Area Forecast Discussion
Issued by NWS St. Louis, MO
FXUS63 KLSX 301105
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
605 AM CDT MON MAY 30 2016
.SHORT TERM... (Through Late This Afternoon)
Issued at 405 AM CDT Mon May 30 2016
A surface warm front extends from northeast Nebraska to northeast
Missouri early this morning and is moving very slowly to tbe east.
Isolated to scattered thunderstorms have developed near and
east of this warm front from the WAA aloft. Otherwise, skies were
mostly clear across the rest of our region with temps mainly in the
60s, with some pockets of 50s in the valley areas of the eastern
Ozarks, and the urban heat island of STL still holding on to some
The situation with the warm front will likely persist to some degree
thru mid-morning, maintaining the threat for isolated showers and
thunderstorms in parts of northeast MO and west-central IL.
Otherwise, things should reset by late this morning with the models
advertising a very weak shear, low-moderate CAPE, no CINH
environment with any focus, surface-based or aloft, hard to come by.
Discrete models are all suggesting the potential for a few showers
and thunderstorms this afternoon with virtually no distinguishment
for one area over another given lack of a discernable focus. With
this in mind, went slight chance PoPs for most of the forecast area
this afternoon for potential of "airmass" type thunderstorms.
Severe potential should be low given the environmental setup.
For much of today, should see decent sunshine for most areas with a
weak southeast to south flow developing as the surface warm front
moves thru. Should see max temps at or above persistence, yielding
readings in the upper 80s to around 90.
.LONG TERM... (Tonight through Sunday)
Issued at 405 AM CDT Mon May 30 2016
Tonight - Wed night
Upper lvl flow will become increasingly more SWrly thru the week as
a short wave strengthens across the ntrhn Plains Mon night/Tue. Even
though there is largely a lack of focus or forcing thru Tue...expect
isld/scttrd precip in the warm moist SW flow. One thing to watch is
the upper lvl system driving the convection across TX tonight. Most
guidance tracks it E or NE today...keeping it just S of the CWA
but...the ECMWF and NAM actually bring the core of that feature
across the CWA tonight. That scenario would obviously create far
different conditions that the current fcst indicates. This is
something the day shift will have to monitor for potential
significant fcst adjustments. This feature will drive a cold front
thru the region Wed/Wed night. A portion of the CWA is outlooked for
a marginal risk of SVR TSTMs on Wed. This would appear appropriate
due to less than 30 kts of shear. Temps should be aoa normal.
Thu - Sun
There is a low potential for a few post frontal SHRAs across SE MO
and sthrn IL on Thu but think most locations will remain dry. SFC
high pressure is fcst to build into the region for the end of the
week providing the area at least one dry day on Fri. Guidance
suggests significant troughs dvlpng along the Coasts with a high
amplitude ridge aligned along the Rockies over the wknd which puts
the...FA in NW flow. Differences exist in timing of short waves over
the wknd assoc with reinforcing shots of cold air and precip
chances. Temps should be near normal.
.AVIATION... (For the 12z TAFs through 12z Tuesday Morning)
Issued at 605 AM CDT Mon May 30 2016
VFR conditions and dry wx are expected for much of the valid
period at the TAF sites. Very low probs for rain until late
tonight when they begin to increase to the west and north of STL
metro. Will maintain a dry forecast due to the very low probs
until around 09z and add a VCSH in to UIN and COU.