Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Mobile Alabama
519 am CDT Wednesday may 27 2015

Short term [today through Thursday night]....with better mixing
near the surface than earlier expected combined with extra high
cloudiness approaching from the west currently not expecting the
development of widespread dense fog for the remainder of this
morning...though some patchy dense fog reducing visibilities to 1/4
of a mile or less will still be possible mostly over low lying areas
locally through about 7 am CDT this morning. For today the main
concern will be effects from a large mesoscale convective system moving down from East Texas into
la early this morning shifting further to the east and southeast
later in the day and overnight. Latest model guidance both the GFS
and European model (ecmwf) show persistent 500 mb trough over the lower MS River Valley and
southeast Continental U.S. Digging somewhat this afternoon and overnight...thus showing
better coverage of showers and thunderstorms mostly inland later this
morning continuing through this evening. The better coverage of
convection will be this afternoon and this evening associated with
marginal instability with possible outflow boundaries moving in from
the west combined with deep moisture continuing in the boundary layer
through tonight. As for strong to possible severe weather today the
best chance for the development of stronger thunderstorms looks to be
over most inland areas generally along and north of the I-10 corridor
where better surface heating and moisture convergence will likely
occur. Current thinking from Storm Prediction Center keeps most of the central Gulf Coast
region in a marginal risk through tonight. Gusty straight line
winds...frequent cloud to ground lightning and very heavy downpours
will be the main threats. With the locally heavy rain some minor to
moderate flooding of streets...low lying areas and small creeks and
streams will be possible through late this evening. Stay tuned to
local media outlets or National oceanic and atmospheric administration weather radio if threatening weather is
occurring in your area. As for temperatures will lean a tad cooler than the
cooler met guidance due to clouds and rain. Highs today will be
mostly in the middle 80s for most areas followed by lows in the middle
to upper 60s inland and the lower 70s closer to the coast. 32/ee

A mean middle level ridge of high pressure will extend from the western
and northern Gulf of Mexico to the eastern Seaboard and western
Atlantic Ocean Thursday and Thursday night...while a middle level
trough continues to dig from the northern Rocky Mountains toward the
northern and Central Plains. A persistent surface ridge of high
pressure will meanwhile continue to stretch from the western Atlantic
Ocean and eastern Seaboard to the northern and central Gulf of Mexico
Thursday and Thursday night. Despite the presence of ridging across
our forecast area...short range models are in good agreement with
keeping plentiful deep layer moisture in place over the region
Thursday...with precipitable water values averaging between 1.7 and
2 inches. The moist airmass...when combined with weak embedded
impulses atop the ridge axis...and decent afternoon instability with
MLCAPE values up to 1500-2000 j/kg will result in the development of
scattered showers and thunderstorms especially during the late
morning and afternoon hours. The typical isolated strong or
marginally severe storm threat will be confined to locations where
instability is greatest...which currently appears to be in southeast
MS and interior portions of southwest Alabama. Strong wind gusts over 40
miles per hour...frequent lightning and locally heavy rains will be possible
with the stronger storms that develop.

Convective coverage will decrease with loss of daytime heating...but
with the potential passing of a weak shortwave on the northern fringe
of the ridge axis and a moist airmass in place across the region...
will opt to keep isolated convection in the forecast through Thursday
night. High temperatures Thursday will mostly range from the middle to
upper 80s with lows Thursday night expected to from the middle to upper
60s inland to the lower to middle 70s near the immediate coast. /21

Long term [friday through tuesday]...the middle level high pressure
ridge axis will continue to stretch from the Gulf of Mexico through
the southeast states/eastern Seaboard and western Atlantic Friday
while the middle level trough over the northern and Central Plains
approaches the upper midwestern states. Deep layer moisture will
remain in place across much of the forecast area between these
features...and daytime heating/instability will support a continued
chance of showers and thunderstorms during the late morning and
afternoon before coverage quickly wanes across all but perhaps far
northwestern areas Friday evening. Medium range solutions then show a
gradual decrease in boundary layer moisture Saturday as the middle level
ridge builds a bit farther westward into the southeastern states.
This should keep convective coverage more limited across the region
Saturday and have only included a slight chance of showers/storms in
the forecast through late Saturday afternoon...with dry conditions
Saturday night.

Medium range solutions show differing scenarios late this weekend
into early next week. A middle level trough is forecast to deepen in the
vicinity of the Mississippi Valley region Sunday...though the depth
and progression of this feature is uncertain in the deterministic
models. Despite the evolution of this next system...there is
agreement that plentiful moisture will be in place to support keeping
a daily chance of showers and thunderstorms in the forecast during
the Sunday-Tuesday time frame. Little change in daily maximum/min
temperatures is anticipated through the extended forecast with lows
mostly in the upper 60s to around 70 inland to the lower to middle 70s
near the coast...and daytime highs averaging in the middle 80s to around
90 each day. /21

&&

Aviation...
27.12z issuance...mostly IFR to MVFR ceilings through 28.12z. Lower
visibilities will also be likely in periods of heavy rain today
continuing through this evening...tapering off late tonight and early
Thursday morning. Winds will be mostly southeast at 5 to 10 knots with
higher gusts mostly near scattered to numerous showers and
thunderstorms occurring most of the day continuing into the evening
hours. 32/ee

&&

Marine...a surface ridge of high pressure over the eastern Seaboard
and western Atlantic will slowly build west over the central Gulf
Coast region through Friday...then weaken from west to east over the
weekend as a weakening cold front approaches from the northwest.
Otherwise...winds and seas will be higher near showers and
thunderstorms through Sunday with the best coverage occurring over
the near shore waters out to 20 nm including inland bays and sounds
during the morning and early afternoon hours.

&&

Preliminary point temps/pops...
Mobile 85 68 86 69 88 / 50 40 50 20 40
Pensacola 84 71 85 71 87 / 50 30 40 20 30
Destin 84 73 84 72 85 / 40 40 40 20 30
Evergreen 84 66 87 67 88 / 60 50 50 20 40
Waynesboro 84 67 87 66 87 / 60 40 50 20 40
Camden 85 66 86 66 88 / 60 40 50 20 40
Crestview 88 66 87 66 90 / 60 40 50 20 30

&&

Mob watches/warnings/advisories...
Alabama...none.
Florida...none.
MS...none.
GM...none.
&&

$$

32/21

National Weather Service Glossary of Abbreviations