Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 171749
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1249 PM CDT Thu Apr 17 2014

.SHORT TERM:  (Through Tonight)
Issued at 300 AM CDT Thu Apr 17 2014

A weak cold front will move into the area today and could serve as
the focus for scattered light rain showers during the afternoon
and evening. Convergence along the front is not very impressive
and the low levels are somewhat dry, but the combination of
increasing large scale ascent ahead of an approaching vort max
along with the presence of a surface boundary merits slight chance
to chance PoPs.

Kanofsky

.LONG TERM:  (Tomorrow through Wednesday)
Issued at 300 AM CDT Thu Apr 17 2014

For the last 4 nights in a row, no two consecutive 00z runs of the
ECMWF/GFS/GEM have had the same solution for upcoming frontal
systems, and there has also been a fair amount of variability
between models regarding the location of important features such as
upper vorticity maxima and surface boundaries. The latest runs keep
a strong vort max and its surface low up near the US/Canada border
on Fri night and Sat, therefore precipitation is no longer expected
with this system across the LSX CWA. The dominant feature for
Fri-Sat now appears to be ridging. Winds should eventually turn
southerly, bringing warmer air into the region for Sat and
reinforcing a baroclinic zone extending from the US/Canada system
as it starts to occlude. A broad trough moving through the desert
southwest could bring precipitation to the area on Sun/Mon. Chance
PoPs remain an acceptable compromise in light of the model
uncertainty. Confidence remains low in the forecast for this
weekend and beyond.

Kanofsky
&&

.AVIATION:  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1249 PM CDT Thu Apr 17 2014

Weak cold front is making very slow progress to the south today.
It has moved through KUIN and KCOU, but is stalled over metro
area as of 17z. Mvfr cigs at KUIN have scattered out. Otherwise,
mid and high clouds prevail over region. As low level moisture
increases, just a bit, will see low end vfr cigs develop north of
frontal boundary late this afternoon and early this evening.
Shower activity will be very sparse so did not add mention to tafs
at this time. Otherwise, southwest winds to veer to the northwest
to north behind the boundary, but remain rather light. Later
tonight cigs to scatter out and winds become light and variable.
Winds will pickup just a bit from the northeast on Friday as
frontal boundary washes out and surface ridge builds in.

Specifics for KSTL:
Weak cold front is making very slow progress to the south today.
It has stalled over metro area as of 17z. Mid and high clouds
prevail over region. As low level moisture increases, just a bit,
will see low end vfr cigs develop north of frontal boundary after
03z Friday. Shower activity will be very sparse so did not add mention
to taf at this time. Otherwise, southwest winds to veer to the
north behind the boundary, but remain rather light. By 09z Friday
cigs to scatter out and winds become light and variable. Winds
will pickup just a bit from the northeast by 19z Friday as
frontal boundary washes out and surface ridge builds in.

Byrd
&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$
WFO LSX





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