Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 241702

Area Forecast Discussion
National Weather Service Mobile AL
1202 PM CDT Fri Mar 24 2017

.DISCUSSION...See updated information for land areas and aviation
discussion below.


.UPDATE...A developing surface low over the western Plains is
combining with a surface ridge stretching southwest along the
East Coast to create moderate to strong southeasterly flow over
the FA attm. Winds have remain just below wind advisory criteria,
so have not issued. Do not expect winds to make that last final
increase into advisory levels, but continue to monitor.
Temperatures currently within tolerances, and with a slight chance
of rain still possible, am not planning on updating the forecast



18Z issuance...Strong southeasterly will preclude fog development,
so CIGS and precip timing are the biggest challenges. General VFR
may see dips into MVFR levels overnight. With increasing precip
coverage expected to be at the end of the forecast into the hours
after, am concentrating any rain chances the last 6hrs of the
forecast. Low end MVFR cigs may occur locally with the rain, but
should be easily navigated around.



.PREV DISCUSSION... /issued 612 AM CDT Fri Mar 24 2017/

DISCUSSION...See updated information for land areas and aviation
discussion below.

UPDATE...Did a quick update to the current zone forecast mainly
to increase winds over inland areas through this afternoon. Most
coastal areas are reporting gusts to around 20 knots already this
morning. 32/ee

12Z issuance...MVFR to VFR cigs through 25.12z. Winds will be
southeast at 12 to 16 knots with frequent gusts from 18 to 28
knots through late this afternoon...diminishing to around 10
knots early Saturday morning. 32/ee

PREV DISCUSSION... /issued 519 AM CDT Fri Mar 24 2017/

NEAR TERM /Now Through Friday night/...Sharp mid to upper ridge
stretching from the central gulf to the TN/OH river valleys this
morning will shift east to the western Atlantic through 12z sat in
response to a deep area of low pressure tracking eastward from
the rockies to the central plains states through tonight. With
this pattern several mid level disturbances round the base of the
deep upper system to the west with the first of a series
approaching western Mississippi from the the south late this
afternoon tracking mainly northward over western and central parts
of the state this evening and overnight. Model soundings depict
increased moisture in the mid to upper levels across the forecast
area with this a pattern through tonight... combined with
increasing low level moisture from the southeast due to a moderate
to strong onshore flow mainly from strong high pressure
continuing along the eastern seaboard and over much of the western
Atlantic generally north of 20N.

For today expect better clouds for all locations in the forecast
area through tonight with gusty southerly winds possible as high as
25 to 30 knots mostly during max heating or from late morning
through mid to late afternoon. With good layer lift still noted west
of the upper ridge will continue to mention light rain for some
western sections of the forecast area with the best chance generally
occurring west of a line stretching from Mobile Al to Waynesboro
Mississippi. For tonight the better forcing aloft will continue to
approach from the west combined with increasing instability in the
boundary layer leading to a better chance for showers and
thunderstorms mainly over western sections of the forecast area
starting late this evening...continuing through early sat morning.
At this time thunderstorms look to remain below severe limits
through tonight followed by a better chance during the day on Sat.

As for temps will continue to lean towards the warmer mos numbers
through tonight due mostly to persistence. Todays highs will be
lower than the last 2 days due to more clouds and a persistent flow
from off the gulf with temps ranging from the mid to upper 70s over
most of the western half of the forecast area and the upper 70s to
near 80 to the east...and the lower to middle 70s along the
immediate coast due to the strong onshore flow and the cooler sea
surface temps. Lows tonight will range from the lower to middle 60s
to the west and along the immediate coast and the upper 50s to the
east. 32/ee

SHORT TERM /Saturday Through Sunday night/...A potent upper level
low in the vicinity of eastern OK/northwest AR early Saturday
morning will take on a bit of a negative tilt as it lifts
northeast across MO during the day Saturday. The associated upper
level trough axis will progress eastward from the Mississippi
Valley early Saturday morning to the central Gulf Coast region
Saturday afternoon and evening. Large scale ascent in advance of
this approaching feature will initially spread across southeast
MS and adjacent portions of southwest AL Saturday morning, where
an organized band/line of convection may continue to develop
eastward through the mid to late morning hours. Forcing continues
to spread eastward across our forecast area Saturday afternoon
into Saturday evening, and numerous to widespread showers and
thunderstorms should continue to develop along and west of I-65
through Saturday afternoon, before the better coverage becomes
focused across eastern and northeastern portions of the region by
Saturday evening. Still looking at the potential for a few strong
to severe storms along the line and possibly with a few discrete
cells in advance of it given MLCAPE values up to 500-1000 J/KG,
35-45 knots 0-6 km shear, up to 30-35 knots of 850 mb flow, and
low wet bulb zero heights. Strong to locally damaging wind gusts
and marginally severe hail will be the primary concerns. Locally
heavy rainfall will also be possible with convection Saturday,
especially along and west of I-65 as precipitable water values
increase to 1.3 to 1.5 inches, with the WRF-ARW also showing a
signal for bands of locally heavy rainfall as the line develops
eastward. Forecast rainfall amounts for Saturday were increased
along and west of I-65 in coordination with WPC and surrounding
offices. The severe potential should decrease Saturday evening as
instability and shear wanes, but scattered showers and possibly a
few thunderstorms may continue through Saturday evening/night as
residual lift moves over the region with the shortwave trough
axis. Highs Saturday should range in the mid to upper 70s over
most locations. Lows Saturday night should continue to range in
the upper 50s to lower 60s inland, with mid 60s along the beaches.

Although a drier zonal flow pattern will develop across the
region Sunday, there still could be enough instability and lift
accompanying another minor perturbation in the mid level flow to
result in isolated to scattered showers and thunderstorms across
the forecast area again Sunday afternoon and evening. No severe
weather is anticipated attm. Highs Sunday should range from the
lower 80s inland to the upper 70s along the coast. Any convection
Sunday should diminish with loss of daytime heating, and will
maintain a dry forecast Sunday night. Overnight lows should range
from the lower to mid 60s. /21

LONG TERM /Monday Through Thursday/...The next upper level trough
is expected to move from the Mississippi Valley to the central
Gulf Coast region during the day Monday. This feature will bring
another round of isolated to scattered showers and thunderstorms
to the region, especially over southeast MS and interior southwest
AL. The atmosphere could become fairly unstable across the region
Monday afternoon with temperatures in the upper 70s and lower 80s
and dewpoints ranging from around 60 to the mid 60s. The GFS and
ECMWF indicate the most unstable airmass with MLCAPE potentially
between 1000-1500 J/KG will reside along and west of I-65 Monday,
where a few strong to marginally severe storms may be possible.
Lapse rates could also steepen Monday afternoon, which could lend
to an increased hail threat with the stronger storms. We will
monitor this potential over the next couple of days. A general
west to southwest flow pattern continues Tuesday with potential
for more isolated showers/storms as minor shortwaves traverse the
region. A bit more subsidence associated with shortwave ridging
aloft may allow for a drier forecast Wednesday. Yet another upper
level low deepens in the vicinity of the southern Plains
Thursday, and an ejecting shortwave trough in advance of this
feature could bring another round of showers/storms to our area
Thursday and Thursday night, a few of which could once again be
strong with locally heavy rainfall. Look for temperatures to
otherwise remain quite warm through the extended forecast period.

MARINE...A strong surface ridge of high pressure to the east
generally along the eastern seaboard and over the western Atlantic
combined with an approaching deep low pressure system to the west
will continue to lead way to a strong southerly wind flow for most
of the marine area through this evening...diminishing slowly
overnight through midday Sat...then better Sat afternoon through Sun
as the surface ridge to the east continues to shift further east. As
a result a small craft advisory will remain in effect for the open
gulf waters out to 60 nm including the lower end of Mobile Bay and
the Mississippi Sound east of Pascagoula through Sat evening.
another concern will be the chance for a few strong thunderstorms
moving across the region on Sat with the best chance occurring sat
afternoon through sat evening. In the wake of this system a light to
moderate onshore continues as a surface ridge of high pressure
continues over the western Atlantic shifting slightly eastward over
the eastern gulf. 32/ee


AL...High Rip Current Risk through late Saturday night for ALZ265-266.

FL...High Rip Current Risk through late Saturday night for FLZ202-204-

GM...Small Craft Advisory until 1 AM CDT Saturday for GMZ631-632-650-



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