Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 251756

Area Forecast Discussion
National Weather Service Mobile AL
1256 PM CDT Tue Jul 25 2017

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


18Z issuance...Numerous SHRA/TSRA will continue to develop and
impact much of the region through the afternoon before gradually
diminishing into the early evening. Localized MVFR to IFR
conditions and gusty winds can be expected in/near storms. VFR is
otherwise generally expected through the period, aside from
potential brief MVFR fog early Wednesday morning. Light west to
northwest winds this afternoon, becoming calm to light northerly
this evening through late tonight. /21


.PREV DISCUSSION... /issued 657 AM CDT Tue Jul 25 2017/

DISCUSSION...Updated for latest aviation discussion below.

12Z issuance...Prevailing VFR conditions expected over the next 24
hours, with occasional MVFR conditions near developing showers
and thunderstorms throughout the day. Light Westerly surface
winds of 5 to 10 knots expected today, becoming north to northwest
around 4 knots after sunset. /22

PREV DISCUSSION... /issued 442 AM CDT Tue Jul 25 2017/

NEAR TERM /Now Through Tuesday night/...An upper level trough
extending from the southern Appalachian Mountains to Louisiana
will move slowly eastward, and extend from east Georgia to
southeast Mississippi by late tonight. An upper high pressure
area will persist over the central and southern plains, but build
slightly eastward into the region as a trough slides east.
Meanwhile, a weak surface high pressure ridge extending westward
from the western Atlantic across the Florida peninsula and
northern Gulf of Mexico will remain intact, resulting in a light
westerly wind through this evening, shifting to the northwest by
late tonight.

The combination of decreasing stability inland areas and weakness
aloft will result in increasing precipitation throughout the day.
Expect the rain to first develop across the western portion of the
forecast area early this morning, and spread eastward into southwest
Alabama through mid morning. By early afternoon, numerous showers
and thunderstorms will cover much of the forecast area, except for
scattered coverage along the coast. Some of the storms again will
capable of producing heavy rainfall, with widespread one-quarter to
one-half inch likley, and localized heavy rainfall of one to two
inches possible.

The shower and thunderstorm activity inland areas will dissipate
through the evening hours, with isolated to scattered coverage
persisting under the upper trough along the coast after midnight.

High temperatures today should be about 3 to 5 degrees below normal
due to increasing cloud and rain coverage, ranging from 84 to 88
degrees. Low temperatures tonight will be in the lower 70s inland
areas, and the mid 70s along the coastal sections. /22

SHORT TERM /Wednesday Through Thursday night/...We begin to see a
drying trend through midweek as the weak upper trough that
provided us with wet weather Monday/Tuesday is pushed off to the
east and high pressure builds from the TX/OK panhandle east into
the Tennessee Valley. At the surface, high pressure over the
northern Gulf maintains light and variable winds across the local
area. Under this setup, expect a more typical summertime diurnal
thunderstorm cycle to dominate, with isolated to scattered
convection offshore each night/early morning moving onshore (with
focus along residual outflow boundaries and the sea breeze) each
afternoon/evening. Temperatures also begin to rise, especially
heading into Thursday, as that aforementioned upper ridge begins
to sag south over our area and mid/upper level subsidence keeps us
drier and less cloudy. Expect temps to return to the low to mid
90`s inland and upper 80`s to around 90 along the immediate coast
each afternoon, with heat indices reaching the 102 to 107 degree
range. Overnight lows remain muggy and in the low to mid 70`s
inland and upper 70`s along the coast each night. /49

LONG TERM /Friday Through Monday/...The hotter and drier
conditions continue Friday as the upper ridge pushes south over
our area and into the central Gulf. Expect typical summertime
diurnal convection (similar to Thursday) and highs in the low to
mid 90`s, with heat indices reaching the 102 to 107 degree range.

In the wake of this upper ridge, a deepening trough over the
eastern CONUS pushes a weak front towards our area from the north,
leading to another increase in showers and thunderstorms Saturday
into the weekend. The precise timing and magnitude of this trough
remains a bit uncertain, with the GFS continuing a more
aggressive solution and pushing the front through the area and
into the Gulf Saturday night. This would result in brief period of
drier weather Sunday/Monday, as opposed to the ECMWF which is
slower and keeps the front north of the area, leading to a bit of
a wetter pattern continuing into early next week. In either case,
looking more and more like a wetter and cooler pattern to at least
start the weekend, so have left likely PoPs in for Saturday,
followed by chance Sunday and Monday. Temps likewise cool off with
the return of the wetter pattern, with highs Saturday through
Monday in the upper 80`s. Lows remain in the low to mid 70`s
inland and mid to upper 70`s along the coast each night. /49

MARINE...A ridge of high pressure will gradually build across the
central Gulf of Mexico this week with light to moderate west to
southwest wind flow prevailing over the marine area. Winds, waves
and seas will be higher near storms. Frequent lightning activity
likely in and near any of the stronger marine storms as well. A few
waterspouts remain possible. Slight increase in seas late in the
period. /22




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