Area Forecast Discussion
Issued by NWS St. Louis, MO
FXUS63 KLSX 250809
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
309 AM CDT Sat Oct 25 2014
.SHORT TERM: (Through Late This Afternoon)
Issued at 308 AM CDT Sat Oct 25 2014
Primary focus this morning will be on fog. Believe fog will continue to
slowly advect southeastward behind a weak cold front. By mid-morning...
expect diurnal effects to alleviate concerns for dense fog with remnant
stratus quickly scattering out and then dissipating by midday. A mostly
clear sky is forecast for the rest of today with high temperatures
about 5 degrees warmer than yesterday.
.LONG TERM: (Tonight through Friday)
Issued at 308 AM CDT Sat Oct 25 2014
(Tonight - Monday Night)
Surface ridge will come across the region tonight with light winds.
Appears to be more of a river valley fog setup as strong radiational
cooling should be the rule. More widespread fog is not expected at this
time as lower dewpoints seep southwestward from the Great Lakes.
For mins tonight...leaned a bit toward cooler guidance due to nearly
ideal radiative conditions...especially across the eastern Ozarks
where NWP guidance notoriously has a warm bias.
High temperatures appear challenging for the day on Sunday. Timing of
a warm front moving through the region is a bit uncertain with the
NAM model nearly 6 hr slower than the GFS. Leaned toward the faster
GFS (and thus warmer) solution due to forecast leeside cyclogenesis...
building mid/upper level heights...and lack of precipitation/convection
to retard the northward progression of the warm front. Still looks like
a decent temp gradient across the area however from southwest to northeast.
Expect highs reaching the mid 80s for portions of central Missouri to
low 70s across south-central Illinois.
One last summer-like day is in store on Monday ahead of an approaching
cold front from the northwest. Went above warmest guidance yielding highs
in the 80s nearly areawide as will range from +15-+19C at 850 hPa.
Cold frontal timing looks ~3 hrs quicker on tonight`s models runs than
last night. Consequently...timing of highest PoPs has shifted southeastward
a bit faster as well through Monday night.
(Tuesday - Friday)
Cooler...more seasonable weather looks in store for the rest of the work
week with highs in the 60s through Thursday. Models forecast an impulse
to come through the mid/upper Mississippi Valley on Thursday with slight
chances of showers. Models diverge greatly Friday and beyond but does
appear cooler weather will be ushered in for Halloween and into the
beginning of next weekend with the potential for a widespread frost/freeze
looming beyond the valid forecast period.
.AVIATION: (For the 06z TAFs through 06z Saturday Night)
Issued at 1033 PM CDT Fri Oct 24 2014
A weak cool front will move southeastward through the area late
tonight. Fog is expected to develop and/or advect southward into
our area from IA and nwrn IL late tonight along/ahead of this
front. Patchy stratus clouds is also possible as well, due to
light surface winds near the front and relatively high surface
dewpoints along and south of the front. The lowest visibilities
will likely be in UIN where they may drop to one quarter of a mile.
This fog will dissipate by late Saturday morning. A s-swly
surface wind will veer around to a nwly direction late
tonight/early Saturday morning after fropa. The surface wind will
become n-nely Saturday evening, albeit light as a surface ridge
moves through the region.
Specifics for KSTL: Just high level clouds late tonight and maybe
scattered low level clouds as well. Light fog can be expected late
tonight/early Saturday morning. A s-swly surface wind will veer
around to a nwly direction early Saturday morning after fropa. The
surface wind will become n-nely Saturday evening, albeit light.
.PRELIMINARY POINT TEMPS/POPS:
Saint Louis 79 51 79 64 / 0 0 5 5
Quincy 74 46 75 64 / 0 0 10 5
Columbia 78 52 84 64 / 0 0 5 5
Jefferson City 80 52 85 61 / 0 0 5 5
Salem 77 48 74 60 / 0 0 5 5
Farmington 79 48 81 61 / 0 0 0 5
MO...DENSE FOG ADVISORY until 9 AM CDT this morning FOR Knox MO-Lewis
MO-Marion MO-Shelby MO.
IL...DENSE FOG ADVISORY until 9 AM CDT this morning FOR Adams IL-