083 
FXUS64 KMOB 181654 AAA
AFDMOB

Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
1054 AM CST Sun Feb 18 2018

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

&&

.UPDATE...We have updated the forecast to remove fog headlines 
and mention of fog in the products as area observations show 
visibility has rapidly improved across the region. Mostly cloudy 
skies should prevail over inland areas today, with some breaks in 
the clouds expected over southern portions of the region. We did 
leave a slight chance of light rain over far northern sections of 
the area through this afternoon, as this region will be on the
southern fringe of weak ascent associated with a mid level
shortwave impulse and also ahead of a northward moving warm
front/surface boundary. Any associated rainfall amounts should be
very light. Above normal temperatures continue into the afternoon
with highs mostly in the 70s appearing to be on track. /21 

&&

.MARINE...We allowed the Dense Marine Fog Advisory to expire on
schedule at 9 AM CST, though we still left mention of patchy fog 
along area bays, sounds and nearshore waters through the late 
morning hours. The latest high resolution and short term guidance
indicates another round of marine fog will likely be of impact
again this evening through early Monday morning, and will assess 
this potential for the afternoon marine forecast package. /21 

&&

.PREV DISCUSSION... /issued 557 AM CST Sun Feb 18 2018/ 

DISCUSSION...Updated for latest aviation discussion below.

AVIATION...
12Z issuance...Will begin with IFR to MVFR ceilings over much of 
the area along with some VLIFR conditions in low ceilings and fog
mainly over the western Florida panhandle. Conditions improve to
primarily VFR ceilings later this morning then there is the
potential for IFR conditions to redevelop again late tonight.
Light northerly winds over the area switch to a southeast
direction by midday with light southerly winds continuing 
overnight. /29

PREV DISCUSSION... /issued 442 AM CST Sun Feb 18 2018/ 

NEAR TERM /Now Through Sunday night/...The axis of an upper ridge 
over the central Gulf shifts closer to the Gulf coast during the 
period resulting in modest deep layer subsidence shifting into the 
forecast area. A weak cold front currently moving southward 
through the coastal counties is expected to have moved into the 
marine area by the beginning of the period. A combination of low 
and mid cloudiness along with northerly winds of 5 to 10 knots in 
the wake of the front has acted to either dissipate or 
significantly limit fog over most of the area except for coastal 
Baldwin county and part of the western Florida panhandle. 
Considering current observations and trends, will keep the Dense 
Fog Advisory in place for coastal Baldwin county and the coastal 
portion of the western Florida panhandle but cancel elsewhere. The
weak front returns northward into the central portion of the 
forecast area later today then exits north of the forecast area 
tonight. Will have small pops well inland today as daytime heating
and the weak front result in a potential for isolated showers, 
while modest subsidence associated with the upper ridge should 
suppress convection elsewhere. Dry conditions follow for tonight 
and patchy fog development is possible for the entire area late 
tonight. /29

SHORT TERM /Monday Through Tuesday night/...An upper-level ridge
builds over the western Atlantic and southeastern U.S. to begin
the short term, shifting flow over the local area from zonal to
more southwesterly as an upper trough simultaneously deepens over
the western CONUS. At the surface, high pressure builds into the 
western Atlantic and eastern Gulf, re-establishing warm and moist
onshore flow across the region. With the return of this pattern
comes increasing rain chances, initially over southeast Mississippi
Monday afternoon and gradually spreading over the remainder of 
the area by Tuesday. Only minimal instability is expected to
develop this quickly after the return of onshore flow, with much
of it remaining offshore. Thus, while a rumble or two of thunder
cannot be ruled out near the coast, activity should remain
generally limited to scattered light showers.

Have continued to lean on the warm side of guidance for high
temperatures through the short term given the combination of an 
anomalous upper ridge and a warm and moist onshore surface flow.
Highs will approach (or possibly even surpass) record levels both
Monday and Tuesday afternoons, reaching the upper 70s to lower 
80s across the area. /49

LONG TERM /Wednesday Through Saturday/...This unseasonably warm 
and moist pattern, one more characteristic of Spring and not mid- 
February, will keep temperatures near record highs and rain 
chances elevated throughout the upcoming week. The broad upper- 
level troughing over the western CONUS finally begins to flatten 
the ridge over the western Atlantic, pushing it south towards the 
end of this week and into next weekend. This shift allows a cold 
front to push southeast across the Great Plains and into the lower
Mississippi River Valley, ultimately stalling somewhere northwest
of our area by late Thursday. Best rain chances throughout the
long term will be over our interior southeast Mississippi and 
southwest Alabama counties ahead of this approaching front. 
Models continue to indicate a fair amount of destabilization 
occurring during afternoon hours (500-1000 J/kg MLCAPE), improving
our chances of seeing thunderstorms mix in with showers as well.
The front lifts back north and away from the area Friday as the 
western Atlantic surface high is reinforced, leading to a brief
reprieve from the rain. However, the front returns (along with
rain chances) by late Saturday, eventually pushing through the 
area as the upper ridge to our east breaks down and the pattern 
becomes more progressive.

Much like the short term, the combination of an anomalous upper
ridge and well-established onshore surface flow will result in 
high temperatures approaching or surpassing record levels pretty 
much every day this week. Highs reach the upper 70s to lower 80s 
each afternoon and lows only dip into the low to mid 60s each 
night. /49

MARINE...A weak front over the northern Gulf moves inland later
this morning with light west to north winds becoming southeasterly.
A light to moderate southeasterly flow continues for Monday through
Thursday. Have continued with a marine dense fog advisory for the
bay and near shore waters of the western Florida panhandle through
early this morning, including Perdido Bay.  Fog development will 
be possible for each following night over the bay and near shore 
waters through early next week. /29

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...None.
FL...None.
MS...None.
GM...None.
&&

$$

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