Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 260113 AAB

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
813 PM CDT SUN SEP 25 2016

.DISCUSSION...See updated information for land areas below.


.UPDATE...Low pressure center at high levels was spinning in place
over southern AL and the western FL panhandle this evening. A
scattering of cold cloud tops within the large scale circulation were
moving counter clock-wise over the central Gulf coast region.
Overall, the coverage of convection was trending much lower since
late in the afternoon as the environment begins to stabilize. Quite a
bit going on in the mesoscale as well with several outflow boundaries
being deposited by storms. These boundaries have also served to
stabilize the environment this evening. Given radar trends,
forecasters have cut back on chances of showers and storms thru the
remainder of the evening.

With pwat values (~1.6") between 100 and 120% of climatological
normals and out of respect for any modest lift provided by the
presence of the upper level low pressure system atop the local area,
will maintain a 10 to 20% pop overnight. No other changes at this
time. /10


.PREV DISCUSSION... /issued 621 PM CDT SUN SEP 25 2016/

DISCUSSION...Updated for latest aviation discussion below.

00Z issuance...An upper level low pressure system spinning over
southern AL and the western FL panhandle is leading to considerable
mid to high based cigs, which look to remain in place in the near
term. Scattered evening convection is forecast to weaken with any
overnight shra/tsra being very isolated in coverage. Winds light to
calm. /10

PREV DISCUSSION... /issued 401 PM CDT SUN SEP 25 2016/

NEAR TERM /Now Through Monday/...Similar to yesterday scattered
showers and thunderstorms continue to develop basically on the
western side of a weak upper low generally located over much of the
Florida panhandle stretching north into lower parts of Al and Ga...
moving southwest at 10 to 15 mph. This pattern has allowed for
slightly better coverage compared to yesterday especially for
locations to the north and west of KMOB. Latest model soundings
depict slightly better instability for most locations combined with
moderate forcing still present in the mid levels due to the
proximity of the upper low just to the west of KMOB. With this
believe most of the thunderstorms will remain below severe limits
with maybe a few isolated cases of damaging straight line
winds...small to medium size hail and frequent cloud to ground
lightning. Showers and thunderstorms will continue to develop and
move southward through early this evening followed by mostly clear
skies overnight and early Mon. For Mon latest model guidance does
show a broad upper low/trof digging quickly south across the
northern plains and Great Lakes lakes through Mon afternoon allowing
a weak frontal boundary to shift southeastward towards the coast
late Mon night into Tue. With this pattern expected about the same
amount of coverage of showers and thunderstorms during late morning
and afternoon hours on Mon with again a few isolated strong to
marginal severe thunderstorms possibly mostly during the mid to late
afternoon hours. Gusty straight line winds...small to medium size
hail and frequent cloud to ground lightning will be the main threats
with the stronger storms on Mon.

As for temps will begin with the blended guidance and adjust closer
to the current mav/met guidance due to persistence. Lows tonight
will range from the upper 60s to near 70 for most inland areas and
the lower to middle 70s near the immediate coast. Highs Mon will
range from the lower 90s inland and the upper 80s to near 90 near
the immediate coast. 32/ee

SHORT TERM /Monday night Through Wednesday night/...A massive upper
low centered over the Great Lakes region moves southeastward to
become centered over the central eastern states. An associated
surface low well to the north will have brought a trailing cold front
to near the western edge of the forecast area by early Monday
evening, which then slowly advances eastward through the forecast
area by Wednesday morning. The frontal boundary remains nearly
stationary just east of the forecast area on Wednesday, then
continues further east of the area Wednesday night as the surface low
reorganizes over the central east coast. Precipitable water values of
1.5-1.75 inches will be in place along and ahead of the front, then
trend much lower on Wednesday to around 0.5 inches. Have gone with
slight chance pops Monday evening, followed by dry conditions
overnight while isolated convection lingers closer to the coast. For
Tuesday will have pops increasing to chance by afternoon for much of
the western Florida panhandle and extreme south central Alabama near
the expected position of the front at that point, with slight chance
pops elsewhere. Mostly slight chance pops follow Tuesday night for
the coastal counties, trending to dry conditions for the entire area
on Wednesday. Lows Monday night will range from the mid/upper 60s
inland to the lower 70s near the coast followed by progressively
cooler temperatures each night, with lows Wednesday night ranging
from the upper 50s inland to the mid 60s near the coast. It`s
interesting to note that these cooler temperatures are actually only
dropping down to seasonable values for this time of year. Highs will
be near the upper 80s for much of the area on Tuesday, then mostly in
the mid 80s on Wednesday. /29

LONG TERM /Thursday Through Sunday/...Dry conditions follow for the
remainder of the period as the upper low remains over the eastern
states, possibly weakening to an upper trof later in the period. This
maintains a dry northerly flow over the area, with precipitable water
values of 0.5 inches recovering slightly to near 0.75 inches by
Sunday. Highs on Thursday will be mostly in the lower 80s, then trend
gradually warmer to the mid 80s by Sunday. Lows Thursday night will
range from the mid 50s inland to the mid 60s at the coast, then
likewise trend warmer to around 60 inland and near 70 at the coast by
the end of the period. /29

MARINE...Weak high pressure will continue over the marine area
through early next week then strengthen later in the week as a
significant cold front moves south over much of the northern gulf by
mid week. Expect a light offshore flow mostly during the overnight
and morning hours followed by a light southerly flow during the
afternoon and evening hours through mid week...followed by a
moderate to occasionally strong northerly flow throughout the day
and overnight hours by mid week. 32/ee


.MOB Watches/Warnings/Advisories...


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