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Area forecast discussion...updated aviation
National Weather Service Saint Louis MO
1108 PM CST Sat Nov 16 2019

Short term... (through late Sunday night)
issued at 304 PM CST Sat Nov 16 2019

Still expect quiet weather through tonight as the surface ridge
exits the region and the atmosphere remains dry through a deep
layer. Satellite is showing some high clouds over the region
currently, but expect a continued increase in mid and high
cloudiness tonight as upper trough currently over the northern
plains drops into the middle Missouri Valley by tomorrow morning. It
still appears that there will be sufficient low level moisture
convergence below mid level ascent associated with this trough to
continue with band of likely pops moving southeast across the County Warning Area on
Sunday. Forecast soundings from both the NAM/GFS look less likely
than yesterday that there will be any wintry precipitation on the
leading edge of the precipitation as the low levels of the
atmosphere will be sufficiently warm to offset wet-bulbing in the
low levels. NAM/GFS are in good agreement that trough axis will move
east of the area by 06z on Sunday evening which should cause the
precipitation to end over the Illinois counties on Sunday evening.

Temperatures were close to normal today and with clouds moving into
the area tonight, expect lows to stay at or above freezing over
central and northeast Missouri. Highs tomorrow will not be as warm
as they were today given the clouds and expected rain.

Britt

Long term... (monday through next saturday)
issued at 304 PM CST Sat Nov 16 2019

Still expect a dry conditions with a warmup into the middle of next
week as both the gefs and the ecwmf ensemble means both show a large
upper ridge building over the central Continental U.S.. the gefs mean temps
support above normal temperatures Tuesday into Thursday as 850mb
temperatures climb into the 5-10c range. Then the gefs mean/ecwmf
ensemble means both show another upper trough dropping southeast out
of Canada through the Great Lakes late next week. This will bring a
cold front south across Missouri and Illinois mostly likely on
Thursday. Will continue with likely pops with the cold front
passage Wednesday night into Thursday. Timing has changed a bit
today with this first system, so have gone with all rain as the cold
air will not move in quick enough before the precipitation ends.

Gefs/European model (ecmwf) ensembles are pointing toward a southern stream system
that will move in by next weekend. Temperatures will be closer to
freezing with this second system, so have gone with a mix of rain
and snow Friday night into Saturday.

Britt

&&

Aviation... (for the 06z tafs through 06z Sunday night)
issued at 1101 PM CST Sat Nov 16 2019

Just mid-high level cloudiness late tonight, then the cloud
ceiling will lower on Sunday as light rain spreads east-
southeastward into the taf sites ahead of an upper level
disturbance and associated cold front. There may be some light fog
late tonight in sus and cps where the wind will be light or even
calm at times. Light rain will move into uin and cou by late
morning and into the St Louis Metro area by late afternoon. The
cloud ceiling will drop into the MVFR category in the late morning
in uin and cou, and by late afternoon or early evening in the St
Louis Metro area as the lower levels of the atmosphere saturate.
The southeast surface wind late tonight will veer around to a
west-northwest direction by late afternoon in uin and cou, and by
early evening in the St Louis Metro area after fropa.

Specifics for kstl: just high level cloudiness tonight, then the
cloud ceiling will lower on Sunday as light rain spreads east-
southeastward into stl ahead of an upper level disturbance and
associated cold front. Light rain will move into stl around 21z
Sunday. The cloud ceiling will drop into the MVFR category around
23-24z as the lower levels of the atmosphere saturate. The
east-southeast surface wind late tonight will veer around to a
west-northwest direction around 00-01z Monday after fropa. The
light rain should move out of stl by 03z Monday.

Gks

&&

Lsx watches/warnings/advisories...
MO...none.
Illinois...none.
&&

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