Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 171144

Area Forecast Discussion
National Weather Service Mobile AL
644 AM CDT Sat Mar 17 2018

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


17/12Z issuance...A few light sprinkles or areas of drizzle early
this morning, with scattered showers and isolated thunderstorms
possible this afternoon. Otherwise MVFR ceilings likely to
continue through most of the days continuing overnight. Should
continue into the daylight hours before lifting slightly as we
head towards afternoon. Showers and few storms will be a
possibility especially at KMOB and KBFM from mid morning into the
afternoon hours. Light south to southwest winds around 10 knots
this afternoon, lighter tonight. Patchy fog possible overnight.


.PREV DISCUSSION... /issued 440 AM CDT Sat Mar 17 2018/

NEAR TERM /Now Through Saturday night/...Overall surface pattern will
continue to remain relatively unchanged today through tonight with
Atlantic high pressure ridging west across the region and a near
stationary frontal boundary sagging south into northern Alabama by
late tonight. Southeast to south low level flow will continue, with
low level moisture and instability gradually increasing. Flow
aloft will continue to be nearly zonal with minor shortwave energy
moving east across the region. Models indicate shortwave energy
aloft will likely be weaker today than yesterday and this appears
to be verified in latest GOES-16 water vapor imagery. As such,
although we expect showers and isolated thunderstorms today,
coverage will likely be less widespread than yesterday with PoPs
of about 30-40 percent today. Rain chances decrease again tonight,
but isolated showers will remain possible, along with patches of
light drizzle and fog. With few showers and storms today, and
potentially a little more sunshine, expect temps to warm above
those of yesterday, with highs in the upper 70s to near 80 over
inland areas and in the middle 70s along the coast. Lows tonight
expected to be in the low to mid 60s. 12/DS

SHORT TERM /Sunday Through Monday night/...Upper level ridge axis
positioned from the Gulf, northward over the MS River Valley
Sunday morning is progged to slide eastward and deamplify going
into Sunday night as lower heights push east out of the Plains.
At the surface, weather maps have a quasi-stationary frontal
boundary aligned east to west from the southeast to the Red River
Valley of TX/OK Sunday. South of the boundary, deep Gulf moisture
pools over the central Gulf coast and with the passage of mid
level impulses ejecting eastward out of the base of the Plains
upper level storm system along with daytime instability, chances
of showers and storms look to increase thru the course of the day
Sunday. The higher chances generally north of the coast. Some of
the storms could become strong to briefly severe Sunday afternoon
and night with a slight risk of severe storms outlooked generally
along and north of the US Highway 84 corridor. As frontal low
pressure tracks eastward over the Tennessee River Valley on
Monday with attendant cold front approaching from the west, a well
defined warm sector and destabilizing environment evolves. Couple
this with a response in the low level H85 jet increasing to
between 35 and 40 kts and short range ensembles showing an
increase in effective bulk shear from 40 to 50 knots continues to
support a marginal to slight risk for severe weather from the
central Gulf coast into the southeast. Severe storms will be
capable of producing large hail, damaging winds and perhaps an
isolated tornado. Stay tuned. May be some lingering severe weather
potential into Monday evening mainly in the eastern zones before
the best instability moves east out of the area as front closes
in. /10

LONG TERM /Tuesday Through Friday/...Front moves east of the area
on Tuesday with temperatures trending closer to seasonal normals
most areas. Will likely also be dealing with southward moving
wrap around cloudiness and a small chance of rain on the west side
of the departing surface frontal low moving east over the
southeast Tuesday. Rain-free Wednesday thru Friday as surface
high pressure tracks east over the MS Valley. Daytime highs
Wednesday, well below seasonal normals begin to moderate by the
end of next week. Overnight lows also trend well below climatology
Wednesday thru Friday mornings. /10

MARINE...A predominately light to occasionally moderate south to
southwest flow is expected to continue over the coastal waters
through Monday as Atlantic high pressure continues to ridge west
across the eastern Gulf and a frontal boundary remains nearly
stationary well to the north of the marine area. A stronger cold
front approaches the marine area Monday night and is expected to
move east across the coastal waters Tuesday. Increasing onshore flow
is anticipated just in advance of this front, with a strong offshore
flow expected in the wake of the front. Both winds and seas likely
to build to at least Exercise Caution levels by early next week,
and probably to Small Craft Advisory levels over the Gulf
marine zones. 12/DS




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