge of high pressure will remain over interior
portions of the southeast U.S. Through the middle part of next
week...but will gradually be weakening as the remnants of Erika move
north across the eastern Gulf of Mexico. Initially this will lead to
a weak pressure pattern...with a light to occasionally moderate diurnal
flow pattern...more southeasterly during the daylight hours and more
northeasterly at night. Will have to monitor the progress of the
remnants of Erika lifting north across the eastern there
is a chance that redevelopment of the system could occur. Due to
this fact...the wind and seas forecast for much of this week is tricky.
For now will go with a wave/trof...moving into the
eastern Gulf through Monday and gradually dissipating through
Wednesday while still over eastern Gulf. Potential for scattered
showers and storms increasing as the remnants of Erika approach.
Regardless of unsettled marine weather week is
anticipated...with locally higher gusty winds and seas/waves near
the showers and storms. 12/ds


Preliminary point temps/pops...
Mobile 70 91 69 92 71 / 20 10 05 20 10
Pensacola 72 90 73 92 75 / 20 10 05 30 10
Destin 74 87 76 91 76 / 20 10 10 30 10
Evergreen 68 89 67 93 69 / 20 20 10 20 10
Waynesboro 67 90 67 93 69 / 20 20 05 05 10
Camden 68 89 68 92 69 / 20 20 10 20 10
Crestview 68 93 68 94 70 / 20 20 10 30 10


Mob watches/warnings/advisories...


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