Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 271721

Area Forecast Discussion
National Weather Service Mobile AL
1221 PM CDT Tue Jun 27 2017

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


18Z issuance...VFR conditions and light easterly flow prevails
through the forecast period. A few isolated showers and storms are
possible along the coast this afternoon, with any activity tapering
off after 28.00Z. /49


.PREV DISCUSSION... /issued 546 AM CDT Tue Jun 27 2017/

DISCUSSION...Updated for latest aviation discussion below.

12Z issuance...Mostly VFR through the period as surface winds
veer from light northeasterly to more easterly by this TAF
period`s end. Mid and high clouds will continue streaming across
the area. An isolated thunderstorm is possible from 27.21 UTC to
28.01 utc generally south of the I-10 Corridor. /23 JMM

PREV DISCUSSION... /issued 349 AM CDT Tue Jun 27 2017/

NEAR TERM /Now Through Tuesday night/...Early this morning a stationary
front was located offshore with developing precipitation along it
across southern LA east to well south of the Alabama coast. Light NE
surface wind flow was in progress. Deep layer moistening is in store
next two days as upper tropospheric wave moves east out of TX today
and beings to reflect down into the mid-troposphere. This happens in
the well know `break between two ridges.` The approach of the wave
excites the lower tropospheric winds to veer to a more SE direction
by tonight. As far as thunderstorm development today, expect them to
mostly remain offshore with the exception of the immediate coast.
The light E->NE boundary layer wind flow will oppose the developing
seabreeze and with the moisture return, so there may be some very
isolated deep convection from 20Z-01Z, or so. Any deep convection
will diminish during the early evening, but thunderstorm coverage
will be above average however over the AL coastal waters tonight as
return flow begins and the aforementioned upper low shear zone
orients itself from SSW to NNE across our area. /23 JMM

SHORT TERM /Wednesday Through Thursday night/...Surface high
pressure over the Mid Atlantic states will slowly migrate offshore
by mid day Wednesday. Moisture levels begin to increase with
southerly return flow around the southwestern periphery of the
surface high. Accordingly, pops will increase into the chance
category for Wednesday afternoon.

Southerly flow will be firmly in place Thursday morning with
increasing deep layer moisture. Precipitable water values will be
above two inches with some areas approaching 2.2 inches. A subtle
weakness in the mid level height field between a strong ridge over
the southwestern Atlantic and another over northern Mexico will
provide modest support for upward vertical motion across the area,
which, when combined with ample deep layer moisture, will result
in likely pops for most areas Thursday afternoon. Showers and
storms will likely be ongoing near and offshore Thursday morning
and will spread inland as the day progresses. Temperatures will be
held down Thursday afternoon due to increased coverage of showers
and storms and associated cloud cover, generally low 80s are
expected with a few mid 80s across our northern counties where
storm coverage will be slightly reduced. Low temperatures Thursday
into Friday will be in the low 70s with mid 70s at the beaches.

LONG TERM /Friday Through Monday/...Not much change on the large
scale pattern for Friday with a continued weakness in the mid
level height field near the area and copious Gulf moisture in
place. Will show likely pops for Friday afternoon into the
evening. Coverage should decrease a few hours after sunset but
some showers and storms will be possible into the overnight.
Temperatures will be slightly warmer on Friday with mid 80s across
the area. Continued warm overnight temps with low to mid 70s

The weakness between the two ridges will begin to fill on Saturday
and Sunday leading to lower coverage of showers and storms for the
weekend. Absent much in the way of mid and upper level support,
storm initiation will likely be closely tied to mesoscale boundaries
(Gulf/bay breezes and old outflow boundaries from previous
convection). This pattern will continue into the first part of the
work week with generally climatological pops expected. With
decreased shower and storm coverage we will see an uptick in
afternoon high temperatures with mid to upper 80s for most Saturday
with perhaps a few 90s inland by Sunday and Monday afternoons.

MARINE...Today a light NE wind flow becomes more easterly. By
early Wednesday, surface winds will become southerly and increase
and seas will then once again build solidly to around 2 feet
wednesday night and early Thursday. Also shower and thunderstorm
coverage increases from the southwest. Waves continue around 2
feet Thursday with an increase to 3 feet in our southwestern zones
late Thursday into Friday with continued southerly flow. Greatest
coverage of showers and storms will come Thursday and Friday
before backing off modestly for the weekend period. 23/05




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