879 
FXUS63 KLSX 151744
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1244 PM CDT Fri Mar 15 2019

.SHORT TERM...  (Through Late Saturday Afternoon)
Issued at 310 AM CDT Fri Mar 15 2019

Intense cyclone that brought strong winds to region yesterday, 
continues to lift northeast away from region. So will see winds 
gradually diminish today. However, still expect enough mixing to 
keep northwest winds around 10 to 20 mph most of the day with gusts 
to 25 to 30 mph at times. In the meantime, a secondary shortwave is 
sliding through the region this morning with some light 
rain/sprinkles, maybe even a few snowflakes, that will taper off by 
midday. As for the cloud cover, majority of models keep decent low 
level RH across the forecast area through 18z, then clear out from 
west to east through the afternoon hours. So could see some sunshine 
late in the day. With lingering cloud cover and gusty northwest 
winds, temperatures will be slow to warm up today with highs in the 
40s, about 5 to 10 degrees below normal for this time of year.

By tonight, surface ridge begins to build in with winds finally 
diminishing. With clear skies and lighter winds, temperatures will 
drop into the mid 20s to low 30s.

On Saturday, surface ridge will be anchored over region with mostly 
sunny skies and light northwest to west winds. Highs will be in the 
mid 40s to low 50s.

Byrd

.LONG TERM...  (Saturday Night through Thursday)
Issued at 310 AM CDT Fri Mar 15 2019

A broad long wave trof will dominate eastern NOAM through Monday and 
then will slowly shift eastward into the western Atlantic by Tuesday 
in response to the development of a strong upstream ridge through
western NOAM. A shortwave trof within the cyclonic upper flow 
will track from the upper MS Valley into the Great Lakes region 
Saturday night, which will send a cold front through the region. 
Forcing is meager at best ahead of the front and moisture limited,
nonetheless the 4km is generating some spotty pre-frontal showers.
Alternatively, the ECWMF is generating a bit of light post-frontal
precipitation (rain or snow) across northeast MO and west central
IL on Saturday night as a result of a slightly more southward 
short wave position and associated forcing along with weak low 
level frontogenesis. The bulk of available guidance is dry during 
this time frame keeping most of the moisture and forcing 
north/northeast of the area. Our current forecast is dry and I am 
going to keep it that way at this time in favor of the consensus 
of the model suite. In the wake of the cold front, surface high 
pressure will slowly settle from the Northern Plains into the 
middle Mississippi Valley Sunday into Monday resulting in dry and 
tranquil weather and slightly below average temperatures.

Heading into the middle of next week, slight progression of the 
narrow but high-amplitude western upper ridge will allow for a trof 
to dig south/southeastward into the Nation's midsection. The upper 
pattern would suggest this trof will be a bit stronger than the 
operational GFS, and more akin to the ECMWF/GFS-FV3. This digging 
trof should bring another cold front through the area Tuesday night 
into Wednesday accompanied by a chance of rain/showers.

Glass
&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1234 PM CDT Fri Mar 15 2019

Windy conditions will be the primary focus through the next 
several hours. 

Ceilings will continue to lift and break through the afternoon 
with a clearing trend expected to proceed from west to east. 
There is enough lingering moisture on the back side of the cloud 
shield that will lead to the development of scattered diurnal 
cloud striations. Temperatures will moderate, allowing deeper 
mixing with limited moisture centered around 5k feet. What does
develop will have little to no impact.

Though stronger winds just off the surface will gradually subside, 
clearing skies and deeper mixing will continue to result in windy 
conditions. Northwesterly gusts of 25-30 knots are likely through
early evening before diurnal energy is lost. High pressure builds
in from the plain with wind becoming light overnight and remaining
light into Saturday. 

SPECIFICS FOR KSTL: 

Windy conditions will continue this afternoon into the early 
evening. Sustained west-northwesterly winds of 15-20 knots will 
occasionally gust 25-30 knots through 23z or so. Light and 
variable winds will settle in overnight along with high pressure.

Visible satellite imagery shows borderline MVFR/VFR ceilings
breaking and scattering out overhead. A clearing trend will 
continue through mid-afternoon. Therefore, we can anticipate VFR 
conditions with mainly clear skies and light winds through the 
end of the period. 

Maples

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX