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fxus64 kmob 300503 aac 

Area forecast discussion...updated
National Weather Service Mobile Alabama
1203 am CDT Tue may 30 2017

Discussion...updated for latest aviation discussion below.


06z issuance...small complex of convection moving steadily
eastward over the central Gulf Coast with showers following
behind its departure over mob/bfm thru 08z or so. Will have tsra
passing across pns thru 08z with gusts potentially 25 to 30 kts.
Cigs forecast to be in the mid to high levels in the wake of
departing tsra. Winds light and variable overnight. /10


Previous discussion... /issued 928 PM CDT Mon may 29 2017/

Discussion...see updated information for land areas below.

Update...30.00z upper air analysis this evening shows a mid level
trof axis from la, southward out into the western Gulf. Ahead of
this feature, a deeply moist environment remains in place over the
central Gulf Coast with pwat values ranging from 1.5 to 1.8 inches
or 110 to 130% of normal. A quasi-stationary surface front was
draped from VA, southwest across central MS to southern Texas. Southeast
of the frontal zone, within the deeply moist airmass and embedded
in the short wave mid level trof position, GOES-r satellite data
shows pockets of cold cloud tops from the central Gulf Coast to
off the southwest la coast. These storm clusters were tracking
northeast in the mean high level southwest flow. The lead
convective cluster is bringing rain across southern MS per latest
radar trends. Current forecast calls for scattered showers and
storms and will leave as is. An assessment of instability shows
mid level lapse rates a bit lower than seen last evening but
MUCAPE (1000-3000 j/kg) remains more than sufficient enough to
maintain storm potential. Despite this, wind shear is weak
resulting in a very low risk of severe weather. Still could see
brief strong wind gusts, locally heavy downpours and occasional to
frequent lightning with the passage of any late evening and early
morning storms. Movement of convection east northeast at around
25 mph. /10

Previous discussion... /issued 627 PM CDT Mon may 29 2017/

Discussion...updated for latest aviation discussion below.

00z issuance...considerable cloudiness over the deep south with
bases at high levels. Potential exists for the return of convection
late in the evening with guidance keeping lowest cig bases at
upper end MVFR categories. Winds mostly light and variable. /10

Previous discussion... /issued 336 PM CDT Mon may 29 2017/

Near term /now through Tuesday/...showers and thunderstorms continue
to lift off to the north and northeast this afternoon as the better
forcing aloft that prompted the convection earlier today shifts
northeast, also. With another mid level impulse approaching from the
west southwest late this evening believe we will see another round
of heavy showers and thunderstorms forming to the west and offshore
late tonight shifting northeast over most of the forecast area after
midnight tonight, continuing through most of Tue morning. The
greatest coverage still looks to be over western and northern
sections of the forecast area by early Tue shifting north to
northeast through Tue afternoon. With slightly better forcing in the
mid levels with this next round combined with some drying/warming in
lower levels believe we could see a few stronger storms early Tue
compared to today though remaining mostly below severe limits. Wind
gusts to 40 to 50 mph and frequent cloud to ground lightning will be
the main threats, along with periods of heavy rain possibly tracking
over the same location which could result in some localized nuisance
flooding, especially in areas with poor drainage. By Tue afternoon
the better forcing aloft will continue to shift northeast and dampen
leading to less coverage through late Tue afternoon.

Skies will continue to be mostly cloudy for the most part through
Tue afternoon though with a few breaks of sun this afternoon and
early this evening returning again by late Tue afternoon as the
heavier rain begins lift off to the north and northeast. With this
lows tonight will continue to be above seasonal averages followed by
highs Tue remaining below average due to the clouds and rain. Lows
tonight will range from the upper 60s to lower 70s for most inland
areas and the mid 70s near the immediate coast. Highs Tue will climb
to the upper 70s to lower 80s for inland areas to the west, the
lower to middle 80s for inland areas to the east and the lower 80s
along the immediate coast. 32/ee

Short term /Tuesday night through Thursday night/...we will see
at least a chance of scattered storms Tuesday night but placement
and coverage is uncertain given the complexities of how the
current shortwave over the northwest Gulf will evolve as it moves east
northeast over the next 24 hours. At this point, will focus best
rain chances in the western zones based on a blend of the guidance,
but confidence is low.

Mid to upper flow will transition from southwesterly to more
zonal by Wednesday, resulting in convective chances becoming more
diurnally driven (best chances during the afternoon hours).
Thursday is a bit more uncertain as the European model (ecmwf) tries to bring in
additional shortwave energy from the southwest while the
GFS/Canadian are a bit more pronounced with shortwave ridging. For
now, given the uncertainties will keep a more typical diurnal
trend for convective chances. Highs will be in the mid to upper
80s with lows in the upper 60s/lower 70s, near normal for this
time of year. 34/jfb

Long term /Friday through Monday/...deep layer southerly flow
develops on Friday and continues into the weekend which will usher
in a tropical airmass with precipitable waters increasing to at or
above 2 inches over the weekend. Meanwhile, the global models are
in fairly good agreement on shortwave energy over the southwest
U.S. Moving east and trying to phase with a northern stream trough
by the end of the weekend as it enters the lower MS valley.
Best storm chances will initially start out over western zones on
Friday where the best deep layer moisture is likely to reside with
better chances spreading across the entire area on Saturday.
Storms could become numerous by Sunday with the aforementioned
trough moving through and creating good upper level forcing in the
presence of an unstable and deeply moist airmass. Scattered to
numerous storms will likely persist into Monday as the upper level
trough pushes a cold front toward the region. Given the pattern,
we will have to monitor the potential for locally heavy rain by
Sunday/Monday. Stayed close to guidance for temps. 34/jfb

Marine...high pressure will continue to weaken and drift east
over the north central and eastern Gulf through midweek in response
to an upper level system and weakening frontal boundary approaching
from the west and northwest. Showers and thunderstorms are expected
with this pattern with the better coverage occurring late tonight
through Tue morning as the weak frontal boundary nears the coast and
stalls. A light southerly flow will become better established late
Wed and continue through late in the week as a weak surface ridge of
high pressure rebuilds over the north central Gulf. Seas will
continue to range from 2 to 3 feet through tonight then subside to 2
feet or less for the remainder of the week. Otherwise...wind and
waves will be higher near showers and thunderstorms through the
forecast period with less coverage expected beginning late Wed
continuing through early Fri. 32/ee


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