864 
FXUS64 KMOB 111111 AAA
AFDMOB

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
611 AM CDT Sat Jul 11 2020

.AVIATION...
12Z issuance...VFR conditions prevail through the period with the
exception of MVFR conditions in patchy late night/early morning
fog and also possibly with some isolated convection near the
coast. Northwesterly winds 5 to 10 knots today become light
northerly tonight. /29

&&

.PREV DISCUSSION... /issued 433 AM CDT Sat Jul 11 2020/ 

NEAR TERM UPDATE /Now Through Sunday/...A vigorous shortwave system 
progresses from the Northern Plains into the interior eastern states 
through Sunday and slightly strengthens an upper trof pattern over 
the eastern states while an expansive upper ridge remains generally 
in place across the southwestern states into the Gulf. A weak 
frontal boundary will have advanced into the southern portion of 
the area by early this morning and continues to along the 
immediate coast by midday where it stalls before continuing into 
the near shore waters this evening. Drier deep layer air flows 
into the area through this afternoon within the northerly flow 
with precipitable water values dropping to around 1.0 inch, 
possibly lower. The potential for convective development looks 
dubious today although have opted to keep slight chance pops for 
this afternoon along and south of a line from Wiggins, Mississippi
to Mobile to Valparaiso, Florida where the weak frontal boundary 
and the sea breeze may manage to generate a few showers and 
storms. The frontal boundary returns slowly northward into the 
central portion of forecast area on Sunday aided by a weak sea 
breeze circulation while increasing deep layer moisture works into
the area. A forecast uncertainty during the period is the 
potential for Mesoscale Convective Systems (MCS') to develop to 
the north and advance southeastward into the area. An MCS may 
develop tonight near the mid Mississippi river valley and advance 
southeastward, but current indications are that the MCS would 
weaken before reaching the forecast area Sunday morning such that 
have just included slight chance pops over interior areas Sunday 
morning. Another MCS could develop Sunday afternoon over northern 
Mississippi or northern Alabama and advance towards the area and 
have included chance pops over interior areas Sunday afternoon for
this potential with slight chance pops elsewhere where the 
frontal boundary/sea breeze could initiate convection. A marginal 
risk of severe storms exists over much of the area on Sunday, 
generally along and north of the I-65 corridor, where MLCAPE 
values possibly as high as around 2500 J/kg will be present along 
with dry mid level air and DCAPE values around 1000 J/kg. Highs 
today will be mostly in the mid 90s and while dewpoints will be 
trending lower through the day, heat index values still look 
sufficient to keep the Heat Advisory in place today along coastal 
portions of the western Florida panhandle, extreme southwest 
Alabama and much of interior southeast Mississippi. Lows tonight 
range from the lower 70s inland to the mid 70s at the coast. Highs
on Sunday will be in the mid to upper 90s, and another Heat 
Advisory may be required in nearly the same area as for today. A 
low risk of rip currents continues through the period. /29

SHORT TERM /Sunday Night Through Monday Night/...The local area 
remains sandwiched between an upper level ridge building east out of 
the Desert Southwest and an upper level trough along the East Coast. 
A shortwave dives through the northwest flow aloft on Sunday, which 
favors the development of an MCS late in the near term. While the 
MCS may not make it into the local area, residual cloud cover will 
stream into the area and an outflow from the earlier convection
has the potential to spark more convection as we head into the 
overnight hours Sunday into early Monday. For now, keeping 
scattered showers and storms in the forecast for much of the area,
especially across south central Alabama and northwest Florida, 
through the overnight hours on Sunday into early Monday. As we 
head through the day on Monday, scattered thunderstorm activity is
expected during the heat of the day generally to the south and 
east of I-65 where precipitable water and instability remain 
higher. Further to the north and west of I-65, drier air aloft 
filters into the region and should act to suppress some of the 
convection. Showers may linger a little past sunset across south 
central Alabama on Monday night, but otherwise it should be a dry 
night.

Afternoon highs will top out in the mid to low 90s on Monday. The 
heat index will generally range from 102°-109° on Monday (near 
Heat Advisory criteria yet again). The overnight lows will not 
provide any relief from the heat as we only fall into the mid to 
low 70s inland with upper 70s to nearly 80° at the beaches on 
both nights. 07/mb

EXTENDED TERM /Tuesday Through Friday/...East Coast U.S. upper 
trough lifts out to the northeast Tuesday through Wednesday as the 
large upper ridge axis over the Southern Plains begins to extend 
eastward over the southeastern states. This ridge axis should be 
centered just to the north of the coast through late week with 
increasing mid layer easterly flow developing mid to late week. Weak 
upper level disturbances in the easterly flow aloft will aid in the 
development of showers and thunderstorms each day, primarily of the 
diurnal nature as a very moist low level airmass will remain in 
place and residual thunderstorm outflow boundaries and afternoon sea 
breezes near the coast will all act as a low level focus. Convective 
coverage should be rather low during the overnight hours of the 
extended term period. The hot and humid conditions will continue 
through the period as well with daytime highs ranging from lower 90s 
near the coast to mid (and even localized upper) 90s over the 
interior. This heat will only be tempered each day by the diurnally 
driven afternoon showers and storms. Daytime heat indices still 
easily in the 102 to 107 degree range during the extended period, 
and we may still have the potential for even higher heat indices and 
possible continuation of Heat Advisories across portions of the 
area. Overnight lows stay warm and muggy during the extended term as 
well, mainly in the mid 70s for inland locations and upper 70s 
for coastal locations. /12 

MARINE...No impacts are forecast except winds and waves higher near 
showers and storms. /29

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...Heat Advisory from 11 AM this morning to 6 PM CDT this evening 
     for ALZ263>266.

FL...Heat Advisory from 11 AM this morning to 6 PM CDT this evening 
     for FLZ202-204-206.

MS...Heat Advisory from 11 AM this morning to 6 PM CDT this evening 
     for MSZ075-076-078-079.

GM...None.
&&

$$

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