Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 142104
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
304 PM CST Sat Jan 14 2017

.SYNOPSIS...
Issued at 254 PM CST Sat Jan 14 2017

No changes to current headlines with ice storm warnings continuing
into Sunday. Next main wave of precipitation/freezing rain
spreads into the area after midnight and impacts the region
through Sunday morning, diminishing Sunday afternoon. Additional
ice accumulations generally 0.10-.20 with localized area near 0.25
inches.

&&

.SHORT TERM...  (Through Late Sunday Afternoon)
Issued at 254 PM CST Sat Jan 14 2017

Focus thru this period continues to be the impending icing event.

Ongoing rain will continue across extreme srn portions of the CWA
thru this afternoon. Can not rule out a passing shower this evening
across this region, but believe much of the evening will remain dry.

A s/w currently over nrn TX/wrn OK region is progd to lift enewd
today and tonight. This is expected to spread precip into the area,
mainly after Midnight tonight. However, mdls depict enuf forcing to
indicate some light precip ahead of the s/w. After the first wave of
precip pushes thru the area Sun morning, precip shud refocus across
nrn and into central portions of the CWA.

As for temps, expect temps to drop a degree or two across the region
after sunset. Temps shud remain fairly steady overnight and may
actually rise a degree or so with onset of precip. Temps shud slowly
rise late Sun morning into the afternoon. Expect most of the CWA to
be aoa the freezing mark by 21z Sun, except far northern MO and
west central IL.

Given the temps expected thru Sun, may see an additional tenth or
two of ice accumulation at any given spot thru the period.

Tilly

.LONG TERM...  (Sunday Night through Next Saturday)
Issued at 254 PM CST Sat Jan 14 2017

The main wave of significant precipitation from Sunday should have
shifted north of the CWA, or be close to exiting north of the CWA at
00Z Monday. In the wake of this wave, an additional precipitation
will be spotty or scattered on Sunday night with the highest
probability across northern MO into central IL. Surface temperatures
will generally be in the 31-33F range across northeast MO/west
central IL during the evening. Overnight however, temps should
uniformly warm above freezing as the surface high pressure dome
continues to retreat eastward from the Great Lakes region, surface
winds slowly veer and increase, and as upper flow exhibits
prounouced backing.

The models have come into better agreement in the Monday/Tuesday time
frame, then diverge some thereafter. The general consensus is the
primary upper low will lift northeastward through the central
Plains on Monday and into the Upper MS Valley on Monday night.
Correspondingly, the accompanying surface low will track into
northwest MO by 00Z Tuesday and into the western Great Lakes
region by Tuesday morning. Deepening and strengthening
south/southwesterly flow aloft and strengthening/veering surface
winds associated with the movement of the aforementioned upper
level and surface systems will transport unseasonably mild air
across the CWA on Monday/Monday evening ahead of the surface low
and advancing cold front. This will not only result in well above
average temps and melting to any residual ice, but will also help
promote enough instability to mention the possibility of embedded
thunderstorms as a band of rain/showers translates across the area
Monday/Monday night. The cold front should completely exit east of
the area by midday Tuesday with weak CAA in its wake and potentially
some "wrap-around" precipitation in northeast MO and west central
IL. The air in the wake of this front however is not all that cold
for January.

Temperatures moderate quickly by Wednesday as a WAA regime becomes
re-established and persists with varying degrees through the
remainder of the week. Temperatures looks to be well above average
Wed-Fri.

Glass

&&

.AVIATION...  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1134 AM CST Sat Jan 14 2017

Precip is expected to remain south of terminals thru about
Midnight tonight. FZRA is expected to move into the region from
west to east late tonight. Temps are expected to slowly warm Sun
morning with KCOU/KSTL/KSUS/KCPS expected to be above freezing
around 18z Sun and KUIN around 21z Sun.

More uncertain is visby and cig trends. Sites are generally in
LIFR conditions with much improved conditions not far away from
KUIN. However, with temps warming slightly and little temp or dry
air advection into the area, believe melting and light fog will
keep conditions lower for much of today. Conditions may improve
this evening, but not certain at this point. Will continue to
monitor and updates as needed.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Ice Storm Warning until 6 AM CST Sunday for Crawford MO-Iron MO-
     Madison MO-Reynolds MO-Saint Francois MO-Sainte Genevieve
     MO-Washington MO.

     Ice Storm Warning until 3 PM CST Sunday for Audrain MO-Lincoln
     MO-Monroe MO-Pike MO-Ralls MO.

     Ice Storm Warning until noon CST Sunday for Boone MO-Callaway MO-
     Cole MO-Franklin MO-Gasconade MO-Jefferson MO-Moniteau MO-
     Montgomery MO-Osage MO-Saint Charles MO-Saint Louis City MO-
     Saint Louis MO-Warren MO.

     Ice Storm Warning until 6 PM CST Sunday for Knox MO-Lewis MO-
     Marion MO-Shelby MO.

IL...Ice Storm Warning until 6 AM CST Sunday for Randolph IL.

     Ice Storm Warning until 3 PM CST Sunday for Calhoun IL-Greene IL-
     Jersey IL-Macoupin IL-Montgomery IL-Pike IL.

     Ice Storm Warning until noon CST Sunday for Bond IL-Clinton IL-
     Fayette IL-Madison IL-Marion IL-Monroe IL-Saint Clair IL-
     Washington IL.

     Ice Storm Warning until 6 PM CST Sunday for Adams IL-Brown IL.

&&

$$

WFO LSX


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