Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 232352

Area Forecast Discussion
National Weather Service Mobile AL
652 PM CDT Fri Aug 23 2019

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


00Z issuance...A few SHRA and an isolated TSRA over portions of
southeast MS and interior southwest and south central AL are
gradually diminishing. Patchy fog with localized visibility
reductions to MVFR to IFR levels will be possible again late
tonight through early Saturday morning over portions of southeast
MS and interior southwest/south central AL. Isolated to scattered
SHRA/TSRA are forecast to re-develop near the coast Saturday
morning, before increasing in coverage again late Saturday morning
into Saturday afternoon, especially over southeast MS and
interior southwest AL. Mentioned PROB30 for TSRA at KMOB/KBFM for
now where confidence in convective development is a little higher
Saturday afternoon. VFR otherwise prevails through the period. /21


.PREV DISCUSSION... /issued 353 PM CDT Fri Aug 23 2019/

NEAR TERM /Now Through Saturday/...The central Gulf coast will
remain between two upper troughs, one over the western Gulf and one
over the Bahamas. Plenty of deep layer moisture will remain over the
area with precipitable water values over 2 inches. The upper trough
to our west will move slowly east on Saturday and have aligned rain
chances with this in mind, with numerous showers and thunderstorms
to the west and scattered coverage to the east. The moist
atmosphere, when combined with daytime heating and instability, will
continue to support a diurnal convective pattern with mostly
afternoon and evening showers and storms. Locally heavy rainfall
will continue to be the primary threat. Lows tonight in the lower
70s most areas except along the coast where mid to upper 70s are
expected. Highs on Saturday will be in the upper 80s and low 90s.

SHORT TERM /Saturday night Through Monday night/...An upper trof
over the central and northern Plains amplifies through Sunday
night while advancing to near the lower/mid Mississippi river
valley. The upper trof advances further into the southeastern
states through Monday night and also begins to be absorbed into a
longwave trof developing mostly over the central states. A weak
frontal boundary located across the northern portions of
Mississippi and Alabama moves southward to extend from south
central Alabama to central Mississippi on Sunday in response to a
strengthening surface ridge along the Appalachians. The weak
boundary is expected to dissipate on Monday as the Appalachians
surface ridge weakens and another frontal boundary approaches from
the Plains. Deep layer moisture remains elevated on Sunday with
precipitable water values around 2.0 inches then increases to
2.0-2.25 inches on Monday, values which are 125-150% of normal.
The presence of the weak boundary in the area on Sunday and a
series of shortwaves moving across the area on Monday will support
numerous showers and storms developing each day with convection
lingering into the evening hours. Expect that aggregate coverage
will be sufficient to support categorical pops over the interior
portion of the area on Sunday then most of the area on Monday.
Highs on Sunday range from the upper 80s to around 90 then for
Monday expect highs to be in the mid to upper 80s. Lows each night
range from the lower 70s inland to the mid 70s at the coast. A
low risk of rip currents is anticipated through the period. /29

LONG TERM /Tuesday Through Friday/...The longwave upper trof
amplifies while advancing into the eastern states through
Wednesday, then weakens by Friday to a broad upper trof pattern
over the interior eastern states. A cold front located near the
mid Mississippi river valley to the Red river valley Tuesday
morning weakens to a surface trof while shifting slowly through
the forecast area and into the northern Gulf on Wednesday.
Elevated moisture in place over the region along with a continuing
(albeit weakening) series of shortwaves moving across the area
will support likely pops on Tuesday. Have gone with chance pops
across the area on Wednesday, then slight chance pops at best
follow for Thursday and Friday as a light northerly flow prevails
in the wake of the front along with drier deep layer air flowing
into the region. Highs each day will be mostly in the lower 90s.
Lows Tuesday night and Wednesday night range from the lower 70s
inland to the mid 70s near the coast, then trend slightly cooler
for Thursday night and range from around 70 inland to the lower
70s near the coast. /29

MARINE...A light and predominately onshore wind flow will continue
today and tonight, becoming more variable and at times light
offshore over the weekend before becoming mostly light to moderate
onshore again by early next week. Seas will range between one and
two feet outside of scattered late night and early morning shower
and thunderstorm activity. /13




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