Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 212334

Area Forecast Discussion
National Weather Service Mobile AL
634 PM CDT Thu Sep 21 2017

.DISCUSSION...Updated for latest aviation discussion below.


00Z issuance...Isolated TSRA will impact portions of the
northwest FL panhandle and far southwest AL early this evening,
but should gradually dissipate over the next couple of hours. VFR
should otherwise prevail through the period, except for potential
of localized patchy fog and associated MVFR visibility reductions
early Friday morning. Additional isolated to scattered SHRA/TSRA
will develop again Friday, and have opted to include VCTS mention
in the KMOB/KBFM/KPNS TAFs after 22.18Z. /21


.PREV DISCUSSION... /issued 403 PM CDT Thu Sep 21 2017/

NEAR TERM /Now Through Friday/...Ongoing showers and thunderstorms
along the coast this afternoon will dissipate after sunset this
evening, giving way to a mostly clear night as a slug of dry air
moves through from northeast to southwest. Expect overnight lows
to dip into the upper 60`s to around 70 inland and the mid 70`s
along the immediate coast.

A weak mid to upper level trough builds southwest from Tropical
Storm Jose into the northeastern Gulf through Friday, squeezed
between a large area of high pressure over the Midwestern U.S. and
the broad area of low pressure around Hurricane Maria east of the
Bahamas. At the surface, a weak ridge extends southwest from the
Great Lakes into the lower Mississippi River Valley, maintaining a
generally light easterly flow across our area. Given this pattern,
expect diurnally driven shower and thunderstorm activity to
continue through Friday, with the best chances Friday afternoon
and evening over interior portions of the area northwest of I-65.
Stronger storms will be capable of producing locally heavy
rainfall, gusty winds, and frequent lightning. High temps Friday
reach the upper 80`s to low 90`s inland and mid to upper 80`s
along the coast. /49

SHORT TERM /Friday night Through Sunday night/...The northern
portion of the elongated upper level ridge extending from the
central Texas to the Great Lakes region will shift east over the
northeast conus through the short term. A cutoff upper low
pressure area is expected to develop over southern Georgia out the
east coast upper level trough by Saturday morning. The upper low
is then expected to slowly drift west over the forecast area over
the weekend, reaching southern Mississippi by late Sunday night.
A surface ridge across the eastern conus and Gulf of Mexico will
also remain intact as Hurricane Jose remains stalled off the coast
of New England, and Hurricane Maria tracks northward of Caribbean
Islands. Isolated showers and thunderstorms are expected Saturday,
followed by scattered to numerous showers and thunderstorms on
Sunday as the upper low passes overhead.

Low temperatures over the weekend will range from 66 to 70
degrees inland areas, with lower 70s along the coastal sections.
High temperatures Saturday will range from 87 to 90 degrees inland
areas, with mid 80s along the immediate coastal sections. High
temperatures Sunday will be in the mid 80s across the entire
forecast area due to increasing clouds. /22

LONG TERM /Monday Through Thursday/...Hurricane Maria is forecast
to continue moving slowly northward over the western Atlantic
through the long term. Meanwhile, the upper low pressure area over
southern Mississippi will begin to fill and weaken on Monday,
followed by upper level ridging building over the region from the
west. Surface high pressure will continue across the region, but
generally weaken. The high rain chances will continue through
Monday, especially in the vicinity of the upper low, followed by
lower rain chances on Tuesday and dry conditions Tuesday night
through Thursday. High temps each day will range from the upper
80s to near 90 inland and the middle 80s along the immediate
coast. Lows each night will range from the mid to upper 60s inland
and the lower 70s along the immediate coast. /22

MARINE...A weak surface ridge extending southwest into the northern
Gulf will maintain light to occasionally moderate easterly winds
through the period, with a diurnal cycle adding a slight onshore
component each day and offshore component each night. Seas around
a foot on Friday increase to 2 to 3 feet this weekend into early
next week before settling back to around 1 to 2 feet by the middle
of next week. Isolated to scattered showers and storms will be
possible through the period, with locally higher winds and waves
in and around the stronger storms. /49




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