Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service St Louis MO
327 PM CDT Thu Jul 31 2014

Short term: (through late tonight)
issued at 319 PM CDT Thu Jul 31 2014

Another cool and quiet night is expected, as lows overnight drop to
the low to middle 60s across the area, still below normal for this
time of year. Water vapor imagery indicates a shortwave currently
over southwestern Minnesota and northwestern Iowa, and a northwest-southeast
oriented band of precipitation over western Iowa. The shortwave will
continue to drop southeastward this evening and tonight, and
could be enough to trigger some showers and perhaps an isolated
thunderstorm over far northeast Missouri and west central Illinois.
Feel the window for precipitation in this area is fairly small, as
the shortwave will remain transient and should be east of the
Mississippi River and out of our County warning forecast area by around 06-07z. Otherwise,
diurnal cumulus is expected to dissipate across much of the area not
long after sunset, with winds remaining light and variable through
the night.


Long term: (friday through next thursday)
issued at 319 PM CDT Thu Jul 31 2014

Slight changes may be in the offing regarding sensible weather
Friday/Saturday as longwave trough continues to dominate weather not
only over our region...but also the eastern two-thirds of the country.
Although shra/ts has been largely non-existent the past several days...
do believe there is a better chance of seeing isolated activity on
Friday/Saturday...due to better upper-level support and better instability.
Otherwise...persistence is the way to go wrt temps...seasonably cool for
early August.

Temperatures will moderate back toward normal to start off the new work
week with seasonably warm conditions expected for the middle of next week.
Pattern may become more favorable for rain as mid/upper levels become
quasi-zonal and moisture increases ahead of a slow-moving cold front.
However...pops only climb into the chance category due to substantial
differences in timing/track of closed low which develops from the northern



Aviation: (for the 18z tafs through 18z Friday afternoon)
issued at 1225 PM CDT Thu Jul 31 2014

VFR conditions and generally light and variable winds will prevail
through the period for all taf sites with just a couple
exceptions. First, recent guidance indicates the potential for
light showers overnight tonight over southern Iowa and northern MO,
but given uncertainty whether it will occur at the terminal, have
not mentioned in the taf. Second exception is radiation fog
development during the late overnight and early morning, which
would be similar to what occurred last night. Have included a few
hours of fog for ksus, kcps, and KUIN, which could reduce
visibilities down to MVFR/IFR conditions. However, any fog that
develops should be quick to burn off after sunrise Friday.

Specifics for kstl:

VFR conditions will prevail through the period. Scattered diurnal
cumulus today will return Friday, becoming broken by the early
afternoon. There is a possibility for some showers and
thunderstorms Friday afternoon, but given uncertainties regarding
timing and coverage, have not included mention in the taf at this
time. Light and variable winds today and tonight will become
easterly around 05kt on Friday, and while some radiation fog is
expected around the area late tonight and early Friday morning,
temperature/dewpoint spreads at kstl do not indicate impacts at
the terminal.



Preliminary point temperatures/pops:
Saint Louis 66 85 65 86 / 10 20 10 20
Quincy 63 81 61 82 / 20 20 10 20
Columbia 63 85 62 84 / 10 20 5 10
Jefferson City 62 85 62 84 / 10 20 5 10
Salem 63 84 61 85 / 10 20 10 20
Farmington 60 81 60 82 / 10 20 5 10


Lsx watches/warnings/advisories:


Weather forecast office lsx

National Weather Service Glossary of Abbreviations