Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 201114 AAA

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
614 AM CDT Thu Jul 20 2017

.DISCUSSION...Updated for latest aviation discussion below.


12Z issuance...General VFR CIGs/VISBYs expected through the
forecast. Isolated shra/tsra are possible along and southeast of
I65 today, but am expecting minimal impact to operations.



.PREV DISCUSSION... /issued 400 AM CDT Thu Jul 20 2017/

NEAR TERM /Now Through Thursday night/...An upper high situated
over the Southern Plains dominates into tonight. This upper high has
created a surface high over the Lower and Mid Mississippi River. A
combination of subsidence from the upper high and northerly flow in
the low levels will help to bring above seasonal temperatures to the
forecast area, especially along and west of the Tombigbee River.
This flow will also help to push in a somewhat drier airmass over
the area, shifting the better moisture southeast. With general north
to northeasterly flow developing, any Gulf Breeze will see
resistance moving inland today, keeping the best chance being along
and southeast of I65. Have put best chance of rain these areas, but
still went a bit below seasonal. Temps today in the 93 to 97 degree
range expected, with upper 80s along the immediate coast.

With the above seasonal temps today, enough moisture remains to
allow Heat Indices to rise into the 101 to 107 degree range today,
with a few localities seeing 107 to 110, heat advisory criteria.
These areas will be limited enough in coverage to preclude the
issuance of a Heat Advisory today, but will put into HWO.

Tonight, an upper low located over the Carolina coast shifts south,
to over the NE Florida. This will disrupt the effects of the surface
high over the Mississippi River, and bring a light low level flow.
With this, am expecting offshore development of shra/tsra to return
tonight. With respect to temps, am expecting the weakening
subsidence  from the upper high to remain strong enough to keep
overnight temps a bit above seasonal. Lows generally in the low 70s,
mid 70s along the immediate coast. /16

SHORT TERM /Friday Through Saturday night/...An upper low over
the northern Florida peninsula moves slowly westward and evolves
into an elongated weak upper trof extending from the Texas coast
eastward across much of the Gulf coast states. A surface ridge
over the northern/central Gulf becomes somewhat better defined
during the period and promotes a light southerly flow over the
forecast area. With daytime heating, expect scattered showers and
storms to develop over the area and linger into the evening
hours. May see some strong storms develop each day which produce
gusty winds, frequent lightning and heavy downpours. Highs on
Friday will be in the lower to mid 90s, then highs on Saturday
will be mostly in the lower 90s. Afternoon heat indices look to
range from 103 to 107 on Friday for much of the area, and it`s
possible that a Heat Advisory could become necessary if daytime
highs trend slightly higher. Heat indices on Saturday look to
remain within a 100 to 105 range. Lows each night range from the
lower 70s inland to the mid 70s near the coast. /29

LONG TERM /Sunday Through Wednesday/...A weak upper trof
extending from the Texas coast into the central Gulf coast states
is absorbed on Monday into an amplifying upper trof over the
eastern states. A surface low (associated with the eastern
states upper trof) passes well north of the region and brings a
weak surface trof into the Gulf coast states on Tuesday which is
expected to dissipate on Wednesday.  A continuing pattern of
scattered showers and storms developing each day and lingering
into the evening hours is expected through the period, though
there is the potential for better coverage over interior areas on
Monday and Tuesday mainly due to a series of shortwaves moving
across the region. Highs each day will be mostly in the lower 90s,
except a bit cooler near the coast, while lows range from the
lower 70s inland to the mid 70s at the coast. /29

MARINE...A surface ridge over the Lower Mississippi River will
weaken into tonight, with a general northerly flow becoming light
tonight. A surface ridge builds west over the northern Gulf of
Mexico, bringing a more organized south to southwest flow to the
marine area Friday through the weekend. A weak front will moves south
over the Southeast, bringing a more variable flow to the marine area
mid week. /16




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