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Area forecast discussion 
National Weather Service Mobile Alabama
643 am CDT sun Oct 4 2015

Discussion...updated for latest aviation discussion below.


12z issuance...widespread MVFR ceilings are in place early this morning
with IFR level ceilings noted over interior south central Alabama. Ceilings should
gradually rise late this morning into this afternoon...but may hold
at MVFR thresholds across much of the region. Northwest to north
winds 8-13 knots with a few higher gusts will continue today. /21


Previous discussion... /issued 453 am CDT sun Oct 4 2015/

Near term /now through Sunday night/...water vapor satellite
animation shows the persistent upper level low now spinning in the
vicinity of southern Georgia and northern Florida early this morning. 06z
surface analysis meanwhile shows surface low pressure in the vicinity
of the SC coast with an associated surface trough axis extending
westward through southeastern Georgia...while a ridge of surface high
pressure extended from Quebec and southwestward through the Great
Lakes...upper Midwest and Mississippi Valley region. A cool northerly
surface flow pattern continues across our forecast area between these
features early this morning...with 11-3.9u satellite imagery
continuing to show an extensive deck of low cloud cover blanketing
our entire forecast area in the cool low level northerly regime.
Early morning temperatures are starting off a little cooler across
our County warning forecast area... with 4 am CDT readings in the middle 50s over the interior
to the upper 50s to near 60 closer to the coast.

The upper level low will continue to dig southeastward toward
northeastern Florida through late this afternoon before finally advancing
into the adjacent western Atlantic late tonight. A mean northerly
flow pattern aloft will prevail across our forecast area to the west
of this system and also to the east of an upper level ridge that
will be positioned from the western Gulf to the arklatex region.
Remnant layer moisture and weak lift will support keep a slight
chance of light rain showers in the forecast across our northeastern
/interior south central Alabama/ zones today. A moist northerly low level
flow pattern otherwise looks to keep the low cloud cover in place
across our forecast area yet again through a good portion if not all
of the day today...and have once again undercut MOS guidance by a
few degrees across most locations. The current forecast calls for
highs to range from the upper 60s to lower 70s across the region.
Continued mostly cloudy to overcast skies are expected again tonight
as NAM and GFS both show a near saturated 925-850 mb layer overhead.
Lows tonight appear to be a little warmer with readings ranging from
near 60 to the middle 60s. /21

Short term /Monday through Tuesday night/...a medium amplified
upper ridge extending from the western Gulf of Mexico to the lower
Great Lakes region Monday morning will have two massive bookend
upper lows with one centered over Southern California and the other
off the Georgia coast. The western upper low will move over southern
Arizona by late Tuesday night...while the eastern low lifts northeast
an evolves into an open wave over the western Atlantic. This will
allow the upper ridge to remain largely in place over the same area
but broaden in scope. The surface low pressure area over the western
Atlantic will also lift northeast...with high pressure building into
the southeast states from the north. The persistent low stratus
clouds across the forecast area will finally decrease from west to
east Monday afternoon through Monday night as both the upper and low
low pressure areas to our east depart. With the lack of any lifting
mechanisms and drier air moving in from the will be dry
across the entire forecast area through the remainder of the short

Went on the lower end of guidance for high temperatures Monday
across our western zones and undercut guidance by a degree or two
across our eastern zones where the clouds will remain. So expect
high temperatures Monday to range from 76 to 80 degrees across south
central Alabama and the western Florida Panhandle...with lower 80s
elsewhere. High temperatures Tuesday will range from 81 to 86
degrees. Low temperatures both Monday and Tuesday nights will drop
back into the lower 60s inland areas...with middle 60s along the
immediate coastal sections. /22

Long term /Wednesday through Saturday/...the upper ridge will shift
eastward and deamplify through the rest of the week in response to
the western Upper Cutoff low initially moves southeast over the
southwest Texas-Mexico border by Thursday night. The models depart
from the track of the upper low afterwards...with the European model (ecmwf) taking
low over southwest over the southern Baja California California region by late
in the week. The GFS lifts the low northeast and has it evolving
into an open wave over the Southern Plains...while deepening a
second upper low over southern Baja California California.

The northern half of the eastern U.S. Surface high will be pushed
eastward over the northern Atlantic as a surface low deepens over the
northern plains and moves quickly east across the Great Lakes
region. A surface ridge however will remain across the southeast
states. Regardless of the movement of the upper low to our west...we
will a gradual increase of upper level clouds as a cirrus canopy
spreads eastward from the upper low over the region. A return to
east to southeast low level winds will allow scattered cumulus
clouds to region to the area. Mostly clear to partly cloudy skies
will persist through Thursday...while mostly cloudy skies are
expected Friday and Saturday due to a mix of the low and upper level

With the low level moisture on the increase once again...we should
see a return of isolated rain showers along the coast on Friday and
across the entire forecast area on Saturday. High temperatures will
reach the low to middle 80s each day through the long term. Lows
Wednesday night will range from 59 to 64 degrees inland areas...with
middle 60s along the coastal sections. The low temperatures will then
moderate throughout the long term...with lows Saturday night ranging
from 63 to 67 degrees inland areas...with lower 70s along the
immediate coastal sections. /22

Marine...a moderate to occasionally strong northerly surface flow
pattern will prevail over the marine area through early next week as
low pressure remains in the vicinity of the southeastern states and
adjacent western Atlantic Ocean and a ridge of high pressure
continues to build from the Great Lakes region to the Southern
Plains states. Small craft exercise caution headlines will likely be
needed over the offshore waters through at least Monday night. A
light to moderate northeast to east flow pattern will prevail
Tuesday through Friday as a ridge of high pressure gradually builds
eastward across the eastern half of the country. /21


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