Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion...updated 
National Weather Service Mobile Alabama
1000 PM CDT Wednesday Jul 9 2014

Update...the coverage of showers and thunderstorms has decreased
for the evening and have lowered the probability of precipitation slightly for the remainder
of the night. Also made a slight adjustment to hourly temperatures based on
latest observation. Otherwise...the forecast remains on track. /13

Aviation [10.00z terminal forecast discussion]...VFR conditions
will prevail through much of the overnight hours before convection
redevelops on Thursday. Scattered to numerous showers and
thunderstorms can be expected in and around the terminals on
Thursday with IFR/MVFR conditions possible in and around
thunderstorms. /13


Near term...(through tonight)...a broad middle level trough extends
southward across the Ohio/Tennessee Valley region into the deep south from a
parent low spinning in the vicinity of the Hudson Bay this
afternoon...while ridging aloft was prevalent from the Southern
Plains to the Rocky Mountains region. At the surface...high pressure
remained centered over the north central Gulf while a weak boundary
continued to edge southward across central MS/Alabama and northern Georgia.
Convection that had developed over interior southeast MS/southwest Alabama
along outflow from overnight convection has gradually dissipated as
of early afternoon...though new convection was developing along the
seabreeze near the coast. Temperatures were widely variant across the
region as locations affected by showers and storms had fallen into
the 70s to low 80s...while locations outside of convection had warmed
into the lower 90s.

Our forecast area will remain at the base of the broad middle level
trough through tonight. Short range solutions are in agreement with
bringing an increase to deep layer moisture over the County warning forecast area through
tonight...with precipitable water values rising to the 1.8 to 2.1
inch range by 12z Thursday morning. The moist airmass combined with
continued impulses rounding the base of the trough...and a southward
sagging boundary will bring a continued chance of showers and
thunderstorms across our forecast area through tonight. We will keep
probability of precipitation in the 40-50 percent range across most locations through the
early morning hours Thursday. Storms that develop will be capable of
producing very heavy rainfall and possibly localized
addition to frequent lightning strikes and gusty winds. Otherwise...
mostly cloudy skies are expected through tonight. We trended lows
toward a persistence forecast...and these are close in line to
guidance numbers. /21

The wet microburst risk remains in the moderate category.

Short term...(thursday through Thursday night) increase in
shower and thunderstorm activity is expected tomorrow afternoon as
the frontal boundary currently draped across northern Alabama and MS sags
southward towards the coast. Layer precipitable water values will
increase to around a 2.25 inches in a conditionally unstable
airmass. Deep convection will develop by early afternoon as outflow
boundaries propagating southward from the mesoscale convective
systems developing along the frontal boundary provide ample lift and
minor shortwave troughs aloft tap into and release the overlying
instability. The thunderstorms will have the potential to be heavy
rainers and localized flooding especially in poor drainage areas is
quite possible. By late evening...the remnants of the weakening
boundary will move offshore and the supporting upper level dynamics
will have shifted east and south of the forecast area so most of the
convection should dissipate. Lowered maximum temperatures a couple of
degrees Thursday due to the expected increase in thunderstorm
activity and cloud cover. /08 jw

Long term...(friday through wednesday)...the upper level ridge to
the west noses in providing increased subsidence leading to a
decrease in precipitable water amounts...1.3 to 1.7 inches by Friday.
The remnants of the frontal boundary near the coast should be the
focus for scattered afternoon convection and nocturnal convection
over the coastal waters...though coverage at this time expected to
remain in the isolated to low end scattered range. Daytime high
temperatures will trend a few degrees above climatological norms.

GFS is advertising the return of a more active convective pattern next
Tuesday into Wednesday...creating a scenario similar to the current
one. Whereas the European model (ecmwf) is slower and weaker with the scenario...will
lean a little more toward the European model (ecmwf) solution for the time being.

/08 jw


Marine...a weak surface pressure gradient will persist through the
weekend producing light winds and low seas. Scattered to numerous
thunderstorms are expected to develop Thursday afternoon into early
evening. Otherwise storm coverage is expected to remain isolated to
scattered for the next few days. Wind and seas will be higher in and
around thunderstorm activity.


Preliminary point temps/pops...
Mobile 73 91 72 92 74 / 40 60 30 30 10
Pensacola 75 91 76 92 77 / 40 60 30 30 10
Destin 76 88 77 86 77 / 40 60 30 30 10
Evergreen 71 91 68 95 69 / 40 60 20 20 10
Waynesboro 70 92 68 94 71 / 50 60 20 20 10
Camden 71 92 69 94 70 / 50 60 20 20 05
Crestview 71 93 68 93 69 / 40 60 30 30 10


Mob watches/warnings/advisories...


National Weather Service Glossary of Abbreviations