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fxus64 kmob 200347 
afdmob

Area forecast discussion
National Weather Service Mobile Alabama
947 PM CST sun Feb 19 2017

Discussion...see updated information for land and marine areas below.

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Update...fog formation across the area remains favorable again
tonight with areas of dense fog most likely over our southeast
Mississippi and southwest Alabama counties as well as Escambia
County, Florida. Fog should once lift and dissipate mid to late
Monday morning. /08

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Marine...updated forecast package to issue a dense fog advisory
for Perdido and Mobile Bay as well as the Mississippi Sound and
near coastal waters extending from Pensacola Bay westward to
Pascagoula. Fog is expected to dissipate by mid to late Monday
morning. /08

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Previous discussion... /issued 552 PM CST sun Feb 19 2017/

Discussion...updated for latest aviation discussion below.

Aviation...
00z issuance...currently, VFR conditions exist across the flying
area. However, conditions are expected to deteriorate with fog
setting up across the region again this evening. Widespread IFR
conditions appear likely to develop by around midnight with
locally vlifr possible. Fog should lift and dissipate between 14z
to 16z Monday with VFR conditions then prevailing for the
remainder of the day. /08

Previous discussion... /issued 348 PM CST sun Feb 19 2017/

Near term /now through Monday/...a highly amplified upper level
height field is noted on weather maps today. As upper level trof
moves east off the southeast US coast, a narrow but sharp upper
ridge moves atop the area tonight then over the southeast US on
Monday. At the surface, an elongated north to south surface high
from the Great Lakes to the eastern Gulf pushes east from over the
mid-Atlantic to the Bahamas by Monday. Surface based moisture
looks to be sufficient for the re-development of night-time/early
am fog. Fog likely to be dense, especially near area bays and
river valleys. Unseasonably mild night with overnight lows
forecast to be about 10 degrees above normal on average, ranging
from the lower to mid 50s interior to the upper range of the 50s
close to the coast. For Monday, Spring-like temperatures
anticipated. In fact, from a climatological perspective, high
temperatures mostly in the mid to upper 70s will rest to some 10
to 15 degrees above seasonal. Considering the warmth, here's the
break down of a few past record high temperatures for February
20th:

Mobile area: 79/1981
brookley field: 75/1952
Pensacola area: 80/1981
Crestview fl: 78/2011
Evergreen al: 82/1917
Waynesboro ms: 81/2014

After a record setting Sunday, a few of these records may be tied
or broken again on Monday. /10

Short term /Monday night through Wednesday night/...the axis of a
large highly amplified upper level ridge extending from the
Caribbean Sea to southeast Canada will continue to move east over
the western Atlantic by Tuesday evening, while an upper level
trough extending from south central Canada to eastern Mexico moves
east over the eastern conus. The ECMWF, GFS, and NAM models still
develop a cutoff upper low pressure area within the southern
portion of the upper trough, and although there remains slight
differences in the exact timing/area of development, they are now
in much better agreement developing the upper low generally over
southern Texas by late Monday afternoon or early evening. All the
models then move the system east-southeast, reaching the central
Gulf of Mexico Wednesday afternoon. It will be dry through Monday
evening, followed by gradually increasing rain chances from west
to east across the forecast area late Monday night through
Tuesday, with a few embedded thunderstorms possible on Tuesday.
Scattered rain showers will remain across the area on Wednesday
north of the low, followed by the precipitation gradually ending
as the low moves further away from the area.

Widespread total rainfall amounts through the short term are
expected to range from one-tenth to four-tenths of an inch east
of the Tombigbee river, and from four-tenths of an inch to near
one inch west of the river.

Low temperatures Monday, Tuesday and Wednesday nights will range
from 53 to 60 degrees. Very warm temperatures will continue on
Tuesday with afternoon highs ranging from 74 to 80 degrees inland
areas, with lower 70s along the coastal sections. Highs on
Wednesday will be a couple of degrees cooler compared to tuesday's
highs. /22

Long term /Thursday through Sunday/...we will see a brief dry
period on Thursday as the system moves eastward as weak upper
ridging builds over the region and a surface ridge of high
pressure settling in from the north. A large broad upper level
trough will straddle much of the northern United States by late in
the week, with a very strong low pressure area developing over
the Central Plains Thursday afternoon that lifts northeast into
southeast Canada by the start of the weekend. An associated strong
cold front quickly approaching the region from the northwest
Friday evening will pass through the area late Friday night into
Saturday morning. Isolated to scattered rain chances with
embedded thunderstoms will return to the region on Friday ahead of
the cold front, followed by another dry period over the weekend.
There is still a good deal of uncertainty pertaining to the local
impacts with this system, but at this time there appears to be
the chance of strong storms developing on Friday due to the
overall strength of the upper and low level winds across the
region. Temperatures will continue to trend above normal through
Friday prior to the passage of the cold front. /22

Marine...fog is forecast to redevelop over area bays and sounds
tonight and again Monday night. Surface high pressure moves east of
the marine area early this week... while a weak trough of surface
low pressure takes shape over the central Gulf by mid week. The
position of these pressure systems favors a light to moderate east
to southeast flow for much of the week. Seas generally 2 to 4 feet.
Chances of showers trend higher Tuesday through Wednesday. A few
storms possibly mixed in as well. /10

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Mob watches/warnings/advisories...
Alabama...dense fog advisory until 9 am CST Monday for alz052-261>266.

Florida...dense fog advisory until 9 am CST Monday for flz201-202.

MS...dense fog advisory until 9 am CST Monday for msz067-075-076-078-
079.

GM...dense fog advisory until 9 am CST Monday for gmz630>633-650.

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