Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 260446 AAA
AFDMOB

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
1146 PM CDT Sun Jun 25 2017

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

&&

.AVIATION...
06Z issuance...Mostly VFR conditions through 27.00z. Could see a
brief period of MVFR cigs in isolated to scattered showers and
thunderstorms through the forecast pd. Winds will continue from
the north northeast at 4 to 8 knots through the Mon morning then
shift northeast to east at 3 to 8 knots through Mon afternoon.
32/ee

&&

.PREV DISCUSSION... /issued 721 PM CDT Sun Jun 25 2017/

DISCUSSION...See updated information below.

UPDATE...Did a quick update to the current zone forecast mainly
to reflect current radar trends across the region and to adjust
pops a tad for later this evening and overnight. Latest hi-res
data conditions to show less coverage of precip for later this
evening and overnight generally inland from the coast, maintaining
scattered coverage along the immediate coast and offshore this
evening then shifting further to the south or offshore overnight
through Mon morning. 32/ee

MARINE...Did a quick update to the current marine forecast
mainly to reflect current conditions and increase winds from the
north northeast overnight through Mon morning similar to today.
Most of the current model guidance depict a moderate offshore
over the marine area through Mon morning. Seas will range from 2
to 3 ft over the open gulf waters later this evening through Mon
morning. 32/ee

AVIATION...
00Z issuance...Mostly VFR conditions through 27.00z. Could see a
brief period of MVFR cigs in isolated to scattered showers and
thunderstorms through the forecast pd. Winds will continue from
the north northeast at 4 to 8 knots through the Mon morning then
shifting northeast to east at 3 to 8 knots through Mon afternoon.
32/ee

PREV DISCUSSION... /issued 323 PM CDT Sun Jun 25 2017/

NEAR TERM /Now Through Monday/...
Forecast not exactly straight-forward in the short term. While a
cold front is forecast to move offshore tonight with weak lower
tropospheric dry air advection, latest satellite and upper air data
indicate a filling upper low that is about to also open up over the
NW Gulf of Mexico. A very notable southerly wind flow on its east
side is advecting mid and high level moisture back into the
region. We think this will tend to shut off somewhat tonight as
winds in that deep layer go more westerly and advect the moisture
more along and to the rear of the low level front. After dark,
cooling of the land will act to accelerate the low level front`s
southern progression once again. Thunderstorms will mainly affect
the I-10 Corridor and points further SE through this evening and
then again in the heat of the afternoon tomorrow. Rain chances
will be decidedly lower along the coast tomorrow, but it will not
be totally dry either. Most areas north of the I-10 Corridor will
remain dry. Lows tonight could fall to near 60 deg(F) north of the
Highway 84 corridor (especially the far northern reaches of
Wilcox and Choctaw counties of Alabama). highs tomorrow in the
upper 80s. /23 JMM

SHORT TERM /Monday night Through Wednesday night/...
The upper trough over the eastern United States will weaken as it
moves offshore the Eastern Seaboard Tuesday night into Wednesday. A
weak northwesterly flow aloft will aid in advecting slightly drier
air into the region for the short term. Precipitable water values
briefly drop below 1.5 inches across inland areas before quickly
moderating toward seasonal values (between 1.7 and 1.8 inches)
Wednesday.

Overall, I think convective coverage should be limited during the
short term given (slightly) drier boundary layer conditions.
Still, though, some diurnally-driven convection is expected given
mesoscale processes, ample ground moisture, and the continued
presence of a weakness in the upper ridge over the northwestern
Gulf of Mexico. Between Tuesday and Wednesday, I suspect we`ll see
a slightly greater convective coverage Wednesday. /02/

LONG TERM /Thursday Through Sunday/...
Generally speaking, good agreement within the medium range ensembles
is leading toward better than average forecast confidence for the
long term portion of the forecast.

A large-scale zonal pattern is expected to continue across much of
the country through the end of the week. The previously-mentioned
weakness in the upper ridge, over the northwestern Gulf of Mexico,
is forecast to retrograde and weaken over the mountains of Northeast
Mexico. This should allow ridging to rebuild across the southern
part of the country, leading to afternoon temperatures warming
slightly (overall) as soil moisture continues decreasing.

Question then revolves around convective coverage. Increased
subsidence, plus the heavy reliance on mesoscale processes, will
likely result in a lower convective coverage (broadly speaking) for
the long term portion of the forecast. However, a strengthening low-
level ridge, centered in the Atlantic off the Southeast U.S. coast,
will allow moisture from the Gulf of Mexico to increase across the
region during the period. With a southeast to south wind, we`ll
likely see at least climatological odds of seeing some diurnally-
driven showers and thunderstorms along the sea breeze through the
period. /02/

MARINE...
A cold front moves further south into the marine waters and then
stalls. Surface winds become northeast then east to northeast
through late Monday and increase a bit into the 8 to 13 knot range.
Seas should remain 2 feet or less. Scattered thunderstorms and
rainshowers remain a possibility both ahead of and behind the front
this evening through late tomorrow. /23 JMM

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...None.
FL...None.
MS...None.
GM...None.
&&

$$

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