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Area forecast discussion 
National Weather Service Mobile Alabama
620 am CDT Wednesday Apr 1 2015

Update...colliding outflow boundaries have generated some showers
and a few thunderstorms across interior portions of the forecast
area. The forecast has been updated to adjust probability of precipitation in these areas for
the morning hours. /13


Previous discussion... /issued 406 am CDT Wednesday Apr 1 2015/

Short term (today through Friday night)...for today and
tonight...a stalled front remains across central portions of Alabama
this morning. Meanwhile...radar images indicate an outflow boundary
from earlier convection across northern Alabama moving southward.
Mesoscale models indicate this outflow boundary moving south into
northern portions of the area later this morning. The outflow
boundary may be enough to initiate an isolated rain showers or thunderstorms and rain later
this morning across northern zones...however increased ridging across
the area along with large amounts of low and middle level dry air will
likely keep much of the area dry. Forecast soundings indicate the low
and middle level dry air remains in place through the afternoon
especially across the southern half of the region. Convective
coverage will remain largely confined areas along and north of the
boundary across central Alabama. Isolated to scattered showers and
thunderstorms will remain possible across extreme northern areas this
afternoon. If storms are able to develop they will be capable of
becoming strong to briefly severe with large hail the main threat due
to cold middle level temperatures.

High temperatures will again climb into the low 80s in most areas. Coastal
locations will reach the middle 70s. Dry conditions expected overnight
with lows in the low 60s inland to upper 60s along the coast. /13

For Thursday through Friday night...a subtle shortwave trough located
near the Lower/Middle Mississippi River valley moves across the
southeast states on Thursday while a vigorous upper trough advances
across the western states. The upper trough advances across the plains
and into the interior eastern states Friday night. A surface ridge
near the northern Gulf maintains a southerly flow through Friday while
a surface low well to the north associated with the upper trough
advancing into the eastern states brings a trailing cold front into
the southeast states. Will have slight chance probability of precipitation well inland on
Thursday due to modest isentropic lift with dry conditions Thursday
night. Abundant dry middle level air will be present Thursday along with
0-3 km MUCAPES of 1000-1300 j/kg well inland...and convection that
does develop will certainly have the ability to produce strong gusty
winds and small or larger hail. The limiting factor at this time is
the lack of forcing and the resulting expected sparse coverage of
convection. Active convection is expected to develop Friday along and
just ahead of the cold front north of the area...but will weaken
while moving through the forecast area with the cold front Friday
night with the loss of daytime heating and weakening deep layer lift.
Considering this...will have slight chance to chance probability of precipitation returning
to the northwest portion of the area Friday afternoon...then likely
probability of precipitation over the northern fringe Friday night with chance to good chance
probability of precipitation for most of the remaining portion.

0-3 km MUCAPES of 500-800 j/kg will be present over the
northwesternmost portion of the area Friday afternoon with values
near 500 j/kg Friday evening as the front moves into the northern
portion of the area before dropping off quickly overnight. 0-1 km
helicity values of 150-200 m2/s2 will be present over the forecast
area in advance of the front...although this axis of fairly high
shear is somewhat out of phase with the best deep layer lift and best
instability. Despite some phasing concerns of shear and
instability...expect a potential for strong storms over the northern
portion of the area mainly Friday evening...possibly late Friday
afternoon as well. Daytime highs will be about 8 degrees above
normal and mostly in the lower 80s. Lows Thursday night will be mild
and range from the upper 50s over south central Alabama to Lower/Middle
60s elsewhere. Lows Friday night will be cooler but still at least a
few degrees above normal and range from the lower 50s well inland to
lower 60s near the coast. /29

Long term (saturday through tuesday)...the upper trough over the
interior eastern states moves off into the western Atlantic by Sunday
with broad upper ridging over the plains gradually amplifying while building
into the eastern states through Tuesday. A surface high builds into
the region in the wake of the cold frontal passage Friday night...and
later moves into the western Atlantic on Sunday allowing for a light
return flow to ensue which continues through Tuesday. Will have
slight chance probability of precipitation Saturday morning for lingering rain in the wake of
the front then dry conditions through Sunday. A series of southern
stream shortwaves move across the area on Monday and support chance
probability of precipitation...then slight chance probability of precipitation follow for Tuesday as upper ridging
builds into the region. Highs on Saturday will be about 5 degrees
below normal and mainly in the upper 60s with lows Saturday night
ranging from the lower 40s well inland to around 50 at the coast.
Temperatures gradually trend warmer with highs on Tuesday in the
lower 80s. /29

Marine...a ridge of high pressure will weaken and shift east
through the end of the week as a cold front approaches from the
west. Southerly winds and seas will build ahead of the front which
will move through the marine area Friday night. A moderate to strong
offshore flow will follow in the wake of the front through through
Saturday. A moderate to strong easterly flow is expected by late
Sunday into early next week as a strong surface ridge of high
pressure builds along the Carolina coast. /13

12z issuance...VFR conditions expected through much of the period.
MVFR conditions in patchy fog expected late tonight into Thursday
morning. /13


Preliminary point temps/pops...
Mobile 81 62 82 62 81 / 10 10 10 05 10
Pensacola 79 67 80 65 80 / 10 10 10 05 05
Destin 76 67 77 65 78 / 10 10 10 05 05
Evergreen 83 60 83 58 82 / 30 10 10 05 10
Waynesboro 83 61 83 62 80 / 30 10 20 10 30
Camden 84 61 83 59 82 / 30 20 20 10 20
Crestview 83 58 83 57 83 / 20 10 10 05 05


Mob watches/warnings/advisories...


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