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Area forecast discussion 
National Weather Service Mobile Alabama
347 PM CDT Thursday Jul 24 2014

Short term [tonight and friday]...middle to upper trough of low
pressure over much of the eastern Continental U.S. Will continue to dig
southward towards the central and eastern Gulf Coast through early
this evening then begin to weaken and lift northward late tonight
and on Friday as broad middle to upper ridge of high pressure over the
Lower Plains states shifts east. At the surface a weak frontal boundary
associated with the upper system to the north and east will continue
to move south into northern and western sections of the County warning forecast area this
afternoon and this evening then stall generally from east central Alabama
stretching southwest to the MS coast by 12z Friday. Latest hi res data
continues to show the best middle level forcing or lift to move into
northern and eastern sections of the County warning forecast area this afternoon and this
evening resulting in better coverage of showers and thunderstorms
near and along the stalling front from late this afternoon and early
this evening then begin to decrease in coverage late this evening
and overnight mostly due to the lack of daytime heating. For Friday
with better instability near the coast and offshore showers and
thunderstorms will form near the coast early Friday then shift inland
forming mostly along and south of the weak front during the day on
Friday. With the upper system lifting out to the north on Friday less
forcing in the middle levels can be expected generally resulting in
less coverage of showers and thunderstorms especially over northern
and western parts of the County warning forecast area Friday afternoon and early Friday evening.
As for temperatures will use a blend of the 00z European model (ecmwf) and mav MOS guidance
through Friday afternoon resulting in lows in the lower 70s for most
inland areas tonight and the middle 70s near the coast or generally
south of the I-10 corridor. Highs on Friday will range from the lower
to middle 90s inland and the upper 80s to lower 90s closer to the
coast. 32/ee

[friday night through Saturday night] upper level anticyclone
will build over the plains states and a deepening upper trough over
the eastern third of the country provides reinforcement to a surface
front over the forecast area by late Friday night. Low level forcing
along and ahead of the approaching surface front will bring scattered
showers and afternoon thunderstorms. The loss of sunlight will bring
an expectation of showers and thunderstorms decreasing across most of
the forecast area by middle to late evenings...with isolated showers and
thunderstorms primarily in the coastal third of our region overnight
driven by the land breeze. The higher frequency components of the 500
mb jet appear to dampen an upper trough over the eastern United
States. However...when we back away from this situation the
wavenumber 5 pattern appears more or less to be steady state. In fact
it is showing a slight to moderate intensification over Labrador and
the Gulf of Alaska...and an intensifying ridge over the Colorado and
Wyoming region. In our region...the environment has returned to being
more we are located under the centroid of a large
500 mb ridge extending from Colorado/Wyoming into the eastern Gulf.
This would leave US devoid of most upper dynamics and leave
everything up to the seabreeze...albeit with a somewhat suppressed
convective environment because of the presence of that upper high. To
summarize: even a 1.75 inch precipitable water content...daytime cape
of 2400 j/kg...and Li of -2 in the north to -4 along the coast around
1800z Saturday...would barely bring a chance of convection due to
synoptic scale subsidence. Temperature slightly above seasonal. 77/blowing dust

Long term [sunday through wednesday] significant changes. For
Saturday night through Sunday night...the upper low that will have
passed the US/Canadian rockies will moves over the northern plains
and dampen as it gets absorbed into the upper trough over
northeastern North America. The eastern trough will re-intensify into
a closed low and the upper ridge over the western United States will
strengthen along The Rockies. Another front will approach from the
lower Mississippi Valley...into northern Alabama/MS by Monday morning.
Temperature slightly above seasonal...and probability of precipitation slightly below...are
being indicated by guidance. For Monday through Tuesday
night...vorticity maxima will continue streaming into the eastern
trough which would enable a southward push of the surface front to
just off the Gulf Coast by Tuesday evening. Despite the presence of
the front...guidance is not indicating more than a chance of
shra/tsra. Temperature trending slightly below seasonal with
dewpoints drying out slightly. For Wednesday through Thursday...GFS
model calculations indicate slight cold advection aloft on the west
side of the 500 mb trough over the eastern United States. This would
strengthen yet another surface front approaching the lower
Mississippi Valley...bringing another chance of rain later next week.
77/blowing dust


Marine...high pressure will continue over the eastern and north
central Gulf through early next week. This will maintain a light to
moderate southwest flow over the marine area through early next
week. High pressure will weaken later in the week as a developing
upper level trough of low pressure and weakening cold front approach
from the northwest. Winds are expected to build from the west with
this pattern next week resulting in building seas later in the week.
Otherwise...little change in seas is expected through early next
week...generally up to around 2 feet...then building to around 4
feet later in the week as winds build from the southwest and west.


Aviation...[24.18z-25.00z issuances]...mostly VFR to MVFR
conditions through the next 24 hours. Lower ceilings will be mainly
in and around scattered showers and thunderstorms occurring
periodically through most of the forecast period. Winds will be mostly
south to southwest at 6 to 10 knots through early this evening
diminishing to 3 to 5 knots late this evening continuing through middle
to late morning on Friday then build to 8 to 10 knots during the
afternoon hours. Higher winds will be possible in the some of the
stronger thunderstorms through the forecast period. 32/ee


Preliminary point temps/pops...
Mobile 74 91 74 92 74 / 20 40 30 20 20
Pensacola 76 89 76 91 76 / 20 40 20 30 20
Destin 78 87 77 89 78 / 20 30 20 20 20
Evergreen 70 92 71 93 73 / 30 40 30 30 10
Waynesboro 70 93 72 94 73 / 30 30 20 10 10
Camden 70 93 71 93 74 / 30 40 20 20 10
Crestview 71 93 71 93 73 / 20 40 30 30 20


Mob watches/warnings/advisories...


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